Volatiles of bacteria associated with parasitoid habitats elicit distinct olfactory responses in an aphid parasitoid and its hyperparasitoid

1.   To locate mating partners and essential resources such as food, oviposition sites and shelter, insects rely to a large extent on chemical cues. While most research has focused on cues derived from plants and insects, there is mounting evidence that indicates that microorganisms emit volatile compounds that may play an important role in insect behaviour.

2.    In this study, we assessed how volatile compounds emitted by phylogenetically diverse bacteria affected the olfactory response of the primary parasitoid Aphidius colemani and one of its secondary parasitoids, Dendrocerus aphidum. Olfactory responses were evaluated for volatile blends emitted by bacteria isolated from diverse sources from the parasitoid’s habitat, including aphids, aphid mummies and honeydew, and from the parasitoids themselves.

3.    Results revealed that A. colemani showed wide variation in response to bacterial volatiles, ranging from significant attraction over no response to significant repellence. O...