Defensive behaviors of the Oriental armyworm in response to different parasitoid species (Hymenoptera: Braconidae).

This study examined defensive behaviors of (Lepidoptera: Noctuidae) larvae varying in body size in response to two parasitoids varying in oviposition behavior; females sting the host with the ovipositor after climbing onto it while females make the sting by standing at a close distance from the host. larvae exhibited evasive (escaping and dropping) and aggressive (thrashing) behaviors to defend themselves against parasitoids and . Escaping and dropping did not change in probability with host body size or parasitoid species. Thrashing did not vary in frequency with host body size, yet performed more frequently in response to than to . Parasitoid handling time and stinging likelihood varied depending not only on host body size but also on parasitoid species. Parasitoid handling time increased with host thrashing frequency, similar in slope for both parasitoids yet on a higher intercept for than for . Handling time decreased with host size for but not for . The likelihood of realizing an ovipositor sting decreased with thrashing frequency of both small and large hosts for , while this was true only for large hosts for . Our results suggest that the thrashing behavior of larvae has a defensive effect on parasitism, depending on host body size and parasitoid species with different oviposition behaviors.