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Wang Y, Gao S, Liu Y, Zhu H. Modeling Study of the Effects of Ageratum conyzoides on the Transmission and Control of Citrus Huanglongbing. PLANTS (BASEL, SWITZERLAND) 2023; 12:3659. [PMID: 37896122 PMCID: PMC10609694 DOI: 10.3390/plants12203659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 10/18/2023] [Accepted: 10/18/2023] [Indexed: 10/29/2023]
Abstract
Ageratum conyzoides (A. conyzoides) is commonly found or intentionally planted in citrus orchards due to its ability to provide habitat and breeding grounds for the natural enemies of citrus pests. This study aims to expand from a switching Huanglongbing model by incorporating the effects of A. conyzoides, vector preferences for settling, and pesticide application intervals on disease transmission. Additionally, we establish the basic reproduction number R0 and its calculation for a general switching compartmental epidemic model. Theoretical findings demonstrate that the basic reproduction number serves as a threshold parameter to characterize the dynamics of the models: if R0<1, the disease will disappear, whereas if R0>1, it will spread. Numerical results indicate that the recruitment rate of A. conyzoides not only affects the spread speed of Huanglongbing but also leads to paradoxical effects. Specifically, in cases of high infection rates, a low recruitment rate of A. conyzoides can result in a decrease, rather than an increase, in the basic reproduction number. Conversely, a high recruitment rate can accelerate the spread of Huanglongbing. Furthermore, we show how different vector bias and pesticide spraying periods affect the basic reproduction number.
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Affiliation(s)
- Ying Wang
- Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou 341000, China; (Y.W.)
| | - Shujing Gao
- Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou 341000, China; (Y.W.)
| | - Yujiang Liu
- Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou 341000, China; (Y.W.)
| | - Huaiping Zhu
- LAMPS and CDM, Department of Mathematics and Statistics, York University, Toronto, ON M3J 1P3, Canada;
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2
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Nguyen VA, Bartels DW, Gilligan CA. Modelling the spread and mitigation of an emerging vector-borne pathogen: Citrus greening in the U.S. PLoS Comput Biol 2023; 19:e1010156. [PMID: 37267376 PMCID: PMC10266658 DOI: 10.1371/journal.pcbi.1010156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 06/14/2023] [Accepted: 05/08/2023] [Indexed: 06/04/2023] Open
Abstract
Predictive models, based upon epidemiological principles and fitted to surveillance data, play an increasingly important role in shaping regulatory and operational policies for emerging outbreaks. Data for parameterising these strategically important models are often scarce when rapid actions are required to change the course of an epidemic invading a new region. We introduce and test a flexible epidemiological framework for landscape-scale disease management of an emerging vector-borne pathogen for use with endemic and invading vector populations. We use the framework to analyse and predict the spread of Huanglongbing disease or citrus greening in the U.S. We estimate epidemiological parameters using survey data from one region (Texas) and show how to transfer and test parameters to construct predictive spatio-temporal models for another region (California). The models are used to screen effective coordinated and reactive management strategies for different regions.
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Affiliation(s)
- Viet-Anh Nguyen
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - David W. Bartels
- United States Department of Agriculture, Animal and Plant Health Inspection Service, Plant Protection and Quarantine, Fort Collins, Colorado, United States of America
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3
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Tang S, Gao S, Zhang F, Liu Y. Role of vector resistance and grafting infection in Huanglongbing control models. Infect Dis Model 2023; 8:491-513. [PMID: 37252229 PMCID: PMC10209492 DOI: 10.1016/j.idm.2023.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 04/06/2023] [Accepted: 04/16/2023] [Indexed: 05/31/2023] Open
Abstract
Citrus huanglongbing (HLB) is one of the most devastating diseases affecting citrus almost worldwide due to the lack of a cure. To better understand the impact of insecticide resistance and grafting infection on the spread of HLB disease, a vector-borne compartmental model is formulated to describe the transmission dynamics of HLB between citrus and Asian citrus psyllid (ACP). The basic reproduction number R0 is computed by using the next generation matrix approach, which is a threshold value of the uniform persistence and disappearance of HLB disease. By applying the sensitivity analysis of R0, we obtain some parameters with the most significant influence on the transmission dynamics of HLB. Moreover, we also obtain that grafting infection has the least influence on the transmission dynamics of HLB. Additionally, a time-dependent control model of HLB to minimize the cost of implementing control efforts and infected trees and ACPs is formulated. By using Pontryagin's Minimum Principle, we obtain the optimal integrated strategy and prove the uniqueness of optimal control solution. The simulation results illustrate that the strategy involving two time-dependent optimal controls is the most effective to suppress the spread of the disease. However, insecticide spraying is more effective measure compared with infected tree removing.
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Current Epidemic Situation and Control Status of Citrus Huanglongbing in Guangdong China: The Space–Time Pattern Analysis of Specific Orchards. Life (Basel) 2023; 13:life13030749. [PMID: 36983905 PMCID: PMC10055705 DOI: 10.3390/life13030749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/04/2023] [Accepted: 03/05/2023] [Indexed: 03/12/2023] Open
Abstract
Huanglongbing (HLB) is the most harmful bacterial disease in citrus production in the world, and has been seriously ravaging the citrus groves of South China since the 1930s. The surveillance of the epidemiological characteristics of HLB is of utmost priority for citrus production in this region. In order to explore the effects of disease control measures, analyses on the space–time statistical features of the HLB epidemic, from 2019 to 2021, within six orchards in the Guangdong province are presented. Overall, the number of citrus plants in the orchards usually slightly decreased year by year. The reduction was mainly related to the level of plant susceptibility, which is correlated with citrus varieties. The maximum disease severity (incidence and race increment) was correlated with the awareness of this disease and the management intensity applied by the manager. A higher disease index was found in the conventional management orchards than in the comprehensive prevention and control orchards. Proper insect-protective screen houses can effectively prevent the epidemic of HLB, without affecting the fruit quality, and can also aid with higher yields. A high correlation was found between the geometry and topography of orchards and the HLB epidemic due to the wind direction from May to September and the Asia citrus psyllid activity characteristics. For flat orchards, the incidence of HLB in the north and entrance areas was higher than that in the southwest. In the mountain area, the incidence of the windward side in the south was higher than that of the leeward side in the north. Diseased trees tended to have an edge effect in the grove, whereas the trees of the same disease scale were found clustered in their distribution. These results allow a better understanding of HLB epidemiology and provide guidance for the early warning of HLB in new groves in areas that are severely affected by this disease. Furthermore, they also provide a scientific basis for the comprehensive prevention and control of HLB in old groves.
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Xi M, Deyett E, Stajich JE, El-Kereamy A, Roper MC, Rolshausen PE. Microbiome diversity, composition and assembly in a California citrus orchard. Front Microbiol 2023; 14:1100590. [PMID: 36910183 PMCID: PMC9992537 DOI: 10.3389/fmicb.2023.1100590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 02/03/2023] [Indexed: 02/24/2023] Open
Abstract
The citrus root and rhizosphere microbiomes have been relatively well described in the literature, especially in the context of Huanglonbing disease. Yet questions addressing the assembly of root microbial endophytes have remained unanswered. In the above ground tree tissues, leaves and stems have been the research focus point, while flush and flower microbiomes, two important tissues in the vegetative and reproductive cycles of the tree, are not well described. In this study, the fungal and bacterial taxa in five biocompartments (bulk soil, rhizosphere, root endosphere, flower and flush) of citrus trees grown in a single California orchard were profiled using an amplicon-based metagenomic Illumina sequencing approach. Trees with no observable signs of abiotic or biotic stresses were sampled for two consecutive years during the floral development phase. The rhizosphere was the most biodiverse compartment compared to bulk soil, root endosphere, flower and flush microbiomes. In addition, the belowground bacteriome was more diverse than the mycobiome. Microbial richness decreased significantly from the root exosphere to the endosphere and was overall low in the above ground tissues. Root endophytic microbial community composition shared strong similarities to the rhizosphere but also contained few taxa from above ground tissues. Our data indicated compartmentalization of the microbiome with distinct profiles between above and below ground microbial communities. However, several taxa were present across all compartments suggesting the existence of a core citrus microbiota. These findings highlight key microbial taxa that could be engineered as biopesticides and biofertilizers for citriculture.
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Affiliation(s)
- MengYuan Xi
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA, United States
| | - Elizabeth Deyett
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA, United States
| | - Jason E Stajich
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
| | - Ashraf El-Kereamy
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA, United States
| | - M Caroline Roper
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
| | - Philippe E Rolshausen
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA, United States
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Lin Y, Huang J, Akutse K, Hou Y. Phytopathogens Increase the Preference of Insect Vectors to Volatiles Emitted by Healthy Host Plants. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:5262-5269. [PMID: 35426311 DOI: 10.1021/acs.jafc.2c00131] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Phytopathogen infections not only affect the physiology of host plants but also the preference of insect vectors; these modifications may increase the spread of infection. For this, we determined the effects of "Candidatus Liberibacter asiaticus" (CLas) infection on the preference of an insect vector (Diaphorina citri) for its uninfected or CLas-infected host (Citrus sinensis) and found that the infected vector preferred uninfected citrus, while the uninfected vector preferred infected citrus. We identified two compounds, (Z)-3 hexenyl and methyl salicylate, that were differentially abundant in the volatiles emitted by infected and uninfected citrus and two odorant-binding protein (OBP) genes differentially expressed between infected and uninfected vectors. The results of receptor-ligand binding assays indicated that CLas upregulated OBP A10 expression in the infected vector to target (Z)-3 hexenyl acetate emitted by uninfected citrus and induced citrus to emit more methyl salicylate for binding to OBP2 in the uninfected vector. Our results might be useful for the effective control of CLas infections.
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Affiliation(s)
- Yongwen Lin
- Zhangzhou Institute of Technology, Zhangzhou Institute of Food Industrial Technology, Zhangzhou 363000, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fuzhou 350002, China
| | - Jing Huang
- Zhangzhou Institute of Technology, Zhangzhou Institute of Food Industrial Technology, Zhangzhou 363000, China
| | - Komivi Akutse
- International Centre of Insect Physiology and Ecology, P.O. Box 30772-00100 Nairobi, Kenya
| | - Youming Hou
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fuzhou 350002, China
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Jain M, Cai L, Black I, Azadi P, Carlson RW, Jones KM, Gabriel DW. ' Candidatus Liberibacter asiaticus'-Encoded BCP Peroxiredoxin Suppresses Lipopolysaccharide-Mediated Defense Signaling and Nitrosative Stress In Planta. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2022; 35:257-273. [PMID: 34931906 DOI: 10.1094/mpmi-09-21-0230-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The lipopolysaccharides (LPS) of gram-negative bacteria trigger a nitrosative and oxidative burst in both animals and plants during pathogen invasion. Liberibacter crescens strain BT-1 is a surrogate for functional genomic studies of the uncultured pathogenic 'Candidatus Liberibacter' spp. that are associated with severe diseases such as citrus greening and potato zebra chip. Structural determination of L. crescens LPS revealed the presence of a very long chain fatty acid modification. L. crescens LPS pretreatment suppressed growth of Xanthomonas perforans on nonhost tobacco (Nicotiana benthamiana) and X. citri subsp. citri on host orange (Citrus sinensis), confirming bioactivity of L. crescens LPS in activation of systemic acquired resistance (SAR). L. crescens LPS elicited a rapid burst of nitric oxide (NO) in suspension cultured tobacco cells. Pharmacological inhibitor assays confirmed that arginine-utilizing NO synthase (NOS) activity was the primary source of NO generation elicited by L. crescens LPS. LPS treatment also resulted in biological markers of NO-mediated SAR activation, including an increase in the glutathione pool, callose deposition, and activation of the salicylic acid and azelaic acid (AzA) signaling networks. Transient expression of 'Ca. L. asiaticus' bacterioferritin comigratory protein (BCP) peroxiredoxin in tobacco compromised AzA signaling, a prerequisite for LPS-triggered SAR. Western blot analyses revealed that 'Ca. L. asiaticus' BCP peroxiredoxin prevented peroxynitrite-mediated tyrosine nitration in tobacco. 'Ca. L. asiaticus' BCP peroxiredoxin (i) attenuates NO-mediated SAR signaling and (ii) scavenges peroxynitrite radicals, which would facilitate repetitive cycles of 'Ca. L. asiaticus' acquisition and transmission by fecund psyllids throughout the limited flush period in citrus.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Mukesh Jain
- Plant Pathology Department, University of Florida, Gainesville, FL 32611, U.S.A
| | - Lulu Cai
- Plant Pathology Department, University of Florida, Gainesville, FL 32611, U.S.A
| | - Ian Black
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, U.S.A
| | - Parastoo Azadi
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, U.S.A
| | - Russell W Carlson
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, U.S.A
| | - Kathryn M Jones
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, U.S.A
| | - Dean W Gabriel
- Plant Pathology Department, University of Florida, Gainesville, FL 32611, U.S.A
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8
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Kumar P, Baleanu D, Erturk VS, Inc M, Govindaraj V. A delayed plant disease model with Caputo fractional derivatives. ADVANCES IN CONTINUOUS AND DISCRETE MODELS 2022; 2022:11. [PMID: 35450199 PMCID: PMC8799979 DOI: 10.1186/s13662-022-03684-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 01/08/2022] [Indexed: 04/25/2023]
Abstract
We analyze a time-delay Caputo-type fractional mathematical model containing the infection rate of Beddington-DeAngelis functional response to study the structure of a vector-borne plant epidemic. We prove the unique global solution existence for the given delay mathematical model by using fixed point results. We use the Adams-Bashforth-Moulton P-C algorithm for solving the given dynamical model. We give a number of graphical interpretations of the proposed solution. A number of novel results are demonstrated from the given practical and theoretical observations. By using 3-D plots we observe the variations in the flatness of our plots when the fractional order varies. The role of time delay on the proposed plant disease dynamics and the effects of infection rate in the population of susceptible and infectious classes are investigated. The main motivation of this research study is examining the dynamics of the vector-borne epidemic in the sense of fractional derivatives under memory effects. This study is an example of how the fractional derivatives are useful in plant epidemiology. The application of Caputo derivative with equal dimensionality includes the memory in the model, which is the main novelty of this study.
