Responses to Bt toxin Vip3Aa by pink bollworm larvae resistant or susceptible to Cry toxins. Issue 10 (13th June 2022)

• Record Type: Journal Article
• Authors: Tabashnik, Bruce E; Unnithan, Gopalan Chandran; Yelich, Alexander J; Fabrick, Jeffrey A; Dennehy, Timothy J; Carrière, Yves
• Is Part Of: Pest management science. Volume 78:Issue 10(2022)
• Page Start: 3973
• Page End: 3979
• Publication Date: 2022-06-13
• Subjects: Bacillus thuringiensis -- Pectinophora gossypiella -- sustainability -- genetically engineered cotton -- cross‐resistance -- resistance management; Pests -- Control -- Periodicals; Pesticides -- Periodicals; 632.9
• DOI: 10.1002/ps.7016
• Languages: English
• ISSNs: 1526-498X

Abstract

Abstract: 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. © 2022 Society of Chemical Industry. Abstract : Transgenic cotton producing Bacillus thuringiensis (Bt) toxins can be useful for managing the pink bollworm ( Pectinophora gossypiella ), one of the world's most damaging pests of cotton. Laboratory‐selected pink bollworm strains AZP‐R and AZP‐R2 were highly resistant to crystalline Bt toxins such as Cry1Ac, but not cross‐resistant to the Bt vegetative insecticidal protein Vip3Aa.