Efficacy of alternative sweet corn pest control agents and their impact on honey bees
European corn borer (ECB), 'Ostrinia nubilalis' (Hu?bner), is a serious pest of sweet corn. Corn flea beetle (CFB), ' Chaetocnema pulicaria' Melsheimer, which vectors Stewart's wilt (' Erwinia' stewartii Smith) is another pest of sweet corn. Concern of Ontario sweet corn growers and beekeepers over the impact on honey bees (' Apis mellifera' L.) of the insecticides, carbofuran and imidacloprid, used for ECB and CFB control led to investigation of alternative pest control agents. Efficacy and impact on honey bees of recently registered insecticides, spinosad, clothianidin and Bt-sweet corn were evaluated to determine their suitability for use in ECB and CFB IPM programs. Field efficacy trials demonstrated that spinosad and Bt-sweet corn provided ECB control equivalent to commonly used insecticides, carbofuran and lambda-cyhalothrin. Clothianidin proved more effective than imidacloprid at reducing CFB feeding. Laboratory bioassays indicated that ECB control agents, spinosad and Bt-sweet corn, have reduced risk to honey bees. The ECB insecticide, lambda-cyhalothrin, was also found less toxic to honey bees relative to the industry standard, carbofuran. Results indicate that CFB insecticidal seed treatments, imidacloprid and clothianidin, pose minimal risk to honey bees.