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Affiliation(s)
- Pushpendra Kumar
- Department of Mathematics, National Institute of Technology Puducherry, Karaikal, 609609 India
| | - Dumitru Baleanu
- Department of Mathematics, Cankaya University, Ankara, Turkey
- Institute of Space Sciences, Magurele-Bucharest, R76900 Romania
| | - Vedat Suat Erturk
- Department of Mathematics, Ondokuz Mayis University, Atakum, 55200 Samsun Turkey
| | - Mustafa Inc
- Department of Computer Engineering, Biruni Universiity, Istanbul, Turkey
- Department of Mathematics, Science Faculty, Firat University, Elazig, 23119 Turkey
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan
| | - V. Govindaraj
- Department of Mathematics, National Institute of Technology Puducherry, Karaikal, 609609 India
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Keremane ML, McCollum TG, Roose ML, Lee RF, Ramadugu C. An Improved Reference Gene for Detection of " Candidatus Liberibacter asiaticus" Associated with Citrus Huanglongbing by qPCR and Digital Droplet PCR Assays. PLANTS 2021; 10:plants10102111. [PMID: 34685920 PMCID: PMC8540500 DOI: 10.3390/plants10102111] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 09/30/2021] [Accepted: 09/30/2021] [Indexed: 11/16/2022]
Abstract
Citrus huanglongbing (HLB) disease associated with the 'Candidatus Liberibacter asiaticus' (CLas) bacterium has caused significant financial damage to many citrus industries. Large-scale pathogen surveys are routinely conducted in California to detect CLas early in the disease cycle by lab-based qPCR assays. We have developed an improved reference gene for the sensitive detection of CLas from plants in diagnostic duplex qPCR and analytical digital droplet PCR (ddPCR) assays. The mitochondrial cytochrome oxidase gene (COX), widely used as a reference, is not ideal because its high copy number can inhibit amplification of small quantities of target genes. In ddPCRs, oversaturation of droplets complicates data normalization and quantification. The variable copy numbers of COX gene in metabolically active young tissue, greenhouse plants, and citrus relatives suggest the need for a non-variable, nuclear, low copy, universal reference gene for analysis of HLB hosts. The single-copy nuclear gene, malate dehydrogenase (MDH), developed here as a reference gene, is amenable to data normalization, suitable for duplex qPCR and ddPCR assays. The sequence of MDH fragment selected is conserved in most HLB hosts in the taxonomic group Aurantioideae. This study emphasizes the need to develop standard guidelines for reference genes in DNA-based PCR assays.
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Affiliation(s)
- Manjunath L. Keremane
- USDA ARS National Clonal Germplasm Repository for Citrus and Dates, Riverside, CA 92507, USA; (M.L.K.); (R.F.L.)
| | | | - Mikeal L. Roose
- Department of Botany and Plant Sciences, University of California Riverside, Riverside, CA 92521, USA;
| | - Richard F. Lee
- USDA ARS National Clonal Germplasm Repository for Citrus and Dates, Riverside, CA 92507, USA; (M.L.K.); (R.F.L.)
| | - Chandrika Ramadugu
- Department of Botany and Plant Sciences, University of California Riverside, Riverside, CA 92521, USA;
- Correspondence:
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Raiol-Junior LL, Cifuentes-Arenas JC, Cunniffe NJ, Turgeon R, Lopes SA. Modeling ' Candidatus Liberibacter asiaticus' Movement Within Citrus Plants. PHYTOPATHOLOGY 2021; 111:1711-1719. [PMID: 33724870 DOI: 10.1094/phyto-12-20-0559-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The phloem-limited 'Candidatus Liberibacter asiaticus' (Las) causes huanglongbing, a destructive citrus disease. Graft-inoculated potted plants were used to assess Las speed of movement in phloem in the greenhouse, and the impacts of temperature on plant colonization in growth-chamber experiments. For assessment of Las speed, plants were inoculated at the main stem and assessed over time by quantitative PCR (qPCR) or symptoms at various distances from the inoculum. For colonization, the plants were inoculated in one of two opposite top branches, maintained at from 8 to 20°C, from 18 to 30°C, or from 24 to 38°C daily range, and assessed by qPCR of samples taken from noninoculated shoots. For all experiments, frequencies of Las-positive sites were submitted to analysis of variance and binomial generalized linear model and logistic regression analyses. Probabilities of detecting Las in greenhouse plants were functions of time and distance from the inoculation site, which resulted in 2.9 and 3.8 cm day-1 average speed of movement. In growth chambers, the temperature impacted plant colonization by Las, new shoot emission, and symptom expression. After a 7-month exposure time, Las was absent in all new shoots in the cooler environment (average three per plant), and present in 70% at the milder environment (six shoots, severe symptoms) and 25% in the warmer environment (eight shoots, no visible symptoms). Temperature of 25.7°C was the optimum condition for plant colonization. This explains the higher impact and incidence of huanglongbing disease during the winter months or regions of milder climates in Brazil.
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Affiliation(s)
- Laudecir L Raiol-Junior
- Unversidade Estadual Paulista "Júlio de Mesquita Filho," 14884-900 Jaboticabal, São Paulo, Brazil
| | - Juan C Cifuentes-Arenas
- Unversidade Estadual Paulista "Júlio de Mesquita Filho," 14884-900 Jaboticabal, São Paulo, Brazil
- Fundo de Defesa da Citricultura, 14807-040 Araraquara, São Paulo, Brazil
| | - Nik J Cunniffe
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, U.K
| | - Robert Turgeon
- Department of Plant Biology, Cornell University, Ithaca, NY 14853, U.S.A
| | - Silvio A Lopes
- Fundo de Defesa da Citricultura, 14807-040 Araraquara, São Paulo, Brazil
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Legros M, Marshall JM, Macfadyen S, Hayes KR, Sheppard A, Barrett LG. Gene drive strategies of pest control in agricultural systems: Challenges and opportunities. Evol Appl 2021; 14:2162-2178. [PMID: 34603490 PMCID: PMC8477592 DOI: 10.1111/eva.13285] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 06/24/2021] [Accepted: 07/19/2021] [Indexed: 12/18/2022] Open
Abstract
Recent advances in gene-editing technologies have opened new avenues for genetic pest control strategies, in particular around the use of gene drives to suppress or modify pest populations. Significant uncertainty, however, surrounds the applicability of these strategies to novel target species, their efficacy in natural populations and their eventual safety and acceptability as control methods. In this article, we identify issues associated with the potential use of gene drives in agricultural systems, to control pests and diseases that impose a significant cost to agriculture around the world. We first review the need for innovative approaches and provide an overview of the most relevant biological and ecological traits of agricultural pests that could impact the outcome of gene drive approaches. We then describe the specific challenges associated with using gene drives in agricultural systems, as well as the opportunities that these environments may offer, focusing in particular on the advantages of high-threshold gene drives. Overall, we aim to provide a comprehensive view of the potential opportunities and the remaining uncertainties around the use of gene drives in agricultural systems.
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Affiliation(s)
- Mathieu Legros
- CSIRO Agriculture and FoodCanberraACTAustralia
- CSIRO Synthetic Biology Future Science PlatformCanberraACTAustralia
| | - John M. Marshall
- Divisions of Biostatistics and Epidemiology – School of Public HealthUniversity of CaliforniaBerkeleyCAUSA
| | | | | | | | - Luke G. Barrett
- CSIRO Agriculture and FoodCanberraACTAustralia
- CSIRO Synthetic Biology Future Science PlatformCanberraACTAustralia
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12
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Widmer TL, Costa JM. Impact of the United States Department of Agriculture, Agricultural Research Service on Plant Pathology: 2015-2020. PHYTOPATHOLOGY 2021; 111:1265-1276. [PMID: 33507089 DOI: 10.1094/phyto-09-20-0393-ia] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
There is an increasing need to supply the world with more food as the population continues to grow. Research on mitigating the effects of plant diseases to improve crop yield and quality can help provide more food without increasing the land area devoted to farming. National Program 303 (NP 303) within the U.S. Department of Agriculture, Agricultural Research Service is dedicated to research across multiple fields in plant pathology. This review article highlights the research impact within NP 303 between 2015 and 2020, including case studies on wheat and citrus diseases and the National Plant Disease Recovery System, which provide specific examples of this impact.
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Affiliation(s)
- Timothy L Widmer
- United States Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705
| | - José M Costa
- United States Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705
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13
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Yuan X, Chen C, Bassanezi RB, Wu F, Feng Z, Shi D, Li J, Du Y, Zhong L, Zhong B, Lu Z, Song X, Hu Y, Ouyang Z, Liu X, Xie J, Rao X, Wang X, Wu DO, Guan Z, Wang N. Region-Wide Comprehensive Implementation of Roguing Infected Trees, Tree Replacement, and Insecticide Applications Successfully Controls Citrus Huanglongbing. PHYTOPATHOLOGY 2021; 111:1361-1368. [PMID: 33356429 DOI: 10.1094/phyto-09-20-0436-r] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Huanglongbing (HLB) is a devastating citrus disease worldwide. A three-pronged approach to controlling HLB has been suggested, namely, removal of HLB-symptomatic trees, psyllid control, and replacement with HLB-free trees. However, such a strategy did not lead to successful HLB control in many citrus-producing regions, such as Florida. We hypothesize that this is because of the small-scale or incomprehensive implementation of the program; conversely, a comprehensive implementation of such a strategy at the regional level can successfully control HLB. To test our hypothesis, we investigated the effects of region-wide comprehensive implementation of this scheme to control HLB in Gannan region, China, with a total planted citrus acreage of over 110,000 ha from 2013 to 2019. With the region-wide implementation of comprehensive HLB management, the overall HLB incidence in Gannan decreased from 19.71% in 2014 to 3.86% in 2019. A partial implementation of such a program (without a comprehensive inoculum removal) at the regional level in Brazil resulted in HLB incidence increasing from 1.89% in 2010 to 19.02% in 2019. Using dynamic regression model analyses with data from both Brazil and China, we constructed a model to predict HLB incidence when all three components were applied at 100%. It was predicated that in a region-wide comprehensive implementation of such a program, HLB incidence would be controlled to a level of less than 1%. We conducted economic feasibility analyses and showed that average net profits were positive for groves that implemented the comprehensive strategy, but groves that did not implement it had negative net profits over a 10-year period. Overall, the key for the three-pronged program to successfully control HLB is the large scale (region-wide) and comprehensiveness in implementation. This study provides valuable information to control HLB and other economically important endemic diseases worldwide.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Xiaoyong Yuan
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Cixiang Chen
- Ganzhou Plant Protection Department of Fruit Industry/Jiangxi Navel Orange Engineering Research Center, Ganzhou, Jiangxi, China
| | | | - Feng Wu
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, U.S.A
| | - Zheng Feng
- Department of Electrical & Computer Engineering, University of Florida, Gainesville, FL, U.S.A
| | - Damin Shi
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Jinyun Li
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, U.S.A
| | - Yimin Du
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Ling Zhong
- Plant Protection Bureau, Department of Agriculture, Nanchang, Jiangxi, China
| | - Balian Zhong
- National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Zhanjun Lu
- National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Xiang Song
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Yan Hu
- Ganzhou Plant Protection Department of Fruit Industry/Jiangxi Navel Orange Engineering Research Center, Ganzhou, Jiangxi, China
| | - Zhigang Ouyang
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Xinjun Liu
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Jinzhao Xie
- Ganzhou Plant Protection Department of Fruit Industry/Jiangxi Navel Orange Engineering Research Center, Ganzhou, Jiangxi, China
| | - Xi Rao
- Plant Protection Bureau, Department of Agriculture, Nanchang, Jiangxi, China
| | - Xi Wang
- Plant Protection Bureau, Department of Agriculture, Nanchang, Jiangxi, China
| | - Dapeng Oliver Wu
- Department of Electrical & Computer Engineering, University of Florida, Gainesville, FL, U.S.A
| | - Zhengfei Guan
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, U.S.A
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, U.S.A
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14
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Huanglongbing Model under the Control Strategy of Discontinuous Removal of Infected Trees. Symmetry (Basel) 2021. [DOI: 10.3390/sym13071164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
By using differential equations with discontinuous right-hand sides, a dynamic model for vector-borne infectious disease under the discontinuous removal of infected trees was established after understanding the transmission mechanism of Huanglongbing (HLB) disease in citrus trees. Through calculation, the basic reproductive number of the model can be attained and the properties of the model are discussed. On this basis, the existence and global stability of the calculated equilibria are verified. Moreover, it was found that different I0 in the control strategy cannot change the dynamic properties of HLB disease. However, the lower the value of I0, the fewer HLB-infected citrus trees, which provides a theoretical basis for controlling HLB disease and reducing expenditure.
