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Yang F, Head GP, Price PA, Santiago González JC, Kerns DL. Inheritance of Bacillus thuringiensis Cry2Ab2 protein resistance in Helicoverpa zea (Lepidoptera: Noctuidae). PEST MANAGEMENT SCIENCE 2020; 76:3676-3684. [PMID: 32419321 DOI: 10.1002/ps.5916] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 05/07/2020] [Accepted: 05/18/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND The corn earworm, Helicoverpa zea (Boddie), is a major target pest of pyramided Bt corn and cotton in the United States. Field-evolved practical resistance to Cry1 and Cry2 proteins in H. zea has been documented in multiple locations in the United States. Understanding the genetic basis of Bt resistance is essential in developing insect resistance management (IRM) strategies for the sustainable use of the Bt crop technology. In this study, we characterized the genetic bases of Cry2Ab2 resistance in H. zea using diet-overlay bioassays with two different forms of Cry2Ab2 protein. RESULTS Laboratory bioassays using a Cry2Ab2-resistant (RR) strain, a susceptible (SS) strain, as well as cross and backcross strains, revealed that resistance to Cry2Ab2 was autosomally inherited and controlled by more than one locus. In diet bioassays, the dominance of Cry2Ab2 resistance in H. zea varied from incompletely recessive to incompletely dominant across all tested Cry2Ab2 concentrations of either Bt corn leaf powder or solubilized protein. On leaf tissue of TwinLink cotton (expressing Cry1Ab and Cry2Ae), Cry2Ab2 resistance in H. zea was completely dominant. CONCLUSION These results have significant implications for understanding the widespread field-evolved resistance of H. zea against Cry1 and Cry2 proteins in Bt corn and cotton and should be useful in developing effective IRM strategies for H. zea. © 2020 Society of Chemical Industry.
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Affiliation(s)
- Fei Yang
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | | | | | | | - David L Kerns
- Department of Entomology, Texas A&M University, College Station, TX, USA
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52
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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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53
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Reay-Jones FPF, Bilbo TR, Reisig DD. Decline in Sublethal Effects of Bt Corn on Corn Earworm (Lepidoptera: Noctuidae) Linked to Increasing Levels of Resistance. JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:2241-2249. [PMID: 32740662 DOI: 10.1093/jee/toaa163] [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: 05/01/2020] [Indexed: 06/11/2023]
Abstract
As part of an ongoing longitudinal study in North and South Carolina, this study reports the recovery of Helicoverpa zea (Boddie) pupae in field trials with genetically engineered corn, Zea mays L., hybrids that produce insecticidal toxins from Bacillus thuringiensis (Bt) in 2017-2019. In total, 10,400 corn ears were collected, which led to 3,927 H. zea pupae (2,215 in South Carolina and 1,712 in North Carolina). Late-planted corn led to a 3.39-fold increase in recovery of pupae compared to early-planted corn. Bt corn expressing Cry1F + Cry1Ab and Cry1A.105 + Cry2Ab2 had 1.67-fold and 2.51-fold fewer pupae than non-Bt near-isolines, respectively. Only six pupae were recovered from the hybrid expressing Cry1F + Cry1Ab + Vip3Aa20. Averaged across trials, Bt corn expressing either Cry1A.105 + Cry2Ab2 or Cry1F + Cry1Ab significantly reduced pupal weight compared to non-Bt near-isolines in North and South Carolina. Combining our data with a previous study at the same locations (Bilbo et al. 2018), reduction in pupal weight between Bt and non-Bt near-isolines significantly declined from 2014 to 2019 for Cry1Ab + Cry1F in North and South Carolina. This decline in levels of a sublethal effect of Bt corn expressing Cry1Ab + Cry1F on H. zea at both locations is likely correlated with resistance development.
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Affiliation(s)
- Francis P F Reay-Jones
- Department of Plant and Environmental Sciences, Clemson University, Pee Dee Research and Education Center, Florence, SC
| | - Thomas R Bilbo
- Department of Plant and Environmental Sciences, Clemson University, Pee Dee Research and Education Center, Florence, SC
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, the Vernon G. James Research and Extension Center, Plymouth, NC
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54
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Coates BS, Abel CA, Swoboda-Bhattarai KA, Palmquist DE, Montezano DG, Zukoff SN, Wang Y, Bradshaw JD, DiFonzo CD, Shields E, Tilmon KJ, Hunt TE, Peterson JA. Geographic Distribution of Bacillus thuringiensis Cry1F Toxin Resistance in Western Bean Cutworm (Lepidoptera: Noctuidae) Populations in the United States. JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:2465-2472. [PMID: 32740653 DOI: 10.1093/jee/toaa136] [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: 01/29/2020] [Indexed: 06/11/2023]
Abstract
The western bean cutworm (WBC), Striacosta albicosta (Lepidoptera: Noctuidae), can be a severe pest of transgenic corn in the western Plains and Great Lakes regions of North America, including on hybrids expressing the Bacillus thuringiensis (Bt) Cry1F toxin. The level and geographic distribution of Cry1F resistance are not completely known. Neonate S. albicosta from 10 locations between Nebraska and New York state were subjected to dose-response trypsin-activated native Cry1F toxin overlay bioassays. In 2017, the mean estimated lethal concentration causing 50% larval mortality (LC50) ranged from 15.1 to 18.4 µg Cry1F cm-2, and were not significantly different among locations. In 2018, LC50 estimates at Scottsbluff, NE (22.0 µg Cry1F cm-2) and Watertown, NY (21.7 µg Cry1F cm-2) were significantly higher when compared to locations in Michigan (15.8 µg Cry1F cm-2). Significantly lower 14-day larval weight among survivors was correlated with higher Cry1F dose. Results from this study indicate that S. albicosta survivorship on purified Bt Cry1F toxin shows a relatively even distribution across the native and range expansion areas where seasonal field infestations typically occur.
