D3112: Insecticidal activity of Heligen (HearNPV) against Helicoverpa zea in response to temperature and ultraviolet light exposure

Helicoverpa zea and other species in the Heliothine pest complex are global pests of row crops as well as leafy and fruiting vegetables, accounting for a significant proportion of chemical insecticide applications made. Heligen, a nucleopolyhedrovirus (HearNPV), is highly effective against this important pest complex. It belongs to the new IRAC mode-of-action group 31 (host-specific occluded pathogenic viruses) and may play an important role in managing target pest resistance to chemical insecticides across a wide range of crops. In general, NPV-based insecticide formulations have demonstrated low temperature and UV stability. In this study, samples of Heligen were set yo fir evaluation of cumulative incubation periods from 1 to 30 days at 40°C and with or without exposure to UV light. Intrinsic potency of the product subjected to different temperature and UV regimes was evaluated in a diet surface treated bioassay of 2^nd instar H. zea larvae. Larval mortality was recorded daily for 7 days. At pre-established time points, samples were also visually evaluated for occlusion body (OB) counts and morphology (size and shape) for subsequent analyses of possible correlation with temperature and UV exposure treatments. Results from this work and implications for product use will be discussed.