Fate of Helicoverpa zea (Lepidoptera: Noctuidae) Larvae Exposed to Low Concentrations of Chlorantraniliprole

ABSTRACT

In recent years, chlorantraniliprole has been one of the most used active ingredients for the control of lepidopteran pests, including the corn earworm, Helicoverpa zea (Boddie), on row crops in the southern US Chlorantraniliprole is in the diamide class of insecticides. It possesses high efficacy and long residual activity for the control of susceptible caterpillar species. These desirable properties have led to an increase in its usage since its introduction in the US Several studies have examined the susceptibilities of H. zea to chlorantraniliprole. These studies generally test neonate or third‐instar caterpillars using insecticide‐diet‐incorporated bioassays and present lethal concentration (e.g., LC ₅₀ ) values based on survival at a particular time point. These assays provide partial information of the survival of H. zea for only a fragmented part of their development. We examined the ultimate survival of the F ₁ generation of an H. zea colony originally collected from crimson clover ( Trifolium incarnatum L., Fabaceae). Neonate larvae were placed on an artificial diet incorporating six different concentrations (0–16 ng/mL) of chlorantraniliprole and allowed to grow inside cups filled with the treated diet. Surviving male and female moths were paired within each treatment concentration, and the number of eggs laid per female was recorded. Survival to the pupal stage ranged from ~12% to 85%, while survival from pupae to moths ranged from 60% to 90%. As insecticide concentration increased, days to reach the pupal stage increased, and pupal weight decreased. Once moths reached the pupal stage, days to emergence were similar for all concentrations. The number of eggs laid per adult female were not significantly related to the insecticide and averaged 45–120 eggs. These data present the fate of H. zea larvae that develop on chlorantraniliprole for their entire larval development and may be used to supplement traditional insecticide bioassays.