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Gagnon AÈ, Fortier AM, Audette C. Biological Control and Habitat Management for the Control of Onion Thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), in Onion Production in Quebec, Canada. INSECTS 2024; 15:232. [PMID: 38667362 PMCID: PMC11050518 DOI: 10.3390/insects15040232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 03/19/2024] [Accepted: 03/21/2024] [Indexed: 04/28/2024]
Abstract
Onion thrips (Thrips tabaci) can pose a significant threat to onion crops, causing leaf damage, reduced bulb size and quality, and yield loss during severe infestations. Conventional insecticide use has been the primary method for managing this pest species, but the efficacy of this approach is inconsistent. Furthermore, emerging pest resistance is a growing concern in some regions. This two-year field study aimed to assess the effectiveness of several pest management strategies in controlling onion thrips populations and limiting their impact on onion yields. The strategies tested consisted of habitat manipulations (including flower strips and straw mulch), biological control agents (Stratiolaelaps scimitus, Neoseiulus cucumeris, Amblyseius swirskii, and Beauveria bassiana), as well as physical barrier control methods (exclusion nets, kaolin, and mineral oil). Habitat manipulation techniques, particularly the use of flower strips, reduced thrips populations by up to 50% and increased onion yields by 25%. In contrast, exclusion nets had a detrimental effect on onion yields, and the other alternative control methods produced results comparable to those obtained for untreated controls. When used alone, biological control agents were not effective at maintaining thrips populations below economically damaging levels. This study offers valuable insights into effective and sustainable pest management practices for the onion industry.
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Affiliation(s)
- Annie-Ève Gagnon
- Saint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food Canada, 430 Gouin Boulevard, Saint-Jean-sur-Richelieu, QC J3B 3E6, Canada;
| | - Anne-Marie Fortier
- Compagnie de Recherche Phytodata Inc., 291 Rue de la Coopérative, Sherrington, QC J0L 2N0, Canada;
| | - Carolane Audette
- Saint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food Canada, 430 Gouin Boulevard, Saint-Jean-sur-Richelieu, QC J3B 3E6, Canada;
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Jouraku A, Tomizawa Y, Watanabe K, Yamada K, Kuwazaki S, Aizawa M, Toda S, Sonoda S. Evolutionary origin and distribution of amino acid mutations associated with resistance to sodium channel modulators in onion thrips, Thrips tabaci. Sci Rep 2024; 14:3792. [PMID: 38360913 PMCID: PMC10869772 DOI: 10.1038/s41598-024-54443-9] [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: 11/23/2023] [Accepted: 02/13/2024] [Indexed: 02/17/2024] Open
Abstract
In onion thrips Thrips tabaci, reduced sensitivity of the sodium channel caused by several sodium channel mutations have been correlated with pyrethroid resistance. For this study, using mitochondrial cytochrome c oxidase subunit I gene sequences, we examined the phylogenetic relation among a total of 52 thelytokous and arrhenotokous strains with different genotypes of the sodium channel mutations. Then, we used flow cytometry to estimate their ploidy. Results showed that the strains are divisible into three groups: diploid thelytoky, triploid thelytoky, and diploid arrhenotoky. Using 23 whole genome resequencing data obtained from 20 strains out of 52, we examined their genetic relation further using principal component analysis, admixture analysis, and a fixation index. Results showed that diploid and triploid thelytokous groups are further classifiable into two based on the sodium channel mutations harbored by the respective group members (strains). The greatest genetic divergence was observed between thelytokous and arrhenotokous groups with a pair of T929I and K1774N. Nevertheless, they shared a genomic region with virtually no polymorphism around the sodium channel gene loci, suggesting a hard selective sweep. Based on these findings, we discuss the evolutionary origin and distribution of the sodium channel mutations in T. tabaci.