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Affiliation(s)
- Brad S Coates
- USDA-ARS, Corn Insects & Crop Genetics Research Unit, Ames, IA
| | - Craig A Abel
- USDA-ARS, Corn Insects & Crop Genetics Research Unit, Ames, IA
| | - Katharine A Swoboda-Bhattarai
- University of Nebraska-Lincoln, Department of Entomology, West Central Research and Extension Center, North Platte, NE
| | | | - Débora G Montezano
- University of Nebraska-Lincoln, Department of Entomology, West Central Research and Extension Center, North Platte, NE
| | - Sarah N Zukoff
- Kansas State University, Department of Entomology, Southwest Research and Extension Center, Garden City, KS
| | - Yangzhou Wang
- Jilin Academy of Agricultural Sciences, Plant Protection Institute, Changchun, Jilin Province, China
| | - Jeffrey D Bradshaw
- University of Nebraska-Lincoln, Department of Entomology, Panhandle Research and Extension Center, Scottsbluff, NE
| | | | - Elson Shields
- Cornell University, Department of Entomology, Ithaca, NY
| | | | - Thomas E Hunt
- University of Nebraska-Lincoln, Department of Entomology, Haskell Agricultural Laboratory, Concord, NE
| | - Julie A Peterson
- University of Nebraska-Lincoln, Department of Entomology, West Central Research and Extension Center, North Platte, NE
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55
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Lawrie RD, Mitchell III RD, Deguenon JM, Ponnusamy L, Reisig D, Pozo-Valdivia AD, Kurtz RW, Roe RM. Multiple Known Mechanisms and a Possible Role of an Enhanced Immune System in Bt-Resistance in a Field Population of the Bollworm, Helicoverpa zea: Differences in Gene Expression with RNAseq. Int J Mol Sci 2020; 21:E6528. [PMID: 32906662 PMCID: PMC7555151 DOI: 10.3390/ijms21186528] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/01/2020] [Accepted: 09/01/2020] [Indexed: 12/13/2022] Open
Abstract
Several different agricultural insect pests have developed field resistance to Bt (Bacillus thuringiensis) proteins (ex. Cry1Ac, Cry1F, etc.) expressed in crops, including corn and cotton. In the bollworm, Helicoverpa zea, resistance levels are increasing; recent reports in 2019 show up to 1000-fold levels of resistance to Cry1Ac, a major insecticidal protein in Bt-crops. A common method to analyze global differences in gene expression is RNA-seq. This technique was used to measure differences in global gene expression between a Bt-susceptible and Bt-resistant strain of the bollworm, where the differences in susceptibility to Cry1Ac insecticidal proteins were 100-fold. We found expected gene expression differences based on our current understanding of the Bt mode of action, including increased expression of proteases (trypsins and serine proteases) and reduced expression of Bt-interacting receptors (aminopeptidases and cadherins) in resistant bollworms. We also found additional expression differences for transcripts that were not previously investigated, i.e., transcripts from three immune pathways-Jak/STAT, Toll, and IMD. Immune pathway receptors (ex. PGRPs) and the IMD pathway demonstrated the highest differences in expression. Our analysis suggested that multiple mechanisms are involved in the development of Bt-resistance, including potentially unrecognized pathways.
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Affiliation(s)
- Roger D. Lawrie
- Department of Biology/Environmental and Molecular Toxicology Program, 850 Main Campus Dr, North Carolina State University, Raleigh, NC 27695, USA;
- Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC 27695, USA; (J.M.D.); (L.P.)
| | - Robert D. Mitchell III
- Knipling-Bushland US Livestock Insects Research Laboratory Genomics Center, 2700 Fredericksburg Road, United States Department of Agriculture-Agricultural Research Service, Kerrville, TX 78028, USA;
| | - Jean Marcel Deguenon
- Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC 27695, USA; (J.M.D.); (L.P.)
| | - Loganathan Ponnusamy
- Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC 27695, USA; (J.M.D.); (L.P.)
| | - Dominic Reisig
- Department of Entomology and Plant Pathology, Vernon G. James Research & Extension Center, 207 Research Station Road, Plymouth, NC 27962, USA; (D.R.); (A.D.P.-V.)
| | - Alejandro Del Pozo-Valdivia
- Department of Entomology and Plant Pathology, Vernon G. James Research & Extension Center, 207 Research Station Road, Plymouth, NC 27962, USA; (D.R.); (A.D.P.-V.)
| | - Ryan W. Kurtz
- Cotton Incorporated, 6399 Weston Parkway, Cary, NC 27513, USA;
| | - R. Michael Roe
- Department of Biology/Environmental and Molecular Toxicology Program, 850 Main Campus Dr, North Carolina State University, Raleigh, NC 27695, USA;
- Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC 27695, USA; (J.M.D.); (L.P.)
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56
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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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57
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Perera OP, Fescemyer HW, Fleischer SJ, Abel CA. Temporal Variation in Genetic Composition of Migratory Helicoverpa Zea in Peripheral Populations. INSECTS 2020; 11:E463. [PMID: 32717838 PMCID: PMC7469216 DOI: 10.3390/insects11080463] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 07/14/2020] [Accepted: 07/20/2020] [Indexed: 12/12/2022]
Abstract
Migrant populations of Helicoverpa zea (Boddie) captured during 2002, 2005, 2016, and 2018 from Landisville and Rock Springs in Pennsylvania, USA were genotyped using 85 single nucleotide polymorphism (SNP) markers. Samples (n = 702) genotyped were divided into 16 putative populations based on collection time and site. Fixation indices (F-statistics), analysis of molecular variance, and discriminant analysis of principal components were used to examine within and among population genetic variation. The observed and expected heterozygosity in putative populations ranged from 0.317-0.418 and 0.320-0.359, respectively. Broad range of FST (0.0-0.2742) and FIS (0.0-0.2330) values indicated different genotype frequencies between and within the populations, respectively. High genetic diversity within and low genetic differentiation between populations was found in 2002 and 2005. Interestingly, high genetic differentiation between populations from two collection sites observed in 2018 populations was not evident in within-site comparisons of putative populations collected on different dates during the season. The shift of H. zea population genetic makeup in 2018 may be influenced by multiple biotic and abiotic factors including tropical storms. Continued assessment of these peripheral populations of H. zea will be needed to assess the impacts of genetic changes on pest control and resistance management tactics.
