The Australian Fruit Fly parasitoid Diachasmimorpha kraussii (Fullaway): mating behavior, modes of sexual communication and crossing tests with D. longicausdata (Ashmead) (Hymenoptera: Braconidae: Opiinae)

Abstract

We describe the mating behavior of Diachasmimorpha kraussii for the first time, and confirm with cross-mating tests the separate species status of D. kraussii and D. longicaudata. Flight cage experiments suggest that mating takes place on foliage and that a distance attractant pheromone is secreted by the females, and perhaps also by the males. The most obvious aspect of the sexual interaction between males and females is the wing vibration performed by males in the nearby presence (about 1 cm) of a conspecific virgin female. Wing vibration produces an acoustic signal critical to mating success, for wingless males could seldom mate. Experimental manipulations demonstrate that males vibrate their wings in response to a chemical associated with the female, but not present in males. The chemical appears to be associated with the cuticle, as it is present (as demonstrated by male behavior) in recently-killed females, and it can be stripped from these females with acetone. The interaction proceeds only if the female is receptive (starting 6-48 h after emergence) and when she adopts a particular stance. Receptive females stand still, fold both pairs of wings over the abdomen, hold their antennae back together over their wings and allow males to mount. Males continue tapping their antennae on the females' thoraces while intromission takes place. The mating sequence of D. longicaudata is generally similar to that of D. kraussii, but individuals of the two species did not mate in small cages, which confirms their species status. In crossing tests all males vibrated their wings, indicating that the female's cuticular chemicals are similar across species. No females in mixed pairs assumed the receptive stance, suggesting the acoustic signals differ across species