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Pezzini DT, Reisig DD, Buntin GD, Del Pozo-Valdivia AI, Gould F, Paula-Moraes SV, Reay-Jones FP. Impact of seed blend and structured maize refuge on Helicoverpa zea (Lepidoptera: Noctuidae) potential phenological resistance development parameters in pupae and adults. PEST MANAGEMENT SCIENCE 2023; 79:3493-3503. [PMID: 37139844 DOI: 10.1002/ps.7529] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 04/29/2023] [Accepted: 05/04/2023] [Indexed: 05/05/2023]
Abstract
BACKGROUND Helicoverpa zea, an economic pest in the south-eastern United States, has evolved practical resistance to Bacillus thuringiensis (Bt) Cry toxins in maize and cotton. Insect resistance management (IRM) programs have historically required planting of structured non-Bt maize, but because of its low adoption, the use of seed blends has been considered. To generate knowledge on target pest biology and ecology to help improve IRM strategies, nine field trials were conducted in 2019 and 2020 in Florida, Georgia, North Carolina, and South Carolina to evaluate the impact of Bt (Cry1Ab + Cry1F or Cry1Ab + Cry1F + Vip3A) and non-Bt maize plants in blended and structured refuge treatments on H. zea pupal survival, weight, soil pupation depth, adult flight parameters, and adult time to eclosion. RESULTS From a very large sample size and geography, we found a significant difference in pupal mortality and weight among treatments in seed blends with Vip3A, implying that cross-pollination occurred between Bt and non-Bt maize ears. There was no treatment effect for pupation depth, adult flight distance, and eclosion time. CONCLUSION Results of this study demonstrate the potential impact of different refuge strategies on phenological development and survival of an important pest species of regulatory concern. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Daniela T Pezzini
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, Plymouth, NC, USA
| | - G David Buntin
- Department of Entomology, University of Georgia - Griffin Campus, Griffin, GA, USA
| | - Alejandro I Del Pozo-Valdivia
- Department of Entomology, Hampton Roads Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Virginia Beach, VA, USA
| | - Fred Gould
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Silvana V Paula-Moraes
- Entomology and Nematology Department, West Florida Research and Education Center, University of Florida, Jay, FL, USA
| | - Francis Pf Reay-Jones
- Department of Plant and Environmental Sciences, Clemson University, Florence, SC, USA
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Lin S, Head G, Price P, Niu Y, Huang F. Relative fitness of susceptible and Cry1A.105/Cry2Ab2-single-/dual-protein-resistant Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) on non-Bt diet and a diet containing a low concentration of two proteins. INSECT SCIENCE 2023; 30:398-410. [PMID: 35670378 DOI: 10.1111/1744-7917.13087] [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: 03/23/2022] [Revised: 05/22/2022] [Accepted: 05/26/2022] [Indexed: 06/15/2023]
Abstract
Helicoverpa zea (Boddie) is a destructive agricultural pest species that is targeted by both Bacillus thuringiensis (Bt) maize and cotton in the United States. Cry1A.105 and Cry2Ab2 are two Bt proteins expressed in a widely planted maize event MON 89034. In this study, two tests (Test-I and Test-II) were conducted to evaluate the relative fitness of Bt-susceptible and -resistant H. zea on non-Bt diet (Test-I and Test-II) and a diet containing a mix of Cry1A.105 and Cry2Ab2 at a low concentration (Test-II only). Insect populations evaluated in Test-I were two Bt-susceptible strains and three Bt-resistant strains (a single-protein Cry1A.105-, a single-protein Cry2Ab2-, and a dual-protein Cry1A.105/Cry2Ab2-resistant strains). Test-II analyzed the same two susceptible strains, three backcrossed-and-reselected Cry1A.105/Cry2Ab2-single-/dual-protein-resistant strains, and three F1 heterozygous strains. Measurements of life table parameters showed that neither the single- nor dual-protein Cry1A.105/Cry2Ab2 resistance in H. zea was associated with fitness costs under the test conditions. The single Cry protein resistances at a concentration of a mix of Cry1A.105 and Cry2Ab2 that resulted in a zero net reproductive rate for the two susceptible strains were functionally incomplete recessive or codominant, and the dual-protein resistance was completely dominant. The lack of fitness costs could be a factor contributing to the rapid revolution of resistance to the Cry proteins in this species. Data generated from this study should aid our understanding of Cry protein resistance evolution and help in refining IRM programs for H. zea.
