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Introduced (Nonnative) Bees

There are known to be a total of 23 introduced bees in North America, and 21 of them occur in New York state (Ascher 2001, Cane 2003, Sheffield et al. 2011). All of the known introduced bees have been transported from the Old World (Eurasia) either accidentally or through intentional introduction. The most common and conspicuous of our introduced European bees is the honey bee, Apis mellifera, which is managed commercially for honey and pollination services. Other introduced bees include species of MegachileHylaeusChelostomaHoplitisAnthidium and Andrena (Ascher 2001, Miller et al. 2002, Cane 2003, Sheffield et al. 2011). Ascher (2001) estimated that accidentally introduced bees account for 0.5 percent of the North American bee species. While they comprise a small number of species, introduced bees make up, in some cases, a large proportion of the individuals in New York State. This is especially true of the European honey bee. Most accidentally introduced bees are stem- or cavity-nesting species. These species (in the Hylaeinae, Megachilidae, and Xylocopinae) are easily transported in plant materials (e.g., wood) or in man-made materials.

Nonnative bee species can have a negative impact on native species for a variety of reasons. Nonnative species may compete with native species for floral and nesting resources, they may carry pathogens that can infect native species, and they can cause mating disruption when they are closely related to native species (Stout and Morales 2009). Unfortunately, we know very little about the impact of nonnative bees on native eastern North American bees. 

Transcontinental transport of bumblebee colonies for greenhouse tomato pollination is thought to have led to the introduction of nonnative bumblebee pathogens - specifically microsporidian pathogens in the genus Nosema (Cameron et al. 2011, Cordes et al. 2012). Introduction of nonnative pathogens is one of the leading hypotheses for the decline in several bumblebee species in North America, including Bombus affinisB. terricola, and B. pensylvanicus.

Osmia cornifrons, also known as the horn-faced bee, is a nonnative mason bee that was intentionally introduced into the US (along with Osmia taurus) for fruit pollination in the 1970s (Batra 1979, 1982). Both nonnative Osmia species have host-plant ranges and nesting requirements that are similar to those of our native “blue orchard bee” (Osmia lignaria). Apparent declines in Osmia lignaria in the eastern US may be linked to the arrival of O. cornifrons and O. taurus, but a careful examination of the historical data on the abundance of O. lignaria has not been conducted. A recent report by Hedtke et al. (2015) indicates that feral populations of O. cornifrons in the US host Ascosphaera pathogens originally reported from Japan, suggesting that intentional introduction of O. cornifrons has led to the unintentional introduction of a nonnative fungal pathogen into North American Osmia populations. Whether this pathogen is present in O. lignaria populations has not yet been established.

Megachile sculpturalis, also known as the giant resin bee, was introduced into the southeastern US (North Carolina) in the early 1990s (Mangum and Brooks 1997, Mangum and Sumner 2003, Hinojosa-Díaz et al. 2005, Maier 2009). It has since spread throughout much of eastern North America (as far north as Ontario), as far south as Alabama (Mangum and Sumner 2003), and was recently reported as far west as Kansas (Hinojosa-Díaz 2008). The bee is also a nonnative invader that is spreading across much of western Europe from Belgium (Vereecken and Barbier 2009) to Italy (Quaranta et al. 2014). This large, aggressive resin bee has been reported to forcibly usurp active nests of our native large carpenter bee (Xyocopa virginica). Roulston and Malfi (2012) reported an attack on an active carpenter bee nest in which the giant resin bee attacked and physically removed adult carpenter bees guarding the nest entrance. During the attack the resin bee grabbed the legs of the carpenter bee, bit the carpenter bee near the head, and made repeated attempts to sting it. In addition, the resin bee appeared to use sticky resins to gum up the wings of the carpenter bee—a remarkable case of what appears to be chemical warfare in the bee world. Laporte and Minckley (2012) reported a similar example of nest usurpation that included the use of sticky resin against the resident carpenter bees in Rochester, NY. The rapid spread of the giant resin bee throughout the eastern US (and Europe) and the reports of nest usurpation suggest that this bee may have a very significant impact on native carpenter bee populations across an enormous geographic range.