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Affiliation(s)
| | - Howard W. Fescemyer
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA;
| | - Shelby J. Fleischer
- Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA;
| | - Craig A. Abel
- Corn Insects and Crop Genetics Research Unit, USDA-ARS, Ames, IA 50011, USA;
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Mutations in a Novel Cadherin Gene Associated with Bt Resistance in Helicoverpa zea. G3-GENES GENOMES GENETICS 2020; 10:1563-1574. [PMID: 32179620 PMCID: PMC7202007 DOI: 10.1534/g3.120.401053] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Transgenic corn and cotton produce crystalline (Cry) proteins derived from the soil bacterium Bacillus thuringiensis (Bt) that are toxic to lepidopteran larvae. Helicoverpa zea, a key pest of corn and cotton in the U.S., has evolved widespread resistance to these proteins produced in Bt corn and cotton. While the genomic targets of Cry selection and the mutations that produce resistant phenotypes are known in other lepidopteran species, little is known about how selection by Cry proteins shape the genome of H. zea. We scanned the genomes of Cry1Ac-selected and unselected H. zea lines, and identified twelve genes on five scaffolds that differed between lines, including cadherin-86C (cad-86C), a gene from a family that is involved in Cry1A resistance in other lepidopterans. Although this gene was expressed in the H. zea larval midgut, the protein it encodes has only 17 to 22% identity with cadherin proteins from other species previously reported to be involved in Bt resistance. An analysis of midgut-expressed cDNAs showed significant between-line differences in the frequencies of putative nonsynonymous substitutions (both SNPs and indels). Our results indicate that cad-86C is a likely target of Cry1Ac selection in H. zea. It remains unclear, however, whether genomic changes at this locus directly disrupt midgut binding of Cry1Ac and cause Bt resistance, or indirectly enhance fitness of H. zea in the presence of Cry1Ac by some other mechanism. Future work should investigate phenotypic effects of these nonsynonymous substitutions and their impact on fitness of H. zea larvae that ingest Cry1Ac.
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59
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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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60
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Yang F, González JCS, Little N, Reisig D, Payne G, Dos Santos RF, Jurat-Fuentes JL, Kurtz R, Kerns DL. First documentation of major Vip3Aa resistance alleles in field populations of Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) in Texas, USA. Sci Rep 2020; 10:5867. [PMID: 32246037 PMCID: PMC7125131 DOI: 10.1038/s41598-020-62748-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 03/17/2020] [Indexed: 11/18/2022] Open
Abstract
The corn earworm, Helicoverpa zea, is a major target pest of the insecticidal Vip3Aa protein used in pyramided transgenic Bt corn and cotton with Cry1 and Cry2 proteins in the U.S. The widespread resistance to Cry1 and Cry2 proteins in H. zea will challenge the long-term efficacy of Vip3Aa technology. Determining the frequency of resistant alleles to Vip3Aa in field populations of H. zea is critically important for resistance management. Here, we provided the first F2 screen study to estimate the resistance allele frequency for Vip3Aa in H. zea populations in Texas, U.S. In 2019, 128 H. zea neonates per isofamily for a total of 114 F2 families were screened with a diagnostic concentration of 3.0 μg/cm2 of Vip3Aa39 protein in diet-overlay bioassays. The F2 screen detected two families carrying a major Vip3Aa resistance allele. The estimated frequency of major resistance alleles against Vip3Aa39 in H. zea in Texas from this study was 0.0065 with a 95% CI of 0.0014-0.0157. A Vip3Aa-resistant strain (RR) derived from the F2 screen showed a high level of resistance to Vip3Aa39 protein, with a resistance ratio of >588.0-fold relative to a susceptible population (SS) based on diet-overlay bioassays. We provide the first documentation of a major resistance allele conferring high levels of Vip3Aa resistance in a field-derived strain of H. zea in the U.S. Data generated from this study contribute to development of management strategies for the sustainable use of the Vip3Aa technology to control H. zea in the U.S.
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Affiliation(s)
- Fei Yang
- Department of Entomology, Texas A&M University, College Station, TX, 77843-2475, USA.
| | | | - Nathan Little
- Southern Insect Management Research Unit, USDA-ARS, Stoneville, MS, 38776, USA
| | - Dominic 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
| | - Gregory Payne
- Department of Biology, State University of West Georgia, Carrolton, GA, 30118, USA
| | | | - Juan Luis Jurat-Fuentes
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN, 37996-4560, USA
| | - Ryan Kurtz
- Cotton Incorporated, 6399 Weston Parkway, Cary, NC, 27513, USA
| | - David L Kerns
- Department of Entomology, Texas A&M University, College Station, TX, 77843-2475, USA.
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61
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Tabashnik BE, Carrière Y. Global Patterns of Resistance to Bt Crops Highlighting Pink Bollworm in the United States, China, and India. JOURNAL OF ECONOMIC ENTOMOLOGY 2019; 112:2513-2523. [PMID: 31254345 DOI: 10.1093/jee/toz173] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Indexed: 05/29/2023]
Abstract
Crops genetically engineered to produce insecticidal proteins from Bacillus thuringiensis (Bt) have advanced pest control, but their benefits have been reduced by evolution of resistance in pests. The global monitoring data reviewed here reveal 19 cases of practical resistance to Bt crops, which is field-evolved resistance that reduces Bt crop efficacy and has practical consequences for pest control. Each case represents the responses of one pest species in one country to one Bt toxin. The results with pink bollworm (Pectinophora gossypiella) and Bt cotton differ strikingly among the world's three leading cotton-producing nations. In the southwestern United States, farmers delayed resistance by planting non-Bt cotton refuges from 1996 to 2005, then cooperated in a program that used Bt cotton, mass releases of sterile moths, and other tactics to eradicate this pest from the region. In China, farmers reversed low levels of pink bollworm resistance to Bt cotton by planting second-generation hybrid seeds from crosses between Bt and non-Bt cotton. This approach yields a refuge of 25% non-Bt cotton plants randomly interspersed within fields of Bt cotton. Farmers adopted this tactic voluntarily and unknowingly, not to manage resistance, but apparently because of its perceived short-term agronomic and economic benefits. In India, where non-Bt cotton refuges have been scarce and pink bollworm resistance to pyramided Bt cotton producing Cry1Ac and Cry2Ab toxins is widespread, integrated pest management emphasizing shortening of the cotton season, destruction of crop residues, and other tactics is now essential.
