Response of Spodoptera frugiperda and Agrotis ipsilon to exposure to Bt event 1507 corn

Bacillus thuringiensis (Bt) corn was developed primarily for North American pests such as European corn borer (Ostrinia nubilalis). However, most Bt corn products also are cultivated outside of North America, where the primary pests are different and often have lower susceptibility to Bt toxins. As these Bt corn products are commercialized in new geographies, insect resistance management (IRM) plans for those geographies need to consider each pest and toxin combination, instead of assuming the high-dose refuge strategy applies to all pests in all geographies. Before implementing an IRM plan that includes size, placement and configuration of refuge, stakeholders must understand the biology and susceptibility of the primary pest(s) for each geography. Fall armyworm (Spodoptera frugiperda) and black cutworm (Agrotis ipsilon) susceptibility to Cry1F (expressed in event 1507) are examples of pest-by-toxin interactions that do not meet the high-dose definition. Both insects are important pests of corn in geographies outside of North America. We tested the behavioral response of both species to 1507 corn by measuring the percentage of time naïve third instars spent feeding during a three minute exposure. We also investigated whether these species had a behavioral and/or toxic response to 1507 corn. We exposed third instars to 1507 corn and measured weight gain and survival for 14-days. Results are discussed in the context of global IRM plan development for non-high dose Bt products.