Parasitoid foraging decisions mediated by artificial vibrations

In any host-parasitoid interaction, the detection of the host in its microhabitat is a crucial step in the interaction that has a major influence on the parasitoid's fitness. We used bioassays to investigate whether the parasitoid Sympiesis sericeicornis (Hymenoptera: Eulophidae) uses the vibrations of its host Phyllonorycter sp. gr. blancardella (Lepidoptera: Gracillariidae) to detect it in the leaf mine. From the large variety of signals produced by the host, we identified a unitary signal that could be reproduced artificially. We then sent this signal into emptied mines to analyse the reaction of the parasitoid. The wasps reacted by increasing both the time spent foraging on the mine and the number of insertions of the ovipositor to detect the ‘virtual’ host. This study is the first to show that parasitoids detect host vibrations.