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Affiliation(s)
| | - Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ
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62
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Caprio MA, Kurtz R, Catchot A, Kerns D, Reisig D, Gore J, Reay-Jones FPF. The Corn-Cotton Agroecosystem in the Mid-Southern United States: What Insecticidal Event Pyramids Should be Used in Each Crop to Extend Vip3A Durability. JOURNAL OF ECONOMIC ENTOMOLOGY 2019; 112:2894-2906. [PMID: 31375824 DOI: 10.1093/jee/toz208] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Indexed: 06/10/2023]
Abstract
Recent studies suggest that resistance in Helicoverpa zea (Boddie) (Lepidoptera, Noctuidae) to Cry1A(b/c) and Cry2Ab2 toxins from the bacterium Bacillus thuringiensis Berliner (Bacillales: Bacillaceae) has increased and field efficacy is impacted in transgenic corn and cotton expressing these toxins. A third toxin, Vip3A, is available in pyramids expressing two or more Bt toxins in corn hybrids and cotton varieties, but uncertainty exists regarding deployment strategies. During a growing season, H. zea infests corn and cotton, and debate arises over use of Vip3A toxin in corn where H. zea is not an economic pest. We used a three-locus, spatially explicit simulation model to evaluate when using Vip3A in corn might hasten evolution of resistance to Vip3A, with implications in cotton where H. zea is a key pest. When using a conventional refuge in corn and initial resistance allele frequencies of Cry1A and Cry2A were 10%, transforming corn with Vip3A slowed resistance to these toxins and delayed resistance evolution to the three-toxin pyramid as a whole. When Cry resistance allele frequencies exceeded 30%, transforming corn with Vip3A hastened the evolution of resistance to the three-toxin pyramid in cotton. When using a seed blend refuge strategy, resistance was delayed longest when Vip3A was not incorporated into corn and used only in cotton. Simulations of conventional refuges were generally more durable than seed blends, even when 75% of the required refuge was not planted. Extended durability of conventional refuges compared to other models of resistance evolution are discussed as well as causes for unusual survivorship in seed blends.
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Affiliation(s)
- Michael A Caprio
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State, MS
| | | | - Angus Catchot
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State, MS
| | - David Kerns
- Department of Entomology, Texas A&M University, TAMU, College Station, TX
| | - Dominic Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, Plymouth, NC
| | - Jeff Gore
- Delta Research & Extension Center, Mississippi State University, Stoneville, MS
| | - Francis P F Reay-Jones
- Department of Plant and Environmental Sciences, Pee Dee Research and Education Center, Clemson University, Florence, SC
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Carrière Y, Degain B, Unnithan GC, Harpold VS, Li X, Tabashnik BE. Seasonal Declines in Cry1Ac and Cry2Ab Concentration in Maturing Cotton Favor Faster Evolution of Resistance to Pyramided Bt Cotton in Helicoverpa zea (Lepidoptera: Noctuidae). JOURNAL OF ECONOMIC ENTOMOLOGY 2019; 112:2907-2914. [PMID: 31587050 DOI: 10.1093/jee/toz236] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Indexed: 06/10/2023]
Abstract
Under ideal conditions, widely adopted transgenic crop pyramids producing two or more distinct insecticidal proteins from Bacillus thuringiensis (Bt) that kill the same pest can substantially delay evolution of resistance by pests. However, deviations from ideal conditions diminish the advantages of such pyramids. Here, we tested the hypothesis that changes in maturing cotton producing Cry1Ac and Cry2Ab affect evolution of resistance in Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), a pest with low inherent susceptibility to both toxins. In terminal leaves of field-grown Bt cotton, the concentration of both toxins was significantly higher for young, squaring plants than for old, fruiting plants. We used laboratory bioassays with plant material from field-grown cotton to test H. zea larvae from a strain selected for resistance to Cry1Ac in the laboratory, its more susceptible parent strain, and their F1 progeny. On young Bt cotton, no individuals survived to pupation. On old Bt cotton, survival to pupation was significantly higher for the lab-selected strain and the F1 progeny relative to the unselected parent strain, indicating dominant inheritance of resistance. Redundant killing, the extent to which insects resistant to one toxin are killed by another toxin in a pyramid, was complete on young Bt cotton, but not on old Bt cotton. No significant fitness costs associated with resistance were detected on young or old non-Bt cotton. Incorporation of empirical data into simulations indicates the observed increased selection for resistance on old Bt cotton could accelerate evolution of resistance to cotton producing Cry1Ac and Cry2Ab in H. zea.
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Affiliation(s)
- Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ
| | - Ben Degain
- Department of Entomology, University of Arizona, Tucson, AZ
| | | | | | - Xianchun Li
- Department of Entomology, University of Arizona, Tucson, AZ
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Bilbo TR, Reay-Jones FPF, Reisig DD, Greene JK, Turnbull MW. Development, survival, and feeding behavior of Helicoverpa zea (Lepidoptera: Noctuidae) relative to Bt protein concentrations in corn ear tissues. PLoS One 2019; 14:e0221343. [PMID: 31425563 PMCID: PMC6699733 DOI: 10.1371/journal.pone.0221343] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 08/05/2019] [Indexed: 12/02/2022] Open
Abstract
The corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), preferentially oviposits and feeds on ears of corn (Zea mays L.) and can be managed using transgenic hybrids that produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt). Concentrations of Bt proteins can vary spatially and temporally in plant tissues, creating a heterogeneous environment that can increase the risk of resistance development. We planted small-plot trials of nine Bt and non-Bt corn hybrids in South Carolina in 2016 and 2017 and investigated the development, survival, feeding injury, and feeding behavior in corn ear tissues. ELISA was used to quantify the concentrations of Cry1F and Cry2Ab2 in young silk, old silk, maternal tip tissue, kernels, and husk. Cry1F and Cry2Ab2 significantly varied with silk age and both proteins were generally highest in the silk and tip tissue. Hybrids with pyramided proteins significantly reduced feeding injury to the silk, tip, and kernel ear tissues, which was less apparent with single Bt protein hybrids. The pyramided hybrid expressing Vip3A incurred no injury to either the ear tip or kernels, and only eight 1st instar larvae were collected in the silk of 520 sampled ears. Age of larvae significantly varied among ear tissues but not between hybrids. Depending on hybrid family, mean larval instar in the silk, tip, and kernels was 1st or 2nd, 3rd, and 5th, respectively. Instar-specific feeding penetrance into corn ears increased with age but did not differ between hybrids. We characterized the instar- and tissue-specific feeding behavior of H. zea larvae but did not detect differences in feeding behavior between Bt and non-Bt hybrids. Implications for resistance management strategies such as seed mixtures are discussed.
