D3203: (2nd Place) Mortality of western bean cutworm after exposure to leaves treated by aerial application and chemigation

Western bean cutworm (Striacosta albicosta) is an important lepidopteran pest that can impact the yield of corn. This pest can be difficult to control, partially because of developing resistance to Bt traits and chemical products. In Nebraska, aerial application and chemigation are used to apply foliar insecticides targeting this pest. We evaluated survival rates for the first and third instars of S. albicosta exposed to corn leaves treated in the field using these methods.  We evaluated 5 treatments: two active ingredients (chlorantraniliprole or bifenthrin) applied by airplane or chemigation, plus an untreated control. After insecticide application, two leaves were collected at both ear and tassel height from each plot on the day of application (0 DAT) and five days after treatment (5 DAT). Each Petri dish with tassel leaves was infested with 20 S. albicosta neonates, while ear leaves were infested with 10 larvae of the third instar. Survival of larvae was observed after 16, 24, and 48 hours. Overall, results at 0 DAT showed that aerially applied chlorantraniliprole significantly reduced survival compared with the untreated control. Surprisingly, survival of neonates and third instars was not significantly different at 0 DAT. However, neonates did have significantly lower survival compared to third instars at 5 DAT. The lowest survival rate was observed 48h after infestation but was not statistically different from 24h for 5 DAT. The knowledge gained in this study will aid growers in choosing cost-effective application methods that support resistance management for S. albicosta.