Evaluation of control strategies for the soybean pest Chrysodeixis includens

Abstract

The United States generates half of the world’s soybean (Glycine max) crop. Soybeans are subject to several pest, and in the Southeast crop loss and pest management totaled $1.2 million. Soybean loopers (Chrysodeixis includens), whose larvae feed on soybean leaves, can be managed with multiple strategies including pesticides and genetically modified (GM) soybeans, but these control efforts are hindered because C. includens has developed resistance to many pesticides. To evaluate these strategies we exposed C. includens to GM soybeans and Spinosad, an insecticide to which C. includens has shown no evidence of resistance. Time spent in each instar and weight at pupation were measured. Populations reared on GM soybeans and conventional soybeans had similar time in each instar and low pupation weights. Populations reared on GM soybeans and Spinosad died before pupation, but populations reared on GM soybeans spent more time in the larval stages than the populations treated with Spinosad. Comparison between Spinosad and GM soybeans in a lab setting showed that Spinosad is a better control mechanism due to the limited time spent in the larval phase before death.