Perception of aphid infested tomato plant volatiles by the predator Episyrphus balteatus

In a tritrophic interaction including tomato plant (Lycopersicon esculentum Miller), the herbivore Myzus persicae (Sulzer) and the predator Episyrphus balteatus (De Geer), the perception of the tomato plants produced volatile organic compounds (VOC) by Episyrphus balteatus is investigated. In a first step, an odour sampling device has been set up aiming the headspace collection of the tomato plant VOC and their adsorption on Tenax adsorbent cartridges (Supelco®). Following desorption is held using a thermodesorption injector (Gerstel®) coupled with GC-MS. Intact and aphid infested plants are studied for their VOC emissions, as well as the comparison of the VOC emission of different tomato cultivars. These VOC consist mainly in mono- and sesquiterpenes (such as - and -pinene ; -humulene ; …) as well as in C6-volatiles like hexenal in case of infestation by herbivores Once the tomato plants VOC identified and quantified, they are tested for their perception by Episyrphus balteatus using electroantennography (EAG). Accordingly, an EAG device has been installed and configured for the study of VOC using Diptera antennas. The monoterpenes limonene and linalool showed high EAG activity whereas other terpenes like cymene seem to be inactive