Submitted to: Journal of Vector Ecology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/5/2004
Publication Date: 12/1/2004
Citation: Herrero, M.V., Yarnell, W.E., Schmidtmann, E.T. 2004. Landscape associations of the sand fly, Lutzomyia (Heleocyrtomyia) apache (Diptera: Psychodidae), in the southwestern United States: a geographic information system analysis. Journal of Vector Ecology. 29: 205-211. Interpretive Summary: We used Geographic Information System (GIS) methods to investigate the possible role of a sand fly as a vector of the virus that causes the disease of livestock known as vesicular stomatitis (VS) in the southwestern U.S. The study was conduced because sand flies are known vectors of VS virus in the southeastern U.S. and Central America. The GIS analysis was used: 1) to accurately map the distribution of sites where sand flies were captured on a cattle ranch and National Wildlife Refugein the mid-Rio Grande river valley, New Mexico, 2) to characterize environmental conditions where the sand fly has been captured at other locations in Colorado and Arizona, and 3) to estimate the potential distribution of the species in the southwestern U.S. We determined that the estimated range covers large areas in north-central Colorado, east-central New Mexico and west Texas, the lower mid-Rio Grande river valley and southern Arizona, along with smaller, patchy, areas in northern Arizona, Nevada, Utah and central Idaho. The locations where livestock were first discovered with VS at the onset of recent VS outbreaks were then plotted to show the estimated distribution of the sand fly and affected livestock. Each of the six early cases of VS were found to occur within the estimated distribution of the sand fly. This does not mean that the sand fly is a vector of VS virus, but it suggests that it may be a vector and shows where further study can best be conducted.
Technical Abstract: Landscape associations of the sand fly, Lutzomyia apache, Young and Perkins in the southwestern U.S. were investigated by light/suction trap sampling and the development of a GIS-generated distribution map. In the mid-Rio Grande River Valley, N.M., female and male L. apache were captured in up-draft light/suction traps set in desert shrubland, irrigation levee, and bosque vegetation communities. Small numbers of flies were captured, but the presence of males and females in spatially separated and diverse plant communities at two locations suggest that L. apache is neither focal in range nor restricted to a single plant community. These data, along with 22 previously published collection records, were used with a suite of physiographic features (meta-data) to characterize the biogeographic conditions suitable for L. apache; suitable conditions encompass three life zones, the Rocky Mountain Steppe Province, the Colorado Semi-Plateau Province, and the American Semi-Desert Province in southern Arizona, all within the Dry Domain region of the western U.S. Using the same collection data, the potential range of L. apache was then estimated based on elevation, mean and max - min temperature, precipitation, wet days, and relative humidity data. The estimated range includes large contiguous areas in north-central Colorado, east-central New Mexico and west Texas, the lower mid-Rio Grande River Valley, and southern Arizona, along with smaller, patchy, areas in northern Arizona, Nevada, Utah and central Idaho. The spatial relationship between the estimated distribution of L. apache and location of livestock exposed to vesicular stomatitis virus at the onset of recent outbreaks is presented.