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Affiliation(s)
- Shucong Lin
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, USA
| | - Graham Head
- Bayer Crop Science, Chesterfield, Missouri, USA
| | - Paula Price
- Bayer Crop Science, Chesterfield, Missouri, USA
| | - Ying Niu
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, USA
| | - Fangneng Huang
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, USA
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Stahlke AR, Chang J, Tembrock LR, Sim SB, Chudalayandi S, Geib SM, Scheffler BE, Perera OP, Gilligan TM, Childers AK, Hackett KJ, Coates BS. A Chromosome-Scale Genome Assembly of a Helicoverpa zea Strain Resistant to Bacillus thuringiensis Cry1Ac Insecticidal Protein. Genome Biol Evol 2023; 15:evac131. [PMID: 35959935 PMCID: PMC9990077 DOI: 10.1093/gbe/evac131] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 08/01/2022] [Accepted: 08/09/2022] [Indexed: 11/14/2022] Open
Abstract
Helicoverpa zea (Lepidoptera: Noctuidae) is an insect pest of major cultivated crops in North and South America. The species has adapted to different host plants and developed resistance to several insecticidal agents, including Bacillus thuringiensis (Bt) insecticidal proteins in transgenic cotton and maize. Helicoverpa zea populations persist year-round in tropical and subtropical regions, but seasonal migrations into temperate zones increase the geographic range of associated crop damage. To better understand the genetic basis of these physiological and ecological characteristics, we generated a high-quality chromosome-level assembly for a single H. zea male from Bt-resistant strain, HzStark_Cry1AcR. Hi-C data were used to scaffold an initial 375.2 Mb contig assembly into 30 autosomes and the Z sex chromosome (scaffold N50 = 12.8 Mb and L50 = 14). The scaffolded assembly was error-corrected with a novel pipeline, polishCLR. The mitochondrial genome was assembled through an improved pipeline and annotated. Assessment of this genome assembly indicated 98.8% of the Lepidopteran Benchmark Universal Single-Copy Ortholog set were complete (98.5% as complete single copy). Repetitive elements comprised approximately 29.5% of the assembly with the plurality (11.2%) classified as retroelements. This chromosome-scale reference assembly for H. zea, ilHelZeax1.1, will facilitate future research to evaluate and enhance sustainable crop production practices.
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Affiliation(s)
- Amanda R Stahlke
- USDA, Agricultural Research Service, Beltsville Agricultural Research Center, Bee Research Laboratory, 10300 Baltimore Avenue, Beltsville, Maryland 20705
| | - Jennifer Chang
- USDA, Agricultural Research Service, Jamie Whitten Delta States Research Center, Genomics and Bioinformatics Research Unit, 141 Experiment Station Road, Stoneville, Mississippi 38776
- USDOE, Oak Ridge Institute for Science and Education, P.O. Box 117, Oak Ridge, Tennessee 37831
- Genome Informatics Facility, Office of Biotechnology, Iowa State University, Ames, Iowa 50010
| | - Luke R Tembrock
- USDA, Animal and Plant Health Inspection Service, Plant Protection and Quarantine, Science & Technology, Identification Technology Program, 2301 Research Boulevard, Fort Collins, Colorado 80526
- Department of Agricultural Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Sheina B Sim
- USDA, Agricultural Research Service, U.S. Pacific Basin Agricultural Research Center, Tropical Crop and Commodity Protection Research Unit, 64 Nowelo Street, Hilo, Hawaii 96720
| | - Sivanandan Chudalayandi
- Genome Informatics Facility, Office of Biotechnology, Iowa State University, Ames, Iowa 50010
| | - Scott M Geib
- USDA, Agricultural Research Service, U.S. Pacific Basin Agricultural Research Center, Tropical Crop and Commodity Protection Research Unit, 64 Nowelo Street, Hilo, Hawaii 96720
| | - Brian E Scheffler
- USDA, Agricultural Research Service, Jamie Whitten Delta States Research Center, Genomics and Bioinformatics Research Unit, 141 Experiment Station Road, Stoneville, Mississippi 38776
