ON Parasitoids use herbivore - induced information to adapt patch exploitation behaviour CÉDRIC TENTELIER , ERIC WAJNBERG and XAVIER FAUVERGUE

1. Optimal foraging models ultimately predict that female parasitoids should exploit rich host patches for longer than poorer ones. At the proximate level, mechanistic models and experimental studies show that parasitoids use both chemicals produced by their hosts and direct encounters with their hosts to estimate patch quality. Although it has been extensively studied in the context of host location, the use of herbivore-induced plant response by insect parasitoids has never been considered in the context of patch time allocation. 2. In this study, the respective roles of herbivore-induced plant response and direct contact with hosts on the foraging behaviour of Lysiphlebus testaceipes females on an aphid patch were quantified. For this, the level of herbivoreinduced plant response and the number of aphids on the leaf bearing the patch were manipulated independently. Different levels of plant response were obtained by varying the duration of infestation on another leaf. 3. Parasitoid residence time and number of attacks increased with both the level of plant response and the number of aphids. 4. These results suggest that L. testaceipes females use the combination of herbivore-induced response of plants and direct encounters with hosts to assess patch quality and adjust their patch use behaviour.