Parasitoids, Predators, and Group Size in the Paper Wasp, Polistes Exclamans

Abstract

The paper wasp Polistes exclamans loses part of its brood to the parasitoids Chalcoela iphitalis (Lepidoptera:Pyralidae) and Elasmus polistis (Hymenoptera:Chalcidoidea:Eulophidae) and loses entire nests to bird predation, Crematogaster laeviuscula (Hymenoptera:Formicidae) predation, and orphanage (loss of all adult wasps). More nests fail because of bird predation than from all other causes combined. Larger nests are neither better protected nor more vulnerable to nest predators, though larger nests are less likely to fail because of orphanage than are smaller nests. Larger nests are more heavily attacked by Elasmus polistis, which reinfests its natal nest. Polistes exclamans may subdivide larger groups of females by forming satellite nests because of the lack of an overall advantage to large nests. Satellite nests increase the probability that the brood in either the original nest or satellite nest will avoid bird predation.