LAUSR

Abstract Striacosta albicosta (Smith; Lepidoptera: Noctuidae) is a pest of corn (Zea mays L.), which has recently expanded its range into Ontario, Canada. Genetically modified corn expressing Vip3A insecticidal protein from Bacillus thuringiensis is a biotechnological option for the control of S. albicosta.To support an insect resistance management program, we conducted a study of baseline susceptibility of 10-field collected S. albicosta populations in Ontario, Canada to Vip3A before widespread commercial adoption. Neonates were exposed to artificial diet overlaid with Vip3A. The LC50 ranged from 22.7 to 53.5 ng Vip3A cm–2. The EC50 ranged from 11.4 to 30.2 ng Vip3A cm–2. There was low inter-population variation in susceptibility to Vip3A, which we believe represents the natural geographical variation in response and not variation caused by previous exposure to selection pressure of the Vip3A protein.