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Ibrahim YE, Al-Saleh MA, Widyawan A, El Komy MH, Al Dhafer HM, Brown JK. Identification and Distribution of the ' Candidatus Liberibacter asiaticus'-Asian Citrus Psyllid Pathosystem in Saudi Arabia. PLANT DISEASE 2024; 108:1083-1092. [PMID: 37953230 DOI: 10.1094/pdis-07-23-1460-re] [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: 11/14/2023]
Abstract
Citrus greening disease was first reported in Saudi Arabia during the 1970s when characteristic foliar and fruit symptoms were observed in commercial citrus groves. However, 'Candidatus Liberibacter asiaticus' (CLas) was not detected in symptomatic trees until 1981 to 1984 when CLas-like cells were observed by transmission electron microscopy in leaves collected from symptomatic citrus groves in southwestern Saudi Arabia. Despite the anticipated establishment of the CLas-Asian citrus psyllid (ACP) (Diaphorina citri Kuwayama) pathosystem, CLas presence has not been verified in suspect trees nor have ACP infestations been documented. Given the recent expansion of citrus production in Saudi Arabia, a systematic country-wide survey was carried out to determine the potential CLas distribution in the 13 citrus-growing regions of the country. Citrus trees were surveyed for the presence of CLas-psyllid vector(s) and characteristic disease symptoms in commercial and urban citrus trees. Adult psyllids collected from infested citrus trees were identified as ACP based on morphological characteristics. Real-time quantitative PCR amplification (qPCR) of the CLas β-subunit of the ribonucleotide reductase (RNR) gene from citrus leaf and fruit samples and/or ACP adults revealed that trees were positive for CLas detection in 10 of the 13 survey regions; however, CLas was undetectable in ACP adults. Phylogenetic and single nucleotide polymorphism (SNP) analyses of a PCR-amplified, cloned fragment of the CLas 16S rRNA gene (∼1.1 kbp) indicated Saudi Arabian isolates were most closely related to Florida, U.S.A., isolates. Analysis of climate variables indicated that the distribution of the ACP-CLas pathosystem observed in Saudi Arabia was consistent with published predictions of terrains most likely to support establishment.
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Affiliation(s)
- Yasser E Ibrahim
- Plant Protection Department, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia
- Bacterial Diseases Research Department, Plant Pathology Research Institute, Agricultural Research Center, Giza, Egypt
| | - Mohammed A Al-Saleh
- Plant Protection Department, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Arya Widyawan
- Plant Protection Department, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Mahmoud H El Komy
- Plant Protection Department, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Hathal M Al Dhafer
- Plant Protection Department, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Judith K Brown
- School of Plant Sciences, The University of Arizona, Tucson, AZ 85721, U.S.A
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McCartney MM, Eze MO, Borras E, Edenfield M, Batuman O, Manker DC, da Graça JV, Ebeler SE, Davis CE. A Metabolomics Assay to Diagnose Citrus Huanglongbing Disease and to Aid in Assessment of Treatments to Prevent or Cure Infection. PHYTOPATHOLOGY 2024; 114:84-92. [PMID: 37486097 PMCID: PMC11014742 DOI: 10.1094/phyto-04-23-0134-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
Citrus greening disease, or Huanglongbing (HLB), has devastated citrus crops globally in recent years. The causal bacterium, 'Candidatus Liberibacter asiaticus', presents a sampling issue for qPCR diagnostics and results in a high false negative rate. In this work, we compared six metabolomics assays to identify HLB-infected citrus trees from leaf tissue extracted from 30 control and 30 HLB-infected trees. A liquid chromatography-mass spectrometry-based assay was most accurate. A final partial least squares-discriminant analysis (PLS-DA) model was trained and validated on 690 leaf samples with corresponding qPCR measures from three citrus varieties (Rio Red grapefruit, Hamlin sweet orange, and Valencia sweet orange) from orchards in Florida and Texas. Trees were naturally infected with HLB transmitted by the insect vector Diaphorina citri. In a randomized validation set, the assay was 99.9% accurate to classify diseased from nondiseased samples. This model was applied to samples from trees receiving plant defense-inducer compounds or biological treatments to prevent or cure HLB infection. From two trials, HLB-related metabolite abundances and PLS-DA scores were tracked longitudinally and compared with those of control trees. We demonstrate how our assay can assess tree health and the efficacy of HLB treatments and conclude that no trialed treatment was efficacious.
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Affiliation(s)
- Mitchell M McCartney
- Mechanical and Aerospace Engineering, University of California Davis, Davis, CA, USA
| | - Michael O Eze
- Mechanical and Aerospace Engineering, University of California Davis, Davis, CA, USA
| | - Eva Borras
- Mechanical and Aerospace Engineering, University of California Davis, Davis, CA, USA
| | | | - Ozgur Batuman
- Plant Pathology, University of Florida, Gainesville, FL, USA
- Southwest Florida Research and Education Center, University of Florida, Immokalee, FL, USA
| | | | - John V da Graça
- Texas A&M University-Kingsville Citrus Center, Weslaco, TX, USA
| | - Susan E Ebeler
- Viticulture and Enology, University of California Davis, Davis, CA, USA
| | - Cristina E Davis
- Mechanical and Aerospace Engineering, University of California Davis, Davis, CA, USA
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Yang T, Li Z, Shu J, Fang L, He X, Li Q, Jiang G, Chen S, Yang B. Rapid Detection of Potential Natural Food Preservatives and Identification of Artemisia Species via High-Sensitivity Photoionization Mass Spectrometry. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023. [PMID: 37022303 DOI: 10.1021/acs.jafc.3c00290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Natural food preservatives are being sought extensively as a safe alternative to chemical food preservatives. This study aimed to identify potential natural preservatives from herbs using single-photon ionization time-of-flight mass spectrometry (SPI-TOF-MS). Five Artemisia species and four other herbs were analyzed, and the random forest (RF) algorithm was used to simulate olfaction and distinguish the Artemisia species by identifying the characteristic peaks of volatile terpenoids (VTPs). Results showed that the terpenoid synthase (TPS) gene family was expanded in Artemisia species, potentially contributing to the increased production of VTPs, which have potential as natural preservatives and specifically identify these species. The limits of detections (LODs) for principle VTPs in Artemisia species were as low as 22-39 parts-per-trillion-by-volume (pptv) using SPI-TOF-MS. This study highlights the potential for headspace mass spectrometry to be used in the development of natural preservatives and the identification of plant species.
