Pheromones and kairomones in the sexual communication of parasitic wasps

For successful reproduction, parasitoids have to be able to locate their mates and hosts. In several species chemical orientation plays a decisive role in these essential behaviors. Our knowledge about chemical cues that are involved in the sexual communication of parasitic Hymenoptera is scarce when compared to other insect taxa. The taxon Pteromalidae is predestined to achieve progress because many species can be reared on economically relevant insect pests and thus, can be obtained in sufficient numbers for pheromone studies. We study the model organisms Lariophagus distinguendus and Nasonia vitripennis. L. distinguendus parasitizes larvae and pupae of stored product infesting beetles whereas N. vitripennis uses puparia of several fly species for parasitization. Chemical cues involved in sexual communication of these parasitoids include cuticular lipids functioning as female-derived courtship pheromones, male sex attractants, and host-associated kairomones.

Pheromones and kairomones in the sexual communication herbivorous beetles

We study the role of plant volatiles and sex pheromones in the olfactory orientation of European scarab beetles. Field and laboratory experiments revealed that cockchafer males (Melolontha sp.) swarming at dusk use plant volatiles as primary attractants for mate finding. These green leaf volatiles (GLV) are released by almost any green plant after mechanical damage due to female feeding. Beetle-derived benzoquinone derivatives function as sex pheromones that synergize the male response to the damage-induced GLV and thereby increase the reliability of this rather unspecific chemical cue. We will address the question whether the use of those plant-derived sexual kairomones is more common among phytophagous scarab beetles or herbivorous insects in general. We hypothesize that a behavioral dimorphism between males and females (e.g. male swarming behavior) and feeding adults are prerequisites for the evolution of the described phenomenon.

This research may not only lead to a better understanding of herbivore ecology but also contributes to the development of environmentally safe control methods.