| | - Omaththage P Perera
- USDA, Agricultural Research Service, Jamie Whitten Delta States Research Center, Southern Insect Management Research Unit, 141 Experiment Station Road, Stoneville, Mississippi 38776
| | - Todd M Gilligan
- USDA, Animal and Plant Health Inspection Service, Plant Protection and Quarantine, Science & Technology, Identification Technology Program, 2301 Research Boulevard, Fort Collins, Colorado 80526
| | - Anna K Childers
- USDA, Agricultural Research Service, Beltsville Agricultural Research Center, Bee Research Laboratory, 10300 Baltimore Avenue, Beltsville, Maryland 20705
| | - Kevin J Hackett
- USDA, Agricultural Research Service, Office of National Programs, Crop Production and Protection, 5601 Sunnyside Avenue, Beltsville, Maryland 20705
| | - Brad S Coates
- USDA, Agricultural Research Service, Corn Insects and Crop Genetics Research Unit, 819 Wallace Road, Ames, Iowa 50011
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Arends BR, Reisig DD, Gundry S, Greene JK, Kennedy GG, Reay‐Jones FP, Huseth AS. Helicoverpa zea (Lepidoptera: Noctuidae) feeding incidence and survival on Bt maize in relation to maize in the landscape. PEST MANAGEMENT SCIENCE 2022; 78:2309-2315. [PMID: 35233922 PMCID: PMC9310716 DOI: 10.1002/ps.6855] [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] [Received: 09/22/2021] [Revised: 02/23/2022] [Accepted: 03/02/2022] [Indexed: 05/12/2023]
Abstract
BACKGROUND Characterizing Helicoverpa zea (Boddie) damage to maize (Zea mays L.) in relation to the spatiotemporal composition of Bt crops is essential to understand how landscape composition affects H. zea abundance. To examine this relationship, paired Bt (expressing Cry1A.105 + Cry2Ab2) and non-Bt maize plots were sampled across North and South Carolina during 2017-2019. Kernel damage and larval exit holes were measured following larval development. To understand how maize abundance surrounding sample sites related to feeding damage and larval development, we quantified maize abundance in a 1 km buffer surrounding the sample site and examined the relationship between local maize abundance and kernel damage and larval exit holes. RESULTS Across the years and locations, damage in Bt maize was widespread but significantly lower than in non-Bt maize, indicating that despite the widespread occurrence of resistance to Cry toxins in maize, Bt maize still provides a measurable reduction in damage. There were negative relationships between kernel injury and ears with larval exit holes in both Bt and non-Bt maize and the proportion of maize in the landscape during the current year. CONCLUSION Despite the widespread occurrence of resistance to Cry toxins in maize, this resistance is incomplete, and on average Bt maize continues to provide a measurable reduction in damage. We interpret the negative relationship between abundance of maize within 1 km of the sample location and maize infestation levels, as measured by kernel damage and larval exit holes, to reflect dispersion of the ovipositing moth population over available maize within the local landscape. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Benjamin R. Arends
- Department of Entomology and Plant PathologyNorth Carolina State UniversityPlymouthNCUSA
| | - Dominic D. Reisig
- Department of Entomology and Plant PathologyNorth Carolina State UniversityPlymouthNCUSA
| | - Shawnee Gundry
- Department of Entomology and Plant PathologyNorth Carolina State UniversityPlymouthNCUSA
| | - Jeremy K. Greene
- Department of Plant and Environmental SciencesClemson University, Edisto Research and Education CenterBlackvilleSCUSA
| | - George G. Kennedy
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNCUSA
| | - Francis P.F. Reay‐Jones
- Department of Plant and Environmental SciencesClemson University, Pee Dee Research and Education CenterFlorenceSCUSA
| | - Anders S. Huseth
- Department of Entomology and Plant PathologyNorth Carolina State UniversityPlymouthNCUSA
