Investigating headspace extract from aphid infested plants to analyze the role of semiochemicals in the attraction of the natural enemy Eupeodes corollae (Diptera: Syrphidae)

Sammanfattning

Plants constitutively emit volatile organic compounds (VOCs) affecting their surroundings. Under attack by herbivores, plants emit additional distinct volatile compounds, so called herbivore induced plant volatiles(HIPVs), that may act as indirect defense by attracting natural enemies of the herbivore. Hoverflies (Diptera: Syrphidae) play a crucial role in biological pest control by preying on aphids. Gravid females using visual and chemical cues—including aphid stress secretions and HIPVs—to locate suitable oviposition sites. We investigate the attraction of Eupeodes corollae to VOCs from aphid-infested radish plants to better understand the semiochemicals involved in natural enemy attraction. E.corollae (Syrphidae) showed flight attraction towards a stream of headspace volatiles directly injected into a wind tunnel, but not towards headspace samples that were dissolved and vaporized in organic solvents. Headspace volatiles in organic solvent did not induce oviposition, suggesting that the lack of behavioral response towards headspace samples was due to the absence or wrong ratio of behavioral active chemicals, or a negative effect of the solvent.