Inheritance of Resistance to Cry1A.105 in Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae)

Yu, Wenbo; Head, Graham P.; Huang, Fangneng

doi:10.3390/insects13100875

Cited by 4 publications

(2 citation statements)

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“…Studies using F2 screening methods have reported high levels of resistance alleles to individual Cry toxins in H. zea populations from southeastern states. Yu et al [36] showed RAFs averaging 0.41 for Cry1A.105 and 0.33 for Cry2Ab2, while Santiago-Gonzalez et al [53] estimated RAF to be 0.722 (95%CL: 0.688-0.764) for Cry1Ac and 0.217 (95%CL: 0.179-0.261) for Cry2Ab2. Altogether, given these studies, the high PFRs at most trial locations, and the reduced control efficacy in the field, the evidence clearly documents widespread H. zea resistance to Cry1A.105 and Cry2Ab2.…”

Section: Phenotypic Resistance and Estimated Range Of Resistance Alle...mentioning

confidence: 99%

“…Early resistance monitoring studies and reports by registrants did not show strong evidence of significant changes in the baseline level of susceptibility to Bt toxins in corn earworm/cotton bollworm (Helicoverpa zea (Boddie) Lepidoptera: Noctuidae) populations [25][26][27]. However, more recent studies demonstrate widespread field-evolved resistance in H. zea to Cry1Ab, Cry1Ac, Cry2Ab2, and Cry1A.105 in Bt corn and Bt cotton [28][29][30][31][32][33][34][35][36][37][38][39]. Helicoverpa zea is not highly susceptible to Cry toxins, implying that key conditions underlying the success of the refuge strategy (i.e., high dose, recessive inheritance, and complete redundancy killing) for Bt crops producing these toxins may not be met [40][41][42].…”

Section: Introductionmentioning

confidence: 99%

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Extended Sentinel Monitoring of Helicoverpa zea Resistance to Cry and Vip3Aa Toxins in Bt Sweet Corn: Assessing Changes in Phenotypic and Allele Frequencies of Resistance

Dively

Kuhar

Taylor

et al. 2023

Insects

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Transgenic corn and cotton that produce Cry and Vip3Aa toxins derived from Bacillus thuringiensis (Bt) are widely planted in the United States to control lepidopteran pests. The sustainability of these Bt crops is threatened because the corn earworm/bollworm, Helicoverpa zea (Boddie), is evolving a resistance to these toxins. Using Bt sweet corn as a sentinel plant to monitor the evolution of resistance, collaborators established 146 trials in twenty-five states and five Canadian provinces during 2020–2022. The study evaluated overall changes in the phenotypic frequency of resistance (the ratio of larval densities in Bt ears relative to densities in non-Bt ears) in H. zea populations and the range of resistance allele frequencies for Cry1Ab and Vip3Aa. The results revealed a widespread resistance to Cry1Ab, Cry2Ab2, and Cry1A.105 Cry toxins, with higher numbers of larvae surviving in Bt ears than in non-Bt ears at many trial locations. Depending on assumptions about the inheritance of resistance, allele frequencies for Cry1Ab ranged from 0.465 (dominant resistance) to 0.995 (recessive resistance). Although Vip3Aa provided high control efficacy against H. zea, the results show a notable increase in ear damage and a number of surviving older larvae, particularly at southern locations. Assuming recessive resistance, the estimated resistance allele frequencies for Vip3Aa ranged from 0.115 in the Gulf states to 0.032 at more northern locations. These findings indicate that better resistance management practices are urgently needed to sustain efficacy the of corn and cotton that produce Vip3Aa.

