A comparative study of some aspects of the reproduction of three Caryedon serratus strains in presence of its potential host plants.

Some reproductive features of an oligophagous Bruchid (Caryedon serratus 01) were analysed on three populations: - The first was harvested on one of the insect's wild host plants (Bauhinia rufescens) in an area where no groundnuts are grown. - The second was collected on Arachis hypogea in a region where wild host plants are abundant. - The third on A. hypogea in a region where only one wild host plant was found in low abundance. The fecundity, ovarian production and the choice of oviposition sites of females of all three populations was studied by placing them either in presence of A. hypogea pods, or pods of B. rufescens, or in presence of pods of both species.Females of the first and third strains showed a marked preference for their original host plant irrespective of where they completed their larval development. Results were less clear-cut for the second strain: some females prefered B. rufescens whilst others oviposited preferentially on A. hypogea. Moreover, the substrate used for larval development appeared to influence the choice of subsequent oviposition sites. These three populations could represent three possible evolutionary situations arising through a process of disruptive selection gradually adapting some C. serratus populations to a recently introduced host plant: A. hypogea.