N O T E A Survey of Cavity-Nesting Bees and Wasps in Loblolly Pine Stands of the Savannah River Site, Aiken County, South Carolina’

In recent years concern over widespread losses in biodiversity has grown to inc lude a poss ib le dec l ine o f many na t ive po l l ina to rs , p r imar i l y bees (Buchmann and Nabhan 1996, The Forgotten Pollinators, Island Press). Factors such as habitat fragmentation, agricultural practices, use of pesticides, the introduction of invasive species, or changes in land use may negatively impact these vital organisms (Kearns et al. 1998, Ann. Rev. Ecol. Syst. 29: 83-l 12). Most reported studies show that human impacts on pollinators are overwhelmingly negative (Vinson et al. 1993, Hymenoptera and Biodiversity, CAB International; Buchmann and Nabhan 1996). Because 60 to 70% of plant species rely on insects for pollination (Richards 1986, Plant breeding systems, Chapman and Hall), reductions in pollinator populations may profoundly impact plant population dynamics (Bond 1994, Philos. Trans. R. Sot. Lond. B. Biol. Sci. 34: 83-90). Consequently, decreases in native pollinator diversity and abundance may severely impact ecosystem function (Druess and Tscharntke 1994, Science 264: 1581l 584 ; S te f fan-Dewenter and Tscharn tke 1999, Oeco log ia 121: 432-440. ) . Although floral resources are clearly important to pollinator success, an equally important factor defining bee communities is the availability of nesting habitat (Barthell et al. 1998, Environ. Entomol. 27: 117-124). Despite this, Cane (2001, Cons. Ecol. 5: 3) stated that pollinator habitat “fragmentation” studies have focused on patches of flowering plants without regard to the negative impacts that losses in nesting substrates undoubtedly have on bee species. The availability of suitable nesting habitat is likely to be a major determinant of animal movement (Crist et al. 1992, Funct. Ecol. 6: 536-544; Carter and Real 1997, Oecologia 112: 430-434) and may be as important to the success of local populations as floral resources. Typically, nests are constructed within holes left by wood-boring beetles, hollowed plants stems, or in soils of appropriate texture, depth, and moisture (Cane 2001).