J. HYM. RES. Vol. 14(1), 2005, pp. 69-77 The North American Invasion of the Giant Resin Bee (Hymenoptera: Megachilidae) Ismael A. Hinojosa-Diaz, Olivia YAnez-Ordonez, Guojun Chen, A. Townsend Peterson, and Michael S. Engel (IAH, MSE) Division of Entomology, Natural History Museum, and Department of Ecology & Evolutionary Biology, 1460 Jayhawk Boulevard, Snow Hall, University of Kansas, Lawrence, Kansas 66045-7523, USA; (OY) Museo de Zoologia "Alfonso L. Herrera," Departamento de Biologia Evolutiva, Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, Apdo. postal 70-399 CP 04510 Mexico D.F., Mexico; (GC, ATP) Division of Ornithology, Natural History Museum, 1345 Jayhawk Boulevard, Dyche Hall, University of Kansas, Lawrence, Kansas 66045-7561, USA — Abstract. The giant resin bee, Megachile sculpturalis Smith (Megachilidae: Megachilinae), is a species originally of Asia recently adventive in North America. This large and conspicuous species was first recorded at a few localities in the mid-Atlantic states of the United States, but is now found from southeastern Canada (Ontario) to Georgia, and as far west as western Pennsylvania and northwestern Alabama. Known occurrences of this species in its native distributional areas were used to generate an ecological niche model for the species, which can be used to anticipate the geographic potential for species in novel landscapes. The niche model was tested on the native range of the species for robustness in predicting independent suites of occurrence points. The niche model was then used to the distribution of M. in North Amer- — predict potential sculpturalis ica our results indicate that this species has the potential eventually to occupy the entire eastern half of the continent, as far west as the Great Plains. The model also predicts that the species would find appropriate conditions along the Pacific Coast, in Mexico, and in the West Indies. Impacts of M. sculpturalis on native Megachile species are entirely unknown. As the most significant and efficient pol- lifera Linnaeus native to Africa, Europe, linators of flowering plants, bees are crit- the Middle East, and northwestern Asia ical for many aspects of the diversity and (Ruttner 1988), now globally distributed stability of both natural and agricultural as human colonists have transported bee ecosystems; in addition, honey bees have colonies. A famous episode in the pres- long been appreciated for their products ence of honey bees in the Americas was introduction in 1957 of (e.g., honey and wax; Michener 2000). the experimental These beneficial features make it difficult the African A. mellifera scutellata Lepeletier to think of bees as threats when intro- de Saint Fargeau ("Africanized" honey duced into areas outside their native rang- bees) into Brazil, and the later establish- es, despite the widely known negative ef- ment of feral populations throughout fect of exotic species in general (Goulson South and Central America, reaching the 2003, Lawton and Brown 1986, William- southern United States (Kerr 1957, 1967, son 1999, NAS 2002, Perrings ct al. 2002). Michener 1975, Taylor 1977, Sheppard and Several bee species have been intro- Smith 2000). Goulson (2003) mentioned to im- duced into novel regions by man, either other bee introductions carried out deliberately or not. The most famous ex- prove pollination, among the most signif- ample is the western honey bee Apis niel- icant, species of the genera Bombus, Me- 70 Journal of Hymenoptera Research Ascher and Brooks gachile, Osmia and Nomia. (2001) polylectic (Mangum 1997). mentioned the presence of 17 adventive Combining the records reported by Batra and bee species in North America, providing (1998), Ascher (2001), and Mangum taxonomic, geographic and biological in- Sumner (2003), in North America, M. formation for Hylaeus (Spatulariella) hyali- sculpturalis has been recorded foraging on natus Smith, and occurrence notes for Au- flowers of at least 16 plants of 12 families, thidium (Anthidium) manicatum (Linnaeus), the most commonly visited being ever- A. (Proanthidium) oblongatwu (Illiger), Hop- lasting pea, Lathyrus latifolius Linnaeus Che- litis (Hoplitis) anthocopoides (Schenck), (Leguminosae); Japanese pagoda, Sophora lostoma (Gyrodromclla) rapunculi (Lepeletier japouica Linnaeus (Leguminosae); privet, 1 C. de Saint Fargeau) , (Fovcosmin) campan- Ligustrum lucidum W. T. Aiton (Oleaceae); and ularum (Kirby), (our subject herein) and golden-rain tree, Koelreuteria panicu- Megachile (Callomegachile) sculpturalis lata Laxmann (Sapindaceae), the first na- Smith. tive to Europe and the remainder to Asia. The resin bee, M. is a giant sculpturalis, Female M. sculpturalis leave a trace of their robust bee distributed in eastern widely foraging activity on