Combined effects of three crystalline toxins from Bacillus thuringiensis with seven proteinase inhibitors on beet armyworm, Spodoptera exigua Hübner (Lepidoptera: Noctuidae)

► Exposure S. exigua larvae to Bt toxin and proteinase inhibitor mixtures synergistically reduced weight. ► The mixtures increased larval mortality. ► Trypsin-, chymotrypsin-, and elastase-like proteinases in S. exigua larval midgut may involve in Bt toxin hydrolyzation.