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Affiliation(s)
- Tom R. Bilbo
- Clemson University, Department of Plant and Environmental Sciences, Pee Dee Research and Education Center, Florence, South Carolina, United States of America
| | - Francis P. F. Reay-Jones
- Clemson University, Department of Plant and Environmental Sciences, Pee Dee Research and Education Center, Florence, South Carolina, United States of America
| | - Dominic D. Reisig
- North Carolina State University, Department of Entomology and Plant Pathology, Vernon G. James Research and Extension Center, Plymouth, North Carolina, United States of America
| | - Jeremy K. Greene
- Clemson University, Department of Plant and Environmental Sciences, Edisto Research and Education Center, Blackville, South Carolina, United States of America
| | - Matthew W. Turnbull
- Clemson University, Department of Plant and Environmental Sciences, Department of Biological Sciences, Clemson, South Carolina, United States of America
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65
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Braswell LR, Reisig DD, Sorenson CE, Collins GD. Helicoverpa zea (Lepidoptera: Noctuidae) Preference for Plant Structures, and Their Location, Within Bt Cotton Under Different Nitrogen and Irrigation Regimes. JOURNAL OF ECONOMIC ENTOMOLOGY 2019; 112:1741-1751. [PMID: 31329903 DOI: 10.1093/jee/toz105] [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: 11/26/2018] [Indexed: 06/10/2023]
Abstract
Helicoverpa zea Boddie is a common economic pest of cotton (Gossypium hirsutum L.), including transgenic cotton varieties that express Bacillus thuringiensis (Bt). Helicoverpa zea oviposition is similar in Bt and non-Bt cotton, but behavior of H. zea larvae can be different in the presence of Bt, with neonates moving away from terminals faster in single-toxin Bt than non-Bt cotton or avoiding Bt-treated diet in the lab. We quantified H. zea oviposition and larval distribution on structures within cotton plants in small plot experiments of Cry1Ac + Cry1F cotton for 2 yr under different irrigation and nitrogen treatments. More eggs were oviposited on plants receiving nitrogen application during 2016 and on leaves in the top section of irrigated plants during 2017, but other treatment effects on eggs or larvae were minimal. Helicoverpa zea eggs were most common on leaves in the top third of plants at position zero and middle section of cotton plants throughout the season, but some oviposition occurred on fruiting structures as well. First and second instars were more common on squares in the top section of plants during 2016 and bolls in the middle and lower sections during 2017 due to oviposition lower in the canopy during 2017. During both years, third through fifth instars were more common on bolls in the middle and lower section of plants closer to the main stem. These findings have resistance management implications as extended larval feeding on bolls could optimize nutrition, decrease Bt susceptibility, and potentially influence behavioral resistance.
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Affiliation(s)
- Lewis R Braswell
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, Plymouth, NC
| | - Clyde E Sorenson
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC
| | - Guy D Collins
- Department of Crop and Soil Science, North Carolina State University, Upper Coastal Plain Research Station, Rocky Mount, NC
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66
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Bilbo TR, Reay-Jones FPF, Reisig DD, Greene JK. Susceptibility of Corn Earworm (Lepidoptera: Noctuidae) to Cry1A.105 and Cry2Ab2 in North and South Carolina. JOURNAL OF ECONOMIC ENTOMOLOGY 2019; 112:1845-1857. [PMID: 30924858 DOI: 10.1093/jee/toz062] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Indexed: 06/09/2023]
Abstract
The corn earworm, Helicoverpa zea (Boddie), is managed in corn and cotton in the United States primarily using transgenic cultivars that produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt). However, increasing reports of resistance to one or more Bt proteins threaten the continued efficacy of Bt traits. To better understand the development of resistance of H. zea to Bt corn and cotton in the southeastern United States, we monitored for resistance to Cry1A.105 and Cry2Ab2 among 22 field populations of H. zea collected in non-Bt and Bt corn expressing Cry1A.105 + Cry2Ab2 during 2017 and 2018. Colonies were established in the laboratory and progeny were screened in diet-overlay bioassays to purified Cry1A.105 and Cry2Ab2 proteins. Compared with two susceptible laboratory colonies, all 14 field colonies tested with Cry1A.105 were highly resistant, with resistance ratios (RRs) ranging from 13.5 to >4,000. For Cry2Ab2, 19 colonies were tested and RRs ranged from 0.26 to 33.7. Field populations were significantly more susceptible to Cry2Ab2 than Cry1A.105. We documented variability in F0 and F1 pupal weight and developmental rates of natural populations of H. zea, but observed no significant correlation with susceptibility to either Cry1A.105 or Cry2Ab2. Our results expand on the recent reports of H. zea resistance to Cry1A and Cry2A proteins and will aid in the design and deployment of future pyramided crops in the United States.
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Affiliation(s)
- Tom R Bilbo
- Department of Plant and Environmental Sciences, Pee Dee Research and Education Center, Clemson University, Florence, SC
| | - Francis P F Reay-Jones
- Department of Plant and Environmental Sciences, Pee Dee Research and Education Center, Clemson University, Florence, SC
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, the Vernon G. James Research and Extension Center, Plymouth, NC
| | - Jeremy K Greene
- Department of Plant and Environmental Sciences, Edisto Research and Education Center, Clemson University, Blackville, SC
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67
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Braswell LR, Reisig DD, Sorenson CE, Collins GD. Helicoverpa zea (Lepidoptera: Noctuidae) Oviposition and Larval Vertical Distribution in Bt Cotton Under Different Levels of Nitrogen and Irrigation. JOURNAL OF ECONOMIC ENTOMOLOGY 2019; 112:1237-1250. [PMID: 30768671 DOI: 10.1093/jee/toz023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Indexed: 06/09/2023]
Abstract
In some Bt cotton (Gossypium hirsutum L.) varieties, bollworm (Helicoverpa zea Boddie) larval behavior differs from non-Bt varieties. Laboratory assays indicate bollworm larvae can detect Bt proteins, which may cause behavioral differences. Plant stress from factors including fertility and water availability causes changes in plant physiology and Bt expression. Our objective was to determine whether nitrogen and irrigation influenced bollworm behavior in Bt cotton by recording the vertical distribution of eggs and larvae over time. We conducted small plot experiments with Cry1Ac + Cry1F cotton in 2016 and 2017 with three nitrogen rates, along with irrigated and nonirrigated treatments during 2017. Bollworm locations were determined by in-field examination of 10-20 cotton plants per plot over 6-8 wk. The location of each egg and larva was recorded by node, with instar estimation of each larva. Oviposition was higher in in plots receiving nitrogen; first and second instars were also more common in plots receiving nitrogen or irrigation, whereas older instars had similar numbers among treatments. Oviposition was more evenly distributed throughout the canopy earlier in the sampling period than during later weeks, with more eggs in the top third of the canopy in only three of 14-wk. Early instars were also evenly distributed throughout the canopy. Later, instars moved to the middle portions of the canopy, away from bottom nodes, and did not move toward the terminal. Understanding bollworm behavior can inform both crop scouting and resistance management decisions.
