Courtship acoustics and mating in Cotesia, a genus of parasitoid wasps

Cotesia are parasitoid wasps (Hymenoptera: Braconidae) that are used for biological control of pest moths (Lepidoptera: Noctuidae, Pyralidae) that damage agricultural crops. This dissertation investigated courtship acoustics and mating, and their relevance to biological control, in members of the Cotesia flavipes species complex, and a noncomplex member, Cotesia marginiventris. The first study investigated whether courtship acoustics were species specific for two members of the Cotesia flavipes complex, C. flavipes and C. sesamiae, and for C. marginiventris. During courtship, male Cotesia fan their wings and produce low amplitude sounds and substrate vibrations. The airborne and substrate components of courtship were similar within a species. However, the courtship acoustics of each species was distinct. The duration and frequency of several courtship acoustic components distinguished each species, while some components did not differ among species. The second study investigated mating success and transmission of courtship vibrations on natural and artificial rearing substrates for Cotesia marginiventris. Mating success was measured on plastic, glass, corn and bean leaves, and chiffon fabric. Mating success was lowest on plastic and glass, intermediate on corn and bean leaves, and highest on chiffon. Substrate influenced transmission of courtship vibrations. Durations of courtship vibrations were longer on corn, bean and chiffon than on plastic. Frequency modulation occurred on corn, bean and chiffon, and amplitude was greatest on chiffon. The mating success of normal and dealated males was higher on chiffon than on glass, suggesting that courtship communication relied in part on substrate vibrations. The third study examined female and male mate choice in a solitary and a gregarious species, C. marginiventris and C. flavipes, respectively. Females of the solitary species, C. marginiventris, mated more frequently with large than small males, and this did not appear to be the result of male competition. Male choice for female size was not apparent in C. marginiventris. Females of the gregarious parasitoid, C. flavipes, mated with large or small males with similar frequencies, and male-male competition was not observed. In the male choice experiment, C. flavipes males attempted copulation and mated more with smaller females, and smaller females accepted males more than large females.