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Affiliation(s)
- Akiya Jouraku
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, 305-8634, Japan
| | - Yui Tomizawa
- School of Agriculture, Utsunomiya University, Utsunomiya, Tochigi, 321-8505, Japan
| | - Kazuki Watanabe
- School of Agriculture, Utsunomiya University, Utsunomiya, Tochigi, 321-8505, Japan
| | - Kiyoshi Yamada
- School of Agriculture, Utsunomiya University, Utsunomiya, Tochigi, 321-8505, Japan
| | - Seigo Kuwazaki
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, 305-8634, Japan
| | - Misato Aizawa
- Seisan Regional Agricultural Extension Center, Mitoyo, Kagawa, 769-1503, Japan
| | - Satoshi Toda
- Institute for Plant Protection, National Agriculture and Food Research Organization, Higashihiroshima, Hiroshima, 739-2494, Japan
| | - Shoji Sonoda
- School of Agriculture, Utsunomiya University, Utsunomiya, Tochigi, 321-8505, Japan.
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Moural TW, Koirala B K S, Bhattarai G, He Z, Guo H, Phan NT, Rajotte EG, Biddinger DJ, Hoover K, Zhu F. Architecture and potential roles of a delta-class glutathione S-transferase in protecting honey bee from agrochemicals. CHEMOSPHERE 2024; 350:141089. [PMID: 38163465 DOI: 10.1016/j.chemosphere.2023.141089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 12/19/2023] [Accepted: 12/29/2023] [Indexed: 01/03/2024]
Abstract
The European honey bee, Apis mellifera, serves as the principle managed pollinator species globally. In recent decades, honey bee populations have been facing serious health threats from combined biotic and abiotic stressors, including diseases, limited nutrition, and agrochemical exposure. Understanding the molecular mechanisms underlying xenobiotic adaptation of A. mellifera is critical, considering its extensive exposure to phytochemicals and agrochemicals present in the environment. In this study, we conducted a comprehensive structural and functional characterization of AmGSTD1, a delta class glutathione S-transferase (GST), to unravel its roles in agrochemical detoxification and antioxidative stress responses. We determined the 3-dimensional (3D) structure of a honey bee GST using protein crystallography for the first time, providing new insights into its molecular structure. Our investigations revealed that AmGSTD1 metabolizes model substrates, including 1-chloro-2,4-dinitrobenzene (CDNB), p-nitrophenyl acetate (PNA), phenylethyl isothiocyanate (PEITC), propyl isothiocyanate (PITC), and the oxidation byproduct 4-hydroxynonenal (HNE). Moreover, we discovered that AmGSTD1 exhibits binding affinity with the fluorophore 8-Anilinonaphthalene-1-sulfonic acid (ANS), which can be inhibited with various herbicides, fungicides, insecticides, and their metabolites. These findings highlight the potential contribution of AmGSTD1 in safeguarding honey bee health against various agrochemicals, while also mitigating oxidative stress resulting from exposure to these substances.
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Affiliation(s)
- Timothy W Moural
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA.
| | - Sonu Koirala B K
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA.
| | - Gaurab Bhattarai
- Institute of Plant Breeding, Genetics & Genomics, University of Georgia, Athens, GA 30602, USA.
| | - Ziming He
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA.
| | - Haoyang Guo
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA.
| | - Ngoc T Phan
- Department of Entomology and Plant Pathology, University of Arkansas, AR 72701, USA; Research Center for Tropical Bees and Beekeeping, Vietnam National University of Agriculture, Gia Lam, Hanoi 100000, Viet Nam.
| | - Edwin G Rajotte
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA.
| | - David J Biddinger
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA; Penn State Fruit Research and Extension Center, Biglerville, PA 17307, USA.
| | - Kelli Hoover
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA.
| | - Fang Zhu
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA; Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA.
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Porta B, Vosman B, Visser RGF, Galván GA, Scholten OE. Genetic diversity of thrips populations on Allium species around the world. PLoS One 2023; 18:e0289984. [PMID: 37590309 PMCID: PMC10434924 DOI: 10.1371/journal.pone.0289984] [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: 03/03/2023] [Accepted: 07/28/2023] [Indexed: 08/19/2023] Open
Abstract
Thrips are a serious pest in many crops. In onion cultivation, Thrips tabaci is the most important, but not the only thrips species causing damage. We investigated which thrips species affects onion and related species worldwide, how much genetic variation there is within T. tabaci populations, and how this evolves. Furthermore, we determined the reproductive mode and the correlation between the genetic and geographic distances. Thrips samples from infested onions or related species were obtained from 14 different locations worldwide. Species and haplotypes were determined through DNA barcoding with the mitochondrial Cytochrome Oxidase subunit I (COI) gene. Thrips tabaci was the most commonly observed species, but Scirtothrips dorsalis, Thrips palmi, Frankliniella intonsa, Frankliniella occidentalis and Frankliniella tenuicornis were also found, especially at the beginning of the growing seasons and depending on the location. The Nei's genetic distance within T. tabaci was less than 5% and the haplotypes were clustered into two phylogenetic groups, each linked to a specific mode of reproduction, thelytokous or arrhenotokous. Thelytokous thrips were more common and more widely distributed than arrhenotokous thrips. A high percentage of heteroplasmy was detected in the arrhenotokous group. Heteroplasmic thrips were only found in populations where thelytokous and arrhenotokous were present in sympatry. Some T. tabaci haplotypes were present in high frequency at several sampled locations. No correlation was found between the genetic and geographic distances, which points to anthropic activities spreading thrips haplotypes throughout the world.