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Affiliation(s)
- Teng Yang
- National Engineering Laboratory for VOCs Pollution Control Material & Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhen Li
- National Engineering Laboratory for VOCs Pollution Control Material & Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jinian Shu
- National Engineering Laboratory for VOCs Pollution Control Material & Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Longfa Fang
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems. Engineering Research Center of Grassland Industry, Ministry of Education, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China
| | - Xiaojuan He
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems. Engineering Research Center of Grassland Industry, Ministry of Education, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China
| | - Qirun Li
- National Engineering Laboratory for VOCs Pollution Control Material & Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guoxia Jiang
- National Engineering Laboratory for VOCs Pollution Control Material & Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Siwei Chen
- National Engineering Laboratory for VOCs Pollution Control Material & Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bo Yang
- National Engineering Laboratory for VOCs Pollution Control Material & Technology, University of Chinese Academy of Sciences, Beijing 100049, China
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Snyder J, Dickens KL, Halbert SE, Dowling S, Russell D, Henderson R, Rohrig E, Ramadugu C. The Development and Evaluation of Insect Traps for the Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Psyllidae), Vector of Citrus Huanglongbing. INSECTS 2022; 13:insects13030295. [PMID: 35323593 PMCID: PMC8954215 DOI: 10.3390/insects13030295] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/14/2022] [Accepted: 03/14/2022] [Indexed: 02/05/2023]
Abstract
Simple Summary Citrus cultivation is affected in many parts of the world because of a devastating disease, huanglongbing (HLB) or citrus greening. In Florida, nearly all commercial citrus is compromised due to HLB, and the disease has spread to other citrus-growing regions of the United States, California and Texas. In California, testing Asian citrus psyllids (ACPs) for the HLB pathogen has been an essential part of integrated pest management. ACP and HLB surveys are essential for disease management in areas where HLB is not widespread. We developed improved ACP traps that can be deployed in the field along with the standard yellow sticky traps. The reusable traps were designed with Rhinoceros computer software and a 3D printer. These traps can be deployed for several months and provide a dynamic sampling mechanism for an improved disease survey strategy. In the present study, ACPs from the 3D-printed traps are collected in a preservative and appear suitable for HLB testing. The evaluation of traps in Florida and California under laboratory, greenhouse, and field conditions indicates that the 3D-printed traps can capture ACPs with about the same efficiency as the sticky traps. They are easy to handle and provide an important field tool for HLB management. Abstract Citrus huanglongbing (HLB) is a severe problem for citrus cultivation. The disease management programs benefit from improved field tools suitable for surveying the ACP vector (Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae)) and the associated pathogen. In the present study, we utilize three-dimensional (3D) printers and design tools to develop traps that can capture and preserve ACPs. Three novel, 3D-printed traps were designed and evaluated: stem trap, and cylinder traps 1 and 2. The traps and yellow sticky cards were deployed weekly for 8 months in 2 non-commercial citrus groves in Florida; in California, the traps were evaluated for 12 months in field cages and 4 citrus groves. The stem traps captured lower numbers of ACPs at all experimental sites compared to the cylinder traps. Capture rates in the cylinder traps were comparable to the sticky trap, making the device a viable tool for monitoring field ACPs. The two main advantages of using the reusable 3D traps over standard methods of ACP and HLB surveys include dynamic sampling that can be conducted year-round and the capture of ACPs that can be preserved and tested. Improved trapping may facilitate quick management decisions and mitigate HLB.
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Affiliation(s)
- James Snyder
- Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville, FL 32608, USA; (J.S.); (K.L.D.); (S.E.H.); (S.D.); (D.R.); (E.R.)
| | - Katrina L. Dickens
- Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville, FL 32608, USA; (J.S.); (K.L.D.); (S.E.H.); (S.D.); (D.R.); (E.R.)
| | - Susan E. Halbert
- Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville, FL 32608, USA; (J.S.); (K.L.D.); (S.E.H.); (S.D.); (D.R.); (E.R.)
| | - Stefanie Dowling
- Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville, FL 32608, USA; (J.S.); (K.L.D.); (S.E.H.); (S.D.); (D.R.); (E.R.)
| | - Dyrana Russell
- Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville, FL 32608, USA; (J.S.); (K.L.D.); (S.E.H.); (S.D.); (D.R.); (E.R.)
| | | | - Eric Rohrig
- Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville, FL 32608, USA; (J.S.); (K.L.D.); (S.E.H.); (S.D.); (D.R.); (E.R.)
