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Title: Mosquito larval habitat mapping using remote sensing and GIS: Implications of coalbed methane development and the West Nile Virus

item Schmidtmann, Edward

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2006
Publication Date: 9/1/2006
Citation: Zou, L., Miller, S.N., Schmidtmann, E.T. 2006. Mosquito larval habitat mapping using remote sensing and GIS: Implications of coalbed methane development and the West Nile Virus. J. of Medical Entomology 43(5):1034-1041.

Interpretive Summary: Often man-made developments affect the environment in unexpected ways. Development of coal bed methane gas wells to extract the gas for US energy needs requires that the water associated with the coal beds in Wyoming be removed before the methane gas can be pumped out of the well. Large quantities of water are removed from the coal beds and held in detention/impoundment ponds on the surface. In Wyoming the coal bed methane wells are located in arid regions of the state. Creation of thousands of water impoundments has the possibility of providing new breeding grounds for mosquitoes and other biting flies that can transmit diseases like West Nile virus. A computer software program was developed that analyzes GIS and Landsat TM and ETM data that identifies/classifies possible biting fly habitats. Such software systems are valuable in making risk assessments of insect-vectored disease areas.

Technical Abstract: Potential larval habitats of the mosquito Culex tarsalis (Coquillett), implicated as a primary vector of West Nile virus in Wyoming, were identified using integrated remote sensing and geographic information sytem (GIS) analyses. The study area is in the Powder River Basin of north central Wyoming, an area that has been undergoing a significant increase in coalbed methane gas extractions since the late 1990s. Large volumes of water are discharged, impounded, and released during the extraction of methane gas, creating aquatic habitats that have the potential to support immature mosquito development. Landsat TM and ETM+ data were initially classified into spectrally distinct water and vegetation classes, which were in turn used to identify suitable larval habitat sites. This initial habitat classification was refined using knowledge-based GIS techniques requiring spatial data layers for topography, streams and soils to reduce the potential for overestimation of habitat. Accuracy assessment was carried out using field data and high-resolution aerial photography commensurate with one of the Landsat images. The classifier can identify likely habitat for ponds larger than .08 ha (2acres)with generally satisfactory results (72.1%) with a lower detection limit of ~0.4 ha (1 acre). Results show a 75% increase in potential larval habitats from 1999 to 2004 in the study area, primarily becasue of the large increase in small coalbed methane water discharge ponds. These results may facilitate mosquito abatement programs in the Powder River Basin with the potential for application throughout the state and region.