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（Plutella xylostella）是芸苔属植物的主要害虫，基于苏云金芽孢杆菌（Bt）的产品常被用于其生物防治策略。本研究旨在评估以Bt为基的生物杀虫剂捕食小菜蛾时是否会影响Ceraeochrysa cincta的捕食行为。使用了三只捕食的幼虫幼虫以及蛾类的卵和第二龄的幼虫，该猎物未经处理或已用基于Bt的产品（Xentari®）处理。结果表明，C。cincta的第一龄幼虫捕食未经处理的卵时呈现II型功能性反应，捕食经Bt处理的卵呈现II型功能性反应，而第二龄和第三龄幼虫在两种情况下分别呈现II型和III型反应。捕食者的第一和第三龄幼虫在捕食未经处理的幼虫时表现出II型功能反应，而在捕食经过Bt处理的幼虫时表现出III型反应。但是，在两种处理中，捕食者的第二龄幼虫均表现出II型反应。获得的结果使我们得出结论，所测试的基于Bt的杀虫剂会影响C. cincta的第一龄幼虫在卵上的捕食行为，以及该捕食者对P. xylostella幼虫的第一龄和第三龄幼虫的捕食行为。