Abstract

High-dose and refuge are the most important strategies for delaying resistance evolution in Bt crops. Insecticide sprays in refuge areas could be necessary and may limit refuge effectiveness. Here, we evaluated the sublethal effects of two diamide insecticides (chlorantraniliprole and flubendiamide) on Chloridea virescens life history traits and flight performance. Sublethal concentrations of chlorantraniliprole and flubendiamide increased larval and pre-pupal development times and decreased larval weight; flubendiamide increased pupal development times. Chlorantraniliprole increased adult male longevity and reduced female fertility, while flubendiamide reduced fecundity. Overall life table parameters were negatively impacted by both treatments. Males exposed to either insecticide showed significant reductions in flight duration and distance for unsustained flights (<30 min). The duration and distance of the first flights were reduced when exposed to chlorantraniliprole. Sustained flights (>30 min) were generally unaffected by insecticide exposure and both sexes flew >6400 m in a single flight. The sublethal effects of flubendiamide and chlorantraniliprole on C. virescens’ population dynamics could lead to generation asynchrony and provide insufficient susceptible moths when sprayed on refuge crops. However, the distance and duration of flight may still be sufficient to ensure mixing of potentially resistant and susceptible populations from refuge plots.

Highlights

  • The tobacco budworm, Chloridea (=Heliothis) virescens Fabricius [Lepidoptera: Noctuidae]) is an important economic pest of several crops in southern Canada, the United States, and throughoutSouth America, except for Chile and southern Argentina [1,2,3]

  • We found that sublethal exposure of C. virescens to several common diamide insecticides can reduce population growth and alter phenological timing

  • Our flight mill results suggest that this sublethal exposure would not be expected to reduce the moths’ ability to disperse an adequate distance from non-Bt refuges, but additional research will be needed to define the extent of sublethal exposure in the field

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Summary

Introduction

The tobacco budworm, Chloridea (=Heliothis) virescens Fabricius [Lepidoptera: Noctuidae]) is an important economic pest of several crops in southern Canada, the United States, and throughoutSouth America, except for Chile and southern Argentina [1,2,3]. × MON 89788 (Intacta RR2 PRO® ) were commercially introduced in Brazil This soybean event expresses genes encoding the insecticidal protein Cry1Ac of Bacillus thuringiensis Berliner (Bt) and the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPs) protein of Agrobacterium sp. The high-dose strategy requires that Bt plants express high enough concentrations of B. thuringiensis insecticidal proteins to ensure mortality of more than 95% of heterozygous insects [8,9]. Because of this high efficacy and associated yield protection, soybean MON 87701 × MON 89788 has been widely adopted by growers in most regions of Brazil

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