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Resistance Allele Frequency to Cry1Ab and Vip3Aa20 in Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) in Louisiana and Three Other Southeastern U.S. States. Toxins (Basel) 2022; 14:toxins14040270. [PMID: 35448879 PMCID: PMC9028807 DOI: 10.3390/toxins14040270] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 03/31/2022] [Accepted: 04/02/2022] [Indexed: 01/27/2023] Open
Abstract
The corn earworm/bollworm, Helicoverpa zea (Boddie), is a pest species that is targeted by both Bacillus thuringiensis (Bt) maize and cotton in the United States. Cry1Ab and Vip3Aa20 are two common Bt toxins that are expressed in transgenic maize. The objective of this study was to determine the resistance allele frequency (RAF) to Cry1Ab and Vip3Aa20 in H. zea populations that were collected during 2018 and 2019 from four southeastern U.S. states: Louisiana, Mississippi, Georgia, and South Carolina. By using a group-mating approach, 104 F2 iso-lines of H. zea were established from field collections with most iso-lines (85) from Louisiana. These F2 iso-lines were screened for resistance alleles to Cry1Ab and Vip3Aa20, respectively. There was no correlation in larval survivorship between Cry1Ab and Vip3Aa20 when the iso-lines were exposed to these two toxins. RAF to Cry1Ab maize was high (0.256) and the RAFs were similar between Louisiana and the other three states and between the two sampling years. In contrast, no functional major resistance allele (RA) that allowed resistant insects to survive on Vip3Aa20 maize was detected and the expected RAF of major RAs with 95% probability was estimated to 0 to 0.0073. However, functional minor RAs to Vip3Aa20 maize were not uncommon; the estimated RAF for minor alleles was 0.028. The results provide further evidence that field resistance to Cry1Ab maize in H. zea has widely occurred, while major RAs to Vip3Aa20 maize are uncommon in the southeastern U.S. region. Information that was generated from this study should be useful in resistance monitoring and refinement of resistance management strategies to preserve Vip3A susceptibility in H. zea.
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Reisig DD, DiFonzo C, Dively G, Farhan Y, Gore J, Smith J. Best Management Practices to Delay the Evolution of Bt Resistance in Lepidopteran Pests Without High Susceptibility to Bt Toxins in North America. JOURNAL OF ECONOMIC ENTOMOLOGY 2022; 115:10-25. [PMID: 34922393 DOI: 10.1093/jee/toab247] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Indexed: 06/14/2023]
Abstract
Canadian and United States (US) insect resistance management (IRM) programs for lepidopteran pests in Bacillus thuriengiensis (Bt)-expressing crops are optimally designed for Ostrinia nubilalis Hübner in corn (Zea mays L.) and Chloridea virescens Fabricius in cotton (Gossypium hirsutum L.). Both Bt corn and cotton express a high dose for these pests; however, there are many other target pests for which Bt crops do not express high doses (commonly referred to as nonhigh dose pests). Two important lepidopteran nonhigh dose (low susceptibility) pests are Helicoverpa zea Boddie (Lepidoptera: Noctuidae) and Striacosta albicosta Smith (Lepidoptera: Noctuidae). We highlight both pests as cautionary examples of exposure to nonhigh dose levels of Bt toxins when the IRM plan was not followed. Moreover, IRM practices to delay Bt resistance that are designed for these two ecologically challenging and important pests should apply to species that are more susceptible to Bt toxins. The purpose of this article is to propose five best management practices to delay the evolution of Bt resistance in lepidopteran pests with low susceptibility to Bt toxins in Canada and the US: 1) better understand resistance potential before commercialization, 2) strengthen IRM based on regional pest pressure by restricting Bt usage where it is of little benefit, 3) require and incentivize planting of structured corn refuge everywhere for single toxin cultivars and in the southern US for pyramids, 4) integrate field and laboratory resistance monitoring programs, and 5) effectively use unexpected injury thresholds.
