A research team led by Binghamton University biologists has identified two previously unknown parasitic wasp species living in the United States, with genetic evidence linking them to Europe. The finding highlights the complexity of biodiversity, species introductions, and the role of citizen science in uncovering hidden organisms.
Parasitic wasps target oak gall wasps, small insects that form tumor-like plant growths called galls. North America is home to about 90 oak species and roughly 800 oak gall wasp species, which in turn support hundreds of parasites. Until now, scientists were unaware that European species of Bootanomyia dorsalis had crossed the Atlantic.
According to Associate Professor Kirsten Prior, “Only when we have a large, concerted effort to search for biodiversity can we uncover surprises — like new or introduced species.”
Field surveys and genetic sequencing revealed two distinct clades of B. dorsalis: one found in New York, genetically close to populations from Portugal, Iran, and Italy; the other on the Pacific Coast, linked to species from Spain, Hungary, and Iran. The evidence suggests at least two separate introductions.
The wasps may have arrived with imported oak trees such as English oak (Quercus robur) or Turkey oak (Q. cerris), or by hitchhiking on human transport. Researchers remain uncertain whether the newcomers pose risks to native insects. Prior noted, “They could be affecting populations of native oak gall wasp species or other native parasites of oak gall wasps.”
Citizen scientists played a key role in the discovery through Gall Week, a community project encouraging people to collect galls and share observations online. With continued monitoring, researchers hope to determine how widespread the introduced wasps are and what ecological impacts they may bring.
Parasitic Wasps From Europe Found Thriving in the U.S.
