Boletín de la AeE

The foraging behaviour of parasitoids has found much attention during the last decades. Most studies focus on the effíciency of the parasitoids´ foraging behaviour at the long range where chemical cues seein to play a major role (see Vinson, 1985 for a review). interactions on the cióse range have been proved to be more diverse, and are guided by several different stimuli (see Schmidt, 1991 for a review). Visual, contact chemical, as well as physical stimuli function as information source for the foraging parasitoid once it approaches a prospective host. But these cióse range stimuli generally bear a special feature: most of them cannot be sensed by the parasitoid unless it gives away information to the approached host on its part. The parasitoid e. g. may need to come so cióse to its target that it accidentally emits various stimuli itself. These stimuli might provide information for the alert host larva that tries to avoid contact with its antagonist. Therefore studying cióse range stimuli in a host parasitoid-system usually means to dea! with a two-way relationship of sensory modalities and cues of both opponents

Casas (1989) hypothesized that the foraging behaviour of the parasitoid Sympiesis sericeicornis Nees (Hymenoptera, Eulophidae) is influenced on the cióse range by mechanical stimuli triggered by the leafmining host larva, Phylionorycter mole/la Ger. (Lepidoptera, Gracillariidae). Not only the host larva but also the foraging parasitoid probably triggers vibrational signáis while foraging on the leaf lamina. The stimuli are transmitted by way of the leaf lamina in both cases. Therefore the investigation of the role of vibrational stimuli in the cióse range interactions between parasitoid and leafmining host larva requires a two step set-up: (1) characterisation of vibrational stimuli triggered by the host larva and those triggered by the foraging parasitoid and (2) characterisation of behavioural interactions between both species as influenced by vibrational signáis.