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Affiliation(s)
- Bettina Porta
- Plant Breeding, Wageningen University and Research Centre, Wageningen, The Netherlands
- Departamento de Biología Vegetal, Facultad de Agronomía, Universidad de la República, Montevideo, Uruguay
| | - Ben Vosman
- Plant Breeding, Wageningen University and Research Centre, Wageningen, The Netherlands
| | - Richard G. F. Visser
- Plant Breeding, Wageningen University and Research Centre, Wageningen, The Netherlands
| | - Guillermo A. Galván
- Departamento de Producción Vegetal, Centro Regional Sur (CRS), Facultad de Agronomía, Universidad de la República, Progreso, Canelones, Uruguay
| | - Olga E. Scholten
- Plant Breeding, Wageningen University and Research Centre, Wageningen, The Netherlands
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Pang S, Lin Z, Chen WJ, Chen SF, Huang Y, Lei Q, Bhatt P, Mishra S, Chen S, Wang H. High-efficiency degradation of methomyl by the novel bacterial consortium MF0904: Performance, structural analysis, metabolic pathways, and environmental bioremediation. JOURNAL OF HAZARDOUS MATERIALS 2023; 452:131287. [PMID: 37003005 DOI: 10.1016/j.jhazmat.2023.131287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/21/2023] [Accepted: 03/23/2023] [Indexed: 05/03/2023]
Abstract
Methomyl is a widely used carbamate pesticide, which has adverse biological effects and poses a serious threat to ecological environments and human health. Several bacterial isolates have been investigated for removing methomyl from environment. However, low degradation efficiency and poor environmental adaptability of pure cultures severely limits their potential for bioremediation of methomyl-contaminated environment. Here, a novel microbial consortium, MF0904, can degrade 100% of 25 mg/L methomyl within 96 h, an efficiency higher than that of any other consortia or pure microbes reported so far. The sequencing analysis revealed that Pandoraea, Stenotrophomonas and Paracoccus were the predominant members of MF0904 in the degradation process, suggesting that these genera might play pivotal roles in methomyl biodegradation. Moreover, five new metabolites including ethanamine, 1,2-dimethyldisulfane, 2-hydroxyacetonitrile, N-hydroxyacetamide, and acetaldehyde were identified using gas chromatography-mass spectrometry, indicating that methomyl could be degraded firstly by hydrolysis of its ester bond, followed by cleavage of the C-S ring and subsequent metabolism. Furthermore, MF0904 can successfully colonize and substantially enhance methomyl degradation in different soils, with complete degradation of 25 mg/L methomyl within 96 and 72 h in sterile and nonsterile soil, respectively. Together, the discovery of microbial consortium MF0904 fills a gap in the synergistic metabolism of methomyl at the community level and provides a potential candidate for bioremediation applications.
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Affiliation(s)
- Shimei Pang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China
| | - Ziqiu Lin
- The Hong Kong University of Science and Technology, Hong Kong, China
| | - Wen-Juan Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Shao-Fang Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Yaohua Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Qiqi Lei
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Pankaj Bhatt
- Department of Agricultural & Biological Engineering, Purdue University, West Lafayette 47906, USA
| | - Sandhya Mishra
- Environmental Technologies Division, CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow 226001, India
| | - Shaohua Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China.
| | - Huishan Wang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China.
