Host-Finding Behavior and Parasitism Rate of Cotesia glomerata (Hymenoptera: Braconidae) on Pieris brassicae Larvae

Abstract

Host-finding behavior and parasitism rate of Cotesia glomerata (Hymenoptera: Braconidae) on Pieris brassicae larvae were investigated to evaluate its efficiency as a biological control agent in cruciferous cropping systems. Laboratory and semi-field experiments were conducted to assess parasitoid orientation, host-searching activity, parasitism success, and host stage preference under controlled environmental conditions. Results indicated that C. glomerata relies strongly on host-induced plant volatiles and larval feeding cues for efficient host location, exhibiting increased searching activity in infested cabbage plants. Parasitism rate varied significantly with host density and larval instar, with higher parasitism observed on early instars of P. brassicae. The parasitoid demonstrated efficient host discrimination ability, selectively ovipositing in suitable host stages that maximize offspring development success. Behavioral observations revealed that host aggregation and feeding damage enhanced parasitoid attraction, improving host-finding efficiency. Parasitism performance declined at extreme host densities, likely due to increased handling time and host defensive behaviors. The study highlights the strong ecological adaptation of C. glomerata to crucifer-associated herbivore complexes and its potential role in regulating P. brassicae populations. These findings support the integration of C. glomerata into biological control programs as an effective natural enemy for sustainable management of cabbage butterfly infestations in cruciferous vegetable production systems.