| | - Chandrika Ramadugu
- Department of Botany and Plant Sciences, University of California Riverside, Riverside, CA 92521, USA
- Correspondence:
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Larson NR, Nega M, Zhang A, Feldlaufer M. Toxicity of Methyl Benzoate and Analogs to Adult Aedes aegypti. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2021; 37:83-86. [PMID: 34184043 DOI: 10.2987/19-6896.1] [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
Methyl benzoate is a natural product (floral volatile organic compound) that is currently used as a food flavoring ingredient. This compound has shown to be insecticidal in laboratory studies against agricultural and urban pests, including spotted wing drosophila Drosophila suzukii, brown marmorated stink bug Hyalomorpha halys, the diamondback moth Plutella xylostella, and the common bed bug Cimex lectularius, to name several insect taxa. In this study we topically treated adult Aedes aegypti females with methyl benzoate and analogs and determined their toxicities. We found that among adult females, 4 analogs-butyl benzoate, n-pentyl benzoate, vinyl benzoate, and methyl 3-methoxybenzoate-were more toxic than the parent compound, methyl benzoate.
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A Multimodal Attract-and-Kill Device for the Asian Citrus Psyllid Diaphorina citri (Hemiptera: Liviidae). INSECTS 2020; 11:insects11120870. [PMID: 33302349 PMCID: PMC7762613 DOI: 10.3390/insects11120870] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 12/01/2020] [Accepted: 12/03/2020] [Indexed: 11/17/2022]
Abstract
Simple Summary Control of Asian citrus psyllid (Diaphorina citri), a vector of Candidatus liberibacter asiaticus (CLas), contributes to management of citrus greening disease (huanglongbing). We developed two prototypes of a multimodal attract-and-kill (AK) device with specific elements of color, attractant, phagostimulant, ultraviolet (UV) reflectant, and toxicant. Key sensory stimuli comprising the AK ingredients were identified in our current and previous research studies and incorporated into a yellow, slow-release wax matrix (SPLAT). This formulation was applied directly to the surface of yellow cylinders, or to corrugated plastic cards housed within perforated cylinders. Psyllids landing on the devices attempted to feed from the wax matrix, became intoxicated, died, and fell from device surfaces. Our laboratory and field experiments showed that AK devices attracted and killed significantly more adult D. citri than ordinary yellow sticky cards and remained fully active over a period of 12 weeks. Effective use of attract-and-kill for management of D. citri could reduce need for broad-spectrum insecticide sprays and encourage biological control as part of an integrated approach to huanglongbing (HLB) management in citrus. Abstract Phytophagous insects, including Asian citrus psyllids (Diaphorina citri Kuwayama), use multiple sensory modalities (vision, olfaction, and gustation,) to locate and accept host plants. We explored incorporation of several sensory cues into a multi-modal attract-and-kill device (AK device) using a three-dimensional shape to increase visibility, as well as elements of color, attractant, phagostimulant, UV reflectant, and toxicant. Attraction of adult D. citri to the device was mediated by a combination of a highly reflective yellow cylinder, a UV reflectant compound (magnesium oxide), and an odorant blend as a short-range attractant. The device surface was coated with a slow-release wax matrix (SPLAT™) augmented with a phagostimulant consisting of a 3-component blend (formic acid, acetic acid, and para-cymene) and an insecticide (β-cyfluthrin). Psyllids landing on the device attempted to feed from the wax matrix, became intoxicated, died, and fell from the device. The device remained fully active over a period of 12 weeks partly because dead psyllids or nontargets did not adhere to the surface as occurs on adhesive yellow sticky cards, the industry standard. Laboratory and field assays showed that the device attracted and killed significantly more adult D. citri than ordinary yellow sticky cards. This device or a future iteration based on the design elements of this device is expected to contribute to sustainable and environmentally appropriate management of D. citri by exploiting the psyllid’s innate behavioral responses to visual, olfactory, and gustatory stimuli.
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Martini X, Hoyte A, Mafra-Neto A, Aksenov AA, Davis CE, Stelinski LL. Progress Toward an Attract-and-Kill Device for Asian Citrus Psyllid (Hemiptera: Liviidae) Using Volatile Signatures of Citrus Infected With Huanglongbing as the Attractant. JOURNAL OF INSECT SCIENCE (ONLINE) 2020; 20:5978894. [PMID: 33180945 PMCID: PMC7751137 DOI: 10.1093/jisesa/ieaa126] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Indexed: 05/04/2023]
Abstract
Asian citrus psyllid, Diaphorina citri (Kuwayama), preferentially orient toward citrus hosts infected with the phytopathogenic bacterium, Candidatus liberibacter asiaticus (CLas) the agent of citrus greening (Huanglongbing, HLB), compared to uninfected counterparts. We investigated whether this preference for the odors of infected plants could be useful for the development of an attract-and-kill (AK) device for D. citri. Twenty-nine blends of volatile organic compounds derived from the odor of citrus infected with CLas were tested in laboratory olfactometer tests, and two blends were also assessed under field conditions. A seven component blend of tricosane: geranial: methyl salicylate: geranyl acetone: linalool: phenylacetaldehyde: (E)-β-ocimene in a 0.40: 0.06: 0.08: 0.29: 0.08: 0.06: 0.03 ratio released from a proprietary slow-release matrix attracted twice more D. citri to yellow sticky traps compared with blank control traps. The attractive blend was subsequently co-formulated with spinosad insecticide into a slow-release matrix to create a prototype AK formulation against D. citri. This formulation effectively reduced the population density of D. citri up to 84% as measured with tap counts when deployed at a density of eight 2.5 g dollops per tree as compared with untreated controls in small plot field trials conducted in citrus orchards. Psyllid populations were not statistically affected at a deployment rate of four dollops per tree. Our results indicate that an AK formulation incorporating spinosad and a volatile blend signature of citrus greening into a slow-release matrix may be useful to suppress D. citri populations.