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Fan Z, Qian L, Chen Y, Fan R, He S, Gao Y, Gui F. Effects of elevated CO 2 on activities of protective and detoxifying enzymes in Frankliniella occidentalis and F. intonsa under spinetoram stress. PEST MANAGEMENT SCIENCE 2022; 78:274-286. [PMID: 34480397 DOI: 10.1002/ps.6630] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 08/15/2021] [Accepted: 09/04/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Elevated CO2 can directly affect the toxicity of insecticides to insects and the physiological response of insects to insecticides. Frankliniella occidentalis and F. intonsa are highly destructive pests that target horticultural crops. Spinetoram is an effective pesticide against thrips. This study sought to explore the effect of elevated CO2 on efficacy of spinetoram against F. occidentalis and F. intonsa and effect of the spinetoram on activities of protective and detoxifying enzymes under elevated CO2 . Notably, these enzymes can be exploited in further studies to develop interventions for thrips resistance management. RESULTS Toxicity bioassay showed that the LC50 values of F. occidentalis and F. intonsa exposed to spinetoram at elevated CO2 (800 μL L-1 concentration) for 48 h was 0.08 and 0.006 mg L-1 , respectively, which is 0.62 and 0.75 times of the values at ambient CO2 (400 μL L-1 concentration). The findings showed that elevated CO2 decreased activities of the superoxide dismutase and acetylcholinesterase in thrips, while increasing the activities of carboxylesterase and glutathione S-transferase. However, spinetoram increased activities of protective and detoxifying enzymes in both thrips under the two CO2 levels. Elevated CO2 and spinetoram affect the physiological enzyme activity in thrips synergistically, and the activities of analyzed enzymes were generally higher in F. occidentalis than in F. intonsa. CONCLUSION Elevated CO2 amplifies the efficacy of spinetoram on thrips, F. intonsa is more susceptibility to spinetoram than F. occidentalis and the latter showed better adaptation to adverse conditions than the former. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Zongfang Fan
- State Key Laboratory of Conservation and Utilization of Biological Resources of Yunnan, College of Plant Protection, Yunnan Agricultural University, Kunming, China
| | - Lei Qian
- Institute of Leisure Agriculture, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Yaping Chen
- State Key Laboratory of Conservation and Utilization of Biological Resources of Yunnan, College of Plant Protection, Yunnan Agricultural University, Kunming, China
| | - Rui Fan
- State Key Laboratory of Conservation and Utilization of Biological Resources of Yunnan, College of Plant Protection, Yunnan Agricultural University, Kunming, China
| | - Shuqi He
- State Key Laboratory of Conservation and Utilization of Biological Resources of Yunnan, College of Plant Protection, Yunnan Agricultural University, Kunming, China
| | - Yulin Gao
- State Key Laboratory for Biology of Plant Diseases and Insect Pest, Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing, China
| | - Furong Gui
- State Key Laboratory of Conservation and Utilization of Biological Resources of Yunnan, College of Plant Protection, Yunnan Agricultural University, Kunming, China
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Schnaars-Uvino K, Baker MB. High-level field-evolved resistance to spinosad in Colorado potato beetle, Leptinotarsa decemlineata, in organically managed fields. PEST MANAGEMENT SCIENCE 2021; 77:4393-4399. [PMID: 33973695 DOI: 10.1002/ps.6473] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 04/05/2021] [Accepted: 05/11/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Organic pest management eschews synthetic pesticides and insecticide resistance is rarely studied in organically managed systems. Spinosad is a biologically based insecticide used widely by both organic and conventional growers. Colorado potato beetle, Leptinotarsa decemlineata, is infamous for its ability to evolve resistance to insecticides. Spinosad resistance was surveyed in conventionally managed fields in eastern New York in 2006. In response to grower reports of spinosad failure on two organic farms in 2009, resistance to spinosad was assayed in both conventionally and organically managed fields the following year, and growers were surveyed for their prior spinosad use. RESULTS In 2006, spinosad resistance measured as median lethal dose (LD50 ) varied 9.8-fold among the eight conventional fields sampled and a laboratory susceptible strain. In 2010, the resistance ratios of LD50 values relative to a laboratory susceptible strain ranged from 17.5 to 40.6 in conventionally managed fields, and from 128.7 to 5750.3 in organically managed fields, a dramatic increase from 2006 with higher resistance ratios in organically managed fields. Organic growers reported much heavier use of spinosad in the years prior to 2010. CONCLUSION This is the first report of high-level resistance to spinosad in Coleopterans. Selection strength due to number of years used and number of applications per season appear to have been the primary factors driving the evolution of resistance to spinosad, highlighting the need for resistance management in organic production, where fewer alternative active ingredients for resistance management are available. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Kathleen Schnaars-Uvino
