We know very little about the conservation status of most bee species in New York State because there is no long-term monitoring program for wild bees. However, one way to monitor historical changes in wild bee populations is to use specimen record data from natural history museums, such as the American Museum of Natural History and the Cornell University Insect Collection. Museum records can give us a historical perspective on the change in the absolute and relative abundance of a species over time. A recent study (Bartomeus et al. 2013) examined historical museum records for 438 bee species across the eastern US in order to identify evidence of significant declines over the past 140 years. Sample sizes were sufficient to examine historical trends in 187 species. Of those 187, 49 species occurring in NY were found to be in decline or rare and potentially threatened.
Bumble bees, because of their large size and ease of observation, are perhaps the best known bees in terms of conservation status. A number of eastern bumble bee species are known to have experienced significant declines over the past 30 years. Bombus terricola, B. bohemicus, B. insularis, B. pensylvanicus, and B. terricola are all in decline over part or all of their ranges. Bombus affinis, a common eastern bumble bee prior to 1996, is now extremely rare and may be close to extinction. The cause of these declines are not clear but may include loss of natural habitat, exposure to pesticides, and the arrival of nonnative pathogens (especially Nosema bombi from Europe; Cameron et al. 2011, Cordes et al. 2012).
Besides the bumble bees, which are well-studied and charismatic pollinators, the list of declining bee species detected by Bartomeus et al. (2013) includes solitary ground-nesting bees (e.g., Andrena, Melissodes, and Colletes), solitary stem- and cavity-nesting bees (e.g., Osmia and Megachile), social ground-nesting bees (e.g., Lasioglossum subgenus Dialictus), narrow host-plant specialists (e.g., Peponapis pruinosa, some Andrena and Colletes), and cleptoparasites (e.g., Coelioxys and Epeolus). The study of Bartomeus et al. (2013) is likely an underestimate of the number of threatened bee species in the Northeast because the rarest bees were excluded from the analysis because of their small sample size.
Bees in the family Melittidae are among the rarest of New York’s bees. Melittidae is an enigmatic, seemingly ancient group of bees with its greatest diversity in southern Africa. Virtually all melittid bees are narrow host-plant specialists (Michez 2008) and many groups seem to prefer sandy soils for nesting. In New York we have just five species in two genera: Melitta and Macropis. Melitta eickworti and Melitta americana are both specialists on Vaccinium (Ericaceae). Melitta americana can be common in and around blueberry and cranberry fields (Payette 2013, Cariveau et al 2013), but Melitta eickworti is restricted to shady forest understory with deerberry (Vaccinium stamineum; Cane et al. 1985). Macropis includes highly specialized “oil bees” that are narrow host-plant specialists on Lysimachia (yellow loosestrife). Female Macropis nest in humid, boggy habitats (where their host-plants occur) and they use the floral oils for lining the brood cell as well as for larval nutrition (Cane et al. 1983). The collection of floral oils may be an adaptation for nesting in saturated, marshy soils along streams, rivers and on the edge of ponds and lakes. In New York we have three Macropis species, all of which are rare and geographically restricted. Their narrow host-plant preferences and obligate association with oil-producing host-plants (Lysimachia) contributes to both the rarity of these bees as well as their status as potentially endangered pollinators.
Epeoloides pilosula is likely the most threatened and endangered bee species in New York (and the Northeast). E. pilosula is a cleptoparasite of Macropis, a rare bee for reasons outlined above. E. pilosula has not always been rare. There are many records of E. pilosula prior to 1940 and the known range of E. pilosula includes 18 states and 4 Canadian provinces (Sheffield et al. 2004, Wagner and Ascher 2008). However, in the past 60 years the bee has only been collected four times: in Montana (1958), Ontario (1960), Nova Scotia (2002), and Connecticut (2008). This bee is a prime candidate for listing as an endangered species in North America.
- Bartomeus, I., J.S. Ascher, J. Gibbs, B.N. Danforth, D.L. Wagner, S.M. Hedtke, and R. Winfree (2013). Historical changes in northeastern United States bee pollinators related to shared ecological traits. Proceedings of the National Academy of Sciences (USA) 110(12): 4656-4660.
- 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., G.C. Eickwort, F.R. Wesley, and J. Spielholz (1983). Foraging, grooming and mate-seeking behaviors of Macropis nuda (Hymenoptera, Melittidae) and use of Lysimachia ciliata (Primulaceae) oils in larval provisions and cell linings. American Midland Naturalist 110(2): 257-264.
- Cariveau, D.P., N.M. Williams, F.E. Benjamin, and R. Winfree (2013). Response diversity to land use occurs but does not consistently stabilise ecosystem services provided by native pollinators. Ecology Letters 16: 903-911.
- 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.
- Michez, D., S. Patiny, P. Rasmont, K. Timmermann, and N.J. Vereecken (2008). Phylogeny and host-plant evolution in Melittidae sl (Hymenoptera: Apoidea). Apidologie 39: 146-162.
- Payette, A. (2013). First record of the bee Melitta americana (Smith) (Hymenoptera: Melittidae) for Quebec and Canada. Canadian Field-Naturalist 127(1): 60-63.
- Sheffield, C.S., S.M. Rigby, R.F. Smith, and P.G. Kevan (2004). The rare cleptoparasitic bee Epeoloides pilosula(Hymenoptera: Apoidea: Apidae) discovered in Nova Scotia, Canada, with distributional notes. Journal of the Kansas Entomological Society 77: 161-164.
- Wagner, D.L., and J.S. Ascher (2008). Rediscovery of Epeoloides pilosula (Cresson) (Hymenoptera: Apidae) in New England. Journal of the Kansas Entomological Society 81: 81-83.