Genetic variation in the mechanisms of direct mutual interference in a parasitic wasp: consequences in terms of patch-time allocation

Abstract

1. Direct mutual interference between insect parasitoids has always been considered to have major consequences for the population dynamics of parasitoid-host systems. Furthermore, patch time allocation has also always been presented as an important behavioural component that is closely involved in the demographic features of host-parasitoid interactions. 2. Based on a detailed analysis of within-patch interactions between Trissolcus basalis (Hymenoptera: Scelionidae) females, the present study aimed to understand accurately how direct mutual interference can influence patch time allocation in this species. 3. The genetic variation in the behavioural mechanisms involved in the interaction between the females was also quantified in the study population using the isofemale strains method. 4. Behavioural interactions between the females were analysed using Cox's proportional hazards model. 5. Results indicated that the competitive interaction (through contacts and fights) between females strongly influenced their patch residence time. 6. Corresponding patch-leaving decision rules appeared to be under significant genetic variation. Such genetic variability is likely to correspond to intra-population genetic variation in susceptibility of females to interference. 7. The population dynamics and evolutionary consequences of these results are discussed.