Seasonal dynamics of four potential West Nile vector species in north-central Texas

A population survey was conducted from April through September 2002 on mosquito species occurring on the Ray Roberts Greenbelt, a riparian corridor used for public recreation on the Elm Fork of the Trinity River, in Denton County, TX. Geographic information system software was used to set up a stratified random sampling design based on habitat parameters. Mosquitoes were collected using light traps, gravid traps, and resting boxes. A total of 29 species was collected during this study belonging to the following genera: Aedes, Anopheles, Coquillettidia, Culex, Mansonia, Ochlerotatus, Orthopodomyia, Psorophora, and Uranotaenia. The four most common species collected during this study were Aedes vexans, Culex erraticus, Culex salinarius, and Psorophora columbiae. West Nile virus (WNV) has been detected in these species in the United States, and they may serve as important vector species in Denton County. Collections were analyzed by the Texas Department of Health for arboviruses. One pool consisting of both Cx. erraticus and Cx. salinarius, collected in August 2002, tested positive for WNV, making it the first mosquito pool to test positive for WNV in Denton County. Canonical correspondence analysis was performed using abundance data of dominant species with selected weather variables and habitat parameters. Important factors for determining dominant species abundance were temperature, precipitation, dew point, and canopy coverage. Spatial and temporal patterns of these species are discussed.