Characterization of Helicoverpa armigera (Lepidoptera: Noctuidae) resistance to chlorantraniliprole and evaluation of the mixture with Bacillus thuringiensis (Eubacteriales: Bacillaceae) as a resistance management strategy

Author(s)

Fábio Miguel Führ

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2023-04-14

Examining board members

Celso Omoto; Juliano Ricardo Farias; Fábio Maximiano de Andrade Silva

• Advisor: Celso Omoto

Abstract

Diamide insecticides have been used as one of the tools to manage Helicoverpa armigera (Hübner). Recently, significant reductions in the susceptibility of H. armigera to diamide inseticides were reported in Brazil with characterization of resistance to flubendiamide (phthalic acid diamide). The flubendiamide-resistant strain did not show cross-resistance to anthranilic diamides such as chlorantraniliprole. In this context, for a better understanding of the resistance of H. armigera a to diamide insecticides and to implement Insect Resistance Management (IRM) strategies, the objectives of this study were: i) to monitor the susceptibility to chlorantraniliprole in populations of H. armigera iin Brazil; ii) to select a strain of H. armigera i resistant to chlorantraniliprole to understand the inheritance patterns; iii) to evaluate cross-resistance to other diamide insecticides; iv) to assess fitness costs associated with resistance; and v) to evaluate the mixture of chlorantraniliprole with Bacillus thuringiensis Berliner as a resistance management strategy. By using a diagnostic dose bioassay of 0.99 µg i.a. cm-2, a significant reduction in susceptibility to chorontraniliprole was observed in populations of H. armigera i in the 2020/21 and 2021/22 growing seasons, with survival from 4,63% up to 30.8% in different populations evaluated. The selection of the resistant strain of H. armigera i to chlorantraniliprole (R-CHL) was performed by using F2 screen from a population collected in Itiquira, Mato Grosso State in 2020/21 growing season. After 10 generations of selection pressure with increasing doses from the diagnostic dose up to 2.85 µg i.a. cm-2, the resistance ratio (RR) of R-CHL to chlorantraliprole was 142- fold. From reciprocal crosses between the susceptible and R-CHL lines, the inheritance pattern of H. armigera i resistance to chlorantraniliprole was autosomal and incompletely dominant. Backcrosses of heterozygotes with the susceptible strain revealed that resistance of H. armigera i to chlorantraniliprole is polygenic. There was cross-resistance between chlorantraniliprole and the diamides cyclaniliprole (28 fold), cyantraniliprole (422 fold) and flubendiamide (>20,000 fold). The presence of fitness cost associated with resistance of H. armigera i to chlorantraniliprole was observed when the larvae were fed an artificial diet, based on parameters of the fertility life table. However, no fitness cost was observed when larvae were fed on soybean leaves. Finally, based on isobologram analysis and evaluation of persistence of biological activity of the insecticides under field conditions, the mixture of chlorantraniliprole and B. thuringiensis did not show benefits for managing resistance of H. armigera i to chlorantraniliprole. The results of this work show a high risk of resistance evolution of H. armigera i to chlorantraniliprole and other diamides. (AU)

• FAPESP's process: 21/14552-1 - Characterization of Helicoverpa armigera (Lepidoptera: Noctuidae) resistance to chlorantraniliprole and evaluation of the mixture with Bacillus thuringiensis (Eubacteriales: Bacillaceae) as resistance management strategy
• Grantee: Fábio Miguel Führ
• Support Opportunities: Scholarships in Brazil - Master