Activity of wild-type and hybrid Bacillus thuringiensis δ-endotoxins against Agrotis ipsilon

Twelve Cry1 and two Cry9 delta-endotoxins from Bacillus thuringiensis were tested for their activity against black cutworm (Agrotis ipsilon). A. ipsilon was not susceptible to many toxins, but three toxins had significant activity. Cry9Ca was the most toxic, followed by Cry1Aa and Cry1Fb. Hybrids between these three active proteins were made by in vivo recombination and analyzed for activity against A. ipsilon. Analysis of hybrids between Cry1Aa and Cry1Fb indicated that domain 1 of Cry1Aa protein was involved in its higher activity.