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Affiliation(s)
- Xavier Martini
- Department of Entomology and Nematology, North Florida Research and Education Center, Quincy, FL
- Corresponding author, e-mail:
| | - Angelique Hoyte
- Department of Entomology and Nematology, Citrus Research and Education Center, Lake Alfred, FL
| | | | - Alexander A Aksenov
- Mechanical and Aerospace Engineering, University of California, Davis, CA
- Present address: Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA
| | - Cristina E Davis
- Mechanical and Aerospace Engineering, University of California, Davis, CA
| | - Lukasz L Stelinski
- Department of Entomology and Nematology, Citrus Research and Education Center, Lake Alfred, FL
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Mou DF, Lee CC, Hahn PG, Soto N, Humphries AR, Helmick EE, Bahder BW. Effects of Lethal Bronzing Disease, Palm Height, and Temperature on Abundance and Monitoring of Haplaxius crudus. INSECTS 2020; 11:E748. [PMID: 33143096 PMCID: PMC7692074 DOI: 10.3390/insects11110748] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 10/23/2020] [Accepted: 10/28/2020] [Indexed: 11/25/2022]
Abstract
Insect vector feeding preference and behavior play important roles in pathogen transmission, especially for pathogens that solely rely on insect vector transmission. This study aims to examine the effects of the 16SrIV-D phytoplasma, the causal agent of lethal bronzing (LB) disease of palms, on associated auchenorrhynchan insects. The numbers of auchenorrhynchans collected during weekly surveys during a yearlong study using yellow sticky traps were analyzed. The cumulative number of H. crudus was 4.5 times greater on phytoplasma-infected relative to non-infected palms. Other auchenorrhynchans showed no difference between phytoplasma-infected and non-infected palms or were greater on non-infected rather than on infected palms. Furthermore, we examined the effects of LB, palm height, temperature, and the interactive effects of these factors on H. crudus abundance. When the palms were infected with LB, at low temperature, H. crudus was more abundant on shorter than taller palms; however, H. crudus was more abundant on taller than shorter palms at the median and higher temperatures. These results may indicate that H. crudus prefers LB-infected palms over non-infected palms. The interactive effects of LB, palm heights, and temperature further suggest that vector monitoring and disease management should be optimized according to seasonal variation in temperature.
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Affiliation(s)
- De-Fen Mou
- Fort Lauderdale Research and Education Center, Department of Entomology and Nematology, University of Florida, 3205 College Ave., Ft. Lauderdale, FL 33314, USA; (N.S.); (A.R.H.); (E.E.H.); (B.W.B.)
| | - Chih-Chung Lee
- School of Biological Sciences, University of Nebraska-Lincoln, 412 Manter Hall, Lincoln, NE 68588, USA;
| | - Philip G. Hahn
- Department of Entomology and Nematology, University of Florida, 1881 Natural Area Dr., Gainesville, FL 32608, USA;
| | - Noemi Soto
- Fort Lauderdale Research and Education Center, Department of Entomology and Nematology, University of Florida, 3205 College Ave., Ft. Lauderdale, FL 33314, USA; (N.S.); (A.R.H.); (E.E.H.); (B.W.B.)
| | - Alessandra R. Humphries
- Fort Lauderdale Research and Education Center, Department of Entomology and Nematology, University of Florida, 3205 College Ave., Ft. Lauderdale, FL 33314, USA; (N.S.); (A.R.H.); (E.E.H.); (B.W.B.)
| | - Ericka E. Helmick
- Fort Lauderdale Research and Education Center, Department of Entomology and Nematology, University of Florida, 3205 College Ave., Ft. Lauderdale, FL 33314, USA; (N.S.); (A.R.H.); (E.E.H.); (B.W.B.)
| | - Brian W. Bahder
- Fort Lauderdale Research and Education Center, Department of Entomology and Nematology, University of Florida, 3205 College Ave., Ft. Lauderdale, FL 33314, USA; (N.S.); (A.R.H.); (E.E.H.); (B.W.B.)
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Khadka A, Allan SA, Cho D, Weeks ENI. Can the Addition of Odor and Visual Targets Enhance Attraction of the Asian Citrus Psyllid (Hemiptera: Liviidae) to Sticky Traps? JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:2563-2567. [PMID: 32804240 DOI: 10.1093/jee/toaa184] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Indexed: 06/11/2023]
Abstract
Asian citrus psyllid, Diaphorina citri Kuwayama, negatively impacts the citrus industry as it transmits Candidatus Liberibacter spp., the causal agent of citrus greening. Monitoring D. citri population levels is critical for management of vectors and citrus greening and is usually through use of yellow sticky traps. In our study, use of odors, odor blends, and visual targets were evaluated to determine whether attraction to yellow sticky traps could be improved. Methyl salicylate consistently increased D. citri attraction to decoy yellow but not to other yellow or yellow/green traps. Addition of a visual target did not enhance attraction to sticky traps. While several chemical blends were evaluated, they did not increase psyllid attraction to decoy yellow traps. The increased attraction to traps with methyl salicylate is promising and may contribute to trapping efficiency under field conditions.
