Substrate influences mating success and transmission of courtship vibrations for the parasitoid Cotesia marginiventris

The influences of artificial and natural rearing substrates on mating success were investigated for the parasitoid wasp Cotesia marginiventris (Cresson) (Hymenoptera: Braconidae), a candidate for augmentative biological control of various lepidopteran pests. Five rearing substrates were tested: plastic, glass, chiffon fabric, and leaves of two host plants, bean [Vigna unguiculata (L.) (Fabaceae)] and maize [Zea mays L. (Poaceae)]. Mating success was highest on chiffon, lowest on plastic and glass, and intermediate on maize and bean. The transmission characteristics of one component (buzz 1) of the courtship vibrations produced by male wing fanning were investigated using laser vibrometry. The duration of buzz 1 was longer on maize, bean, and chiffon than on plastic and glass. The fundamental frequency of buzz 1 (~300 Hz) was lowest on bean and highest on glass, and intermediate among other substrates. The relative amplitude of buzz 1 was higher on chiffon than on plastic, glass, or bean, and intermediate on maize. The relative importance of airborne sound and substrate vibration as courtship signals was also investigated with experiments that manipulated the production of courtship vibrations and the mating substrates. The amplitude of courtship vibrations on chiffon was significantly higher for winged males than for dealated males. The mating success of males was impacted by both the presence of wings and the mating substrate. These findings suggest that mating success and transmission of courtship vibrations are influenced by the rearing substrate, and that courtship vibrations are critical to mating success in C. marginiventris. Future efforts to mass rear this parasitoid and other insects should consider the potential influences of rearing substrates on mating.