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Affiliation(s)
- Lewis R Braswell
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, Plymouth, NC
| | - Clyde E Sorenson
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC
| | - Guy D Collins
- Department of Crop and Soil Science, North Carolina State University, Upper Coastal Plain Research Station, Rocky Mount, NC
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68
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Kaur G, Guo J, Brown S, Head GP, Price PA, Paula-Moraes S, Ni X, Dimase M, Huang F. Field-evolved resistance of Helicoverpa zea (Boddie) to transgenic maize expressing pyramided Cry1A.105/Cry2Ab2 proteins in northeast Louisiana, the United States. J Invertebr Pathol 2019; 163:11-20. [DOI: 10.1016/j.jip.2019.02.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 12/13/2018] [Accepted: 02/22/2019] [Indexed: 11/28/2022]
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69
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Braswell LR, Reisig DD, Sorenson CE, Collins GD. Development and Dispersal of Helicoverpa zea (Lepidoptera: Noctuidae) on Non-Bt and Bt Pyramided Cotton. ENVIRONMENTAL ENTOMOLOGY 2019; 48:465-477. [PMID: 30715246 DOI: 10.1093/ee/nvz006] [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: 08/23/2018] [Indexed: 06/09/2023]
Abstract
Bollworm (Helicoverpa zea Boddie) (Lepidoptera: Noctuidae) can cause economic losses in both non-Bt and Bt cotton. Larvae modify their behavior in the presence of Bt by moving away from terminals faster in Bt cotton compared to non-Bt cotton and avoiding Bt-treated diets. Our objectives were to understand differences in bollworm egg and larvae populations within, and dispersal away from, non-Bt and Bt pyramided-toxin cotton. We conducted small plot experiments in 2016 and 2017 to monitor on-plant egg and larval numbers, and off-plant dispersal of larvae, from non-Bt and different Bt toxin pyramided cotton. Bollworm adults preferred to oviposit in most Bt toxin pyramids compared to non-Bt; this was likely unrelated to detection of Bt by adults, but rather density-dependent aversion from high larval populations. First instar numbers were similar in all non-Bt/Bt toxin pyramids and dispersed at a similar rate. Second through fifth instar numbers were higher in non-Bt than Bt toxin pyramids but dispersed equally from all non-Bt/Bt toxin pyramids, regardless of Bt pyramid type. Development times of larvae were often slower in Bt toxin pyramids compared to non-Bt. Fifth instars were found in, and dispersing from, Bt toxin pyramids containing Vip3A, raising concerns of resistance development. Furthermore, differences in oviposition rate among non-Bt/Bt toxin pyramids and slowed development rate of larvae on Bt varieties could create inconsistencies in generation times emerging from Bt and non-Bt hosts, which could contribute to resistance development.
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Affiliation(s)
- Lewis R Braswell
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, Plymouth, NC
| | - Clyde E Sorenson
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC
| | - Guy D Collins
- Department of Crop and Soil Science, North Carolina State University, Upper Coastal Plain Research Station, Rocky Mount, NC
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Zhang M, Wei J, Ni X, Zhang J, Jurat-Fuentes JL, Fabrick JA, Carrière Y, Tabashnik BE, Li X. Decreased Cry1Ac activation by midgut proteases associated with Cry1Ac resistance in Helicoverpa zea. PEST MANAGEMENT SCIENCE 2019; 75:1099-1106. [PMID: 30264537 DOI: 10.1002/ps.5224] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 09/19/2018] [Accepted: 09/22/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Field-evolved resistance of Helicoverpa zea to Bacillus thuringiensis (Bt) toxin Cry1Ac was first reported more than a decade ago, yet the underlying mechanisms remain elusive. Towards understanding the mechanisms of resistance to Cry1Ac, we analyzed a susceptible (LAB-S) and two resistant (GA and GA-R) strains of H. zea. The GA strain was derived from Georgia and exposed to Bt toxins only in the field. The GA-R strain was derived from the GA strain and selected for increased resistance to Cry1Ac in the laboratory. RESULTS Resistance to MVPII, a liquid formulation containing a hybrid protoxin similar to Cry1Ac, was 110-fold for GA-R and 7.8-fold for GA relative to LAB-S. In midgut brush border membrane vesicles, activity of alkaline phosphatase and aminopeptidase N did not vary significantly among strains. The activity of total proteases, trypsin-like proteases and chymotrypsin-like proteases was significantly lower for GA-R and GA than LAB-S, but did not differ between GA-R and GA. When H. zea midgut cells were exposed to Cry1Ac protoxin that had been digested with midgut extracts, toxicity was significantly lower for extracts from GA-R and GA relative to extracts from LAB-S, but did not differ between GA-R and GA. Transcriptional analysis showed that none of the five protease genes examined was associated with the decline in Cry1Ac activation in GA-R and GA relative to LAB-S. CONCLUSION The results suggest that decreased Cry1Ac activation is a contributing field-selected mechanism of resistance that helps explain the reduced susceptibility of the GA-R and GA strains. Relative to the LAB-S strain, the two Cry1Ac-resistant strains had lower total protease, trypsin and chymotrypsin activities, a lower Cry1Ac activation rate, and Cry1Ac protoxin incubated with their midgut extracts was less toxic to H. zea midgut cells. © 2018 Society of Chemical Industry.
