Geographic variation in host selection behaviour and reproductive success in the stemborer parasitoidCotesia flavipes(Hymenoptera: Braconidae)

Abstract

AbstractLocal parasitoid populations may be adapted to their sympatric major plant host complex. Parasitoid strains may thus differ in their propensity to search for a particular micro-habitat or host or they may differ in their physiological compatibility with particular plant or host species.Cotesia flavipesCameron, a larval parasitoid used worldwide in biological control against tropical stemborers, has a wide host range in diverse habitats. The existence of plant and/or host specific strains inC. flavipeshas been postulated. To provide insight into the existence of strains inC. flavipes, we compared the plant/host complex selection behaviour, and physiological compatibility with different stemborers, of six different geographic strains ofC. flavipesthat differed in the plant/host complex they were obtained from. The results of the host selection experiments indicate that there is no intraspecific variation in host selection behaviour amongC. flavipesstrains. However, our comparative experiments show variation in reproductive success among strains. The most significant result was that the strain with the longest period of co-existence with the new hostDiatraea saccharalisFabricius had the highest reproductive success on this host species. We argue that the reported existence ofC. flavipesstrains is based not on differences in host selection behaviour, but on differences in physiological compatibility between local parasitoid and host population.