Effective dominance and redundant killing of single‐ and dual‐gene resistant populations of <i>Helicoverpa zea</i> on pyramided Bt corn and cotton

Santiago‐González, José C.; Kerns, David L.; Head, Graham P.; Yang, Fei

doi:10.1002/ps.7052

Cited by 12 publications

(16 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…zea to Cry1Ac, and larval damage to corn expressing similar Cry toxins, are highly dependent on crop composition in the local landscape [ 13 , 14 ]. Furthermore, the dominance of Cry2Ab2 resistance in this pest varies across toxin dose and source [ 33 ]. Therefore, it is not surprising that Bt resistance levels will vary among years, as environmental conditions shift.…”

Section: Discussionmentioning

confidence: 99%

Magnitude and Extent of Helicoverpa zea Resistance Levels to Cry1Ac and Cry2Ab2 across the Southeastern USA

Reisig

Buntin

Greene

et al. 2023

Insects

View full text Add to dashboard Cite

After resistance is first detected, continued resistance monitoring can inform decisions on how to effectively manage resistant populations. We monitored for resistance to Cry1Ac (2018 and 2019) and Cry2Ab2 (2019) from southeastern USA populations of Helicoverpa zea. We collected larvae from various plant hosts, sib-mated the adults, and tested neonates using diet-overlay bioassays and compared them to susceptible populations for resistance estimates. We also compared LC50 values with larval survival, weight and larval inhibition at the highest dose tested using regression, and found that LC50 values were negatively correlated with survival for both proteins. Finally, we compared resistance rations between Cry1Ac and Cry2Ab2 during 2019. Some populations were resistant to Cry1Ac, and most were resistant to CryAb2; Cry1Ac resistance ratios were lower than Cry2Ab2 during 2019. Survival was positively correlated with larval weight inhibition for Cry2Ab. This contrasts with other studies in both the mid-southern and southeastern USA, where resistance to Cry1Ac, Cry1A.105, and Cry2Ab2 increased over time and was found in a majority of populations. This indicates that cotton expressing Cry proteins in the southeastern USA was at variable risk for damage in this region.

show abstract

Section: Discussionmentioning

confidence: 99%

Magnitude and Extent of Helicoverpa zea Resistance Levels to Cry1Ac and Cry2Ab2 across the Southeastern USA

Reisig

Buntin

Greene

et al. 2023

Insects

View full text Add to dashboard Cite

show abstract

“…Infested ears were placed in 5.7-L plastic containers with two pieces of paper towel underneath. 15,[30][31][32][33] The containers were placed in an insect rearing room maintained at 26 ± 1 °C, ∼50% RH, and a photoperiod of 16:8 h (L:D). The survival and development of the insects were monitored until the pupal stage and corn ears were replaced as needed during the experiment.…”

Section: Corn Ear Bioassaysmentioning

confidence: 99%

“…The Petri dishes were sealed with Parafilm® and were maintained at 26 ± 1 °C, ∼50% RH, and a photoperiod of 16:8 h (L:D). 15 Leaf tissues were changed every 1 to 2 days, while filter paper was wetted daily and changed as needed. There were four replications for each insect strain and each cotton variety, and each replication contained 30 larvae.…”

Section: Cotton Leaf Tissue Bioassaysmentioning

confidence: 99%

“…19 For complete redundant killing to occur, the activity and concentration of each Bt protein in the pyramid should be high enough to kill insects fully or partially resistant to the other Bt protein(s), and there should be no cross-resistance among Bt proteins. 15,19,20 Studies indicate that strong cross-resistance is more likely to occur among Bt proteins that are structurally similar and share binding sites in the insect midgut. 18,21 Strong cross-resistance among Bt proteins reduces the durability of gene-pyramiding, as insects exhibiting resistance to one Bt protein are likely to also survive exposure to other Bt proteins expressed in the pyramid.…”

Section: Introductionmentioning

confidence: 99%

“…Gene‐pyramiding involves combining two or more distinct Bt proteins that target the same insect pest so that insects with resistance alleles against one Bt protein in the pyramid are still controlled by the other Bt proteins in the pyramid through redundant killing 19 . For complete redundant killing to occur, the activity and concentration of each Bt protein in the pyramid should be high enough to kill insects fully or partially resistant to the other Bt protein(s), and there should be no cross‐resistance among Bt proteins 15,19,20 . Studies indicate that strong cross‐resistance is more likely to occur among Bt proteins that are structurally similar and share binding sites in the insect midgut 18,21 .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Cross‐resistance and redundant killing of Vip3Aa resistant populations of Helicoverpa zea on purified Bt proteins and pyramided Bt crops