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15
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Luo Y, Zhang F, Liu Y, Gao S. Analysis and optimal control of a Huanglongbing mathematical model with resistant vector. Infect Dis Model 2021; 6:782-804. [PMID: 34189362 PMCID: PMC8214098 DOI: 10.1016/j.idm.2021.05.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 05/24/2021] [Accepted: 05/28/2021] [Indexed: 11/03/2022] Open
Abstract
Huanglongbing (HLB) is an incurable disease that affects citrus trees. To better understand the transmission of HLB, the mathematical model is developed to investigate the transmission dynamics of the disease between Asian citrus psyllid (ACP) and citrus trees. Through rigorous mathematical derivations, we derive the expression of the basic reproduction number (R0) of HLB. The findings show that the disease-free equilibrium is locally asymptotically stable if R0 < 1, and if R0 > 1 the system is uniformly persistent. By applying the global sensitivity analysis of R0, we can obtain some parameters that have the greatest influence on the HLB transmission dynamics. Additionally, the optimal control theory is used to explore the corresponding optimal control problem of the HLB model. Numerical simulations are conducted to reinforce the analytical results. These theoretical and numerical results provide useful insights for understanding the transmission dynamics of HLB and may help policy makers to develop intervention strategies for the disease.
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Affiliation(s)
- Youquan Luo
- Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou, 341000, PR China
| | - Fumin Zhang
- Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou, 341000, PR China
| | - Yujiang Liu
- Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou, 341000, PR China
| | - Shujing Gao
- Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou, 341000, PR China.,National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, 341000, PR China
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16
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Liao Z, Gao S, Yan S, Zhou G. Transmission dynamics and optimal control of a Huanglongbing model with time delay. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2021; 18:4162-4192. [PMID: 34198431 DOI: 10.3934/mbe.2021209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In this paper, a mathematical model has been formulated for the transmission dynamics of citrus Huanglongbing considering latent period as the time delay factor. Existence of the equilibria and their stability have been studied on the basis of basic reproduction number in two cases τ=0 and τ>0. The results show that stability changes occur through Hopf bifurcation in the delayed system. Optimal control theory is then applied to investigate the optimal strategy for curtailing the spread of the disease using three time-dependent control variables determined from sensitivity analysis. By using Pontryagin's Maximum Principle, we obtain the optimal integrated strategy and prove the uniqueness of optimal control solution. Analytical and numerical findings suggest that it is feasible to implement control techniques while minimizing the cost of implementation of optimal control strategies.
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Affiliation(s)
- Zhenzhen Liao
- Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou 341000, China
| | - Shujing Gao
- Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou 341000, China
- National Research Center of Navel Orange Engineering and Technology, Gannan Normal University, Ganzhou 341000, China
| | - Shuixian Yan
- Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou 341000, China
| | - Genjiao Zhou
- Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou 341000, China
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17
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Root samples provide early and improved detection of Candidatus Liberibacter asiaticus in Citrus. Sci Rep 2020; 10:16982. [PMID: 33046775 PMCID: PMC7550583 DOI: 10.1038/s41598-020-74093-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 09/23/2020] [Indexed: 11/08/2022] Open
Abstract
Huanglongbing (HLB), or Citrus Greening, is one of the most devastating diseases affecting agriculture today. Widespread throughout Citrus growing regions of the world, it has had severe economic consequences in all areas it has invaded. With no treatment available, management strategies focus on suppression and containment. Effective use of these costly control strategies relies on rapid and accurate identification of infected plants. Unfortunately, symptoms of the disease are slow to develop and indistinct from symptoms of other biotic/abiotic stressors. As a result, diagnosticians have focused on detecting the pathogen, Candidatus Liberibacter asiaticus, by DNA-based detection strategies utilizing leaf midribs for sampling. Recent work has shown that fibrous root decline occurs in HLB-affected trees before symptom development among leaves. Moreover, the pathogen, Ca. Liberibacter asiaticus, has been shown to be more evenly distributed within roots than within the canopy. Motivated by these observations, a longitudinal study of young asymptomatic trees was established to observe the spread of disease through time and test the relative effectiveness of leaf- and root-based detection strategies. Detection of the pathogen occurred earlier, more consistently, and more often in root samples than in leaf samples. Moreover, little influence of geography or host variety was found on the probability of detection.
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18
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Narouei-Khandan HA, Shakya SK, Garrett KA, Goss EM, Dufault NS, Andrade-Piedra JL, Asseng S, Wallach D, van Bruggen AH. BLIGHTSIM: A New Potato Late Blight Model Simulating the Response of Phytophthora infestans to Diurnal Temperature and Humidity Fluctuations in Relation to Climate Change. Pathogens 2020; 9:pathogens9080659. [PMID: 32824250 PMCID: PMC7459445 DOI: 10.3390/pathogens9080659] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/11/2020] [Accepted: 08/12/2020] [Indexed: 11/21/2022] Open
Abstract
Temperature response curves under diurnal oscillating temperatures differ from those under constant conditions for all stages of the Phytophthora infestans infection cycle on potatoes. We developed a mechanistic model (BLIGHTSIM) with an hourly time step to simulate late blight under fluctuating environmental conditions and predict late blight epidemics in potato fields. BLIGHTSIM is a modified susceptible (S), latent (L), infectious (I) and removed (R) compartmental model with hourly temperature and relative humidity as driving variables. The model was calibrated with growth chamber data covering one infection cycle and validated with field data from Ecuador. The model provided a good fit to all data sets evaluated. There was a significant interaction between average temperature and amplitude in their effects on the area under the disease progress curve (AUDPC) as predicted from growth chamber data on a single infection cycle. BLIGHTSIM can be incorporated in a potato growth model to study effects of diurnal temperature range on late blight impact under climate change scenarios.
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Affiliation(s)
- Hossein A. Narouei-Khandan
- Department of Plant Pathology, University of Florida, 1450 Fifield Hall, P.O. Box 110680, Gainesville, FL 32611-0680, USA; (S.K.S.); (K.A.G.); (E.M.G.); (N.S.D.); (A.H.C.v.B.)
- Emerging Pathogens Institute, University of Florida, Gainesville, 2055 Mowry Road, P.O. Box 100009, Gainesville, FL 32610, USA
- Ministry for Primary Industries, P.O. Box 2526, Wellington 6146, New Zealand
- Correspondence:
| | - Shankar K. Shakya
- Department of Plant Pathology, University of Florida, 1450 Fifield Hall, P.O. Box 110680, Gainesville, FL 32611-0680, USA; (S.K.S.); (K.A.G.); (E.M.G.); (N.S.D.); (A.H.C.v.B.)
| | - Karen A. Garrett
- Department of Plant Pathology, University of Florida, 1450 Fifield Hall, P.O. Box 110680, Gainesville, FL 32611-0680, USA; (S.K.S.); (K.A.G.); (E.M.G.); (N.S.D.); (A.H.C.v.B.)
- Emerging Pathogens Institute, University of Florida, Gainesville, 2055 Mowry Road, P.O. Box 100009, Gainesville, FL 32610, USA
- Food Systems Institute, University of Florida, P.O. Box 110180, Gainesville, FL 32611-0180, USA
| | - Erica M. Goss
- Department of Plant Pathology, University of Florida, 1450 Fifield Hall, P.O. Box 110680, Gainesville, FL 32611-0680, USA; (S.K.S.); (K.A.G.); (E.M.G.); (N.S.D.); (A.H.C.v.B.)
- Emerging Pathogens Institute, University of Florida, Gainesville, 2055 Mowry Road, P.O. Box 100009, Gainesville, FL 32610, USA
| | - Nicholas S. Dufault
- Department of Plant Pathology, University of Florida, 1450 Fifield Hall, P.O. Box 110680, Gainesville, FL 32611-0680, USA; (S.K.S.); (K.A.G.); (E.M.G.); (N.S.D.); (A.H.C.v.B.)
| | - Jorge L. Andrade-Piedra
- International Potato Center (CIP) and CGIAR Research Program on Roots Tubers and Bananas (RTB), P.O. Box 1558, Lima 12, Peru;
| | - Senthold Asseng
- Department of Agricultural and Biological Engineering, University of Florida, 224 Frazier Rogers Hall, P.O. Box 110570, Gainesville, FL 32611-0570, USA;
| | - Daniel Wallach
- Institut National de la Recherche Agronomique (INRA), UMR AGIR, BP 52627, 31326 Castanet Tolosan Cedex, France;
| | - Ariena H.C van Bruggen
- Department of Plant Pathology, University of Florida, 1450 Fifield Hall, P.O. Box 110680, Gainesville, FL 32611-0680, USA; (S.K.S.); (K.A.G.); (E.M.G.); (N.S.D.); (A.H.C.v.B.)
- Emerging Pathogens Institute, University of Florida, Gainesville, 2055 Mowry Road, P.O. Box 100009, Gainesville, FL 32610, USA
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19
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Shimwela MM, Halbert SE, Keremane ML, Mears P, Singer BH, Lee WS, Jones JB, Ploetz RC, van Bruggen AHC. In-Grove Spatiotemporal Spread of Citrus Huanglongbing and Its Psyllid Vector in Relation to Weather. PHYTOPATHOLOGY 2019; 109:418-427. [PMID: 30256188 DOI: 10.1094/phyto-03-18-0089-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Reports of spatial patterns of 'Candidatus Liberibacter asiaticus'-infected asymptomatic citrus trees and 'Ca. L. asiaticus'-positive Asian citrus psyllids (ACP) are rare, as are published relationships between huanglongbing (HLB), ACP, and weather. Here, spatial patterns of 'Ca. L. asiaticus'-positive asymptomatic and symptomatic trees were determined every half year in a small grove over 2.5 years, and of HLB-symptomatic trees and ('Ca. L. asiaticus'-positive) ACP populations every month in two commercial groves for 1 year. Spread of symptomatic trees followed that of asymptomatic 'Ca. L. asiaticus'-positive trees with <6 months' delay. 'Ca. L. asiaticus'-positive asymptomatic and symptomatic fronts moved at 2.5 to 3.6 m month-1. No spatial relationship was detected between ACP populations and HLB-infected trees. HLB incidence and 'Ca. L. asiaticus'-positive ACP dynamics were tentatively positively correlated with monthly rainfall data and, to a lesser extent, with average minimum temperature.