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Affiliation(s)
- Arjun Khadka
- Department of Agriculture, Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, Gainesville, FL
- Entomology and Nematology Department, University of Florida, Gainesville, FL
| | - Sandra A Allan
- Department of Agriculture, Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, Gainesville, FL
| | - Daniel Cho
- Department of Agriculture, Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, Gainesville, FL
| | - Emma N I Weeks
- Entomology and Nematology Department, University of Florida, Gainesville, FL
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Cao S, Sun J, Yuan X, Deng W, Zhong B, Chun J. Characterization of Volatile Organic Compounds of Healthy and Huanglongbing-Infected Navel Orange and Pomelo Leaves by HS-GC-IMS. Molecules 2020; 25:molecules25184119. [PMID: 32916953 PMCID: PMC7570589 DOI: 10.3390/molecules25184119] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/04/2020] [Accepted: 09/04/2020] [Indexed: 01/14/2023] Open
Abstract
The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is the only natural vector of bacteria responsible for Huanglongbing (HLB), a worldwide destructive disease of citrus. ACP reproduces and develops only on the young leaves of its rutaceous host plants. Olfactory stimuli emitted by young leaves may play an important role in ACP control and HLB detection. In this study, volatile organic compounds (VOCs) from healthy and HLB-infected young leaves of navel orange and pomelo were analyzed by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS). A total of 36 compounds (including dimers or polymers) were identified and quantified from orange and 10 from pomelo leaves. Some compounds showed significant differences in signal intensity between healthy and HLB-infected leaves and may constitute possible indicators for HLB infection. Principal component analysis (PCA) clearly discriminated healthy and HLB-infected leaves in both orange and pomelo. HS-GC-IMS was an effective method to identify VOCs from leaves. This study may help develop new methods for detection of HLB or find new attractants or repellents of ACP for prevention of HLB.
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Affiliation(s)
| | | | | | | | | | - Jiong Chun
- Correspondence: ; Tel.: +86-797-839-3068
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11
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Martini X, Malfa K, Stelinski LL, Iriarte FB, Paret ML. Distribution, Phenology, and Overwintering Survival of Asian Citrus Psyllid (Hemiptera: Liviidae), in Urban and Grove Habitats in North Florida. JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:1080-1087. [PMID: 31982907 DOI: 10.1093/jee/toaa011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Indexed: 06/10/2023]
Abstract
Cold hardy citrus is an emerging industry in north Florida. However, it is under the threat of Candidatus Liberibacter asiaticus (CLas), the agent of the citrus disease huanglongbing. Distribution and phenology of the Asian citrus psyllid, Diaphorina citri (Kuwayama), the vector of CLas, was investigated over a 2-year sampling period in north Florida. Diaphorina citri was only found in backyard and ornamental citrus along the Gulf of Mexico, and was not observed in cultivated citrus groves during the 2 years (2017-2018) of the survey. Diaphorina citri population peaks occurred approximately 2 mo later than in central Florida with major population peaks occurring in July. The number of D. citri adults was significantly higher on CLas infected than uninfected citrus trees, whereas more nymphs were found on uninfected trees. Most D. citri were negative for CLas except in Franklin county where both infected trees and psyllids were found. We were able to find adult D. citri during all winter months, despite temperatures as low as -5.5°C. During two consecutive winters, we conducted experiments to determine D. citri cold hardiness by caging D. citri under ambient conditions in mid-November and assessing survivors in the following spring. In 2018, approximately 21%, of D. citri adults survived overwintering whereas 16% survived in 2019 despite lower temperature in 2018 than in 2019. As we are at the earliest stage of HLB infestation, management of D. citri and CLas in north Florida should focus on removal of CLas-infected trees to reduce the reservoir of pathogen.
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Affiliation(s)
- Xavier Martini
- Entomology and Nematology Department, North Florida Research and Education Center, University of Florida, Quincy, FL
| | - Kathi Malfa
- Entomology and Nematology Department, North Florida Research and Education Center, University of Florida, Quincy, FL
| | - Lukasz L Stelinski
- Entomology and Nematology Department, Citrus Research and Education Center, Lake Alfred, FL
| | - Fanny B Iriarte
- Plant Pathology Department, North Florida Research and Education Center, Quincy, FL
| | - Mathews L Paret
- Plant Pathology Department, North Florida Research and Education Center, Quincy, FL
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12
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Sétamou M, Saldaña RR, Hearn JM, Dale J, Feria Arroyo TP, Czokajlo D. Screening Sticky Cards as a Simple Method for Improving Efficiency of Diaphorina citri (Hemiptera: Liviidae) Monitoring and Reducing Nontarget Organisms. JOURNAL OF ECONOMIC ENTOMOLOGY 2019; 112:1167-1174. [PMID: 30869131 DOI: 10.1093/jee/toz045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Indexed: 06/09/2023]
Abstract
Management of Diaphorina citri Kuwayama (Hemiptera: Liviidae) populations is one of the major strategies for reducing the spread and incidence of huanglongbing (HLB). HLB is putatively caused by Candidatus Liberibacter spp. (Rhizobiales: Phyllopbacteriaceae) that are transmitted to citrus by psyllid vectors. Diaphorina citri population monitoring is done to detect its presence and inform on management decisions. Various methods are used for detecting and estimating D. citri densities but trapping with yellow or lime-green sticky cards has proven to be the most effective method. These sticky cards rely on the color preference of adult D. citri, but many flying organisms are attracted to the same color spectrum as psyllids. Hence, in field situations, sticky traps are hampered by large numbers of bycatches of nontarget organisms and debris. Here, we described a method using a mesh laid on the surface of traps as a sift to catch mainly psyllids, while reducing bycatches. By filtering D. citri through this mesh, they can be counted more rapidly and accurately. Although mesh-covered traps captured 5-15% less D. citri relative to uncovered ACP traps, both types of traps statistically agreed on D. citri detection and population densities. The effectiveness of mesh-covered traps did not vary with season. In addition, mesh-covered traps eliminated >90% of nontarget organisms and allowed for quicker enumeration of D. citri. We expect this method will become an important component of redesigning integrated pest management programs in citrus groves by reducing unintended impacts of beneficial arthropods during large scale D. citri monitoring.
