Cry 독소단백질 혼합과 면역억제제 첨가를 통한 Bacillus thuringiensis 살충제 적용범위 및 방제력 증진 기술

Abstract

Abstract An entomopathogenic bacterium, Bacillus thuringiensis (Bt), can sporulate along with productionof insecticidal Cry toxins. Bt Cry toxins exhibit relatively narrow spectrum to target insects due to theirspecific interactions with midgut receptors. This study designed several strategies to enhance Bt efficacy intarget insect spectrum and insecticidal activity. Four Cry toxins were purified from four different Bt strainsand showed relatively narrow target insect spectrum. However, the Cry mixtures significantly expanded theirtarget insect spectra. The additional effect of baculovirus to Cry toxin was tested with recombinantbaculoviruses expressing Cry1Ac or Cry1Ca. However, the baculovirus was little effective to expand targetinsect spectrum. Bacterial culture broth of Xenorhabdus nematophila (Xn) significantly suppressed insectcellular immune response and increased Cry toxicity. The addition of Xn culture broth to Cry mixturesignificantly enhanced Bt efficacy in target insect spectrum and insecticidal activity. Key words Bacillus thuringiensis, Cry toxin, immunosuppression, Xenorhabdus nematophila