Submitted to: Experimental and Applied Acarology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 13, 2007
Publication Date: N/A
Interpretive Summary: The host preferences of mosquitoes that transmit West Nile (WNV)virus in sagebrush ecosystems is unknown. To understand mosquito feeding preferences, we collected blood engorged mosquitoes in the Wyoming Powder River Basin from three areas representing different land use types (sagebrush with coal bed methane ponds, intermittent streams within sagebrush rangeland, and a perennial stream through grassland pasture that was intermittently flood-irrigated). The mosquitoes were analyzed to determine the source of host blood. Feeding preferences for the three most commonly caught mosquitoes were determined. These findings complement other entomological and virological studies in providing useful information concerning the role of mosquitoes in transmitting WNV among wildlife in the sagebrush steppe community.
Female mosquitoes commonly exhibit patterns of blood feeding from vertebrate hosts, a behavior that strongly influences mosquito pathogen infection and transmission. The vertebrate host dynamics of the mosquito transmitted arbovirus, West Nile virus (family Flaviviridae, genus Flavivirus, WNV) in sagebrush ecosystems remain unknown. Cytochrome b (cyt b) gene sequence analysis was used to identify potential sources of WNV in sagebrush ecosystems as part of a study to investigate impacts of the disease on greater sage-grouse (Centrocercus urophasianus), an ecologically imperiled species restricted to sagebrush habitats in western North America. Two hundred and forty-four female mosquitoes captured in light traps and with visually-detectable blood in the gut were analyzed; of these 197 mosquitoes provided 207 DNA sequences for determination from their host blood meals. Of 84 engorged Culex tarsalis analyzed, 60 blood meals were mammalian and 24 were avian in origin, representing 9 mammalian and 14 avian species. No avian species were judged to be primary hosts, but among mammals both mule deer (28%) and cattle (25%) were primary mammalian hosts for Cx. tarsalis. The primary mammalian host for Aedes vexans was white-tailed deer (40%), while the primary avian host was ring-necked pheasant (Phasianus colcichus L.) in 90 % of the avian blood meals. For Aedes dorsalis, no avian blood meals were detected and pronghorn antelope (43%) and cattle (37%) were primary mammalian hosts. A measure of diversity derived from Shannon index values, indicated that Cx. tarsalis, Ae. vexans, and Ae. dorsalis differed in terms of the host species from which blood meals were taken. Furthermore, a comparison of three mosquito sampling areas that represented differing physiographic features showed that Cx. tarsalis adjusted feeding preferences based on host availability. These findings complement other entomological and virological studies in providing useful information concerning the role of mosquitoes in transmitting WNV among wildlife in the sagebrush steppe community.