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Affiliation(s)
- Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, 207 Research Station Road, Plymouth, NC, 27962, USA
| | - Chris DiFonzo
- Department of Entomology, Michigan State University, 288 Farm Lane, East Lansing, MI, 48824, USA
| | - Galen Dively
- Department of Entomology, University of Maryland, College Park, MD, 20742, USA
| | - Yasmine Farhan
- Department of Plant Agriculture, University of Guelph Ridgetown Campus, 120 Main Street East, Ridgetown, ON, N0P 2C0, Canada
| | - Jeff Gore
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, P.O. Box 197, Stoneville, MS, 38776, USA
| | - Jocelyn Smith
- Department of Plant Agriculture, University of Guelph Ridgetown Campus, 120 Main Street East, Ridgetown, ON, N0P 2C0, Canada
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CRISPR-mediated mutations in the ABC transporter gene ABCA2 confer pink bollworm resistance to Bt toxin Cry2Ab. Sci Rep 2021; 11:10377. [PMID: 34001946 PMCID: PMC8128902 DOI: 10.1038/s41598-021-89771-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 04/28/2021] [Indexed: 11/29/2022] Open
Abstract
Crops genetically engineered to produce insecticidal proteins from Bacillus thuringiensis (Bt) have many benefits and are important globally for managing insect pests. However, the evolution of pest resistance to Bt crops reduces their benefits. Understanding the genetic basis of such resistance is needed to better monitor, manage, and counter pest resistance to Bt crops. Previous work shows that resistance to Bt toxin Cry2Ab is associated with mutations in the gene encoding the ATP-binding cassette protein ABCA2 in lab- and field-selected populations of the pink bollworm (Pectinophora gossypiella), one of the world’s most destructive pests of cotton. Here we used CRISPR/Cas9 gene editing to test the hypothesis that mutations in the pink bollworm gene encoding ABCA2 (PgABCA2) can cause resistance to Cry2Ab. Consistent with this hypothesis, introduction of disruptive mutations in PgABCA2 in a susceptible strain of pink bollworm increased the frequency of resistance to Cry2Ab and facilitated creation of a Cry2Ab-resistant strain. All Cry2Ab-resistant individuals tested in this study had disruptive mutations in PgABCA2. Overall, we found 17 different disruptive mutations in PgABCA2 gDNA and 26 in PgABCA2 cDNA, including novel mutations corresponding precisely to single-guide (sgRNA) sites used for CRISPR/Cas9. Together with previous results, these findings provide the first case of practical resistance to Cry2Ab where evidence identifies a specific gene in which disruptive mutations can cause resistance and are associated with resistance in field-selected populations.
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Carrière Y, Degain BA, Tabashnik BE. Effects of gene flow between Bt and non-Bt plants in a seed mixture of Cry1A.105 + Cry2Ab corn on performance of corn earworm in Arizona. PEST MANAGEMENT SCIENCE 2021; 77:2106-2113. [PMID: 33350567 DOI: 10.1002/ps.6239] [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] [Received: 11/05/2020] [Revised: 12/08/2020] [Accepted: 12/17/2020] [Indexed: 06/12/2023]
Abstract
BACKGROUND Using natural populations of Helicoverpa zea from Arizona, we tested the hypotheses that gene flow between Bacillus thuringiensis (Bt) plants and non-Bt plants in a seed mixture of 10% non-Bt corn and 90% Bt corn producing Cry1A.105 and Cry2Ab reduces larval performance on ears from non-Bt plants, or increases performance on ears from Bt plants. RESULTS Gene flow was not detected in blocks of non-Bt or Bt corn but was extensive in seed mixtures. Analyses of larval weight and abundance over a period of 3 to 4 weeks did not indicate consistent effects of gene flow on development rate and survival. However for non-Bt plants, the ear area damaged and percentage of ears with exit holes were significantly lower in the seed mixtures than blocks. By contrast, the percentage of ears with exit holes and ear damage did not differ significantly between the seed mixtures and blocks for Bt plants. Nearly 100% of the ears were damaged and the damaged area was substantial, showing that H. zea is a major ear-feeding pest in Arizona. Relative to non-Bt corn, the pyramided Bt corn did not significantly reduce the percentage of damaged ears and only reduced the ear area damaged by 21 to 39%, indicating that H. zea may have evolved resistance to Cry1A.105, Cry2Ab, or both. CONCLUSIONS Our results indicate that gene flow between Bt and non-Bt plants in seed mixtures reduced effective refuge size, and that block refuges may be needed to manage the evolution of H. zea resistance to Bt corn in Arizona. © 2020 Society of Chemical Industry.
