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Li L, Pang X, Wang C, Yang Y, Wu Y. piggyBac-based transgenic Helicoverpa armigera expressing the T92C allele of the tetraspanin gene HaTSPAN1 confers dominant resistance to Bacillus thuringiensis toxin Cry1Ac. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2024; 204:106096. [PMID: 39277420 DOI: 10.1016/j.pestbp.2024.106096] [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: 07/18/2024] [Revised: 08/15/2024] [Accepted: 08/18/2024] [Indexed: 09/17/2024]
Abstract
Transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt) have revolutionized pest control. However, the evolution of resistance by target pests poses a significant threat to the long-term success of Bt crops. Understanding the genetics and mechanisms underlying Bt resistance is crucial for developing resistance detection methods and management tactics. The T92C mutation in a tetraspanin gene (HaTSPAN1), resulting in the L31S substitution, is associated with dominant resistance to Cry1Ac in a major pest, Helicoverpa armigera. Previous studies using CRISPR/Cas9 technique have demonstrated that knockin of the HaTSPAN1 T92C mutation confers a 125-fold resistance to Cry1Ac in the susceptible SCD strain of H. armigera. In this study, we employed the piggyBac transposon system to create two transgenic H. armigera strains based on SCD: one expressing the wild-type HaTSPAN1 gene (SCD-TSPANwt) and another expressing the T92C mutant form of HaTSPAN1 (SCD-TSPANmt). The SCD-TSPANmt strain exhibited an 82-fold resistance to Cry1Ac compared to the recipient SCD strain, while the SCD-TSPANwt strain remained susceptible. The Cry1Ac resistance followed an autosomal dominant inheritance mode and was genetically linked with the transgene locus in the SCD-TSPANmt strain of H. armigera. Our results further confirm the causal association between the T92C mutation of HaTSPAN1 and dominant resistance to Cry1Ac in H. armigera. Additionally, they suggest that the piggyBac-mediated transformation system we used in H. armigera is promising for functional investigations of candidate Bt resistance genes from other lepidopteran pests.
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Affiliation(s)
- Lin Li
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Xinru Pang
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
| | - Chenyang Wang
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
| | - Yihua Yang
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
| | - Yidong Wu
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
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Gan C, Zhang Z, Jin Z, Wang F, Fabrick JA, Wu Y. Helicoverpa armigera ATP-binding cassette transporter ABCA2 is a functional receptor of Bacillus thuringiensis Cry2Ab toxin. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2023; 197:105658. [PMID: 38072533 DOI: 10.1016/j.pestbp.2023.105658] [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: 08/05/2023] [Revised: 10/17/2023] [Accepted: 10/19/2023] [Indexed: 12/18/2023]
Abstract
Crystalline (Cry) proteins from the bacterium Bacillus thuringiensis (Bt) are widely used in transgenic crops to control important insect pests. Bt crops have many benefits compared with traditional broad-spectrum insecticides, including improved pest control with reduced negative impacts on off-target organisms and fewer environmental consequences. Transgenic corn and cotton producing Cry2Ab Bt toxin are used globally to control several major lepidopteran pests, including the cotton bollworm, Helicoverpa armigera. Resistance to the Cry2Ab toxin and to Bt crops producing Cry2Ab is associated with mutations in the midgut ATP-binding cassette transporter ABCA2 gene in several lepidopterans. Gene-editing knockout has further shown that ABCA2 plays an important functional role in Cry2Ab intoxication. However, the precise role of ABCA2 in the mode of action of Cry2Ab has yet to be reported. Here, we used two in vitro expression systems to study the roles of the H. armigera ABCA2 (HaABCA2) protein in Cry2Ab intoxication. Cry2Ab bound to cultured Sf9 insect cells producing HaABCA2, resulting in specific and dose-dependent susceptibility to Cry2Ab. In contrast, Sf9 cells expressing recombinant mutant proteins missing at least one of the extracellular loop regions 1, 3, 4, and 6 or the intracellular loop containing nucleotide-binding domain 1 lost susceptibility to Cry2Ab, indicating these regions are important for receptor function. Consistent with these results, Xenopus laevis oocytes expressing recombinant HaABCA2 showed strong ion membrane flux in the presence of Cry2Ab, suggesting that HaABCA2 is involved in promoting pore formation during Cry2Ab intoxication. Together with previously published data, our results support HaABCA2 being an important receptor of Cry2Ab where it functions to promote intoxication in H. armigera.