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Affiliation(s)
- M M Shimwela
- 1 Department of Plant Pathology, IFAS, University of Florida, Gainesville 32611
- 2 Emerging Pathogens Institute, University of Florida, Gainesville 32610
| | - S E Halbert
- 3 Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville 32608
| | - M L Keremane
- 4 United States Department of Agriculture-Agricultural Research Service, National Clonal Germplasm Repository for Citrus and Dates, Riverside, CA 92507
| | - P Mears
- 5 Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Immokalee, FL 34142-3829
| | - B H Singer
- 2 Emerging Pathogens Institute, University of Florida, Gainesville 32610
| | - W S Lee
- 6 Department of Agricultural and Biological Engineering, Gainesville, FL 32611; and
| | - J B Jones
- 1 Department of Plant Pathology, IFAS, University of Florida, Gainesville 32611
| | - R C Ploetz
- 7 Plant Pathology Department, TREC, University of Florida, Homestead 33031
| | - A H C van Bruggen
- 1 Department of Plant Pathology, IFAS, University of Florida, Gainesville 32611
- 2 Emerging Pathogens Institute, University of Florida, Gainesville 32610
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20
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Ogden NH, Wilson JRU, Richardson DM, Hui C, Davies SJ, Kumschick S, Le Roux JJ, Measey J, Saul WC, Pulliam JRC. Emerging infectious diseases and biological invasions: a call for a One Health collaboration in science and management. ROYAL SOCIETY OPEN SCIENCE 2019; 6:181577. [PMID: 31032015 PMCID: PMC6458372 DOI: 10.1098/rsos.181577] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 02/18/2019] [Indexed: 05/11/2023]
Abstract
The study and management of emerging infectious diseases (EIDs) and of biological invasions both address the ecology of human-associated biological phenomena in a rapidly changing world. However, the two fields work mostly in parallel rather than in concert. This review explores how the general phenomenon of an organism rapidly increasing in range or abundance is caused, highlights the similarities and differences between research on EIDs and invasions, and discusses shared management insights and approaches. EIDs can arise by: (i) crossing geographical barriers due to human-mediated dispersal, (ii) crossing compatibility barriers due to evolution, and (iii) lifting of environmental barriers due to environmental change. All these processes can be implicated in biological invasions, but only the first defines them. Research on EIDs is embedded within the One Health concept-the notion that human, animal and ecosystem health are interrelated and that holistic approaches encompassing all three components are needed to respond to threats to human well-being. We argue that for sustainable development, biological invasions should be explicitly considered within One Health. Management goals for the fields are the same, and direct collaborations between invasion scientists, disease ecologists and epidemiologists on modelling, risk assessment, monitoring and management would be mutually beneficial.
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Affiliation(s)
- Nick H. Ogden
- National Microbiology Laboratory, Public Health Agency of Canada, Canada
- South African DST-NRF Centre of Excellence in Epidemiological Modelling and Analysis (SACEMA), Stellenbosch University, South Africa
| | - John R. U. Wilson
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, South Africa
- South African National Biodiversity Institute, Kirstenbosch Research Centre, Claremont, Cape Town, South Africa
| | - David M. Richardson
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, South Africa
| | - Cang Hui
- Centre for Invasion Biology, Department of Mathematical Sciences, Stellenbosch University, Matieland 7602, South Africa
- Mathematical and Physical Biosciences, African Institute for Mathematical Sciences (AIMS), Muizenberg 7945, South Africa
| | - Sarah J. Davies
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, South Africa
| | - Sabrina Kumschick
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, South Africa
- South African National Biodiversity Institute, Kirstenbosch Research Centre, Claremont, Cape Town, South Africa
| | - Johannes J. Le Roux
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, South Africa
- Department of Biological Sciences, Macquarie University, Sydney 2109, Australia
| | - John Measey
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, South Africa
| | - Wolf-Christian Saul
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, South Africa
- Centre for Invasion Biology, Department of Mathematical Sciences, Stellenbosch University, Matieland 7602, South Africa
| | - Juliet R. C. Pulliam
- South African DST-NRF Centre of Excellence in Epidemiological Modelling and Analysis (SACEMA), Stellenbosch University, South Africa
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21
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Li W, Yao YN, Wu L, Hu B. Detection and Seasonal Variations of Huanglongbing Disease in Navel Orange Trees Using Direct Ionization Mass Spectrometry. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:2265-2271. [PMID: 30735376 DOI: 10.1021/acs.jafc.8b06427] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Citrus greening disease [Huanglongbing (HLB)] is the most destructive disease of citrus. In this work, we have established a metabolite-based mass spectrometry (MS) method for rapid detection of HLB in navel orange trees. Without sample pretreatment, characteristic mass spectra can be directly obtained from the raw plant samples using the direct MS method. The whole detection process can be accomplished within 1 min. By monitoring and comparisons of the healthy and infected plants throughout a whole year, characteristic MS peaks of metabolites are found to be specific responses from infected plants and, thus, could be used as biomarkers for detection of HLB. Therefore, HLB could be directly detected in the asymptomatic samples, such as stems, using this metabolite-based direct MS method. In addition, principal component analysis and partial least squares discriminant analysis modes of metabolites from healthy and infected trees were established for investigating differentiation and seasonal variations of HLB in leaves, veins, and stems, providing valuable information for understanding the HLB in different seasons.
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22
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Bin S, Pu X, Shu B, Kang C, Luo S, Tang Y, Wu Z, Lin J. Selection of Reference Genes for Optimal Normalization of Quantitative Real-Time Polymerase Chain Reaction Results for Diaphorina citri Adults. JOURNAL OF ECONOMIC ENTOMOLOGY 2019; 112:355-363. [PMID: 30289505 DOI: 10.1093/jee/toy297] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Indexed: 06/08/2023]
Abstract
The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), can cause direct damage to citrus trees and is the main vector for the devastating disease, citrus greening disease or huanglongbing. Most molecular studies on this important insect pest use real-time reverse-transcription quantitative polymerase chain reaction (RT-qPCR) to quantify gene expression, including analyzing molecular basis for insecticide resistance in field populations. One critical factor to cause inaccuracy in RT-qPCR results is the lack of appropriate internal reference genes for optimal data normalization. In this study, the expression levels of 10 selected reference genes were evaluated in different tissue samples of psyllid adults and in the insects treated with different temperatures and insecticides. Data were analyzed using different computational algorithms, including Delta Ct, BestKeeper, NormFinder, geNorm, and RefFinder. According to our results, at least two reference genes should be used for the normalization of RT-qPCR data in this insect. The best choices of reference genes for different samples are as follows: ACT1 and Ferritin for different tissue samples, RPS20 and Ferritin for samples treated with different temperatures, TBP and EF1α for samples treated with imidacloprid, and Ferritin and TBP for samples treated with beta-cypermethrin. The reference genes identified in this study should be useful for future studies to analyze the expression patterns of target genes, especially for genes linked with temperature adaptability and insecticide resistance in this insect species in the future.
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Affiliation(s)
- Shuying Bin
- Guangzhou City Key Laboratory of Subtropical Fruit Trees Outbreak Control, Institute for Management of Invasive Alien Species, Zhongkai University of Agriculture and Engineering, Yingdong Teaching Building, Guangzhou, China
| | - Xinhua Pu
- Guangzhou City Key Laboratory of Subtropical Fruit Trees Outbreak Control, Institute for Management of Invasive Alien Species, Zhongkai University of Agriculture and Engineering, Yingdong Teaching Building, Guangzhou, China
| | - Benshui Shu
- Guangzhou City Key Laboratory of Subtropical Fruit Trees Outbreak Control, Institute for Management of Invasive Alien Species, Zhongkai University of Agriculture and Engineering, Yingdong Teaching Building, Guangzhou, China
| | - Cong Kang
- Guangzhou City Key Laboratory of Subtropical Fruit Trees Outbreak Control, Institute for Management of Invasive Alien Species, Zhongkai University of Agriculture and Engineering, Yingdong Teaching Building, Guangzhou, China
| | - Shaoming Luo
- Guangzhou City Key Laboratory of Subtropical Fruit Trees Outbreak Control, Institute for Management of Invasive Alien Species, Zhongkai University of Agriculture and Engineering, Yingdong Teaching Building, Guangzhou, China
| | - Yu Tang
- Guangzhou City Key Laboratory of Subtropical Fruit Trees Outbreak Control, Institute for Management of Invasive Alien Species, Zhongkai University of Agriculture and Engineering, Yingdong Teaching Building, Guangzhou, China
| | - Zhongzhen Wu
- Guangzhou City Key Laboratory of Subtropical Fruit Trees Outbreak Control, Institute for Management of Invasive Alien Species, Zhongkai University of Agriculture and Engineering, Yingdong Teaching Building, Guangzhou, China
| | - Jintian Lin
- Guangzhou City Key Laboratory of Subtropical Fruit Trees Outbreak Control, Institute for Management of Invasive Alien Species, Zhongkai University of Agriculture and Engineering, Yingdong Teaching Building, Guangzhou, China
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23
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Jain M, Munoz-Bodnar A, Zhang S, Gabriel DW. A Secreted 'Candidatus Liberibacter asiaticus' Peroxiredoxin Simultaneously Suppresses Both Localized and Systemic Innate Immune Responses In Planta. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:1312-1322. [PMID: 29953333 DOI: 10.1094/mpmi-03-18-0068-r] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The oxidative (H2O2) burst is a seminal feature of the basal plant defense response to attempted pathogen invasions. In 'Candidatus Liberibacter asiaticus' UF506, expression of the SC2 prophage-encoded secreted peroxidase (F489_gp15) increases bacterial fitness and delays symptom progression in citrus. Two chromosomal 1-Cys peroxiredoxin genes, CLIBASIA_RS00940 (Lasprx5) and CLIBASIA_RS00445 (Lasbcp), are conserved among all sequenced 'Ca. L. asiaticus' strains, including those lacking prophages. Both LasBCP and LasdPrx5 have only a single conserved peroxidatic Cys (CP/SH) and lack the resolving Cys (CR/SH). Lasprx5 appeared to be a housekeeping gene with similar moderate transcript abundance in both 'Ca. L. asiaticus'-infected psyllids and citrus. By contrast, Lasbcp was expressed only in planta, similar to the expression of the SC2 peroxidase. Since 'Ca. L. asiaticus' is uncultured, Lasbcp and Lasprx5 were functionally validated in a cultured surrogate species, Liberibacter crescens, and both genes significantly increased oxidative stress tolerance and cell viability in culture. LasBCP was nonclassically secreted and, in L. crescens, conferred 214-fold more resistance to tert-butyl hydroperoxide (tBOOH) than wild type. Transient overexpression of Lasbcp in tobacco suppressed H2O2-mediated transcriptional activation of RbohB, the key gatekeeper of the systemic plant defense signaling cascade. Lasbcp expression did not interfere with the perception of 'Ca. L. asiaticus' flagellin (flg22Las) but interrupted the downstream activation of RbohB and stereotypical deposition of callose in tobacco. Critically, LasBCP also protected against tBOOH-induced peroxidative degradation of lipid membranes in planta, preventing subsequent accumulation of antimicrobial oxylipins that can also trigger the localized hypersensitive cell death response.
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Affiliation(s)
- Mukesh Jain
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, U.S.A
| | | | - Shujian Zhang
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, U.S.A
| | - Dean W Gabriel
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, U.S.A
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24
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Shimwela MM, Schubert TS, Albritton M, Halbert SE, Jones DJ, Sun X, Roberts PD, Singer BH, Lee WS, Jones JB, Ploetz RC, van Bruggen AHC. Regional Spatial-Temporal Spread of Citrus Huanglongbing Is Affected by Rain in Florida. PHYTOPATHOLOGY 2018; 108:1420-1428. [PMID: 29873608 DOI: 10.1094/phyto-03-18-0088-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Citrus huanglongbing (HLB), associated with 'Candidatus Liberibacter asiaticus' (Las), disseminated by Asian citrus psyllid (ACP), has devastated citrus in Florida since 2005. Data on HLB occurrence were stored in databases (2005 to 2012). Cumulative HLB-positive citrus blocks were subjected to kernel density analysis and kriging. Relative disease incidence per county was calculated by dividing HLB numbers by relative tree numbers and maximum incidence. Spatiotemporal HLB distributions were correlated with weather. Relative HLB incidence correlated positively with rainfall. The focus expansion rate was 1626 m month-1, similar to that in Brazil. Relative HLB incidence in counties with primarily large groves increased at a lower rate (0.24 year-1) than in counties with smaller groves in hotspot areas (0.67 year-1), confirming reports that large-scale HLB management may slow epidemic progress.
