São Luís Faculty of Education, Jaboticabal, SP, Brazil.
Faculty of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal, SP, Brazil.
Ecotoxicology. 2020 Sep;29(7):856-865. doi: 10.1007/s10646-020-02244-x. Epub 2020 Jul 1.
Plutella xylostella, is the main pest infesting Brassica crops, and products based on Bacillus thuringiensis (Bt) are frequently used in strategies for its biocontrol. The present study aimed to evaluate whether a Bt-based bioinsecticide affects the predation behavior of Ceraeochrysa cincta when preying on P. xylostella. Three larval instars of the predator and the eggs and second-instar larvae of the moth were used, with the prey either untreated or treated with a Bt-based product (Xentari®). Results showed that, the first larval instar of C. cincta presented a type II functional response when preying upon untreated eggs, and a type III response when preying upon Bt-treated eggs, while the second and third instars presented type II and III responses, respectively, in both situations. The predator's first and third larval instars presented a type II functional response when preying upon untreated larvae and a type III response when preying upon Bt-treated larvae. However, the predator's second-instar larvae showed a type II response in both treatments. The results obtained allowed us to conclude that the Bt-based insecticide tested affects the predation behavior of the first-instar larvae of C. cincta on eggs and of both the first- and third-instar larvae of this predator on P. xylostella larvae.
小菜蛾是为害十字花科作物的主要害虫，苏云金芽孢杆菌（Bt）产品常被用于其生物防治策略中。本研究旨在评估基于 Bt 的生物杀虫剂是否会影响三突花蛛捕食小菜蛾幼虫时的捕食行为。本研究使用了三种龄期的捕食者幼虫以及小菜蛾的卵和二龄幼虫作为猎物，猎物要么未经处理，要么用基于 Bt 的产品（Xentari®）处理。结果表明，三突花蛛的第一龄幼虫在捕食未处理的卵时表现出 II 型功能反应，在捕食经 Bt 处理的卵时表现出 III 型反应，而第二和第三龄幼虫在两种情况下均分别表现出 II 型和 III 型反应。捕食者的第一和第三龄幼虫在捕食未处理的幼虫时表现出 II 型功能反应，在捕食经 Bt 处理的幼虫时表现出 III 型反应。然而，捕食者的第二龄幼虫在两种处理中均表现出 II 型反应。研究结果表明，所测试的基于 Bt 的杀虫剂会影响三突花蛛第一龄幼虫对卵的捕食行为，以及该捕食者的第一和第三龄幼虫对小菜蛾幼虫的捕食行为。