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Affiliation(s)
- Chunxia Gan
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Zheng Zhang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Zeng Jin
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Falong Wang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Jeffrey A Fabrick
- USDA ARS, U.S. Arid Land Agricultural Research Center, Maricopa, AZ, USA
| | - Yidong Wu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
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Wang C, Deng Z, Yuan J, Xu K, Sha L, Guan X, Huang Z, Shao E. Removal of an Aminopeptidase N From Midgut Brush Border Does Not Affect Susceptibility of Spodoptera litura (Lepidoptera: Noctuidae) Larvae to Four Insecticidal Proteins of Bacillus thuringiensis (Bacillales: Bacillaceae). JOURNAL OF ECONOMIC ENTOMOLOGY 2023; 116:223-232. [PMID: 36421056 DOI: 10.1093/jee/toac184] [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: 09/07/2022] [Indexed: 06/16/2023]
Abstract
Spodoptera litura is one of the most destructive lepidopteran insects of cabbages and cauliflowers in the world. Cry1 and Vip3 toxins from Bacillus thuringiensis have been reported to show toxicity in multiple lepidopteran insects. Binding of toxic molecules to specific receptors on the midgut epithelial cells is known to be a key step in the action mode of Bt toxins. Aminopeptidase N (APN) -like proteins have been reported to be binding sites of multiple Cry toxins in the midgut of Cry susceptible insects. In the present study, we identified six midgut APNs by analysis of the genome and midgut transcriptome of S. litura. CRISPR/Cas9 mediated gene-knockout system was utilized to mutate the GPI-anchor signal peptide at the C terminus of SlAPN1. SlAPN1 was verified to be removed from the midgut brush border membrane vesicles of a homozygous knockout strain of S. litura (SlAPN1-KO). Bioassay results indicated that susceptibility of the SlAPN1-KO strain to Cry1Aa, Cry1Ac, Cry1Ca, and Vip3Aa toxins was close to that of the wild-type strain of S. litura. RT-qPCR results showed that the transcriptional level of SlAPN2-6 was not up-regulated after knockout of the SlAPN1. Results in this study indicated that the SlAPN1 did not play a critical role in the pathway of toxicity of Cry1Aa, Cry1Ac, Cry1Ca, and Vip3Aa toxins in S. litura.
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Affiliation(s)
- Can Wang
- National Engineering Research Center of JUNCAO Technology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Zhimin Deng
- National Engineering Research Center of JUNCAO Technology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Jin Yuan
- National Engineering Research Center of JUNCAO Technology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Kexin Xu
- National Engineering Research Center of JUNCAO Technology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Li Sha
- National Engineering Research Center of JUNCAO Technology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Xiong Guan
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Zhipeng Huang
- National Engineering Research Center of JUNCAO Technology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Ensi Shao
- National Engineering Research Center of JUNCAO Technology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
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Endo H. Molecular and Kinetic Models for Pore Formation of Bacillus thuringiensis Cry Toxin. Toxins (Basel) 2022; 14:toxins14070433. [PMID: 35878171 PMCID: PMC9321905 DOI: 10.3390/toxins14070433] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/03/2022] [Accepted: 06/22/2022] [Indexed: 02/05/2023] Open
Abstract
Cry proteins from Bacillus thuringiensis (Bt) and other bacteria are pesticidal pore-forming toxins. Since 2010, when the ABC transporter C2 (ABCC2) was identified as a Cry1Ac protein resistant gene, our understanding of the mode of action of Cry protein has progressed substantially. ABCC2 mediates high Cry1A toxicity because of its high activity for helping pore formation. With the discovery of ABCC2, the classical killing model based on pore formation and osmotic lysis became nearly conclusive. Nevertheless, we are still far from a complete understanding of how Cry proteins form pores in the cell membrane through interactions with their host gut membrane proteins, known as receptors. Why does ABCC2 mediate pore formation with high efficiency unlike other Cry1A-binding proteins? Is the “prepore” formation indispensable for pore formation? What is the mechanism underlying the synergism between ABCC2 and the 12-cadherin domain protein? We examine potential mechanisms of pore formation via receptor interactions in this paper by merging findings from prior studies on the Cry mode of action before and after the discovery of ABC transporters as Cry protein receptors. We also attempt to explain Cry toxicity using Cry–receptor binding affinities, which successfully predicts actual Cry toxicity toward cultured cells coexpressing ABC transporters and cadherin.