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Affiliation(s)
- M M Shimwela
- First, tenth, and twelfth authors: Department of Plant Pathology, IFAS, University of Florida, Gainesville 32611; first, eighth, and twelfth authors: Emerging Pathogens Institute, University of Florida, Gainesville 32610; second, third, fourth, fifth, and sixth authors: Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville 33825; seventh author: Department of Plant Pathology, IFAS, SWFREC, University of Florida, Immokalee 34142; ninth author: Department of Agricultural and Biological Engineering, Gainesville, FL 32611; and eleventh author: University of Florida, Plant Pathology Department, TREC-Homestead, FL 33031
| | - T S Schubert
- First, tenth, and twelfth authors: Department of Plant Pathology, IFAS, University of Florida, Gainesville 32611; first, eighth, and twelfth authors: Emerging Pathogens Institute, University of Florida, Gainesville 32610; second, third, fourth, fifth, and sixth authors: Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville 33825; seventh author: Department of Plant Pathology, IFAS, SWFREC, University of Florida, Immokalee 34142; ninth author: Department of Agricultural and Biological Engineering, Gainesville, FL 32611; and eleventh author: University of Florida, Plant Pathology Department, TREC-Homestead, FL 33031
| | - M Albritton
- First, tenth, and twelfth authors: Department of Plant Pathology, IFAS, University of Florida, Gainesville 32611; first, eighth, and twelfth authors: Emerging Pathogens Institute, University of Florida, Gainesville 32610; second, third, fourth, fifth, and sixth authors: Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville 33825; seventh author: Department of Plant Pathology, IFAS, SWFREC, University of Florida, Immokalee 34142; ninth author: Department of Agricultural and Biological Engineering, Gainesville, FL 32611; and eleventh author: University of Florida, Plant Pathology Department, TREC-Homestead, FL 33031
| | - S E Halbert
- First, tenth, and twelfth authors: Department of Plant Pathology, IFAS, University of Florida, Gainesville 32611; first, eighth, and twelfth authors: Emerging Pathogens Institute, University of Florida, Gainesville 32610; second, third, fourth, fifth, and sixth authors: Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville 33825; seventh author: Department of Plant Pathology, IFAS, SWFREC, University of Florida, Immokalee 34142; ninth author: Department of Agricultural and Biological Engineering, Gainesville, FL 32611; and eleventh author: University of Florida, Plant Pathology Department, TREC-Homestead, FL 33031
| | - D J Jones
- First, tenth, and twelfth authors: Department of Plant Pathology, IFAS, University of Florida, Gainesville 32611; first, eighth, and twelfth authors: Emerging Pathogens Institute, University of Florida, Gainesville 32610; second, third, fourth, fifth, and sixth authors: Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville 33825; seventh author: Department of Plant Pathology, IFAS, SWFREC, University of Florida, Immokalee 34142; ninth author: Department of Agricultural and Biological Engineering, Gainesville, FL 32611; and eleventh author: University of Florida, Plant Pathology Department, TREC-Homestead, FL 33031
| | - X Sun
- First, tenth, and twelfth authors: Department of Plant Pathology, IFAS, University of Florida, Gainesville 32611; first, eighth, and twelfth authors: Emerging Pathogens Institute, University of Florida, Gainesville 32610; second, third, fourth, fifth, and sixth authors: Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville 33825; seventh author: Department of Plant Pathology, IFAS, SWFREC, University of Florida, Immokalee 34142; ninth author: Department of Agricultural and Biological Engineering, Gainesville, FL 32611; and eleventh author: University of Florida, Plant Pathology Department, TREC-Homestead, FL 33031
| | - P D Roberts
- First, tenth, and twelfth authors: Department of Plant Pathology, IFAS, University of Florida, Gainesville 32611; first, eighth, and twelfth authors: Emerging Pathogens Institute, University of Florida, Gainesville 32610; second, third, fourth, fifth, and sixth authors: Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville 33825; seventh author: Department of Plant Pathology, IFAS, SWFREC, University of Florida, Immokalee 34142; ninth author: Department of Agricultural and Biological Engineering, Gainesville, FL 32611; and eleventh author: University of Florida, Plant Pathology Department, TREC-Homestead, FL 33031
| | - B H Singer
- First, tenth, and twelfth authors: Department of Plant Pathology, IFAS, University of Florida, Gainesville 32611; first, eighth, and twelfth authors: Emerging Pathogens Institute, University of Florida, Gainesville 32610; second, third, fourth, fifth, and sixth authors: Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville 33825; seventh author: Department of Plant Pathology, IFAS, SWFREC, University of Florida, Immokalee 34142; ninth author: Department of Agricultural and Biological Engineering, Gainesville, FL 32611; and eleventh author: University of Florida, Plant Pathology Department, TREC-Homestead, FL 33031
| | - W S Lee
- First, tenth, and twelfth authors: Department of Plant Pathology, IFAS, University of Florida, Gainesville 32611; first, eighth, and twelfth authors: Emerging Pathogens Institute, University of Florida, Gainesville 32610; second, third, fourth, fifth, and sixth authors: Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville 33825; seventh author: Department of Plant Pathology, IFAS, SWFREC, University of Florida, Immokalee 34142; ninth author: Department of Agricultural and Biological Engineering, Gainesville, FL 32611; and eleventh author: University of Florida, Plant Pathology Department, TREC-Homestead, FL 33031
| | - J B Jones
- First, tenth, and twelfth authors: Department of Plant Pathology, IFAS, University of Florida, Gainesville 32611; first, eighth, and twelfth authors: Emerging Pathogens Institute, University of Florida, Gainesville 32610; second, third, fourth, fifth, and sixth authors: Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville 33825; seventh author: Department of Plant Pathology, IFAS, SWFREC, University of Florida, Immokalee 34142; ninth author: Department of Agricultural and Biological Engineering, Gainesville, FL 32611; and eleventh author: University of Florida, Plant Pathology Department, TREC-Homestead, FL 33031
| | - R C Ploetz
- First, tenth, and twelfth authors: Department of Plant Pathology, IFAS, University of Florida, Gainesville 32611; first, eighth, and twelfth authors: Emerging Pathogens Institute, University of Florida, Gainesville 32610; second, third, fourth, fifth, and sixth authors: Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville 33825; seventh author: Department of Plant Pathology, IFAS, SWFREC, University of Florida, Immokalee 34142; ninth author: Department of Agricultural and Biological Engineering, Gainesville, FL 32611; and eleventh author: University of Florida, Plant Pathology Department, TREC-Homestead, FL 33031
| | - A H C van Bruggen
- First, tenth, and twelfth authors: Department of Plant Pathology, IFAS, University of Florida, Gainesville 32611; first, eighth, and twelfth authors: Emerging Pathogens Institute, University of Florida, Gainesville 32610; second, third, fourth, fifth, and sixth authors: Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville 33825; seventh author: Department of Plant Pathology, IFAS, SWFREC, University of Florida, Immokalee 34142; ninth author: Department of Agricultural and Biological Engineering, Gainesville, FL 32611; and eleventh author: University of Florida, Plant Pathology Department, TREC-Homestead, FL 33031
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Zeilinger AR, Turek D, Cornara D, Sicard A, Lindow SE, Almeida RPP. Bayesian vector transmission model detects conflicting interactions from transgenic disease‐resistant grapevines. Ecosphere 2018. [DOI: 10.1002/ecs2.2494] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Adam R. Zeilinger
- Department of Environmental Science, Policy, and Management University of California 130 Mulford Hall Berkeley California 94720 USA
| | - Daniel Turek
- Department of Mathematics and Statistics Williams College Williamstown Massachusetts 01267 USA
| | - Daniele Cornara
- Instituto de Ciencias Agrarias Consejo Superior de Investigaciones Cientificas ICA‐CSIC Calle Serrano 115 dpdo Madrid 28006 Spain
| | - Anne Sicard
- Department of Environmental Science, Policy, and Management University of California 130 Mulford Hall Berkeley California 94720 USA
| | - Steven E. Lindow
- Department of Plant and Microbial Biology University of California Berkeley Berkeley California 94720 USA
| | - Rodrigo P. P. Almeida
- Department of Environmental Science, Policy, and Management University of California 130 Mulford Hall Berkeley California 94720 USA
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Importance of Remotely-Sensed Vegetation Variables for Predicting the Spatial Distribution of African Citrus Triozid (Trioza erytreae) in Kenya. ISPRS INTERNATIONAL JOURNAL OF GEO-INFORMATION 2018. [DOI: 10.3390/ijgi7110429] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Citrus is considered one of the most important fruit crops globally due to its contribution to food and nutritional security. However, the production of citrus has recently been in decline due to many biological, environmental, and socio-economic constraints. Amongst the biological ones, pests and diseases play a major role in threatening citrus quantity and quality. The most damaging disease in Kenya, is the African citrus greening disease (ACGD) or Huanglongbing (HLB) which is transmitted by the African citrus triozid (ACT), Trioza erytreae. HLB in Kenya is reported to have had the greatest impact on citrus production in the highlands, causing yield losses of 25% to 100%. This study aimed at predicting the occurrence of ACT using an ecological habitat suitability modeling approach. Specifically, we tested the contribution of vegetation phenological variables derived from remotely-sensed (RS) data combined with bio-climatic and topographical variables (BCL) to accurately predict the distribution of ACT in citrus-growing areas in Kenya. A MaxEnt (maximum entropy) suitability modeling approach was used on ACT presence-only data. Forty-seven (47) ACT observations were collected while 23 BCL and 12 RS covariates were used as predictor variables in the MaxEnt modeling. The BCL variables were extracted from the WorldClim data set, while the RS variables were predicted from vegetation phenological time-series data (spanning the years 2014–2016) and annually-summed land surface temperature (LST) metrics (2014–2016). We developed two MaxEnt models; one including both the BCL and the RS variables (BCL-RS) and another with only the BCL variables. Further, we tested the relationship between ACT habitat suitability and the surrounding land use/land cover (LULC) proportions using a random forest regression model. The results showed that the combined BCL-RS model predicted the distribution and habitat suitability for ACT better than the BCL-only model. The overall accuracy for the BCL-RS model result was 92% (true skills statistic: TSS = 0.83), whereas the BCL-only model had an accuracy of 85% (TSS = 0.57). Also, the results revealed that the proportion of shrub cover surrounding citrus orchards positively influenced the suitability probability of the ACT. These results provide a resourceful tool for precise, timely, and site-specific implementation of ACGD control strategies.
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Craig AP, Cunniffe NJ, Parry M, Laranjeira FF, Gilligan CA. Grower and regulator conflict in management of the citrus disease Huanglongbing in Brazil: A modelling study. J Appl Ecol 2018. [DOI: 10.1111/1365-2664.13122] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Andrew P. Craig
- Epidemiology and Modelling Group; Department of Plant Sciences; University of Cambridge; Cambridge UK
| | - Nik J. Cunniffe
- Theoretical and Computational Epidemiology Group; Department of Plant Sciences; University of Cambridge; Cambridge UK
| | - Matthew Parry
- Department of Mathematics and Statistics; University of Otago; Dunedin New Zealand
| | | | - Christopher A. Gilligan
- Epidemiology and Modelling Group; Department of Plant Sciences; University of Cambridge; Cambridge UK
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28
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Munir S, He P, Wu Y, He P, Khan S, Huang M, Cui W, He P, He Y. Huanglongbing Control: Perhaps the End of the Beginning. MICROBIAL ECOLOGY 2018; 76:192-204. [PMID: 29196843 DOI: 10.1007/s00248-017-1123-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 11/23/2017] [Indexed: 05/25/2023]
Abstract
Huanglongbing (HLB) is one of the most destructive citrus plant diseases worldwide. It is associated with the fastidious phloem-limited α-proteobacteria 'Candidatus Liberibacter asiaticus', 'Ca. Liberibacter africanus' and 'Ca. Liberibacter americanus'. In recent years, HLB-associated Liberibacters have extended to North and South America. The causal agents of HLB have been putatively identified, and their transmission pathways and worldwide population structure have been extensively studied. However, very little is known about the epidemiologic relationships of Ca. L. asiaticus, which has limited the scope of HLB research and especially the development of control strategies. HLB-affected plants produce damaged fruits and die within several years. To control the disease, scientists have developed new compounds and screened existing compounds for their antibiotic and antimicrobial activities against the disease. These compounds, however, have very little or even no effect on the disease. The aim of the present review was to compile and compare different methods of HLB disease control with newly developed integrative strategies. In light of recent studies, we also describe how to control the vectors of this disease and the biological control of other citrus plant pathogens. This work could steer the attention of scientists towards integrative control strategies.
