Diversity of parasitoid wasps flying over Delaware

• Charlie Polychrones, Insect Ecology and Conservation, University of Delaware

• Michael Crossley, Entomology & Wildlife Ecology, University of Delaware
• Nellie Heitzman, Entomology & Wildlife Ecology, University of Delaware

The largest order of insects was once thought to be Coleoptera, the beetles. Over time, however, it was realized to be Hymenoptera, the ants, bees, wasps, and sawflies. The vast majority of this group is composed of parasitoid wasps—tiny and nearly invisible, but incredibly important. Fascinatingly, nearly every insect group serves as hosts for parasitic wasps—even other parasitic wasps themselves. Parasitoid wasps attack every insect life stage—from egg and larvae to adult. Parasitoid wasps are used frequently as biocontrol agents for various agricultural pests, including aphids, scales, beetles, caterpillars, and many more. Unfortunately, parasitoid wasps are also one of the most understudied and underrepresented insect groups in literature. Using the University of Delaware’s suction trap located on the school’s farm, I measured parasitic wasp diversity to family-level. In addition, I sampled directly from the field using a sweep net to measure diversity of parasitic wasps at ground-level in order to compare. Species diversity of ground-collected wasps was far higher than diversity of wasps collected by the suction trap, representing far more families and superfamilies. Wasps caught by the suction trap were mostly of the family Encyrtidae with a few exceptions from various other families and superfamilies, while wasps caught by sweep netting were not majorly of any one group. Rather, there were consistently at least five different families caught per sweep netting session. Families included Encyrtidae, Eulophidae, Pteromalidae, Trichogrammatidae (all of superfamily Chalcidoidea), Platygastridae (of superfamily Platygastroidea), Ceraphronidae (of superfamily Ceraphronoidea), and much more. While parasitic wasps are not known to migrate, they do disperse; however, literature regarding dispersal distances and heights is lacking. It appears that the parasitic wasp species caught by the suction trap, primarily Encyrtid wasps, disperse at higher heights, potentially to reach further ground, prompting questions about why this is the case.