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Affiliation(s)
- Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ, USA
| | - Ben A Degain
- Department of Entomology, University of Arizona, Tucson, AZ, USA
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Pinos D, Andrés-Garrido A, Ferré J, Hernández-Martínez P. Response Mechanisms of Invertebrates to Bacillus thuringiensis and Its Pesticidal Proteins. Microbiol Mol Biol Rev 2021; 85:e00007-20. [PMID: 33504654 PMCID: PMC8549848 DOI: 10.1128/mmbr.00007-20] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Extensive use of chemical insecticides adversely affects both environment and human health. One of the most popular biological pest control alternatives is bioinsecticides based on Bacillus thuringiensis This entomopathogenic bacterium produces different protein types which are toxic to several insect, mite, and nematode species. Currently, insecticidal proteins belonging to the Cry and Vip3 groups are widely used to control insect pests both in formulated sprays and in transgenic crops. However, the benefits of B. thuringiensis-based products are threatened by insect resistance evolution. Numerous studies have highlighted that mutations in genes coding for surrogate receptors are responsible for conferring resistance to B. thuringiensis Nevertheless, other mechanisms may also contribute to the reduction of the effectiveness of B. thuringiensis-based products for managing insect pests and even to the acquisition of resistance. Here, we review the relevant literature reporting how invertebrates (mainly insects and Caenorhabditis elegans) respond to exposure to B. thuringiensis as either whole bacteria, spores, and/or its pesticidal proteins.
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Affiliation(s)
- Daniel Pinos
- Instituto Universitario de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, Burjassot, Spain
| | - Ascensión Andrés-Garrido
- Instituto Universitario de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, Burjassot, Spain
| | - Juan Ferré
- Instituto Universitario de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, Burjassot, Spain
| | - Patricia Hernández-Martínez
- Instituto Universitario de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, Burjassot, Spain
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Carrière Y, Degain BA, Harpold VS, Unnithan GC, Tabashnik BE. Gene Flow Between Bt and Non-Bt Plants in a Seed Mixture Increases Dominance of Resistance to Pyramided Bt Corn in Helicoverpa zea (Lepidoptera: Noctuidae). JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:2041-2051. [PMID: 32582955 DOI: 10.1093/jee/toaa138] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Indexed: 06/11/2023]
Abstract
For delaying evolution of pest resistance to transgenic corn producing Bacillus thuringiensis (Bt) toxins, limited data are available to compare the effectiveness of refuges of non-Bt corn planted in seed mixtures versus blocks. Here we addressed this issue in the ear-feeding pest Helicoverpa zea Boddie by measuring its survival and development in the laboratory on ears from field plots with 90% Cry1A.105 + Cry2Ab corn and 10% non-Bt corn planted in a seed mixture or blocks. We compared a strain of H. zea selected for resistance to Cry1Ac in the laboratory, its parent strain not selected in the laboratory, and their F1 progeny. The relative survival of the F1 progeny and dominance of resistance were higher on ears from Bt plants in the seed mixture than the block. Half of the kernels in ears from non-Bt plants in the seed mixture produced both Cry1A.105 and Cry2Ab. However, survival on ears from non-Bt plants did not differ between the block and seed mixture. In simulations based on the observed survival, resistance to Cry1A.105 + Cry2Ab corn evolved faster with the seed mixture than the blocks, because of the higher dominance of resistance in the seed mixture. Increasing the refuge percentage improved durability of Cry1A.105 + Cry2Ab corn more for the blocks than the seed mixture. These findings imply that, for a given percentage of non-Bt corn, resistance of H. zea and other ear-feeding pests to multi-toxin Bt corn is likely to evolve faster for seed mixtures than blocks.
