Patch-marking and optimal search patterns in the parasitoid Venturia canescens

1. We investigate whether Venturia canescens marks areas previously searched for hosts and the implication of this behaviour with respect to optimal search patterns. 2. We show for the first time, that while searching on a host patch, V. canescens deposits a marking chemical on the surface of a patch. 3. This marker influences both the behaviour of parasitoids subsequently visiting the patch and the within-patch search pattern of the foraging parasitoid. 4. Individuals discriminate between the marks left by themselves or by conspecifics. 5. Search is not fully systematic, as marked areas are frequently revisited. 6. The adaptive significance of revisiting marked areas and the implications of systematic search on population dynamics are discussed.