TY - JOUR
T1 - Responses to Bt toxin Vip3Aa by pink bollworm larvae resistant or susceptible to Cry toxins
AU - Tabashnik, Bruce E.
AU - Unnithan, Gopalan Chandran
AU - Yelich, Alexander J.
AU - Fabrick, Jeffrey A.
AU - Dennehy, Timothy J.
AU - Carrière, Yves
N1 - Funding Information: This work was funded in part by ABSTC, BASF, Cotton Incorporated, and Syngenta. Funding Information: The authors thank the Arizona Cotton Research and Protection Council, Cotton Technical Subcommittee of the Agricultural Biotechnology Stewardship Technical Committee (ABSTC), BASF, Cotton Incorporated, and Syngenta for supporting this work, and BASF and Syngenta for providing Vip3Aa. The authors are especially grateful to Jayme Williams of BASF for providing Vip3Aa and technical information that facilitated the bioassays. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture (USDA). USDA is an equal opportunity provider and employer. Publisher Copyright: © 2022 Society of Chemical Industry.
PY - 2022/10
Y1 - 2022/10
N2 - BACKGROUND: Transgenic crops that make insecticidal proteins from Bacillus thuringiensis (Bt) have revolutionized management of some pests. However, evolution of resistance to Bt toxins by pests diminishes the efficacy of Bt crops. Resistance to crystalline (Cry) Bt toxins has spurred adoption of crops genetically engineered to produce the Bt vegetative insecticidal protein Vip3Aa. Here we used laboratory diet bioassays to evaluate responses to Vip3Aa by pink bollworm (Pectinophora gossypiella), one of the world's most damaging pests of cotton. RESULTS: Against pink bollworm larvae susceptible to Cry toxins, Vip3Aa was less potent than Cry1Ac or Cry2Ab. Conversely, Vip3Aa was more potent than Cry1Ac or Cry2Ab against laboratory strains highly resistant to those Cry toxins. Five Cry-susceptible field populations were less susceptible to Vip3Aa than a Cry-susceptible laboratory strain (APHIS-S). Relative to APHIS-S, significant resistance to Vip3Aa did not occur in strains selected in the laboratory for > 700-fold resistance to Cry1Ac or both Cry1Ac and Cry2Ab. CONCLUSIONS: Resistance to Cry1Ac and Cry2Ab did not cause strong cross-resistance to Vip3Aa in pink bollworm, which is consistent with predictions based on the lack of shared midgut receptors between these toxins and previous results from other lepidopterans. Comparison of the Bt toxin concentration in plants relative to the median lethal concentration (LC50) from bioassays may be useful for estimating efficacy. The moderate potency of Vip3Aa against Cry1Ac- and Cry2Ab-resistant and susceptible pink bollworm larvae suggests that Bt cotton producing this toxin together with novel Cry toxins might be useful as one component of integrated pest management.
AB - BACKGROUND: Transgenic crops that make insecticidal proteins from Bacillus thuringiensis (Bt) have revolutionized management of some pests. However, evolution of resistance to Bt toxins by pests diminishes the efficacy of Bt crops. Resistance to crystalline (Cry) Bt toxins has spurred adoption of crops genetically engineered to produce the Bt vegetative insecticidal protein Vip3Aa. Here we used laboratory diet bioassays to evaluate responses to Vip3Aa by pink bollworm (Pectinophora gossypiella), one of the world's most damaging pests of cotton. RESULTS: Against pink bollworm larvae susceptible to Cry toxins, Vip3Aa was less potent than Cry1Ac or Cry2Ab. Conversely, Vip3Aa was more potent than Cry1Ac or Cry2Ab against laboratory strains highly resistant to those Cry toxins. Five Cry-susceptible field populations were less susceptible to Vip3Aa than a Cry-susceptible laboratory strain (APHIS-S). Relative to APHIS-S, significant resistance to Vip3Aa did not occur in strains selected in the laboratory for > 700-fold resistance to Cry1Ac or both Cry1Ac and Cry2Ab. CONCLUSIONS: Resistance to Cry1Ac and Cry2Ab did not cause strong cross-resistance to Vip3Aa in pink bollworm, which is consistent with predictions based on the lack of shared midgut receptors between these toxins and previous results from other lepidopterans. Comparison of the Bt toxin concentration in plants relative to the median lethal concentration (LC50) from bioassays may be useful for estimating efficacy. The moderate potency of Vip3Aa against Cry1Ac- and Cry2Ab-resistant and susceptible pink bollworm larvae suggests that Bt cotton producing this toxin together with novel Cry toxins might be useful as one component of integrated pest management.
KW - Bacillus thuringiensis
KW - Pectinophora gossypiella
KW - cross-resistance
KW - genetically engineered cotton
KW - resistance management
KW - sustainability
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U2 - 10.1002/ps.7016
DO - 10.1002/ps.7016
M3 - Article
C2 - 35633103
SN - 1526-498X
VL - 78
SP - 3973
EP - 3979
JO - Pest management science
JF - Pest management science
IS - 10
ER -