Evaluation of novel and organic foliar insecticides for reduced-risk soybean aphid control in Ontario

In Ontario, Canada, only two foliar products are registered to control economic populations of soybean aphid, dimethoate (Cygon 4 E/Lagon 480 EC) and cyhalothrin-lambda (Matador 120E). To avoid the development of resistance and mitigate the unfavourable environmental impacts of dimethoate, it is desirable to register additional products for use. Consulting with government and industry officials, we identified four candidate products for further evaluation; spirotetramat (Movento, a synthetic), flonicamid (Beleaf, a synthetic), mineral oil (Superior 70 oil, a natural product), and Bauveria bassiana (Botani-gard, an entomopathogenic fungus). Novel products were evaluated relative to the two registered products in several ways: 1) Computation of Environmental Impact Quotient Field Use Ratings (EIQFUR); 2) Evaluation of field efficacy for control of soybean aphid; and 3) Evaluation of direct-contact toxicity to aphid natural enemies Harmonia axyridis and Orius insidiosus. The product with the highest EIQFUR was mineral oil, with a calculated EIQFUR an order of magnitude above the next highest-rated product, dimethoate. Dimethoate, cyhalothrin-lambda, spirotetramat and flonicamid all had similar efficacy for soybean aphid control when applied at recommended rates.