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Affiliation(s)
- Haruka Endo
- Department of Integrated Bioscience, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8562, Japan
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Ma X, Shao E, Chen W, Cotto-Rivera RO, Yang X, Kain W, Fei Z, Wang P. Bt Cry1Ac resistance in Trichoplusia ni is conferred by multi-gene mutations. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2022; 140:103678. [PMID: 34780898 DOI: 10.1016/j.ibmb.2021.103678] [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: 07/15/2021] [Revised: 10/28/2021] [Accepted: 11/03/2021] [Indexed: 06/13/2023]
Abstract
The three-domain Cry toxin Cry1Ac from Bacillus thuringiensis (Bt) is an important insecticidal toxin in Bt sprays and has been used in transgenic Bt-crops to confer insect resistance. The cabbage looper, Trichoplusia ni, has developed resistance to Bt sprays in commercial greenhouses, and the resistance to Cry1Ac has been previously identified to be associated with altered expression of the APN1 and APN6 genes and be genetically linked to a locus on chromosome 15. In this study, the Cry1Ac resistance locus in T. ni was further finely mapped, and the specific Cry1Ac resistance-conferring mutation in the resistance locus was identified to be a 4 bp frameshift insertion in the ABCC2 gene by whole genome resequencing, midgut transcriptome analysis, candidate gene cDNA sequencing and mutation site genomic DNA sequencing. By CRISPR/Cas9 mutagenesis, a series of ABCC2 and ABCC3 mutant T. ni strains were generated, and the role of ABCC2 in the toxicity of Cry1Ac in T. ni was confirmed. The results from this study also showed that knockout of ABCC2 in T. ni conferred resistance to Cry1Ac at a level lower than that in the greenhouse-derived resistant T. ni strain and that the Cry1Ac resistance-associated alteration of APN1 and APN6 expression was independent of ABCC2 gene mutations, indicating that the altered expression of APN1 and APN6 was controlled by another gene mutation in Cry1Ac resistant T. ni. Furthermore, T. ni larval bioassays showed that the level of Cry1Ac resistance in F1 families from reciprocal crosses of the Cry1Ac resistant strain with an ABCC2 knockout CRISPR strain was significantly higher than that in ABCC2 knockout strain, indicating the presence of additional Cry1Ac resistance-conferring mutation(s) in the Cry1Ac resistant strain. Therefore, the resistance to Cry1Ac in T. ni is conferred by a mutation in ABCC2 and an additional mutation (or mutations) which leads to altered expression of APN1 and APN6. The additional Cry1Ac resistance mutation or mutations remain to be identified.
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Affiliation(s)
- Xiaoli Ma
- Department of Entomology, Cornell University, Geneva, NY, 14456, USA
| | - Ensi Shao
- Department of Entomology, Cornell University, Geneva, NY, 14456, USA
| | - Wenbo Chen
- Boyce Thompson Institute, Ithaca, NY, 14853, USA
| | | | - Xiaowei Yang
- Department of Entomology, Cornell University, Geneva, NY, 14456, USA
| | - Wendy Kain
- Department of Entomology, Cornell University, Geneva, NY, 14456, USA
| | - Zhangjun Fei
- Boyce Thompson Institute, Ithaca, NY, 14853, USA; USDA-Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Ithaca, NY, 14853, USA
| | - Ping Wang
- Department of Entomology, Cornell University, Geneva, NY, 14456, USA.
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Knockout of Two Cry-Binding Aminopeptidase N Isoforms Does Not Change Susceptibility of Aedes aegypti Larvae to Bacillus thuringiensis subsp. israelensis Cry4Ba and Cry11Aa Toxins. INSECTS 2021; 12:insects12030223. [PMID: 33807543 PMCID: PMC8002144 DOI: 10.3390/insects12030223] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 02/26/2021] [Accepted: 03/02/2021] [Indexed: 11/17/2022]
Abstract
Simple Summary The midgut aminopeptidase N (APN) isoforms have been identified as the binding receptor of insecticidal Cry toxins in numerous insects, including the major arbovirus vector Aedes aegypti (Ae. aegypti). However, whether the Cry-binding APN acts as an essential functional receptor to mediate Bacillus thuringiensis subsp. israelensis (Bti) toxicity in Ae. aegypti larvae remains to be determined. In this study, our results provide the direct molecular evidence demonstrating that two Cry-binding APN isoforms (AeAPN1 and AeAPN2) did not play a key role in mediating Bti Cry4Ba and Cry11Aa toxicity in Ae. aegypti larvae. Abstract The insecticidal Cry4Ba and Cry11Aa crystal proteins from Bacillus thuringiensis subsp. israelensis (Bti) are highly toxic to Ae. aegypti larvae. The glycosylphosphatidylinositol (GPI)-anchored APN was identified as an important membrane-bound receptor for multiple Cry toxins in numerous Lepidoptera, Coleoptera, and Diptera insects. However, there is no direct molecular evidence to link APN of Ae. aegypti to Bti toxicity in vivo. In this study, two Cry4Ba/Cry11Aa-binding Ae. aegypti GPI-APN isoforms (AeAPN1 and AeAPN2) were individually knocked-out using CRISPR/Cas9 mutagenesis, and the AeAPN1/AeAPN2 double-mutant homozygous strain was generated using the reverse genetics approach. ELISA assays showed that the high binding affinity of Cry4Ba and Cry11Aa protoxins to the midgut brush border membrane vesicles (BBMVs) from these APN knockouts was similar to the background from the wild-type (WT) strain. Likewise, the bioassay results showed that neither the single knockout of AeAPN1 or AeAPN2, nor the simultaneous disruption of AeAPN1 and AeAPN2 resulted in significant changes in susceptibility of Ae. aegypti larvae to Cry4Ba and Cry11Aa toxins. Accordingly, our results suggest that AeAPN1 and AeAPN2 may not mediate Bti Cry4Ba and Cry11Aa toxicity in Ae. aegypti larvae as their binding proteins.
