Prevalence of the parasite Strepsiptera in adult Polistes wasps: field collections and literature overview

The incidence of strepsipteran parasites in temperate Polistes wasps is recorded following the collection and dissection of adults from nests, foraging sites and hibernacula. The mean proportion of infected P. dominulus adults (i.e. parasite prevalence) on nests was around 7%, while wasps which were captured when hunting for prey or collecting water were rarely parasitized. Of the four Polistes species that were recovered from overwintering aggregations (dominulus, gallicus, nimphus and associus) only P. gallicus was uninfected. In P. dominulus, the most numerous host sampled, up to 25% of overwintering females were infected. We discuss our findings in the light of an extensive collation of records of Polistes parasitized by the strepsipteran genus Xenos in old and recent literature.