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Affiliation(s)
- Min Zhang
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
- Department of Entomology, University of Arizona, Tucson, AZ
| | - Jizhen Wei
- Department of Entomology, University of Arizona, Tucson, AZ
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xinzhi Ni
- USDA-ARS, Crop Genetics and Breeding Research Unit, Tifton, GA, USA
| | - Jie Zhang
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Juan L Jurat-Fuentes
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN, USA
| | - Jeffrey A Fabrick
- USDA-ARS, U.S. Arid Land Agricultural Research Center, Maricopa, AZ, USA
| | - Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ
- BIO5 Institute, University of Arizona, Tucson, AZ, USA
| | | | - Xianchun Li
- Department of Entomology, University of Arizona, Tucson, AZ
- BIO5 Institute, University of Arizona, Tucson, AZ, USA
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71
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Kerns CD, Greene JK, Reay-Jones FPF, Bridges WC. Effects of Planting Date on Thrips (Thysanoptera: Thripidae) in Cotton. JOURNAL OF ECONOMIC ENTOMOLOGY 2019; 112:699-707. [PMID: 30597059 DOI: 10.1093/jee/toy398] [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: 08/03/2018] [Indexed: 06/09/2023]
Abstract
At-plant applications of insecticides are the most common method to manage thrips in upland cotton, Gossypium hirstutum L. Because the primary pest species, tobacco thrips, Frankliniella fusca (Hinds), has developed resistance to commonly used neonicotinoid insecticides used in producing cotton, alternative control options are needed for sustainable thrips management programs. A 3-year study (2015-2017) showed that densities of thrips, feeding injury from thrips, cotton growth, and yield varied among 10 planting dates. Densities of thrips were lowest in seedling cotton planted after mid-May in all years. Thrips injury ratings in all years were highest in cotton planted in April, lowest in cotton planted in June, and below intermediate injury (intermediate corresponded to a 3 on the 0-5 scale) levels in cotton planted after mid-May. Cotton planted during May, rather than in April or June, had the highest yield potential, regardless of variety. Results of the study indicated that altering planting date could potentially be useful in mitigating injury and losses from thrips in upland cotton.
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Affiliation(s)
- Cody D Kerns
- Department of Plant and Environmental Sciences, Clemson University, Edisto Research and Education Center, Blackville
| | - Jeremy K Greene
- Department of Plant and Environmental Sciences, Clemson University, Edisto Research and Education Center, Blackville
| | - Francis P F Reay-Jones
- Department of Plant and Environmental Sciences, Clemson University, Pee Dee Research and Education Center, Florence
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72
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Little NS, Elkins BH, Mullen RM, Perera OP, Parys KA, Allen KC, Boykin DL. Differences between two populations of bollworm, Helicoverpa zea (Lepidoptera: Noctuidae), with variable measurements of laboratory susceptibilities to Bt toxins exposed to non-Bt and Bt cottons in large field cages. PLoS One 2019; 14:e0212567. [PMID: 30865645 PMCID: PMC6415783 DOI: 10.1371/journal.pone.0212567] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 02/05/2019] [Indexed: 01/03/2023] Open
Abstract
Interpreting variable laboratory measurements of Helicoverpa zea Boddie susceptibility to toxins from Bacillus thuringiensis Berliner (Bt) has been challenging due to a lack of clear evidence to document declining field control. Research that links laboratory measurements of susceptibility to survival on Bt crops is vital for accurate characterization and any subsequent response to the occurrence of an implied H. zea resistance event. In this study, H. zea survival and the resultant damage to plant fruiting structures of non-Bt, Bollgard II, and Bollgard III cottons from two insect colonies with differing levels of laboratory susceptibility to Bt toxins were evaluated in large field cages. Laboratory bioassays revealed resistance ratios of 2.04 and 622.14 between the two H. zea colonies for Dipel DF and Cry1Ac, respectively. Differences between the two H. zea colonies measured via bioassays with Bollgard II and Bollgard III cotton leaf tissue in the laboratory were not statistically discernable. However, there was 17.6% and 5.3% lower larval mortality in Bollgard II and Bollgard III for the feral relative to the laboratory colony of H. zea, respectively. Although H. zea larval numbers in cages infested with the laboratory susceptible colony did not differ between the two Bt cottons, there were fewer larvae per 25 plants in Bollgard III than in Bollgard II cotton in cages containing tolerant insects. Cages infested with tolerant H. zea moths had higher numbers of total larvae than those containing the laboratory susceptible colony in both Bollgard II and Bollgard III cottons. Bollgard II and Bollgard III cottons received 77.4% and 82.7% more total damage to total plant fruiting structures in cages infested with tolerant insects relative to those containing the laboratory susceptible colony. The damage inflicted to fruiting structures on Bollgard III cotton by a feral H. zea colony with decreased measurements of laboratory susceptibility to Dipel DF and Cry1Ac indicate that the addition of Vip3A to third generation Bt cottons may not provide sufficient control in situations where infestations levels are high.
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Affiliation(s)
- Nathan S. Little
- Southern Insect Management Research Unit, USDA-ARS, Stoneville, Mississippi, United States of America
| | - Blake H. Elkins
- Southern Insect Management Research Unit, USDA-ARS, Stoneville, Mississippi, United States of America
| | - R. Michelle Mullen
- Southern Insect Management Research Unit, USDA-ARS, Stoneville, Mississippi, United States of America
| | - Omaththage P. Perera
- Southern Insect Management Research Unit, USDA-ARS, Stoneville, Mississippi, United States of America
| | - Katherine A. Parys
- Southern Insect Management Research Unit, USDA-ARS, Stoneville, Mississippi, United States of America
| | - K. Clint Allen
- Southern Insect Management Research Unit, USDA-ARS, Stoneville, Mississippi, United States of America
| | - Deborah L. Boykin
- Jamie Whitten Delta States Research Center, USDA-ARS, Stoneville, Mississippi, United States of America
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73
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Yang F, González JCS, Williams J, Cook DC, Gilreath RT, Kerns ADL. Occurrence and Ear Damage of Helicoverpa zea on Transgenic Bacillus thuringiensis Maize in the Field in Texas, U.S. and Its Susceptibility to Vip3A Protein. Toxins (Basel) 2019; 11:toxins11020102. [PMID: 30744120 PMCID: PMC6416581 DOI: 10.3390/toxins11020102] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 02/05/2019] [Accepted: 02/07/2019] [Indexed: 01/04/2023] Open
Abstract
The corn earworm, Helicoverpa zea (Boddie), is a major pest of Bacillus thuringiensis (Bt) maize and cotton in the U.S. Reduced efficacy of Bt plants expressing Cry1 and Cry2 against H. zea has been reported in some areas of the U.S. In this study, we evaluated the occurrence and ear damage of H. zea on transgenic Bt maize expressing Cry proteins or a combination of Vip3A and Cry proteins in the field in Texas in 2018. We found that the occurrence of H. zea larvae and the viable kernel damage area on the ear were not different between non-Bt maize and Bt maize expressing Cry1A.105+Cry2Ab2 and Cry1Ab+Cry1F proteins. A total of 67.5% of the pyramided Bt maize expressing Cry1Ab+Cry1F+Vip3A was damaged by 2nd–4th instar larvae of H. zea. Diet bioassays showed that the resistance ratio against Vip3Aa51 for H. zea obtained from Cry1Ab+Cry1F+Vip3A maize was 20.4 compared to a field population collected from Cry1F+Cry1A.105+Cry2Ab2 maize. Leaf tissue bioassays showed that 7-day survivorship on WideStrike3 (Cry1F+Cry1Ac+Vip3A) cotton leaves was significantly higher for the H. zea population collected from Cry1Ab+Cry1F+Vip3A maize than for a Bt-susceptible laboratory population. The results generated from this study suggest that H. zea has evolved practical resistance to Cry1 and Cry2 proteins. Therefore, it is crucial to ensure the sustainable use of the Vip3A technology in Bt maize and cotton.
