The Establishment and Potential Spread ofOsmia cornuta(Hymenoptera: Megachilidae) in North America

Abstract

AbstractMason bees, subgenusOsmiaPanzer (Hymenoptera: Megachilidae), are economically and ecologically significant pollinators. In eastern North America, the rapid spread of two non-native species from Asia,O. cornifronsRadoszkowski andO. taurusSmith, has coincided with declines in nativeOsmiapopulations, raising concern about the effects of further exotic invasions. Here we investigate the recent establishment in British Columbia, Canada of the European orchard bee,O. cornutaLatreille, previously thought to be limited to Europe and its periphery. We documentO. cornutarecords ranging over 170 km, including sightings of live adults and the discovery of a multigenerational nest with hundreds of cocoons. We tested whether theseO. cornutacocoons could be discriminated from otherOsmiaspecies by training a machine learning classifier on features extracted from images. The best performing model could not reliably discriminate cocoons by species, raising the possibilityO. cornutacould be inadvertently intermingled in future commercial shipments. Spatially isolated records ofO. cornifronsandO. taurusfurther suggest ongoing anthropogenic dispersal of these species. To determine environmentally suitable regions forO. cornutato spread in North America, we estimated its climate niche using native-range occurrence data. This analysis indicated broad regions of the Pacific Northwest and eastern North America contain potentially suitable habitat. Together, our findings document the establishment ofO. cornutain North America and the potential for it to spread broadly. Our study demonstrates the utility of accessible biodiversity data archives and public observation programs in tracking biological invasions and highlights the need for future monitoring of exoticOsmia.