Kennedy

Kerns

Head

et al. 2023

Pest Management Science

Self Cite

View full text Add to dashboard Cite

BackgroundPyramiding Bt proteins is a key strategy to delay insect resistance development. However, the durability of pyramided Bt crops for controlling insect pests is threatened by cross‐resistance among Bt proteins, which can ultimately contribute to resistance development. The corn earworm, Helicoverpa zea, is a major agricultural pest of pyramided Bt crops. Previous studies have examined cross‐resistance and redundant killing of Cry resistance in H. zea, but such information is lacking for Vip3Aa resistance in this pest. Here, we evaluated cross‐resistance and redundant killing of Vip3Aa‐resistant H. zea to purified Bt proteins, as well as Bt corn and Bt cotton.ResultsDiet bioassays demonstrated high susceptibility of Vip3Aa‐resistant H. zea to Cry1Ac, Cry1A.105, and Cry2Ab2 purified proteins. No Vip3Aa‐susceptible, ‐heterozygous, or‐resistant H. zea could survive on pyramided Bt corn containing Cry1 and/or Cry2 proteins. Complete redundant killing was observed in pyramided Bt corn containing Cry1 and/or Cry2 proteins against Vip3Aa resistance in H. zea. Vip3Aa‐susceptible, ‐heterozygous, and ‐resistant H. zea exhibited survival rates ranging from 0.0 to 22.5% on pyramided Bt cotton with Cry1 and/or Cry2 proteins. Incomplete to complete redundant killing was observed for Vip3Aa‐resistant H. zea on pyramided Bt cotton containing Cry1 and/or Cry2 proteins.ConclusionOur findings indicate that Vip3Aa‐resistant H. zea does not exhibit positive cross‐resistance to Cry1 or Cry2 proteins. Additionally, most pyramided Bt crops showed complete or nearly complete redundant killing of Vip3Aa‐resistant H. zea. These results indicate that a pyramiding strategy would often be effective for managing Vip3Aa resistance in regions of the United States where H. zea has not evolved resistance to Cry1 and Cry2 toxins.This article is protected by copyright. All rights reserved.

show abstract

Diverse genetic basis of Vip3Aa resistance in five independent field‐derived strains of Helicoverpa zea in the US

Yang,

Head,

Kerns

et al. 2024

Pest Management Science

Self Cite

View full text Add to dashboard Cite

BACKGROUNDPractical resistance of Helicoverpa zea to Cry proteins has become widespread in the US, making Vip3Aa the only effective Bacillus thuringiensis (Bt) protein for controlling this pest. Understanding the genetic basis of Vip3Aa resistance in H. zea is essential in sustaining the long‐term efficacy of Vip3Aa. The objectives of this study were to characterize the inheritance of Vip3Aa resistance in four distinct field‐derived H. zea strains (M1‐RR, AC4‐RR, R2‐RR and R15‐RR), and to test for shared genetic basis among these strains and a previously characterized Texas resistant strain (LT#70‐RR).RESULTSMaternal effects and sex linkage were absent, and the effective dominance level (DML) was 0.0 across Vip3Aa39 concentrations ranging from 1.0 to 31.6 μg cm−2, in all H. zea resistant strains. Mendelian monogenic model tests indicated that Vip3Aa resistance in each of the four strains was controlled by a single gene. However, interstrain complementation tests indicated that three distinct genetic loci are involved in Vip3Aa resistance in the five resistant H. zea strains: one shared by M1‐RR and LT#70‐RR; another shared by R2‐RR and R15‐RR; and a distinct one for AC4‐RR.CONCLUSIONResults of this study indicate that Vip3Aa resistance in all H. zea strains was controlled by a single, recessive and autosomal gene. However, there were three distinct genetic loci associated with Vip3Aa resistance in the five resistant H. zea strains. The information generated from this study is valuable for exploring mechanisms of Vip3Aa resistance, monitoring the evolution of Vip3Aa resistance, and devising effective strategies for managing Vip3Aa resistance in H. zea. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

show abstract

Effective dominance and redundant killing of single‐ and dual‐gene resistant populations of Helicoverpa zea on pyramided Bt corn and cotton

Cited by 12 publications

References 41 publications

Magnitude and Extent of Helicoverpa zea Resistance Levels to Cry1Ac and Cry2Ab2 across the Southeastern USA

Magnitude and Extent of Helicoverpa zea Resistance Levels to Cry1Ac and Cry2Ab2 across the Southeastern USA

Cross‐resistance and redundant killing of Vip3Aa resistant populations of Helicoverpa zea on purified Bt proteins and pyramided Bt crops

Diverse genetic basis of Vip3Aa resistance in five independent field‐derived strains of Helicoverpa zea in the US

Contact Info

Product

Resources

About