Further Range Extension of Xylocopa micans Lepeletier (Hymenoptera: Apidae)

Abstract

There are seven species in the genus Xylocopa Latreille that occur in North America north of Mexico, and only two of these are known to occur in the Eastern United States: Xylocopa virginica L. and X. micans Lepeletier. While the range of X. virginica extends through much of the Eastern United States, the distribution of X. micans is concentrated along the coastal areas to the far south and east. Until 2010, X. micans had only been recorded in Alabama, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina and Texas (Hurd, 1955). In 2006 and 2007, four specimens of X. micans were collected in southwestern Arkansas, representing the first records of X. micans in Arkansas, about 250 km northwest of its historical range (Warriner, 2010). Additionally, we report here that two males of X. micans were netted on May 10, 2010 north of Biscoe in Prairie County, AR (34.845000uN, 91.415833uW). This location is approximately 50 km northeast of the first specimens found in Arkansas three years prior. The specimens were determined with the keys of Hurd (1955) and Mitchell (1962). The voucher specimens have been deposited at the University of Arkansas’ Arthropod Museum, Department of Entomology in Fayetteville, Arkansas, USA. This is a new locality record for X. micans in the state of Arkansas and supports Warriner’s (2010) suggestion that this represents an extension of its historically recorded range, rather than an incidental introduction. Xylocopa micans is a member of the Neotropical subgenus Schoenherria Lepeletier, and its range may be restricted to warmer climates. In the Lower Rio Grande Valley, Porter (1981) found that X. micans was only collected in the warmer months from spring through summer, while other Xylocopa species were collected year round. The presence of X. micans in Prairie County, Arkansas may reflect a climate-driven northward range expansion as predicted by climate change and already evidenced by the range shifts of species such as the nymphalid Euphydryas editha (Boisduval) (Parmesan, 1996). Conversely, the specimens found in Prairie County, Arkansas may be human-mediated introductions and not representative of a natural expansion. The site at which they were collected is located along Interstate 40, which connects to the southwestern locations via Interstate 30. It is possible that these individuals were transported from their native range to Arkansas and have spread by means of highway traffic. Xylocopa species, including X. micans, nest in dead wood, and may inadvertently be transported long distances in shipments of lumber or other wood products. This was shown to be the case for Xylocopa brasilianorum L. which arrived in San Francisco in a balsa wood shipment from Hawaii (Hurd, 1955). Further sampling of bees in Arkansas may help determine how X. micans arrived in and spread throughout Arkansas. Large bees, such as Bombus and Xylocopa species, have the ability to sonicate the anthers of flowers with poricidal dehiscence, such as Solanum species (King and Buchmann, 2003). Due to this somewhat unique capacity, large bees such as Xylocopa micans are of particular interest as pollinators of many plant species with poricidal anthers. Out of 153 bee visitors, X. micans and two species of Melissodes were shown to be the only effective pollinators of Chamaecrista keyensis Pennell (Fabaceae), the big pine partridge pea, which is listed as an endangered species in the state of Florida (Liu and Koptur, 2003). Clearly, the role of X. micans as generalist pollinator with special abilities can be an important factor in plant communities. If the distribution of X. micans is changing, either as the result of climate change or through anthropogenic introductions, there may be additional ecological repercussions.