Journal ArticleDiscovery of two Palearctic Bootanomyia Girault (Hymenoptera, Megastigmidae) parasitic wasp species introduced to North AmericaBrown, Guerin E [University of Iowa, Iowa City, United States of America] (ORCID:0009000744665601); Lewis, Corey J [University of Iowa, Iowa City, United States of America] (ORCID:0009000338567109); Fridrich, Kathy [Binghamton University, Binghamton, United States of America]; Jones, Dylan G [Binghamton University, Binghamton, United States of America] (ORCID:0000000245461981); Goodwin, Elijah A [Stone Barns Center for Food and Agriculture, Tarrytown, United States of America] (ORCID:0009000046969739); Weinrich, Christian L [University of Iowa, Iowa City, United States of America] (ORCID:0009000631855273); Steffensen, MaKella J [University of Iowa, Iowa City, United States of America] (ORCID:0009000125420947); Prior, Kirsten M [Binghamton University, Binghamton, United States of America] (ORCID:0000000299306370); Forbes, Andrew A [University of Iowa, Iowa City, United States of America] (ORCID:0000000183326652)<p>Invasive species are among the greatest threats to ecosystems, but our ability to detect species introductions varies across taxa. Parasitoid wasps, though one of the most species-rich groups of all animals, are small and have ephemeral adult stages, such that they often go unnoticed. Here, we document two separate introductions of European parasitoids of oak gall wasps into North America. Both wasps key morphologically to<italic>Bootanomyia dorsalis</italic>(Fabricus), which previous genetic data from Europe suggest comprises two distinct species,<italic>B. dorsalis</italic>sp. 1 and<italic>B. dorsalis</italic>sp. 2. We find<italic>B. dorsalis</italic>sp. 1 in oak galls from New York, USA and<italic>B. dorsalis</italic>sp. 2 in oak galls from Washington, Oregon, and British Columbia, Canada. All oak gall wasp hosts were North American natives. We detect no genetic variation at the mtCOI locus within<italic>B. dorsalis</italic>sp. 2 specimens, suggesting this introduction may have had only a small number of founder individuals. In their native ranges, both species attack several different gall wasp hosts, and we likewise reared both from galls of multiple North American gall wasp hosts, suggesting a potential for widespread impact on North American gall insect communities. These introductions were detected only because our research groups are actively sampling and identifying parasitoid communities across gall habitats. Most parasitoid communities are not regularly sampled across hosts, time and space, or are well characterized, such that many more undetected wasp introductions may be impacting native insects worldwide.</p>Pensoft2025-07-0210665750Journal of Hymenoptera Research98653 to 6651070-9428https://doi.org/10.3897/jhr.98.1528672418250National Science Foundation