Variation in the Susceptibility of Field and Laboratory Populations of Culex Tarsalis to Experimental Infection With Western Equine Encephalomyelitis Virus1

Abstract

Four field populations and four laboratory colonies of Culex tarsalis from California were evaluated for their susceptibility to infection with western equine encephalomyelitis (WEE) virus by intrathoracic inoculation and by feeding on pledgets soaked with a virus-blood-sucrose mixture. All mosquito strains were uniformly susceptible to infection by intrathoracic inoculation, but 50% infective doses for field and colonized strains varied as much as 1000- to 1500-fold, respectively, by pledget feeding. Moreover, dose-response curves obtained by pledget feeding revealed that some field and laboratory strains of C. tarsalis were quite heterogeneous for susceptibility since some individual females could be infected after ingestion of small concentrations of virus and others could not 0e infected by increasing the concentration of virus by 1000- to 10,000-fold. Variability in viral susceptibility of different mosquito strains could not be correlated with differences in autogeny rates or organophosphorus insecticede resistance.

Vertical Transmission of West Nile Virus by Three California <I>Culex</I> (Diptera: Culicidae) Species

“…This conclusion is supported by previous studies that demonstrated marked geographical variation in the vector competence of Cx. tarsalis for the Alphavirus, western equine encephalomyelitis (Hardy et al 1976). Geographical variation was also observed in the vector competence of WN virus for mosquitoes in the Cx.…”

Experimental Transmission of Mayaro Virus by Aedes aegypti

“…janthinomys , 32 and active, enzootic transmission of MAYV. To minimize colonization effects [33][34][35] and population variability [36][37][38][39] that could interfere with applicability of these results to the specific geographic context, all studies were conducted with an F 1 generation of an Iquitos strain of Ae. aegypti .…”

THE VECTOR COMPETENCE OF AUSTRALIAN CULEX ANNULIROSTRIS WITH MURRAY VALLEY ENCEPHALITIS AND KUNJIN VIRUSES

“…McLean (1953) demonstrated that mixed C.v annulirostris from two towns in the Murray Valley could transmit MVE efficiently to day-old chickens. Since then, demonstration of a genetic hasis to arbovirus susceptibility (Jones andFoster, 1974, Hardy, Reeves andSjogren, 1976) has stimulated investigations into the competence of geographically isolated populations as vectors of pathogens such as western equine encephalomyelitis (Hardy et ai, 1976), dengue (Gubler and Rosen, 1976), La Crosse (Grimstad etal., 1977) and Japanese encephalitis virus (Takahashi, 1980). In this report we compare susceptibilities of 10 populations of Cx annulirostris from Australia (Kay, Fanning and Carley, 1982, for map) using reference strains of MVE and KUN.…”