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Affiliation(s)
| | | | - James M Hearn
- Citrus Center, Texas A&M University-Kingsville, Weslaco, TX
| | - Jon Dale
- Texas Citrus Pest and Disease Management Corporation, Mission, TX
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13
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Brilli F, Loreto F, Baccelli I. Exploiting Plant Volatile Organic Compounds (VOCs) in Agriculture to Improve Sustainable Defense Strategies and Productivity of Crops. FRONTIERS IN PLANT SCIENCE 2019; 10:264. [PMID: 30941152 PMCID: PMC6434774 DOI: 10.3389/fpls.2019.00264] [Citation(s) in RCA: 116] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 02/19/2019] [Indexed: 05/19/2023]
Abstract
There is an urgent need for new sustainable solutions to support agriculture in facing current environmental challenges. In particular, intensification of productivity and food security needs require sustainable exploitation of natural resources and metabolites. Here, we bring the attention to the agronomic potential of volatile organic compounds (VOCs) emitted from leaves, as a natural and eco-friendly solution to defend plants from stresses and to enhance crop production. To date, application of VOCs is often limited to fight herbivores. Here we argue that potential applications of VOCs are much wider, as they can also protect from pathogens and environmental stresses. VOCs prime plant's defense mechanisms for an enhanced resistance/tolerance to the upcoming stress, quench reactive oxygen species (ROS), have potent antimicrobial as well as allelopathic effects, and might be important in regulating plant growth, development, and senescence through interactions with plant hormones. Current limits and drawbacks that may hamper the use of VOCs in open field are analyzed, and solutions for a better exploitation of VOCs in future sustainable agriculture are envisioned.
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Affiliation(s)
- Federico Brilli
- Institute for Sustainable Plant Protection, National Research Council of Italy, Florence, Italy
- *Correspondence: Federico Brilli,
| | - Francesco Loreto
- Department of Biology, Agriculture and Food Sciences, National Research Council of Italy, Rome, Italy
| | - Ivan Baccelli
- Institute for Sustainable Plant Protection, National Research Council of Italy, Florence, Italy
- Ivan Baccelli,
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14
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Patt JM, Meikle WG, Niedz RP, Woods D. Synthetic Ligands of Olfactory Binding Proteins Modulate Aggregation Response of Asian Citrus Psyllid in the Presence of Host-Plant Volatiles. FRONTIERS IN PLANT SCIENCE 2018; 9:1891. [PMID: 30619436 PMCID: PMC6306466 DOI: 10.3389/fpls.2018.01891] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 12/06/2018] [Indexed: 06/09/2023]
Abstract
There is interest in using ligands of chemosensory binding proteins (CBP) to augment an insect's responsiveness to chemosensory cues. We showed previously that combining a synthetic ligand of a CBP with limonene, a common citrus volatile, enhanced the probing response of Asian citrus psyllid (Diaphorina citri). Here, we determined whether synthetic compounds, which were ligands of D. citri olfactory binding protein (OBP) DCSAP4, influenced the settling and aggregation levels of psyllids on young citrus shoots. The test ligands and Cmac scent were dispensed from a droplet of an emulsified wax product (SPLAT) placed on the bottom of each vial. The shoots were presented: (1) alone (shoot + blank SPLAT), (2) with a mixture of citrus volatiles ("Cmac scent") (shoot + SPLAT with Cmac scent), or (3) with different concentrations of test ligands (shoot + SPLAT with test ligand at concentration 1, shoot + SPLAT with test ligand at concentration 2, etc.). Depending on the availability of test ligands, sprigs, and psyllids, each test included from two to four replicates of each treatment (i.e., shoot only, shoot + Cmac scent, shoot + test ligand at concentration 1, shoot + test ligand at concentration 2, etc.); only a single test ligand was presented in each test. For each test, 200 D. citri were released in the test area and the numbers of psyllids on each sprig were counted 24 h later. Sprigs with ≥7 psyllids were considered to be an aggregation. A total of seven ligands were tested individually. Four of the ligands (654, 717, 784, and 861) modulated psyllid settling and aggregation response, causing greater settling and aggregation to sprigs presented with the Cmac scent than to those sprigs with blank SPLAT. Presentation of one of the ligands (019) resulted in an opposite effect in which psyllid settling and aggregation levels were lower on sprigs with Cmac scent than on those with blank SPLAT. There were no differences in settling levels in the different treatment vials in the Ligand 905 experiment. In the Ligand 937 experiment, settling levels did not vary significantly between treatment vials although settling levels were relatively high in all treatment vials and there was a significant treatment effect. Increased settling and aggregation levels were largely not observed with in the vials with only the test ligands, and there was little effect of ligand concentration on psyllid response levels. This suggests that the test ligands themselves did not attract the psyllids but rather modulated the psyllid's response to the Cmac scent. The results suggest that synthetic ligands of D. citri CBPs can be used to increase the effectiveness of citrus scent lures used to attract psyllids to monitoring traps and attract and kill devices.