flowers of everlasting Asia Taiwan, and (China, Japan, Korea). pea and Japanese pagoda by puncturing The is differentiated from species easily the standard petal (Mangum and Sumner native North American its Megachile by 2003). (14-19 mm in males, 22-27 mm elongate In the last decade, M. sculpturalis has ap- in females) black parallel-sided body, peared in eastern North America, with head, and dark mesosoma with fulvous populations established and spreading setae and Brooks 1997) 1). (Mangum (Fig. from their initial areas of appearance It nests preferentially in shady places, a (probably near Baltimore, accidentally in- minimum of 0.5 m above the ground, in a troduced, via cargo from Japan or China; variety of cavities, e.g., dry, hollow hori- Batra 1998, Mangum and Brooks 1997). zontal stems (bamboo in its native range), Megachile sculpturalis was first collected in and empty burrows made by other hy- North America in 1994 on the campus of menopterans (Iwata 1933, Okada 1995), in- North Carolina State University, and by cluding abandoned wood burrows of car- 1996 was widespread in North Carolina penter bees (Piel 1933). This latter behav- (Mangum and Brooks 1997), also reaching ior has already been documented in North Delaware (Mangum and Sumner 2003). It American populations (Mangum and has since over much of eastern Brooks 1997). Brood cells are made of res- spread North America, with records as far west in from conifers (Iwata 1933) and maple as Athens, Limestone Co., Alabama, as far gum (Piel 1933), from which the name "gi- south as Auburn, Lee Co., Alabama (Kon- ant resin bee" derives (Batra 1998). In Ja- do ct al. 2000), and as far north as Onon- pan, its period of adult activity is from late New York and June through September (Iwata 1933), co- daga Co., (Ascher 2001), Ontario, Canada and Sumner inciding with the blooming of kudzu (Mangum Records also exist from [Pueraria lobata (Willdenow) Ohwi (Legu- 2003). Georgia, South Penn- minosae)], its principal source of pollen Carolina, Virginia, Maryland, West (Batra 1998), although it is known to be sylvania, Virginia, Ohio, Washing- ton D.C., Tennessee, and Connecticut (Mangum and Sumner 2003). Batra (1998) 1 This has often been referred to the old- species by predicted, based on its Asian range, that er, but preoccupied, name of C. fuliginosum (Panzer) M. sculpturalis would come to inhabit the (a junior primary homonym in Apis), which was re- to climates placed by C. nigricorne (Nylander), but this itself is a humid, subtropical temperate synonym of C. rapunculi. of the southeastern and mid-Atlantic Unit- Volume 14, Number 1, 2005 71 habitus. Fig. 1. Megachile sbulpturalis Smith, female from Japan, above dorsal habitus, below lateral ed States, from eastern Texas and Florida, range ecological characteristics provide north to southern New England. excellent predictivity regarding invaded- Herein we have applied methods of eco- range ecological and geographic potential Panetta Suth- logical niche modeling. Extensive previ- of species (Scott and 1993, ous studies have indicated that native- erst et al. 1999, Skov 2000, Zalba ct al. 2000, 72 Journal of Hymenoptera Research Peterson et al. 2003). Although this ap- mental Panel on Climate Change, native proach does not provide comprehensive resolution 50 x 50 km: http://www.ipcc. in scale be- predictions of geographic range because ch/). To minimize conflicts of other complicating factors (Peterson et tween topographic and climatic data, we al. 2003), the resulting predictions never- conducted analyses at an intermediate res- X theless offer an excellent summary of spe- olution (10 10 km). — cies' invasive potential. As such, we use Ecological niche modeling. Ecological this technique to predict the potential ex- niches are herein defined as the set of con- tent of M. sculpturalis' invasive range in ditions under which a species is able to North America. maintain populations without immigra- tion Our METHODS (Grinnell 1917, 1924). approach consisted of three steps. (1) Model ecolog- Input data. —Collections with specimens ical niche requirements of the species of M. sculpturalis were studied to obtain based on known occurrences in the native native-range occurrence data suitable for distribution area of the species. (2) Test the retrospective georeferencing. Specimen accuracy of the native-range predictions data were taken from the Snow Entomo- based on spatially structured subsets of logical Collection, Division of Entomolo- the available information. (3) Project the gy, University of Kansas Natural History niche model onto North America to iden- to in- Museum, Lawrence, KS, USA; Kyushu tify areas predicted to be susceptible University, Japan; Institute of Zoology, vasion. Chinese Academy of Sciences, People's