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Affiliation(s)
- Shahzad Munir
- Faculty of Plant Protection, Yunnan Agricultural University, Kunming, Yunnan, 650201, China
| | - Pengfei He
- Faculty of Plant Protection, Yunnan Agricultural University, Kunming, Yunnan, 650201, China
| | - Yixin Wu
- Faculty of Plant Protection, Yunnan Agricultural University, Kunming, Yunnan, 650201, China
| | - Pengbo He
- Faculty of Plant Protection, Yunnan Agricultural University, Kunming, Yunnan, 650201, China
| | - Sehroon Khan
- World Agroforestry Centre, East and Central Asia, 132 Lanhei Rd, Heilongtan, Kunming, Yunnan, 650201, China
- Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, 650201, China
| | - Min Huang
- Faculty of Plant Protection, Yunnan Agricultural University, Kunming, Yunnan, 650201, China
- Agriculture College and Urban Modern Agriculture Engineering Research Center, Kunming University, Kunming, 650214, China
| | - Wenyan Cui
- Faculty of Plant Protection, Yunnan Agricultural University, Kunming, Yunnan, 650201, China
| | - Pengjie He
- Faculty of Plant Protection, Yunnan Agricultural University, Kunming, Yunnan, 650201, China
| | - Yueqiu He
- Faculty of Plant Protection, Yunnan Agricultural University, Kunming, Yunnan, 650201, China.
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29
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Qian W, Lu Y, Meng Y, Ye Z, Wang L, Wang R, Zheng Q, Wu H, Wu J. Field Detection of Citrus Huanglongbing Associated with ' Candidatus Liberibacter Asiaticus' by Recombinese Polymerase Amplification within 15 min. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:5473-5480. [PMID: 29781618 DOI: 10.1021/acs.jafc.8b01015] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
' Candidatus Liberibacter asiaticus' (Las) is the most prevalent bacterium associated with huanglongbing, which is one of the most destructive diseases of citrus. In this paper, an extremely rapid and simple method for field detection of Las from leaf samples, based on recombinase polymerase amplification (RPA), is described. Three RPA primer pairs were designed and evaluated. RPA amplification was optimized so that it could be accomplished within 10 min. In combination with DNA crude extraction by a 50-fold dilution after 1 min of grinding in 0.5 M sodium hydroxide and visual detection via fluorescent DNA dye (positive samples display obvious green fluorescence while negative samples remain colorless), the whole detection process can be accomplished within 15 min. The sensitivity and specificity of this RPA-based method were evaluated and were proven to be equal to those of real-time PCR. The reliability of this method was also verified by analyzing field samples.
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Affiliation(s)
- Wenjuan Qian
- College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou 310058 , China
| | - Ying Lu
- Zhejiang Plant Protection and Quarantine Bureau, Hangzhou 310020 , China
| | - Youqing Meng
- Zhejiang Plant Protection and Quarantine Bureau, Hangzhou 310020 , China
| | - Zunzhong Ye
- College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou 310058 , China
| | - Liu Wang
- College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou 310058 , China
| | - Rui Wang
- College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou 310058 , China
| | - Qiqi Zheng
- College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou 310058 , China
| | - Hui Wu
- College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou 310058 , China
| | - Jian Wu
- College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou 310058 , China
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Cifuentes-Arenas JC, de Goes A, de Miranda MP, Beattie GAC, Lopes SA. Citrus flush shoot ontogeny modulates biotic potential of Diaphorina citri. PLoS One 2018; 13:e0190563. [PMID: 29304052 PMCID: PMC5755881 DOI: 10.1371/journal.pone.0190563] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 12/18/2017] [Indexed: 11/22/2022] Open
Abstract
The biology and behaviour of the psyllid Diaphorina citri Kuwayama (Hemiptera: Sternorrhyncha: Liviidae), the major insect vector of bacteria associated with huanglongbing, have been extensively studied with respect to host preferences, thermal requirements, and responses to visual and chemical volatile stimuli. However, development of the psyllid in relation to the ontogeny of immature citrus flush growth has not been clearly defined or illustrated. Such information is important for determining the timing and frequency of measures used to minimize populations of the psyllid in orchards and spread of HLB. Our objective was to study how flush ontogeny influences the biotic potential of the psyllid. We divided citrus flush growth into six stages within four developmental phases: emergence (V1), development (V2 and V3), maturation (V4 and V5), and dormancy (V6). Diaphorina citri oviposition and nymph development were assessed on all flush stages in a temperature controlled room, and in a screen-house in which ambient temperatures varied. Our results show that biotic potential of Diaphorina citri is not a matter of the size or the age of the flushes (days after budbreak), but the developmental stage within its ontogeny. Females laid eggs on flush V1 to V5 only, with the time needed to commence oviposition increasing with the increasing in flush age. Stages V1, V2 and V3 were most suitable for oviposition, nymph survival and development, and adult emergence, which showed evidence of protandry. Flush shoots at emerging and developmental phases should be the focus of any chemical or biological control strategy to reduce the biotic potential of D. citri, to protect citrus tree from Liberibacter infection and to minimize HLB dissemination.
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Affiliation(s)
- Juan Camilo Cifuentes-Arenas
- Departamento de Fitossanidade, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista ‘Júlio de Mesquita Filho’, Jaboticabal, São Paulo, Brazil
| | - António de Goes
- Departamento de Fitossanidade, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista ‘Júlio de Mesquita Filho’, Jaboticabal, São Paulo, Brazil
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Qian W, Meng Y, Lu Y, Wu C, Wang R, Wang L, Qian C, Ye Z, Wu J, Ying Y. Rapid, Sensitive, and Carryover Contamination-Free Loop-Mediated Isothermal Amplification-Coupled Visual Detection Method for 'Candidatus Liberibacter asiaticus'. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2017; 65:8302-8310. [PMID: 28858491 DOI: 10.1021/acs.jafc.7b03490] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Huanglongbing is a devastating citrus disease, and 'Candidatus Liberibacter asiaticus' (Las) is the most prevalent huanglongbing-associated bacterium. Its field detection remains challenging. In this work, a visual, rapid, sensitive, and carryover contamination-free method was developed for field detection of Las. Leaf samples were treated with 500 μL of 0.5 M sodium hydroxide solution for 3 min, and 50-fold dilutions were directly amplified by loop-mediated isothermal amplification. Then, a novel SYTO-9-based visual detection method was used to evaluate amplification results without uncapping operation. Negative samples remained colorless, while positive samples generated obvious green fluorescence, which could be easily distinguished by the naked eye with a mini-fluorescent-emission cartridge developed originally. The proposed detection method could be accomplished within 40 min and is about 100 times more sensitive than conventional TaqMan polymerase chain reaction. The reliability of this method was also verified by analyzing practical samples.
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Affiliation(s)
- Wenjuan Qian
- College of Biosystems Engineering and Food Science, Zhejiang University , Hangzhou, Zhejiang 310058, People's Republic of China
- Key Laboratory of On Site Processing Equipment for Agricultural Products, Ministry of Agriculture , Hangzhou, Zhejiang 310058, People's Republic of China
| | - Youqing Meng
- Zhejiang Plant Protection and Quarantine Bureau , Hangzhou, Zhejiang 310020, People's Republic of China
| | - Ying Lu
- Zhejiang Plant Protection and Quarantine Bureau , Hangzhou, Zhejiang 310020, People's Republic of China
| | - Cui Wu
- College of Biosystems Engineering and Food Science, Zhejiang University , Hangzhou, Zhejiang 310058, People's Republic of China
- Key Laboratory of On Site Processing Equipment for Agricultural Products, Ministry of Agriculture , Hangzhou, Zhejiang 310058, People's Republic of China
| | - Rui Wang
- College of Biosystems Engineering and Food Science, Zhejiang University , Hangzhou, Zhejiang 310058, People's Republic of China
- Key Laboratory of On Site Processing Equipment for Agricultural Products, Ministry of Agriculture , Hangzhou, Zhejiang 310058, People's Republic of China
| | - Liu Wang
- College of Biosystems Engineering and Food Science, Zhejiang University , Hangzhou, Zhejiang 310058, People's Republic of China
- Key Laboratory of On Site Processing Equipment for Agricultural Products, Ministry of Agriculture , Hangzhou, Zhejiang 310058, People's Republic of China
| | - Cheng Qian
- College of Biosystems Engineering and Food Science, Zhejiang University , Hangzhou, Zhejiang 310058, People's Republic of China
- Key Laboratory of On Site Processing Equipment for Agricultural Products, Ministry of Agriculture , Hangzhou, Zhejiang 310058, People's Republic of China
| | - Zunzhong Ye
- College of Biosystems Engineering and Food Science, Zhejiang University , Hangzhou, Zhejiang 310058, People's Republic of China
- Key Laboratory of On Site Processing Equipment for Agricultural Products, Ministry of Agriculture , Hangzhou, Zhejiang 310058, People's Republic of China
| | - Jian Wu
- College of Biosystems Engineering and Food Science, Zhejiang University , Hangzhou, Zhejiang 310058, People's Republic of China
- Key Laboratory of On Site Processing Equipment for Agricultural Products, Ministry of Agriculture , Hangzhou, Zhejiang 310058, People's Republic of China
| | - Yibin Ying
- College of Biosystems Engineering and Food Science, Zhejiang University , Hangzhou, Zhejiang 310058, People's Republic of China
- Zhejiang A&F University , Hangzhou, Zhejiang 311300, People's Republic of China
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32
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Tansey JA, Vanaclocha P, Monzo C, Jones M, Stansly PA. Costs and benefits of insecticide and foliar nutrient applications to huanglongbing-infected citrus trees. PEST MANAGEMENT SCIENCE 2017; 73:904-916. [PMID: 27427170 DOI: 10.1002/ps.4362] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 06/14/2016] [Accepted: 07/12/2016] [Indexed: 05/28/2023]
Abstract
BACKGROUND The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Psyllidae), vectors Candidatus Liberibacter asiaticus, which causes huanglongbing (HLB). In Florida, HLB incidence is approaching 100% statewide. Yields have decreased and production costs have increased since 2005. Despite this, some growers are maintaining a level of production and attribute this in part to aggressive psyllid control and foliar nutrition sprays. However, the value of these practices is debated. A replicated field study was initiated in 2008 in a commercial block of 'Valencia' sweet orange trees to evaluate individual and combined effects of foliar nutrition and ACP control. Results from 2012-2016 are presented. RESULTS Insecticides consistently reduced ACP populations. However, neither insecticide nor nutrition applications significantly influenced HLB incidence or PCR copy number in mature trees. In reset trees, infection continued to build and reached 100% in all treatments. Greatest yields (kg fruit ha-1 ) and production (kg solids ha-1 ) were obtained from trees receiving both insecticides and foliar nutrition. CONCLUSION All treatments resulted in production and financial gains relative to controls. However, material and application costs associated with the nutrition component offset these gains, resulting in lesser benefits than insecticides applied alone. © 2016 Society of Chemical Industry.
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Affiliation(s)
- James A Tansey
- University of Florida, Southwest Florida Research and Education Center, Immokalee, FL, USA
| | - Pilar Vanaclocha
- University of Florida, Southwest Florida Research and Education Center, Immokalee, FL, USA
| | - Cesar Monzo
- University of Florida, Southwest Florida Research and Education Center, Immokalee, FL, USA
- Unidad Asociada IVIA-UJI, Instituto Valenciano de Investigaciones Agrarias, Moncada, Valencia, Spain
| | - Moneen Jones
- University of Florida, Southwest Florida Research and Education Center, Immokalee, FL, USA
- Department of Entomology, University of Missouri, Fisher Delta Research Center, Portageville, MO, USA
| | - Philip A Stansly
- University of Florida, Southwest Florida Research and Education Center, Immokalee, FL, USA
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Jain M, Fleites LA, Gabriel DW. A Small Wolbachia Protein Directly Represses Phage Lytic Cycle Genes in " Candidatus Liberibacter asiaticus" within Psyllids. mSphere 2017; 2:e00171-17. [PMID: 28608866 PMCID: PMC5463029 DOI: 10.1128/mspheredirect.00171-17] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 04/20/2017] [Indexed: 01/17/2023] Open
Abstract
Huanglongbing (HLB) is a severe disease of citrus caused by an uncultured alphaproteobacterium "Candidatus Liberibacter asiaticus" and transmitted by Asian citrus psyllids (Diaphorina citri). Two prophage genomes, SC1 and SC2, integrated in "Ca. Liberibacter asiaticus" strain UF506 were described previously, and very similar prophages are found resident in the majority of "Ca. Liberibacter asiaticus" strains described worldwide. The SC1 lytic cycle is marked by upregulation of prophage late genes, including a functional holin (SC1_gp110); these late genes are activated when "Ca. Liberibacter asiaticus" is in planta, but not when infecting the psyllid host. We previously reported that the holin promoter is strongly and constitutively active in Liberibacter crescens (a cultured proxy for uncultured "Ca. Liberibacter asiaticus") but is suppressed in a dose-dependent manner by crude aqueous extracts from D. citri applied exogenously. Here we report that the suppressor activity of the crude psyllid extract was heat labile and abolished by proteinase K treatment, indicating a proteinaceous repressor and of a size smaller than 30 kDa. The repressor was affinity captured from D. citri aqueous extracts using biotinylated holin promoter DNA immobilized on magnetic beads and subjected to liquid chromatography-tandem mass spectrometry (LC-MS/MS). Protein database interrogation was used to identify a small DNA-binding protein encoded by a gene carried by Wolbachia strain wDi, a resident endosymbiont of D. citri as the repressor. The in vitro-translated Wolbachia repressor protein was able to penetrate L. crescens cells, bind to "Ca. Liberibacter asiaticus" promoter DNA, and partially suppress holin promoter-driven β-glucuronidase (GUS) activity, indicating potential involvement of an additional interacting partner(s) or posttranslational modification(s) for complete suppression. Expression of the Wolbachia repressor protein appeared to be constitutive irrespective of "Ca. Liberibacter asiaticus" infection status of the insect host. IMPORTANCE Host acquisition of a new microbial species can readily perturb the dynamics of preexisting microbial associations. Molecular cross talk between microbial associates may be necessary for efficient resource allocation and enhanced survival. Classic examples involve quorum sensing (QS), which detects population densities and is both used and coopted to control expression of bacterial genes, including host adaptation factors. We report that a 56-amino-acid repressor protein made by the resident psyllid endosymbiont Wolbachia can enter cells of Liberibacter crescens, a cultured proxy for the uncultured psyllid endosymbiont "Ca. Liberibacter asiaticus" and repress "Ca. Liberibacter asiaticus" phage lytic cycle genes. Such repression in "Ca. Liberibacter asiaticus" may be critical to survival of both endosymbionts, since phage-mediated lysis would likely breach the immunogenic threshold of the psyllid, invoking a systemic and nonspecific innate immune reaction.
