Overwintering of La Crosse virus in Aedes triseriatus
Watts, D.M.; Thompson, W.H.; Yuill, T.M.; DeFoliart, G.R.; Hanson, R.P.
American Journal of Tropical Medicine and Hygiene 23(4): 694-700
1974
ISSN/ISBN: 0002-9637 PMID: 4847044 Document Number: 77102
In further studies on the overwintering of LaCrosse virus and larvae of Aedes triseriatus (Say), the virus was isolated from 3 suspensions of larvae of A. triseriatus and from 1 suspension of male mosquitos reared from larvae collected from tree holes in Wisconsin in March-June 1973. The virus was also isolated from 5 suspensions of larvae of A. triseriatus and 4 suspensions of male mosquitos originating from old automobile tyres. Virus transmission to suckling mice was accomplished by females of A. triseriatus reared from larvae collected from the tyres. Only two tree holes and the tyres yielded infected larvae and adults. The minimum field infection rate for these tree holes and the tyres, based on one infected larva/pool, was 1/110 larvae from the tree holes and 1/20 larvae from the tyres. The minimum field infection rate for adults was 1/41 male mosquitos originating from one of the tree holes and 1/27 for males originating from the tyres. The minimum field infection rate for females reared from larvae collected from the tyres was 1/110. No virus was isolated from 255 females reared from larvae collected from the tree holes. These findings strongly suggest that A. triseriatus is the reservoir of LaCrosse virus and that transovarial transmission of the virus in A. triseriatus is the mechanism responsible for the survival of this arbovirus during the winter season in the north-central United States.