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Douris V, Denecke S, Van Leeuwen T, Bass C, Nauen R, Vontas J. Using CRISPR/Cas9 genome modification to understand the genetic basis of insecticide resistance: Drosophila and beyond. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2020; 167:104595. [PMID: 32527434 DOI: 10.1016/j.pestbp.2020.104595] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 04/27/2020] [Accepted: 04/28/2020] [Indexed: 06/11/2023]
Abstract
Chemical insecticides are a major tool for the control of many of the world's most damaging arthropod pests. However, their intensive application is often associated with the emergence of resistance, sometimes with serious implications for sustainable pest control. To mitigate failure of insecticide-based control tools, the mechanisms by which insects have evolved resistance must be elucidated. This includes both identification and functional characterization of putative resistance genes and/or mutations. Research on this topic has been greatly facilitated by using powerful genetic model insects like Drosophila melanogaster, and more recently by advances in genome modification technology, notably CRISPR/Cas9. Here, we present the advances that have been made through the application of genome modification technology in insecticide resistance research. The majority of the work conducted in the field to date has made use of genetic tools and resources available in D. melanogaster. This has greatly enhanced our understanding of resistance mechanisms, especially those mediated by insensitivity of the pesticide target-site. We discuss this progress for a series of different insecticide targets, but also report a number of unsuccessful or inconclusive attempts that highlight some inherent limitations of using Drosophila to characterize resistance mechanisms identified in arthropod pests. We also discuss an experimental framework that may circumvent current limitations while retaining the genetic versatility and robustness that Drosophila has to offer. Finally, we describe examples of direct CRISPR/Cas9 use in non-model pest species, an approach that will likely find much wider application in the near future.
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Affiliation(s)
- Vassilis Douris
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 100 N. Plastira Street, 700 13 Heraklion, Crete, Greece; Department of Biological Applications and Technology, University of Ioannina, 45110 Ioannina, Greece.
| | - Shane Denecke
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 100 N. Plastira Street, 700 13 Heraklion, Crete, Greece
| | - Thomas Van Leeuwen
- Laboratory of Agrozoology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium
| | - Chris Bass
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK
| | - Ralf Nauen
- Bayer AG, CropScience Division, R&D Pest Control, D-40789 Monheim, Germany
| | - John Vontas
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, 100 N. Plastira Street, 700 13 Heraklion, Crete, Greece; Laboratory of Pesticide Science, Department of Crop Science, Agricultural University of Athens, Greece.
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Tabashnik BE, Carrière Y. Evaluating Cross-resistance Between Vip and Cry Toxins of Bacillus thuringiensis. JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:553-561. [PMID: 31821498 DOI: 10.1093/jee/toz308] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Indexed: 05/27/2023]
Abstract
Crops genetically engineered to produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) have revolutionized control of some major pests. Some recently introduced Bt crops make Vip3Aa, a vegetative insecticidal protein (Vip), which reportedly does not share binding sites or structural homology with the crystalline (Cry) proteins of Bt used widely in transgenic crops for more than two decades. Field-evolved resistance to Bt crops with practical consequences for pest control includes 21 cases that collectively reduce the efficacy of nine Cry proteins, but such practical resistance has not been reported yet for any Vip. Here, we review previously published data to evaluate cross-resistance between Vip and Cry toxins. We analyzed 31 cases based on 48 observations, with each case based on one to five observations assessing cross-resistance from pairwise comparisons between 21 resistant strains and 13 related susceptible strains of eight species of lepidopteran pests. Confirming results from previous analyses of smaller data sets, we found weak, statistically significant cross-resistance between Vip3 and Cry1 toxins, with a mean of 1.5-fold cross-resistance in 21 cases (range: 0.30-4.6-fold). Conversely, we did not detect significant positive cross-resistance between Vip3 toxins and Cry2Ab. Distinguishing between weak, significant cross-resistance, and no cross-resistance may be useful for better understanding mechanisms of resistance and effectively managing pest resistance to Bt crops.
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Affiliation(s)
| | - Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ
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