Biopesticides based on the entomopathogenic bacterium, Bacillus thuringiensis toxins, have shown high ability to control several pests belonging to order Lepidoptera. Egyptian cotton leaf worm, Spodoptera littoralis (Boisd.) (Lepidoptera:Noctuidae), is a major pest that attacks various crops in Egypt, and Cry1C toxin-based formulations are heavily used to its control. A laboratory investigation was conducted to study the resistance development in S. littoralis against Cry1C toxin. Thus, a field strain of S. littoralis was selected and maintained under laboratory conditions for 12 generations. The selection pressure resulted in 32.12-fold of resistance ratio after 12 generations. The hydrolysis of Cry1C toxin by the midgut extracts of the susceptible line, and the resistant line was compared. Results revealed that Cry1C toxin was hydrolyzed more rapidly in the resistant line than the susceptible one. The Cry1C toxin was processed till 1 hour after incubation in the susceptible line; but in case of resistant line, the Cry1C toxin was degraded in 1 hour after incubation.

中文翻译：

---

苏云金芽孢杆菌Cry1C在埃及棉叶虫：斜纹夜蛾（Boodd。）（鳞翅目：Noctuidae）中的抗性发育及其加工模式

基于昆虫病原性细菌苏云金芽孢杆菌毒素的生物杀虫剂已显示出对几种鳞翅目害虫的控制能力。埃及棉叶虫Spodoptera littoralis（Boisd。）（鳞翅目：Noctuidae）是一种主要害虫，侵袭埃及的各种农作物，Cry1C毒素基制剂被大量用于防治。进行了实验室研究以研究滨海链球菌对Cry1C毒素的抗性发展。因此，选择了滨海链球菌的田间菌株，并在实验室条件下保持12代。选择压力导致12代后的电阻率是32.12倍。比较了易感品系的中肠提取物对Cry1C毒素的水解作用，并比较了抗性品系。结果显示，Cry1C毒素在抗性品系中的水解速度要快于易感性。将Cry1C毒素加工至在易感品系中孵育后1小时；但是如果是抗性品系，则孵育后1小时内Cry1C毒素会降解。