Relative Abundance and Species Composition of Mosquito Populations (Diptera: Culicidae) in a La Crosse Virus-Endemic Area in Western North Carolina

Abstract

Container surveys were conducted in 5 communities on the Cherokee Indian Reservation, an area of western North Carolina endemic for transmission of La Crosse (LAC) virus, to determine the potential for peridomestic mosquito breeding, the relative abundance of mosquito species, and the standing crop of mosquitoes per residence. Eleven species of mosquitoes were collected, but 80.9% of all mosquitoes reared from containers were Aedes triseriatus (Say). All communities averaged > 6 containers per residence, indicating that the potential for mosquito production was high. The Breteau index and mean standing crop of adults per residence in the 5 communities were highly concordant. LAC virus was isolated from 2 pools of 56 female and 36 male Ae. triseriatus adults that were reared from eggs collected by ovitraps. The minimum field infection rate was 0.26 per 1,000 adults tested. Aedes triseriatus, the most frequently collected blood-fed mosquito (98/112 blood-engorged specimens), fed predominantly on dogs (40.4%), rabbits (26.6%), and turtles (22.3%). Only 7.5% of the blood-fed mosquitoes had fed on eastern chipmunks. Peridomestic conditions on the Reservation appear to contribute to the maintenance of LAC virus transmission. Production of Ae. triseriatus occurs in artificial containers discarded around residences, and wooded areas immediately adjacent to residences provide resting cover for mosquitoes as well as suitable habitat for LAC virus reservoir hosts.