Natural selection and genetic differentiation of behaviour between parasitoids from wild and cultivated habitats

Differences in behaviour between individuals in populations living in diffe rent environments may result from evolution proceeding differently in each population. The parasitoid wasp Cotesia glomerata (L.) (Hymenoptera: Bracon idae) parasitizes early instar larvae of butterflies in the family Pieridae . In the study area the only host of C. glomerata is the Small Cabbage Whit e Butterfly [Pieris rapae (L.) (Lepidoptera: Pieridae)], which feeds on cru ciferous host plants in a variety of habitats. The behaviour of this parasi toid wasp collected from two habitat types (wild and agricultural) was obse rved in a reciprocal transplant-style experiment in a greenhouse. Differenc es in behaviour between wasp sources and test habitat type were analysed us ing canonical analysis in multivariate analysis of variance. Directional se lection on parasitoid behaviour in each test habitat type was estimated by regressing the relative rate of parasitism (a measure of relative fitness) on the behavioural character state. We found that there is genetic differen tiation of behaviour between wasps from wild and cultivated habitats and th at a different set of behaviours is associated with short-term fitness with in models of each source habitat. There was no evidence of local adaptation of wasps to either habitat.