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Affiliation(s)
- Fei Yang
- Department of Entomology, Texas A&M University, College Station, TX 77843-2475, USA.
| | | | | | - Donald C Cook
- Delta Research and Extension Center, Mississippi State University, Stoneville, MS 38776, USA.
| | - Ryan T Gilreath
- Department of Entomology, Texas A&M University, College Station, TX 77843-2475, USA.
| | - And David L Kerns
- Department of Entomology, Texas A&M University, College Station, TX 77843-2475, USA.
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Reisig D, Kerns D, Gore J, Musser F. Managing pyrethroid- and Bt-resistant bollworm in southern U.S. cotton. ACTA ACUST UNITED AC 2019. [DOI: 10.2134/cs2019.52.0108] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Dominic Reisig
- North Carolina State University; Department of Entomology and Plant Pathology
| | - David Kerns
- Texas A&M University; Department of Entomology
| | - Jeff Gore
- Mississippi State University; Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology
| | - Fred Musser
- Mississippi State University; Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology
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Reisig DD, Kurtz R. Bt Resistance Implications for Helicoverpa zea (Lepidoptera: Noctuidae) Insecticide Resistance Management in the United States. ENVIRONMENTAL ENTOMOLOGY 2018; 47:1357-1364. [PMID: 30277503 DOI: 10.1093/ee/nvy142] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Indexed: 06/08/2023]
Abstract
Both maize and cotton genetically engineered to express Bt toxins are widely planted and important pest management tools in the United States. Recently, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) has developed resistance to two toxin Bt maize and cotton (Cry1A and Cry2A). Hence, growers are transitioning to three toxin Bt cotton and maize that express both Cry toxins and the Vip3Aa toxin. H. zea susceptibility to Vip3Aa is threatened by 1) a lack of availability of non-Bt refuge crop hosts, including a 1-5% annual decline in the number of non-Bt maize hybrids being marketed; 2) the ineffectiveness of three toxin cultivars to function as pyramids in some regions, with resistance to two out of three toxins in the pyramid; and 3) the lack of a high dose Vip3Aa event in cotton and maize. We propose that data should be collected on current Cry-resistant H. zea in the field to inform future Bt resistance models and that the deployment of Bt toxins and non-Bt refuge crops should be adjusted to favor susceptibility of H. zea to Bt toxins such as Vip3Aa. Finally, maize growers should be incentivized to plant non-Bt structured refuge and have access to hybrids with high-yielding genetic potential at a reasonable price.
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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, Plymouth, NC
| | - Ryan Kurtz
- Agricultural & Environmental Research, Cotton Incorporated, Cary, NC
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Bilbo TR, Reay-Jones FPF, Reisig DD, Musser FR, Greene JK. Effects of Bt Corn on the Development and Fecundity of Corn Earworm (Lepidoptera: Noctuidae). JOURNAL OF ECONOMIC ENTOMOLOGY 2018; 111:2233-2241. [PMID: 29986034 DOI: 10.1093/jee/toy203] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Indexed: 06/08/2023]
Abstract
The corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), is only moderately susceptible to most toxins from the bacterium Bacillus thuringiensis (Bt) expressed in transgenic corn. To better understand the impact of Bt corn on the life cycle of H. zea, we collected pupae of H. zea during 2014-2016 in North Carolina, South Carolina, and Mississippi from corn hybrids expressing Cry1Ab, Cry1F, Cry1F + Cry1Ab, Cry1F + Cry1Ab + Vip3Aa20, Cry1A.105 + Cry2Ab2, and Cry1A.105 + Cry2Ab2 + Cry1F, as well as from non-Bt near-isolines. We investigated the effect of Bt corn on pupal weight, fecundity, and egg viability of H. zea. Pupal weights were significantly reduced for males and females from all Bt hybrids compared with non-Bt near-isolines. Female pupae from the hybrid expressing Cry1F + Cry1Ab were also significantly lighter relative to those from the near-isolines expressing only Cry1F. Reductions in pupal weight did not result in any detectable effects on fecundity or egg viability. The reduction in pupal weight in the hybrids expressing Cry1F and Cry1F + Cry1Ab significantly declined over time in South Carolina, possibly indicating developing resistance to these Bt toxins. These data can be incorporated into insect resistance management models used to improve risk management decisions regarding H. zea in Bt crops in the complex landscapes of the southern United States.
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Affiliation(s)
- Tom R Bilbo
- Department of Plant and Environmental Sciences - Pee Dee Research and Education Center, Clemson University, Florence, SC
| | - Francis P F Reay-Jones
- Department of Plant and Environmental Sciences - Pee Dee Research and Education Center, Clemson University, Florence, SC
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, The Vernon G. James Research and Extension Center, North Carolina State University, Plymouth, NC
| | - Fred R Musser
- Department of Biochemistry, Molecular Biology, Entomology & Plant Pathology, Mississippi State University, Mississippi State, MS
| | - Jeremy K Greene
- Department of Plant and Environmental Sciences - Edisto Research and Education Center, Clemson University, Blackville, SC
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