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Affiliation(s)
- Mukesh Jain
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
| | - Laura A Fleites
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
| | - Dean W Gabriel
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
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Bayles BR, Thomas SM, Simmons GS, Grafton-Cardwell EE, Daugherty MP. Spatiotemporal dynamics of the Southern California Asian citrus psyllid (Diaphorina citri) invasion. PLoS One 2017; 12:e0173226. [PMID: 28278188 PMCID: PMC5344380 DOI: 10.1371/journal.pone.0173226] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 02/19/2017] [Indexed: 11/19/2022] Open
Abstract
Biological invasions are governed by spatial processes that tend to be distributed in non-random ways across landscapes. Characterizing the spatial and temporal heterogeneities of the introduction, establishment, and spread of non-native insect species is a key aspect of effectively managing their geographic expansion. The Asian citrus psyllid (Diaphorina citri), a vector of the bacterium associated with huanglongbing (HLB), poses a serious threat to commercial and residential citrus trees. In 2008, D. citri first began expanding northward from Mexico into parts of Southern California. Using georeferenced D. citri occurrence data from 2008-2014, we sought to better understand the extent of the geographic expansion of this invasive vector species. Our objectives were to: 1) describe the spatial and temporal distribution of D. citri in Southern California, 2) identify the locations of statistically significant D. citri hotspots, and 3) quantify the dynamics of anisotropic spread. We found clear evidence that the spatial and temporal distribution of D. citri in Southern California is non-random. Further, we identified the existence of statistically significant hotspots of D. citri occurrence and described the anisotropic dispersion across the Southern California landscape. For example, the dominant hotspot surrounding Los Angeles showed rapid and strongly asymmetric spread to the south and east. Our study demonstrates the feasibility of quantitative invasive insect risk assessment with the application of a spatial epidemiology framework.
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Affiliation(s)
- Brett R. Bayles
- Department of Entomology, University of California Riverside, Riverside, California, United States of America
- School of Health and Natural Sciences, Dominican University of California, San Rafael, California, United States of America
- * E-mail:
| | - Shyam M. Thomas
- Department of Entomology, University of California Riverside, Riverside, California, United States of America
| | - Gregory S. Simmons
- United States Department of Agriculture, Animal and Plant Health Inspection Service, Salinas, California, United States of America
| | | | - Mathew P. Daugherty
- Department of Entomology, University of California Riverside, Riverside, California, United States of America
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Taylor RA, Mordecai EA, Gilligan CA, Rohr JR, Johnson LR. Mathematical models are a powerful method to understand and control the spread of Huanglongbing. PeerJ 2016; 4:e2642. [PMID: 27833809 PMCID: PMC5101597 DOI: 10.7717/peerj.2642] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 10/01/2016] [Indexed: 11/20/2022] Open
Abstract
Huanglongbing (HLB), or citrus greening, is a global citrus disease occurring in almost all citrus growing regions. It causes substantial economic burdens to individual growers, citrus industries and governments. Successful management strategies to reduce disease burden are desperately needed but with so many possible interventions and combinations thereof it is difficult to know which are worthwhile or cost-effective. We review how mathematical models have yielded useful insights into controlling disease spread for other vector-borne plant diseases, and the small number of mathematical models of HLB. We adapt a malaria model to HLB, by including temperature-dependent psyllid traits, "flushing" of trees, and economic costs, to show how models can be used to highlight the parameters that require more data collection or that should be targeted for intervention. We analyze the most common intervention strategy, insecticide spraying, to determine the most cost-effective spraying strategy. We find that fecundity and feeding rate of the vector require more experimental data collection, for wider temperatures ranges. Also, the best strategy for insecticide intervention is to spray for more days rather than pay extra for a more efficient spray. We conclude that mathematical models are able to provide useful recommendations for managing HLB spread.
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Affiliation(s)
- Rachel A Taylor
- Department of Integrative Biology, University of South Florida , Tampa, Florida , United States
| | - Erin A Mordecai
- Department of Biology, Stanford University , Stanford, California , United States
| | | | - Jason R Rohr
- Department of Integrative Biology, University of South Florida , Tampa, Florida , United States
| | - Leah R Johnson
- Department of Integrative Biology, University of South Florida, Tampa, Florida, United States; Department of Statistics, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, Virginia, United States
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Sétamou M, Alabi OJ, Kunta M, Jifon JL, da Graça JV. Enhanced Acquisition Rates of 'Candidatus Liberibacter asiaticus' by the Asian Citrus Psyllid (Hemiptera: Liviidae) in the Presence of Vegetative Flush Growth in Citrus. JOURNAL OF ECONOMIC ENTOMOLOGY 2016; 109:1973-1978. [PMID: 27451998 DOI: 10.1093/jee/tow171] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 07/04/2016] [Indexed: 06/06/2023]
Abstract
The Asian citrus psyllid preferentially feeds and exclusively reproduces on young, newly emerged flush shoots of citrus. Asian citrus psyllid nymphs feed and complete their life stages on these flush shoots. Recent studies conducted under greenhouse conditions have shown that the transmission rates of 'Candidatus Liberibacter asiaticus' (CLas), the putative causal agent of huanglongbing disease of citrus, are enhanced when flush shoots are present. However, it is unclear if CLas acquisition by migrant adult Asian citrus psyllids is similarly enhanced. To address this knowledge gap, cohorts of Asian citrus psyllid adults were allowed 1-wk acquisition access period (AAP) on flushing and nonflushing shoots of qPCR-tested symptomatic (CLas+) and asymptomatic (CLas-) 10-yr-old sweet orange trees under field conditions. After the AAP, they were tested for CLas by qPCR. Progeny Asian citrus psyllid adults that emerged 4 wk post-AAP were similarly retrieved and tested. Eighty percent of flushing and 30% of nonflushing CLas+ trees produced infective Asian citrus psyllid adults, indicating that flush shoots have greater potential to be inoculum sources for CLas acquisition. Concomitantly, 21.1% and 6.0% infective adults were retrieved, respectively, from flushing and nonflushing CLas+ trees, indicating that Asian citrus psyllid adults acquire CLas more efficiently from flush shoots relative to mature shoots. In addition, 12.1% of infective Asian citrus psyllid adult progeny were obtained from 70% of flushing CLas+ trees. Significantly lower mean Ct values were also obtained from infective adults retrieved from flushing relative to nonflushing trees. The results underscore the role of flush shoots in CLas acquisition and the need to protect citrus trees from Asian citrus psyllid infestations during flush cycles.
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Affiliation(s)
- Mamoudou Sétamou
- Texas A&M University-Kingsville Citrus Center, Weslaco, TX 78599 (; ; )
| | - Olufemi J Alabi
- Department of Plant Pathology & Microbiology, Texas A&M AgriLife Research and Extension Center, Weslaco, TX 78596
| | - Madhurababu Kunta
- Texas A&M University-Kingsville Citrus Center, Weslaco, TX 78599 (; ; )
| | - John L Jifon
- Department of Horticultural Sciences, Texas A&M AgriLife Research and Extension Center, Weslaco, TX 78596
| | - John V da Graça
- Texas A&M University-Kingsville Citrus Center, Weslaco, TX 78599 (; ; )
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Martini X, Willett DS, Kuhns EH, Stelinski LL. Disruption of Vector Host Preference with Plant Volatiles May Reduce Spread of Insect-Transmitted Plant Pathogens. J Chem Ecol 2016; 42:357-67. [DOI: 10.1007/s10886-016-0695-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 03/22/2016] [Accepted: 04/19/2016] [Indexed: 12/01/2022]
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da Graça JV, Douhan GW, Halbert SE, Keremane ML, Lee RF, Vidalakis G, Zhao H. Huanglongbing: An overview of a complex pathosystem ravaging the world's citrus. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2016; 58:373-87. [PMID: 26466921 DOI: 10.1111/jipb.12437] [Citation(s) in RCA: 143] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 10/12/2015] [Indexed: 05/24/2023]
Abstract
Citrus huanglongbing (HLB) has become a major disease and limiting factor of production in citrus areas that have become infected. The destruction to the affected citrus industries has resulted in a tremendous increase to support research that in return has resulted in significant information on both applied and basic knowledge concerning this important disease to the global citrus industry. Recent research indicates the relationship between citrus and the causal agent of HLB is shaped by multiple elements, in which host defense responses may also play an important role. This review is intended to provide an overview of the importance of HLB to a wider audience of plant biologists. Recent advances on host-pathogen interactions, population genetics and vectoring of the causal agent are discussed.
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Affiliation(s)
- John V da Graça
- Texas A&M University-Kingsville Citrus Center, Weslaco, Texas 78599, USA
| | - Greg W Douhan
- Department of Plant Pathology and Microbiology, University of California, Riverside, California 92521, USA
| | - Susan E Halbert
- Florida Department of Agriculture and Consumer Services, Division of Plant Industry, P.O. Box 147100, Gainesville, Florida 32614, USA
| | - Manjunath L Keremane
- USDA ARS National Clonal Germplasm Repository for Citrus and Dates, Riverside, California 92507, USA
| | - Richard F Lee
- USDA ARS National Clonal Germplasm Repository for Citrus and Dates, Riverside, California 92507, USA
| | - Georgios Vidalakis
- Department of Plant Pathology and Microbiology, University of California, Riverside, California 92521, USA
| | - Hongwei Zhao
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
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Jain M, Fleites LA, Gabriel DW. Prophage-Encoded Peroxidase in 'Candidatus Liberibacter asiaticus' Is a Secreted Effector That Suppresses Plant Defenses. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:1330-7. [PMID: 26313412 DOI: 10.1094/mpmi-07-15-0145-r] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
'Candidatus Liberibacter asiaticus' is transmitted by psyllids and causes huanglongbing (HLB), a lethal disease of citrus. Most pathogenic 'Ca. L. asiaticus' strains carry two nearly identical prophages similar to SC1 and SC2 in strain UF506. SC2 was observed to replicate as a moderately high-copy excision plasmid encoding a reactive oxygen species-scavenging peroxidase (SC2_gp095), a predicted lysogenic conversion factor. SC2_gp095 was expressed at significantly higher levels in periwinkle than in citrus and was suppressed in psyllids. SC2_gp095 was cloned in a shuttle vector and transformed into Escherichia coli and Liberibacter crescens, a culturable proxy for 'Ca. L. asiaticus'. Transformed L. crescens cells showed 20 to 25% enhanced resistance to H₂O₂on agar plates, 47% greater enzymatic activity, and enhanced growth in liquid cultures. A nonclassical secretion potential was predicted for SC2_gp095 and secretion from L. crescens was confirmed by enzymatic and Western blot analyses. Transient expression of SC2_gp095 in planta resulted in strong transcriptional downregulation of RbohB, the key gatekeeper of the H₂O₂-mediated defense signaling in plants, helping explain the surprisingly long incubation period (years) before HLB symptoms appear in 'Ca. L. asiaticus'-infected citrus. 'Ca. L. asiaticus' peroxidase is likely a secreted, horizontally acquired effector that suppresses host symptom development, a tactic used by most biotrophic plant pathogens.