- Environmental Science, University of Jamestown, Jamestown, ND, USA
- Hudson Bay Project Division of Vertebrate Zoology, American Museum of Natural History, New York, NY, USA
- Ecology, Evolutionary Biology, and Behavior, The Graduate Center, CUNY, New York, NY, USA
| | - Mitchell B Baker
- Ecology, Evolutionary Biology, and Behavior, The Graduate Center, CUNY, New York, NY, USA
- Biology Department, Queens College of CUNY, Flushing, NY, USA
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Iglesias L, Havey MJ, Nault BA. Management of Onion Thrips ( Thrips tabaci) in Organic Onion Production Using Multiple IPM Tactics. INSECTS 2021; 12:insects12030207. [PMID: 33804399 PMCID: PMC8000123 DOI: 10.3390/insects12030207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 02/06/2021] [Accepted: 02/13/2021] [Indexed: 11/25/2022]
Abstract
Simple Summary Onion thrips (Thrips tabaci) is a major pest in organic onion production and effective integrated pest management strategies are lacking. Our objective was to evaluate pest management programs consisting of several different tactics: (1) two onion plant cultivars with semi-glossy leaves (“Rossa di Milano” and B5336AxB5351C) and one with waxy leaves (“Bradley”), (2) silver reflective and white plastic mulches, and (3) with or without an application of a biopesticide (spinosad + neem oil tank mix). Thrips densities were counted weekly and bulbs weighed at harvest. The application of the biopesticide had the most significant reduction in thrips densities and increase in yield. The cultivar “Rossa di Milano” had lower thrips densities compared with “Bradley” and B5336AxB5351C, but also had the lowest yield. Reflective mulch had lower thrips densities than white mulch but had no effect on yield. None of the other tactics provided any significant additional benefits to thrips management. While biopesticides will still be a key component to onion thrips management programs, their application frequency should be further optimized. Abstract Onion thrips (Thrips tabaci Lindeman) is a major pest in organic onion production and effective integrated pest management strategies are lacking. Our objective was to evaluate combinations of semi-glossy (“Rossa di Milano” and B5336AxB5351C) and waxy (“Bradley”) onion cultivars with reflective mulch, with or without biopesticides (spinosad + neem oil tank mix), to manage T. tabaci in organic onion production. Thrips densities were assessed weekly and bulbs graded and weighed at harvest. Onions sprayed with spinosad + neem oil had fewer T. tabaci (adults: 74% (2019); larvae: 40% (2018), 84% (2019) and produced higher yields (13% (2018), 23% (2019)) than onions that were unsprayed, regardless of mulch type or onion cultivar. “Rossa di Milano” had relatively fewer adult and larval thrips populations compared with “Bradley” (21% (2018), 32% (2019)) and B5336AxB5351C. However, “Rossa di Milano” had the lowest marketable yield in both years. Reflective mulch reduced densities on certain dates in both years compared to white mulch, but the largest and most consistent reduction only occurred in 2019. Reflective mulch had no impact on bulb yield. While spinosad + neem oil reduced thrips numbers and increased yield alone, none of the treatment combinations were effective at suppressing populations of thrips. Future T. tabaci management in organic onions will require optimization of the available effective biopesticides.
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Affiliation(s)
- Lindsy Iglesias
- Department of Entomology, Cornell University, Cornell AgriTech, 15 Castle Creek Dr., Geneva, NY 14456, USA;
| | - Michael J. Havey
- Vegetable Crops Research Unit, Department of Horticulture, Agricultural Research Service, U.S. Department of Agriculture, 1575 Linden Drive, University of Wisconsin, Madison, WI 53706, USA;
| | - Brian A. Nault
- Department of Entomology, Cornell University, Cornell AgriTech, 15 Castle Creek Dr., Geneva, NY 14456, USA;
- Correspondence: ; Tel.: +1-315-787-2354
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