Host-Acceptance Behavior of Campoletis sonorensis1 toward Heliothis zea234

Four successive phases of host-acceptance behavior were displayed by Campoletis sonoreiisis (Cameron) toward larvae of Heliothis zea (Boddie) : antennal examination of larvae, ovipositor thrusting, ovipositor insertion, and oviposition. The duration of the entire sequence averaged 1.8 s. Searching behavior preceded the entire process. The parasitoid could revert to searching behavior after any phase of acceptance behavior or divert to 1 of 2 phases of auxiliary behavior, i.e., grooming or resting. Once the acceptance behavior sequence was interrupted, it could only be reinitiated with antennal examination. Host movement and a chemical served as releasing stimuli. The chemical was associated with a wide variety of host tissues. It was relatively nonvolatile in association with larval integuments and webbing but volatile after extraction with diethyl ether. Host size, as it was correlated with larval aggressive behavior and integumentary thickness, limited the complete expression of the acceptance behavior sequence by the parasitoid. Host-acceptance behavior also seemed to be affected by a period of parasitoid insensitivity to releasing stimuli following oviposition. Host age and color had no influence on acceptance behavior.