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Affiliation(s)
- Mukesh Jain
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611-0680, U.S.A
| | - Laura A Fleites
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611-0680, U.S.A
| | - Dean W Gabriel
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611-0680, U.S.A
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Lee JA, Halbert SE, Dawson WO, Robertson CJ, Keesling JE, Singer BH. Asymptomatic spread of huanglongbing and implications for disease control. Proc Natl Acad Sci U S A 2015; 112:7605-10. [PMID: 26034273 PMCID: PMC4475945 DOI: 10.1073/pnas.1508253112] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Huanglongbing (HLB) is a bacterial infection of citrus trees transmitted by the Asian citrus psyllid Diaphorina citri. Mitigation of HLB has focused on spraying of insecticides to reduce the psyllid population and removal of trees when they first show symptoms of the disease. These interventions have been only marginally effective, because symptoms of HLB do not appear on leaves for months to years after initial infection. Limited knowledge about disease spread during the asymptomatic phase is exemplified by the heretofore unknown length of time from initial infection of newly developing cluster of young leaves, called flush, by adult psyllids until the flush become infectious. We present experimental evidence showing that young flush become infectious within 15 d after receiving an inoculum of Candidatus Liberibacter asiaticus (bacteria). Using this critical fact, we specify a microsimulation model of asymptomatic disease spread and intensity in a grove of citrus trees. We apply a range of psyllid introduction scenarios to show that entire groves can become infected with up to 12,000 psyllids per tree in less than 1 y, before most of the trees show any symptoms. We also show that intervention strategies that reduce the psyllid population by 75% during the flushing periods can delay infection of a full grove, and thereby reduce the amount of insecticide used throughout a year. This result implies that psyllid surveillance and control, using a variety of recently available technologies, should be used from the initial detection of invasion and throughout the asymptomatic period.
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Affiliation(s)
- Jo Ann Lee
- Department of Mathematics, University of Florida, Gainesville, FL 32611-8105;
| | - Susan E Halbert
- Division of Plant Industry, Florida Department of Agriculture and Consumer Services, Gainesville, FL 32608-1201
| | - William O Dawson
- Department of Plant Pathology, Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850-2243
| | - Cecile J Robertson
- Department of Plant Pathology, Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850-2243
| | - James E Keesling
- Department of Mathematics, University of Florida, Gainesville, FL 32611-8105
| | - Burton H Singer
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610-0009
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Ukuda-Hosokawa R, Sadoyama Y, Kishaba M, Kuriwada T, Anbutsu H, Fukatsu T. Infection Density Dynamics of the Citrus Greening Bacterium "Candidatus Liberibacter asiaticus" in Field Populations of the Psyllid Diaphorina citri and Its Relevance to the Efficiency of Pathogen Transmission to Citrus Plants. Appl Environ Microbiol 2015; 81:3728-36. [PMID: 25819961 PMCID: PMC4421049 DOI: 10.1128/aem.00707-15] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 03/17/2015] [Indexed: 01/02/2023] Open
Abstract
Huanglongbing, or citrus greening, is a devastating disease of citrus plants recently spreading worldwide, which is caused by an uncultivable bacterial pathogen, "Candidatus Liberibacter asiaticus," and vectored by a phloem-sucking insect, Diaphorina citri. We investigated the infection density dynamics of "Ca. Liberibacter asiaticus" in field populations of D. citri with experiments using field-collected insects to address how "Ca. Liberibacter asiaticus" infection density in the vector insect is relevant to pathogen transmission to citrus plants. Of 500 insects continuously collected from "Ca. Liberibacter asiaticus"-infected citrus trees with pathological symptoms in the spring and autumn of 2009, 497 (99.4%) were "Ca. Liberibacter asiaticus" positive. The infections were systemic across head-thorax and abdomen, ranging from 10(3) to 10(7) bacteria per insect. In spring, the infection densities were low in March, at ∼ 10(3) bacteria per insect, increasing up to 10(6) to 10(7) bacteria per insect in April and May, and decreasing to 10(5) to 10(6) bacteria per insect in late May, whereas the infection densities were constantly ∼ 10(6) to 10(7) bacteria per insect in autumn. Statistical analysis suggested that several factors, such as insect sex, host trees, and collection dates, may be correlated with "Ca. Liberibacter asiaticus" infection densities in field D. citri populations. Inoculation experiments with citrus seedlings using field-collected "Ca. Liberibacter asiaticus"-infected insects suggested that (i) "Ca. Liberibacter asiaticus"-transmitting insects tend to exhibit higher infection densities than do nontransmitting insects, (ii) a threshold level (∼ 10(6) bacteria per insect) of "Ca. Liberibacter asiaticus" density in D. citri is required for successful transmission to citrus plants, and (iii) D. citri attaining the threshold infection level transmits "Ca. Liberibacter asiaticus" to citrus plants in a stochastic manner. These findings provide valuable insights into understanding, predicting, and controlling this notorious citrus pathogen.
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Affiliation(s)
- Rie Ukuda-Hosokawa
- Okinawa Prefectural Plant Protection Center, Yaeyama Branch Office, Ishigaki, Okinawa, Japan Okinawa Prefectural Agricultural Research Center, Itoman, Okinawa, Japan
| | | | - Misaki Kishaba
- Okinawa Prefectural Yaeyama Agriculture, Forestry and Fisheries Promotion Center, Ishigaki, Okinawa, Japan
| | - Takashi Kuriwada
- Kagoshima University, Faculty of Education, Laboratory of Zoology, Kagoshima, Japan
| | - Hisashi Anbutsu
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Takema Fukatsu
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo, Japan Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
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Boina DR, Bloomquist JR. Chemical control of the Asian citrus psyllid and of huanglongbing disease in citrus. PEST MANAGEMENT SCIENCE 2015; 71:808-823. [PMID: 25491482 DOI: 10.1002/ps.3957] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 12/02/2014] [Accepted: 12/04/2014] [Indexed: 06/04/2023]
Abstract
By 2014, huanglongbing (HLB), the most destructive disease of citrus, and its insect vector, the Asian citrus psyllid (ACP), Diaphorina citri (Kuwayama), became established in all major citrus-growing regions of the world, including the United States, with the exception of California. At present, application of insecticides is the most widely followed option for reducing ACP populations, while application of antibiotics for suppressing HLB disease/symptoms is being practiced in some citrus-growing regions. Application of insecticides during the dormant winter season, along with cultivation of HLB-free seedlings and early detection and removal of symptomatic and asymptomatic trees, has been very effective in managing ACP. Area-wide management of ACP by application of insecticides at low volume in large areas of citrus cultivation has been shown to be effective in managing HLB and reducing management costs. As insecticide resistance is a major problem in sustainable management of ACP, rotation/alternation of insecticides with different chemistries and modes of action needs to be followed. Besides control of the insect vector, use of antibiotics has temporarily suppressed the symptoms of HLB in diseased trees. Recent efforts to discover and screen existing as well as new compounds for their antibiotic and antimicrobial activities have identified some promising molecules for HLB control. There is an urgent need to find a sustainable solution to the HLB menace through chemical control of ACP populations and within HLB-infected trees through the judicious use of labeled insecticides (existing and novel chemistries) and antibiotics in area-wide management programs with due consideration to the insecticide resistance problem.
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Affiliation(s)
- Dhana Raj Boina
- National Institute of Plant Health Management, Department of Agriculture and Cooperation, Ministry of Agriculture, Government of India, Rajendranagar, Hyderabad, Telangana, India
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Fenichel EP, Richards TJ, Shanafelt DW. The control of invasive species on private property with neighbor-to-neighbor spillovers. ENVIRONMENTAL & RESOURCE ECONOMICS 2014; 59:231-255. [PMID: 25346573 PMCID: PMC4207096 DOI: 10.1007/s10640-013-9726-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Invasive pests cross property boundaries. Property managers may have private incentives to control invasive species despite not having sufficient incentive to fully internalize the external costs of their role in spreading the invasion. Each property manager has a right to future use of his own property, but his property may abut others' properties enabling spread of an invasive species. The incentives for a foresighted property manager to control invasive species have received little attention. We consider the efforts of a foresighted property manager who has rights to future use of a property and has the ability to engage in repeated, discrete control activities. We find that higher rates of dispersal, associated with proximity to neighboring properties, reduce the private incentives for control. Controlling species at one location provides incentives to control at a neighboring location. Control at neighboring locations are strategic complements and coupled with spatial heterogeneity lead to a weaker-link public good problem, in which each property owner is unable to fully appropriate the benefits of his own control activity. Future-use rights and private costs suggest that there is scope for a series of Coase-like exchanges to internalize much of the costs associated with species invasion. Pigouvian taxes on invasive species potentially have qualitatively perverse behavioral effects. A tax with a strong income effect (e.g, failure of effective revenue recycling) can reduce the value of property assets and diminish the incentive to manage insects on one's own property.
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Affiliation(s)
- Eli P. Fenichel
- Yale School of Forestry and Environmental Studies, New Haven, CT 06511, 203.432.5114
| | - Timothy J. Richards
- Arizona State University, Morrison School of Agribusiness and Resource Management, Mesa AZ 85212
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Bayesian inference for an emerging arboreal epidemic in the presence of control. Proc Natl Acad Sci U S A 2014; 111:6258-62. [PMID: 24711393 DOI: 10.1073/pnas.1310997111] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The spread of Huanglongbing through citrus groves is used as a case study for modeling an emerging epidemic in the presence of a control. Specifically, the spread of the disease is modeled as a susceptible-exposed-infectious-detected-removed epidemic, where the exposure and infectious times are not observed, detection times are censored, removal times are known, and the disease is spreading through a heterogeneous host population with trees of different age and susceptibility. We show that it is possible to characterize the disease transmission process under these conditions. Two innovations in our work are (i) accounting for control measures via time dependence of the infectious process and (ii) including seasonal and host age effects in the model of the latent period. By estimating parameters in different subregions of a large commercially cultivated orchard, we establish a temporal pattern of invasion, host age dependence of the dispersal parameters, and a close to linear relationship between primary and secondary infectious rates. The model can be used to simulate Huanglongbing epidemics to assess economic costs and potential benefits of putative control scenarios.
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Steinbauer MJ. Shoot feeding as a nutrient acquisition strategy in free-living psylloids. PLoS One 2013; 8:e77990. [PMID: 24194907 PMCID: PMC3806811 DOI: 10.1371/journal.pone.0077990] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 09/14/2013] [Indexed: 11/25/2022] Open
Abstract
Shoot feeding by sucking insects is accepted as an adaptation to feeding where plant nutrients are most concentrated and/or of higher quality. Psylloids are an important hemipteran taxon, most of which are free-living and comprise many shoot feeding species, whose nutritional ecology has been largely ignored. I conducted a longitudinal study of Ctenarytaina eucalypti (Maskell) and C. bipartita Burckhardt et al. (Aphalaridae) feeding on eucalypts to document how within-plant (ontogenic) variation in nutritional quality, in particular of free amino acids, determines host suitability and hence the distribution and abundance of nymphs. Nymphs were most abundant within developing apical buds but were not more abundant on branchlets of greater vigour (indicated by rate of extension). Nymphs could be found up to two (C. bipartita) to three (C. eucalypti) alternate leaf pairs distant from apical buds but infrequently and in low numbers; they were never found on older, fully expanded leaves. The position of a leaf on a branchlet (indicative of age) determined its nutritional quality. Younger leaves had higher water contents, lower chlorophyll contents and differed in amino acid (essential and non-essential) composition compared to older leaves. The abundance of C. eucalypti nymphs on expanding leaves and in buds was positively correlated with the concentrations of methionine, valine and threonine in E. globulus leaves at the same or comparable position on a branchlet. The abundance of C. bipartita nymphs was positively correlated with foliar leucine concentrations. Shoot feeding by these two psyllids facilitates access to more concentrated, better quality plant nutrients but may not entirely explain the adaptive significance of their behaviour. The humid microclimate created by the architecture of the hosts’ apical buds protects eggs and nymphs from desiccation and is suggested to have had a significant influence on the evolution of host utilisation strategies of psyllids within this genus.
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Affiliation(s)
- Martin J. Steinbauer
- Department of Zoology, La Trobe University, Melbourne, Victoria, Australia
- E-mail:
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