No fitness consequence of experimentally induced polyandry in a monandrous wasp
Résumé
Tests of the effects of multiple mating by females on female fitness have been primarily with polyandrous species, where a benefit to multiple mating has usually been found. In contrast, no such benefit was found here for the parasitic wasp Spalangia endius, a highly monandrous species. Females that mated only once prior to oviposition exhibited a rapid decline in daughter production long before they died. The production of daughters, but not sons, is sexual in this species, i.e., requires sperm. Nevertheless, females with greatly decreased daughter production did not then remate. When such females were experimentally manipulated into copulating with a second male, additional sperm were stored in the females' sperm storage organs. However, this sperm increase had no significant effect on daughter production, total offspring production or longevity. There was no evidence that either immediate or delayed polyandry currently benefits females. The lack of benefit may be a general feature of highly monandrous species or a common feature of parasitic hymenopterans regardless of mating system.