  • Ascher, J.S. (2001). Hylaeus hyalinatus Smith, a European bee new to North America, with notes on other adventive bees (Hymenoptera: Apoidea). Proceedings of the Entomological Society Washington 103: 184-90.
  • Batra, S. W. T. (1979). Osmia cornifrons and Pithitis smaragula, two asian bees introduced into the United States for crop pollination. Maryland Agricultural Experiment Station Special Miscellaneous Publications 1: 307-312.
  • Batra, S.W.T. (1982). The hornfaced bee for efficient pollination of small farm orchards. In: H. W. Kerr, Jr. and L. V. Kantson, Eds., Research for Small Farms. USDA Miscellaneous Publications 1422: 117-120.
  • Cameron, S.A., J.D. Lozier, J.P. Strange, J.B. Koch, N. Cordes, L.F. Solter, and T.L.  Griswold (2011). Patterns of widespread decline in North American bumblebees. Proceedings of the National Academy of Sciences (USA) 108: 662-667.
  • Cane, J.H. (2003). Exotic nonsocial bees (Hymenoptera: Apiformes) in North America: ecological implications. In:  For Nonnative Crops, Whence Pollinators of the Future. Edited by Strickler K, Cane JH. Lanham: Proceedings of the Entomological Society of America, pp. 113-126.
  • Cordes, N., W.F. Huang, J.P. Strange, S.A. Cameron, T.L. Griswold, J.D. Lozier, and L.F. Solter (2012). Interspecific geographic distribution and variation of the pathogens Nosema bombi and Crithidia species in United States bumble bee populations. Journal of Invertebrate Pathology 109: 209-216.
  • Hedtke S.M., E.J. Blitzer, G.A. Montgomery, and B.N. Danforth (2015). Introduction of non-native pollinators can lead to trans-continental movement of bee-associated fungi. PLoS ONE 10(6): e0130560
  • Hinojosa-Díaz, I.A., Yáñez-Ordóñez, O., Chen, G., Peterson, A.T., and Engel, M.S. (2005). The North American invasion of the giant resin bee (Hymenoptera: Megachilidae). Journal of Hymenoptera Research 14: 69-77.
  • Hinojosa-Díaz, I. (2008). The giant resin bee making its way west: first record in Kansas (Hymenoptera: Megachilidae). ZooKeys 1: 67-71.
  • Laport, R.G., and Minckley, R.L. (2012). Occupation of active Xylocopa virginica nests by the recently invasive Megachile sculpturalis in upstate New York. Journal of the Kansas Entomological Society 85: 384-386.
  • Maier, C.T. (2009). New distributional records of three alien species of Megachilidae (Hymenoptera) from Connecticut and nearby states. Proceedings of the Entomological Society of Washington 111: 775-784.
  • Mangum, W. A., and R. W. Brooks (1997). First records of Megachile (Callomegachilesculpturalis Smith (Hymenoptera: Megachilidae) in the continental United States. Journal of the Kansas Entomological Society 70(2): 146-148.
  • Mangum, W.A., and S. Sumner (2003). A survey of the North American range of Megachile (Callomegachile) sculpturalis, an adventive species in North America. Journal of the Kansas Entomological Society 76: 658-662.
  • Miller, S.R., R. Gaebel, R.J. Mitchell, and M. Arduser (2002). Occurrence of two species of old world bees, Anthidium manicatum and A. oblongatum (Apoidea: Megachilidae), in northern Ohio and southern Michigan. Great Lakes Entomologist 35: 65-70.
  • Quaranta, M., A. Sommaruga, P. Balzarini, A. Felicioli, and others (2014). A new species for the bee fauna of Italy: Megachile sculpturalis continues its colonization of Europe. Bulletin of Insectology 67: 287-293.
  • Roulston, T. and R. Malfi (2012). Aggressive eviction of the eastern carpenter bee (Xylocopa virginica (Linnaeus)) from its nest by the Giant Resin Bee (Megachile sculpturalis Smith) Journal of the Kansas Entomological Society, 85(4): 387-388.
  • Sheffield, C.S. S. Dumesh, M. Cheryomina (2011). Hylaeus punctatus (Hymenoptera: Colletidae), a bee species new to Canada, with notes on other non-native species. Journal of the Entomological Society of Ontario 142: 29-43.
  • Stout, J.C. and C.L. Morales (2009). Ecological impacts of invasive alien species on bees. Apidologie 40: 388-409.
  • Vereecken, N.J. and E. Barbier (2009).  Premières données sur la présence de l’abeille asiatique Megachile(Callomegachilesculpturalis Smith (Hymenoptera, Megachilidae) en Europe. Osmia 3: 4-6.