Seasonal Blood-Feeding Behavior ofCulex tarsalis(Diptera: Culicidae) in Weld County, Colorado, 2007

Abstract

Studies on Culex tarsalis Coquillett in Colorado have shown marked seasonal variation in the proportion of blood meals from birds and mammals. However, limitations in the specificity of antibodies used in the precipitin test and lack of vertebrate host availability data warrant revisiting Cx. tarsalis blood feeding behavior in the context of West Nile virus (WNV) transmission. We characterized the host preference of Cx. tarsalis during peak WNV transmission season in eastern Colorado and estimated the relative contribution of different avian species to WNV transmission. Cx. tarsalis preferred birds to mammals each month, although the proportion of blood meals from mammals increased in July and August. The distribution of blood meals differed significantly across months, in part because of changes in the proportion of blood meals from American robins, a preferred host. The estimated proportion of WNV-infectious vectors derived from American robins declined from 60 to 1% between June and August. The majority of avian blood meals came from doves, preferred hosts that contributed 25-40% of the WNV-infectious mosquitoes each month. Active WNV transmission was observed in association with a large house sparrow communal roost. These data show how seasonal patterns in Cx. tarsalis blood feeding behavior relate to WNV transmission in eastern Colorado, with the American robin contributing greatly to early-season virus transmission and a communal roost of sparrows serving as a focus for late-season amplification.

Experimental Infection of Cliff Swallows (Petrochelidon pyrrhonota) with Varying Doses of West Nile Virus

“…tarsalis has been positively associated with cliff swallow colonies, 8 and cliff swallows have been identified as a blood meal source for this mosquito species. 27 Culex tarsalis are a competent WNV vector and expectorate a wide range of viral titers (from 10 0.8-3.6 PFU) when feeding or attempting to feed on its host 4 ; the saliva of experimentally inoculated Cx. spp.…”

Bloodmeal identification and feeding habits of mosquitoes (Diptera: Culicidae) collected at five islands in the Ryukyu Archipelago, Japan

“…Recent advances in molecular techniques for bloodmeal analyses by using polymerase chain reaction (PCR) based assay, permits the identification of host species with a higher accuracy than previous serologic techniques. These molecular techniques have been used to examine the host-feeding patterns of vectors of the West Nile virus (WNV) (Molaei et al, 2008;Kent et al, 2009;Sawabe et al, 2010), avian malaria (Ejiri et al, 2008;Kim et al, 2009a, b) and Eastern equine encephalitis virus (EEEV) (Cupp et al, 2004).…”

Vector host-feeding preferences drive transmission of multi-host pathogens: West Nile virus as a model system

“…However, recent developments in molecular methods allow estimation of species-specific vector-host contact rates by identifying the source species from vector blood meals. The potential for vector host preference to influence transmission has been postulated by several empirical studies evaluating mosquito feeding preferences [7][8][9]. In this study, we addressed the question of whether heterogeneity in contact rates between vectors and hosts influenced transmission dynamics, independently of the relative reservoir competence of the hosts.…”