Master degree Andong National University Andong, Kyongsang-bukto, Republic of Korea
Insect immunity plays crucial roles in suppressing the virulence of various entomopathogens including Bacillus thuringiensis (Bt). However, the immune responses against Bt infection were not clearly understood. This study demonstrated the immune responses against Bt infection using a lepidopteran Acrolepiopsis sapporensis. Different strains of Bacillus thuringiensis produce a diversity of Cry proteins that are selectively toxic against a wide range of insect pests. Bacteria of Xenorhabdus and Photorhabdus can synthesize secondary metabolites to induce host immunosuppression. This study hypothesized that bacterial secondary metabolites can enhance the pathogenicity of B. thuringiensis subsp. krustaki (BtK) against A. sapporensis. An addition of X. hominickii (Xh) culture broth significantly enhances the insecticidal activities of BtK. Addition of bacterial secondary metabolites: 3-ethoxy-4-methoxyphenol, oxindole, benzylideneacetone, and GameXPeptide significantly enhance BtK toxicity. Moreover, Xh culture broth or other secondary metabolites significantly suppressed nodule formation. This suggests that the BtK+Xh mixture is used to effectively control target pest (A. sapporensis) by suppressing the immune defense of the target insects.