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Affiliation(s)
- Joseph M. Patt
- USDA-ARS U.S. Horticultural Research Laboratory, Fort Pierce, FL, United States
| | | | - Randall P. Niedz
- USDA-ARS U.S. Horticultural Research Laboratory, Fort Pierce, FL, United States
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15
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Not Led by the Nose: Volatiles from Undamaged Eucalyptus Hosts Do Not Influence Psyllid Orientation. INSECTS 2018; 9:insects9040166. [PMID: 30453652 PMCID: PMC6316837 DOI: 10.3390/insects9040166] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 11/08/2018] [Accepted: 11/14/2018] [Indexed: 12/17/2022]
Abstract
Psyllids (Hemiptera: Psylloidea) are small sucking insects with high host plant specificity. Despite the primitive olfactory system of psyllids, some species have been suggested to rely on host plant volatiles (HPVs) for seasonal migration between summer deciduous hosts and winter coniferous hosts. Similarly, enhanced attraction of psyllid vectors has been observed as a result of the manipulation of host odors by plant pathogens. As yet, there are no studies of olfaction in psyllids that utilize evergreen eucalypt hosts. We investigated the behavioral responses of adults of four Eucalyptus-feeding psyllids—Ctenarytaina eucalypti, C. bipartita, Anoeconeossa bundoorensis and Glycaspis brimblecombei—to their respective HPVs in Y-tube olfactometer bioassays. We also used existing physiological data for C. eucalypti to investigate potential olfactory tuning that may modulate the preference for morphologically juvenile leaves over morphologically adult leaves. Although adult C. eucalypti were consistently repelled by HPVs from damaged host leaves, none of the species exhibited positive chemotaxis to HPVs from undamaged leaves. Surprisingly, G. brimblecombei was repelled by HPVs from undamaged host leaves. Our findings provide little support for a significant role of olfaction in host location by Eucalyptus-feeding psyllids. We propose a number of ecological hypotheses to explain these unexpected findings.
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Martini X, Coy M, Kuhns E, Stelinski LL. Temporal Decline in Pathogen-Mediated Release of Methyl Salicylate Associated With Decreasing Vector Preference for Infected Over Uninfected Plants. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00185] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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17
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Patt JM, Robbins PS, Niedz R, McCollum G, Alessandro R. Exogenous application of the plant signalers methyl jasmonate and salicylic acid induces changes in volatile emissions from citrus foliage and influences the aggregation behavior of Asian citrus psyllid (Diaphorina citri), vector of Huanglongbing. PLoS One 2018; 13:e0193724. [PMID: 29596451 PMCID: PMC5875780 DOI: 10.1371/journal.pone.0193724] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 02/18/2018] [Indexed: 11/18/2022] Open
Abstract
Huanglongbing, also known as citrus greening, is a destructive disease that threatens citrus production worldwide. It is putatively caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus (Las). Currently, the disease is untreatable and efforts focus on intensive insecticide use to control the vector, Asian citrus psyllid (Diaphorina citri). Emerging psyllid resistance to multiple insecticides has generated investigations into the use of exogenously applied signaling compounds to enhance citrus resistance to D. citri and Las. In the present study, we examined whether foliar applications of methyl jasmonate (MJ), a volatile signaling compound associated with the induced systemic resistance pathway, and salicylic acid, a constituent of the systemic acquired resistance pathway, would elicit the emission of defense-related volatiles in citrus foliage, and what effect this might have on the host-plant searching behavior of D. citri. Comparisons were made of volatiles emitted from growing shoots of uninfected and Las-infected 'Valencia' sweet orange (Citrus sinensis) trees over two consecutive sampling days. A settling behavioral assay was used to compare psyllid attraction to MJ-treated vs. Tween-treated citrus sprigs. All three main effects, Las infection status, plant signaler application, and sampling day, influenced the proportions of individual volatile compounds emitted in different treatment groups. MJ- and SA-treated trees had higher emission rates than Tween-treated trees. Methyl salicylate (MeSA) and β-caryophyllene were present in higher proportions in the volatiles collected from Las-infected + trees. On the other hand, Las-infected + MJ-treated trees emitted lower proportions of MeSA than did Las-infected + Tween-treated trees. Because MeSA is a key D. citri attractant, this result suggests that MJ application could suppress MeSA emission from Las-infected trees, an approach that could be used to discourage psyllid colonization during shoot growth. MJ application enhanced emission of E-β-ocimene, indole, volatiles attractive to many of the psyllid's natural enemies, indicating that MJ application could be used in an 'attract and reward' conservation biological control strategy. Volatile emissions in SA-treated trees were dominated by MeSA. MJ application elicited aggregation behavior in D. citri. Similar numbers of psyllids settled on MJ-treated versus Tween-treated sprigs, but a significantly greater percentage of the MJ-treated sprigs had aggregations of nine or more psyllids on them. Taken together, the results of this study indicate that exogenous applications of MJ or SA could be used to influence Asian citrus psyllid settling behavior and attract its natural enemies.
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Affiliation(s)
- Joseph M. Patt
- United States Department of Agriculture, Agricultural Research Service, U.S. Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
- * E-mail:
| | - Paul S. Robbins
- United States Department of Agriculture, Agricultural Research Service, U.S. Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
| | - Randy Niedz
- United States Department of Agriculture, Agricultural Research Service, U.S. Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
| | - Greg McCollum
- United States Department of Agriculture, Agricultural Research Service, U.S. Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
| | - Rocco Alessandro
- United States Department of Agriculture, Agricultural Research Service, U.S. Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
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18
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Wang N, Stelinski LL, Pelz-Stelinski KS, Graham JH, Zhang Y. Tale of the Huanglongbing Disease Pyramid in the Context of the Citrus Microbiome. PHYTOPATHOLOGY 2017; 107:380-387. [PMID: 28095208 DOI: 10.1094/phyto-12-16-0426-rvw] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The Huanglongbing (HLB) disease pyramid is composed of Liberibacters, psyllid vectors, citrus hosts, and the environment. The epidemiological outcomes for Liberibacter-associated plant diseases are collectively determined by the inherent relationships among plant-Liberibacters-psyllids, and how various environmental factors affect plant-Liberibacter-psyllid interactions. Citrus-Liberibacter-psyllid interactions occur in a complex microbiome system. In this review, we focus on the progress in understanding the HLB disease pyramid, and how the microbiome affects the HLB disease pyramid including the interaction between HLB and the citrus microbiome; the interaction between Liberibacters and psyllids; the interaction between Liberibacters and gut microbiota in psyllids; and the effect of HLB on selected above- and belowground citrus pathogens. Their implications for HLB management are also discussed.
