Biopesticides Team LPIP, Centre of Biotechnology of Sfax, University of Sfax, P.O. Box 1177, 3018 Sfax, Tunisia.
J Invertebr Pathol. 2013 Sep;114(1):71-5. doi: 10.1016/j.jip.2013.05.009. Epub 2013 Jun 5.
Bacillus thuringiensis kurstaki strain BNS3 produces parasporal crystals formed by Cry1Aa, Cry1Ac and Cry2Aa delta-endotoxins. In a previous work, we showed that the latter exhibited individually, a weak insecticidal activity against Ephestia kuehniella. In order to improve their toxicities, we studied the combined effect of each delta-endotoxin with X. nematophila cells on E. kuehniella larvae growth. Xenorhabdus cells were used in combination with spore crystal mixture of the wild strain BNS3, known to be active against E. kuehniella, but no improvement in toxicity was observed. This could be due to the high efficiency of BNS3 crystals against this insect. However, when X. nematophila was combined with each of Cry1Aa, Cry1Ac and Cry2Aa, improvement of toxicity was noticed. The best improvements were obtained with Cry1Ac and Cry2Aa, which are more toxic to E. kuehniella than Cry1Aa. The difference in toxicity improvement was attributed to the low affinity of Cry1Aa to BBMV receptors, compared to those of Cry1Ac and Cry2Aa. This synergism between Cry toxins and Xenorhabdus cells could be exploited on control target insect, particularly in case of resistance to Cry toxins.
苏云金芽孢杆菌库斯塔克亚种 BNS3 产生由 Cry1Aa、Cry1Ac 和 Cry2Aa δ-内毒素组成的伴孢晶体。在之前的工作中，我们表明后者单独对粉纹夜蛾具有较弱的杀虫活性。为了提高它们的毒性，我们研究了每种 δ-内毒素与 X. nematophila 细胞对粉纹夜蛾幼虫生长的联合作用。使用 X. nematophila 细胞与已知对粉纹夜蛾有效的野生菌株 BNS3 的孢子晶体混合物联合使用，但没有观察到毒性的提高。这可能是由于 BNS3 晶体对这种昆虫的高效性。然而，当 X. nematophila 与 Cry1Aa、Cry1Ac 和 Cry2Aa 中的每一种结合使用时，毒性得到了提高。Cry1Ac 和 Cry2Aa 的改善效果最好，它们对粉纹夜蛾的毒性比 Cry1Aa 更强。毒性改善的差异归因于 Cry1Aa 与 BBMV 受体的亲和力低于 Cry1Ac 和 Cry2Aa。Cry 毒素与 Xenorhabdus 细胞之间的这种协同作用可用于控制靶标昆虫，特别是在对 Cry 毒素产生抗性的情况下。