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Affiliation(s)
- Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ
| | - Ben A Degain
- Department of Entomology, University of Arizona, Tucson, AZ
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11
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Demographic Performance of Helicoverpa zea Populations on Dual and Triple-Gene Bt Cotton. Toxins (Basel) 2020; 12:toxins12090551. [PMID: 32872277 PMCID: PMC7551585 DOI: 10.3390/toxins12090551] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/10/2020] [Accepted: 08/26/2020] [Indexed: 01/02/2023] Open
Abstract
Insecticidal toxins from Bacillus thuringiensis (Bt) are valuable tools for pest management worldwide, contributing to the management of human disease insect vectors and phytophagous insect pests of agriculture and forestry. Here, we report the effects of dual and triple Bt toxins expressed in transgenic cotton cultivars on the fitness and demographic performance of Helicoverpa zea (Boddie)—a noctuid pest, known as cotton bollworm and corn earworm. Life-history traits were determined for individuals of three field populations from a region where H. zea overwintering is likely. Triple-gene Bt cotton cultivars that express Cry and Vip3Aa toxins killed 100% of the larvae in all populations tested. In contrast, dual-gene Bt cotton that express Cry1Ac+Cry1F and Cry1Ac+Cry2Ab allowed population growth with the intrinsic rate of population growth (rm) 38% lower than on non-Bt cotton. The insects feeding on Bt cotton plants that express Cry1Ac+Cry2Ab, Cry1Ac+Cry1F, or Cry1Ab+Cry2Ae exhibited reduced larval weight, survival rate, and increased development time. Additionally, fitness parameters varied significantly among the insect populations, even on non-Bt cotton plants, likely because of their different genetic background and/or previous Bt toxin exposure. This is the first report of the comparative fitness of H. zea field populations on dual-gene Bt cotton after the recent reports of field resistance to certain Bt toxins. These results document the population growth rates of H. zea from an agricultural landscape with 100% Bt cotton cultivars. Our results will contribute to the development and validation of resistance management recommendations.
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Fabrick JA, LeRoy DM, Unnithan GC, Yelich AJ, Carrière Y, Li X, Tabashnik BE. Shared and Independent Genetic Basis of Resistance to Bt Toxin Cry2Ab in Two Strains of Pink Bollworm. Sci Rep 2020; 10:7988. [PMID: 32409635 PMCID: PMC7224296 DOI: 10.1038/s41598-020-64811-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 04/22/2020] [Indexed: 12/20/2022] Open
Abstract
Evolution of pest resistance threatens the benefits of crops genetically engineered to produce insecticidal proteins from Bacillus thuringiensis (Bt). Field populations of the pink bollworm (Pectinophora gossypiella), a global pest of cotton, have evolved practical resistance to transgenic cotton producing Bt toxin Cry2Ab in India, but not in the United States. Previous results show that recessive mutations disrupting an autosomal ATP-binding cassette gene (PgABCA2) are associated with pink bollworm resistance to Cry2Ab in field-selected populations from India and in one lab-selected strain from the United States (Bt4-R2). Here we discovered that an independently derived, lab-selected Cry2Ab-resistant pink bollworm strain from the United States (BX-R) also harbors mutations that disrupt PgABCA2. Premature stop codons introduced by mis-splicing of PgABCA2 pre-mRNA were prevalent in field-selected larvae from India and in both lab-selected strains. The most common mutation in field-selected larvae from India was also detected in both lab-selected strains. Results from interstrain crosses indicate BX-R has at least one additional mechanism of resistance to Cry2Ab that does not involve PgABCA2 and is not completely recessive or autosomal. We conclude that recessive mutations disrupting PgABCA2 are the primary, but not the only, mechanism of resistance to Cry2Ab in pink bollworm.
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Affiliation(s)
- Jeffrey A Fabrick
- USDA ARS, U.S. Arid Land Agricultural Research Center, Maricopa, AZ, 85138, USA.
| | - Dannialle M LeRoy
- USDA ARS, U.S. Arid Land Agricultural Research Center, Maricopa, AZ, 85138, USA
| | | | - Alex J Yelich
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA
| | - Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA
| | - Xianchun Li
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA
| | - Bruce E Tabashnik
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA
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