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Affiliation(s)
- Nian Wang
- First and fifth authors: Department of Microbiology and Cell Science, second and third authors: Department of Entomology and Nematology, and fourth author: Department of Soil and Water Sciences, Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL
| | - Lukasz L Stelinski
- First and fifth authors: Department of Microbiology and Cell Science, second and third authors: Department of Entomology and Nematology, and fourth author: Department of Soil and Water Sciences, Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL
| | - Kirsten S Pelz-Stelinski
- First and fifth authors: Department of Microbiology and Cell Science, second and third authors: Department of Entomology and Nematology, and fourth author: Department of Soil and Water Sciences, Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL
| | - James H Graham
- First and fifth authors: Department of Microbiology and Cell Science, second and third authors: Department of Entomology and Nematology, and fourth author: Department of Soil and Water Sciences, Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL
| | - Yunzeng Zhang
- First and fifth authors: Department of Microbiology and Cell Science, second and third authors: Department of Entomology and Nematology, and fourth author: Department of Soil and Water Sciences, Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL
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19
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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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20
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Šimpraga M, Takabayashi J, Holopainen JK. Language of plants: Where is the word? JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2016; 58:343-9. [PMID: 26563972 DOI: 10.1111/jipb.12447] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 11/06/2015] [Indexed: 05/03/2023]
Abstract
Plants emit biogenic volatile organic compounds (BVOCs) causing transcriptomic, metabolomic and behavioral responses in receiver organisms. Volatiles involved in such responses are often called "plant language". Arthropods having sensitive chemoreceptors can recognize language released by plants. Insect herbivores, pollinators and natural enemies respond to composition of volatiles from plants with specialized receptors responding to different types of compounds. In contrast, the mechanism of how plants "hear" volatiles has remained obscured. In a plant-plant communication, several individually emitted compounds are known to prime defense response in receiver plants with a specific manner according to the chemical structure of each volatile compound. Further, composition and ratio of volatile compounds in the plant-released plume is important in plant-insect and plant-plant interactions mediated by plant volatiles. Studies on volatile-mediated plant-plant signaling indicate that the signaling distances are rather short, usually not longer than one meter. Volatile communication from plants to insects such as pollinators could be across distances of hundreds of meters. As many of the herbivore induced VOCs have rather short atmospheric life times, we suggest that in long-distant communications with plant volatiles, reaction products in the original emitted compounds may have additional information value of the distance to emission source together with the original plant-emitted compounds.
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Affiliation(s)
- Maja Šimpraga
- Botanical Garden, Faculty of Science, Ghent University, Ledeganck 35, B-9000 Ghent, Belgium
- Department of Environmental Science, University of Eastern Finland, P.O. Box 1627 Kuopio, Finland
| | - Junji Takabayashi
- Center for Ecological Research, Kyoto University, 2-509-3 Hirano, Otsu, Shiga 520-2113, Japan
| | - Jarmo K Holopainen
- Department of Environmental Science, University of Eastern Finland, P.O. Box 1627 Kuopio, Finland
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The Influence of Learning on Host Plant Preference in a Significant Phytopathogen Vector, Diaphorina citri. PLoS One 2016; 11:e0149815. [PMID: 26930355 PMCID: PMC4773162 DOI: 10.1371/journal.pone.0149815] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 02/04/2016] [Indexed: 11/19/2022] Open
Abstract
Although specialist herbivorous insects are guided by innate responses to host plant cues, host plant preference may be influenced by experience and is not dictated by instinct alone. The effect of learning on host plant preference was examined in the Asian citrus psyllid, Diaphorina citri; vector of the causal agent of citrus greening disease or huanglongbing. We investigated: a) whether development on specific host plant species influenced host plant preference in mature D. citri; and b) the extent of associative learning in D. citri in the form of simple and compound conditioning. Learning was measured by cue selection in a 2-choice behavioral assay and compared to naïve controls. Our results showed that learned responses in D. citri are complex and diverse. The developmental host plant species influenced adult host plant preference, with female psyllids preferring the species on which they were reared. However, such preferences were subject to change with the introduction of an alternative host plant within 24–48 hrs, indicating a large degree of experience-dependent response plasticity. Additionally, learning occurred for multiple sensory modalities where novel olfactory and visual environmental cues were associated with the host plant. However, males and females displayed differing discriminatory abilities. In compound conditioning tasks, males exhibited recognition of a compound stimulus alone while females were capable of learning the individual components. These findings suggest D. citri are dynamic animals that demonstrate host plant preference based on developmental and adult experience and can learn to recognize olfactory and visual host plant stimuli in ways that may be sex specific. These experience-based associations are likely used by adults to locate and select suitable host plants for feeding and reproduction and may suggest the need for more tailored lures and traps, which reflect region-specific cultivars or predominate Rutaceae in the area being monitored.
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