A Range Extension for the Large Carpenter Bee Xylocopa micans (Hymenoptera: Apidae) with Notes on Floral and Habitat Associations

Abstract

The carpenter bee subfamily Xylocopinae is represented by two genera in the United States, Ceratina Latreille (small carpenter bees) and Xylocopa Latreille (large carpenter bees). Members of both genera bore into plant tissues, either herbaceous or woody, to construct nest galleries for rearing larvae. In the eastern United States, the genus Ceratina is comprised of five species (Daly, 1973), while Xylocopa is represented by two species (Mitchell, 1960). Xylocopa species typically excavate nest galleries in woody plant material, including dead branches, stalks, stumps, and the structural timbers of buildings (Hurd and Moure, 1963; Hurd, 1978; Gerling et al, 1989). Xylocopa virginica Linnaeus is the most widespread of the eastern species, ranging from the northeastern United States south to Florida and west to Texas and Kansas (Hurd, 1978). As shown in Figure 1, the second species, X. micans Lepeletier has a more restricted distribution north of Mexico, ranging from southeastern Virginia to Florida and along the Gulf Coast into Texas (Hurd, 1978). In 2006 and 2007, I collected specimens of X. micans from southwestern Arkansas (Figure 1). These collections extend the species range approximately 250 km to the northwest from the nearest documented occurrence in Louisiana (Hurd, 1955). Localities in Arkansas are as follows: Clark County: 24 May 2006, Terre Noire Natural Area, 34°04'28.90N, 93°10'30.86W (I9). Hempstead County: 24 May 2006, Rick Evans Grandview Prairie Wildlife Management Area, 33°47'55.71N, 93°47'43.60W (29). Little River County: 24 May 2007, White Cliffs Natural Area, 33°45'38.50N, 94°03'06.25W (I9). All specimens were deposited in the University of Arkansas Arthropod Museum. While a great deal of information is available regarding the habits of X. virginica (Ackerman, 1916; Balduf, 1962; Hurd, 1978), substantially less is known about X. micans. Data on habitat associations and nesting sites are scarce. Given the growing awareness of pollinator declines (Committee on the Status of Pollinators in North America, 2007) and the potential value of Xylocopa species as pollinators in natural and agricultural systems (Gerling et al, 1989), such basic information should be documented in order to define a species' potential conservation and/or management needs. Xylocopa micans localities listed above for southwestern Arkansas are situated in the South Central Plains ecoregion (Woods et al , 2004) and are characterized by a mosaic of pine-hardwood forests and remnant blackland prairies. All X. micans specimens were observed in the latter habitat type. In Arkansas, blackland prairies were historically restricted to the southwestern corner of the state, occurring from Little River and Sevier Counties in the southwest, through Hempstead and Howard Counties, to Clark County in the northeast (Foti, 1989). These prairies were small, ranging from less than a hectare to a few hundred hectares in size. Floristically, Schizachyrium scoparium Nash is the dominant plant in these sites, followed to a lesser extent by Sorghastrum nutans Nash, and Dalea purpurea Ventenat among others (Foti, 1989). Little of this habitat type remains in Arkansas today due to agricultural conversion, degradation from overgrazing, and fire suppression (Foti, 1989). The few blackland prairie remnants that still exist are fragmented and isolated. In May 2006 and 2007, D. purpurea was one of the most abundant flowering plants in the blackland prairies from which X. micans were collected. All female X. micans I observed were foraging for pollen from this species' flowers, their hind legs covered in the orange pollen of D. purpurea. Hurd (1978) lists 39 plant taxa that serve as pollen sources for X. micans. Dalea purpurea is not listed among those. This plant species attracts a diverse bee fauna and is thought to be partially self-incompatible making insect pollination critical for sexual reproduction (Cane, 2006). Xylocopa micans has been noted to be an important pollinator ornative plants elsewhere (Olsen, 1997; Liu and Kopter, 2003) and may play a role in the cross-pollination of D. purpurea in blackland prairie remnants of Arkansas.