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Section: Phenotypic Resistance and Estimated Range Of Resistance Alle...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Extended Sentinel Monitoring of Helicoverpa zea Resistance to Cry and Vip3Aa Toxins in Bt Sweet Corn: Assessing Changes in Phenotypic and Allele Frequencies of Resistance

Dively

Kuhar

Taylor

et al. 2023

Insects

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JAZ Genes in Cotton: Prospects for Improvements to Vegetative and Fibre Growth by Addressing Lepidopteran Herbivory Resistance Mechanisms

Rock,

Adhikari,

Parajulee

2024

Annual Plant Reviews Online

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Evolution of insect resistance is the primary threat to the long‐term efficacy of Bacillus thuringiensis (Bt) transgene technologies. Plants have a deeply conserved defence response to pests: Jasmonic acid (JA) hormone signalling mediated by transcriptional repressors called JASMONATE‐ZIM‐DOMAIN/JAZ. JAZs normally limit expression of plant defence pathways, promoting assimilate partitioning towards growth and reproduction, by their carboxyl terminal Jas motif that antagonises MYeloCytomatosis (MYC) master transcription factor activities. Deletion, alternative splicing/intron retention, or disruption of the Jas motif results in JA insensitivity and increased resistance to pathogens including arthropod herbivores, for example by production of secondary metabolites and new leaves with higher trichome density. JA‐mediated trichome initiation and elongation also impact cotton fibre production. Since its release in 2017, the third‐generation stacked commercial Bt insecticidal Vip3A protein traits are increasingly under severe pressure for evolution of Helicoverpa zea (bollworm) resistance. Regional differences in efficacy of Bollgard ® 3 and WideStrike ® 3 against lepidopteran pests and increasing pesticide use are emerging issues. Future transgenic field control failures from bollworm infestations and incursions of Helicoverpa armigera from Central America are likely in the U.S. Cotton Belt. In this systematic primer on the problem, we take a conceptual approach to consider JAZ genes as means to leverage ‘internal’ host‐derived herbivore resistance in cotton. We consider the genetic redundancy and pleiotropic nature of JAZ master regulators on tissue‐specific growth, development, crosstalk with hormonal and small RNA pathways as nodes in networks, and limitations of JAZ efficacy due to fitness costs/growth trade‐offs versus prospects for enhancing resistance networks to orchestrate transgressive segregation (generation of extreme phenotypes in breeding progeny not seen in parental lines).

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Cross-pollination in seed-blended refuge and selection for Vip3A resistance in a lepidopteran pest as detected by genomic monitoring

Pezzini,

Taylor,

Reisig

et al. 2024

Proc. Natl. Acad. Sci. U.S.A.

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The evolution of pest resistance to management tools reduces productivity and results in economic losses in agricultural systems. To slow its emergence and spread, monitoring and prevention practices are implemented in resistance management programs. Recent work suggests that genomic approaches can identify signs of emerging resistance to aid in resistance management. Here, we empirically examined the sensitivity of genomic monitoring for resistance management in transgenic Bt crops, a globally important agricultural innovation. Whole genome resequencing of wild North American Helicoverpa zea collected from non-expressing refuge and plants expressing Cry1Ab confirmed that resistance-associated signatures of selection were detectable after a single generation of exposure. Upon demonstrating its sensitivity, we applied genomic monitoring to wild H. zea that survived Vip3A exposure resulting from cross-pollination of refuge plants in seed-blended plots. Refuge seed interplanted with transgenic seed exposed H. zea to sublethal doses of Vip3A protein in corn ears and was associated with allele frequency divergence across the genome. Some of the greatest allele frequency divergence occurred in genomic regions adjacent to a previously described candidate gene for Vip3A resistance. Our work highlights the power of genomic monitoring to sensitively detect heritable changes associated with field exposure to Bt toxins and suggests that seed-blended refuge will likely hasten the evolution of resistance to Vip3A in lepidopteran pests.

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Inheritance of Resistance to Cry1A.105 in Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae)

Cited by 4 publications

References 40 publications

Extended Sentinel Monitoring of Helicoverpa zea Resistance to Cry and Vip3Aa Toxins in Bt Sweet Corn: Assessing Changes in Phenotypic and Allele Frequencies of Resistance

Extended Sentinel Monitoring of Helicoverpa zea Resistance to Cry and Vip3Aa Toxins in Bt Sweet Corn: Assessing Changes in Phenotypic and Allele Frequencies of Resistance

JAZ Genes in Cotton: Prospects for Improvements to Vegetative and Fibre Growth by Addressing Lepidopteran Herbivory Resistance Mechanisms

Cross-pollination in seed-blended refuge and selection for Vip3A resistance in a lepidopteran pest as detected by genomic monitoring

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