Foraging behaviour and sequential multisensory orientation in the aphid parasitoid, Pauesia picta (Hym., Aphidiidae) at different spatial scales

Foraging females of Pauesia picta, a parasitoid of the conifer aphid Cinara pinea on pine, used a variety of host plant or host-borne cues to find and recognize its aphid hosts. For long-range detection, females rely mainly o n secondary plant compounds to locate potential host plants. In the medium- range (i.e. on a given host plant), females detected the presence of hosts by encounters with honeydew-collecting workers of the ant Formica polyctena and by perceiving host-borne cues. For short-range detection, after the di scovery of an aphid colony, P. picta females recognize hosts visually. Subs equent antennal tapping, a tactile stimulus, prevents dispersal of aphids a nd increases the oviposition success of the parasitoid. The final host acce ptance is obviously triggered by signals located in the epicuticle of the h ost. The results demonstrate the importance of sequential multisensory fora ging that correspond to a diminishing distance between the parasitoid and t he host.