Host Selection by Culex pipiens Mosquitoes and West Nile Virus Amplification

Abstract

Recent field studies have suggested that the dynamics of West Nile virus (WNV) transmission are influenced strongly by a few key super spreader bird species that function both as primary blood hosts of the vector mosquitoes (in particular Culex pipiens) and as reservoir-competent virus hosts. It has been hypothesized that human cases result from a shift in mosquito feeding from these key bird species to humans after abundance of the key birds species decreases. To test this paradigm, we performed a mosquito blood meal analysis integrating host-feeding patterns of Cx. pipiens, the principal vector of WNV in the eastern United States north of the latitude 36 degrees N and other mosquito species with robust measures of host availability, to determine host selection in a WNV-endemic area of suburban Chicago, Illinois, during 2005-2007. Results showed that Cx. pipiens fed predominantly (83%) on birds with a high diversity of species used as hosts (25 species). American robins (Turdus migratorius) were marginally overused and several species were underused on the basis of relative abundance measures, including the common grackle (Quiscalus quiscula), house sparrow (Passer domesticus), and European starling (Sturnus vulgaris). Culex pipiens also fed substantially on mammals (19%; 7 species with humans representing 16%). West Nile virus transmission intensified in July of both years at times when American robins were heavily fed upon, and then decreased when robin abundance decreased, after which other birds species were selected as hosts. There was no shift in feeding from birds to mammals coincident with emergence of human cases. Rather, bird feeding predominated when the onset of the human cases occurred. Measures of host abundance and competence and Cx. pipiens feeding preference were combined to estimate the amplification fractions of the different bird species. Predictions were that approximately 66% of WNV-infectious Cx. pipiens became infected from feeding on just a few species of birds, including American robins (35%), blue jays (17%, Cyanocitta cristata), and house finches (15%, Carpodacus mexicanus).

Host compatibility rather than vector–host-encounter rate determines the host range of avian Plasmodium parasites

“…Thus, bloodfeeding patterns effectively set the encounter rate between vector-borne parasites and hosts. Mosquitoes, which are important vectors for a diversity of pathogens, are known to feed heterogeneously across hosts by using some species disproportionately, relative to their abundance [13][14][15]. This heterogeneity in mosquito-feeding patterns can strongly influence disease transmission dynamics [3,4,13,16].…”

“…This heterogeneity in mosquito-feeding patterns can strongly influence disease transmission dynamics [3,4,13,16]. Mosquito-feeding networks may also be compartmentalized [17], with certain vector species using a distinct subset of available host species [14,[18][19][20][21]. For instance, in the northeastern United States, Culex restuans, Culex pipiens, and Culiseta melanura obtain blood meals from birds, while the sympatric Aedes vexans, Ochlerotatus and Anopheles species rely primarily on mammals for blood meals [18,22,23].…”

Uranotaenia novobscura ryukyuana (Diptera: Culicidae) Population Dynamics are Denso-Dependent and Autonomous from Weather Fluctuations

“…larvae have been primarily collected from stable permanent, that is, unlikely to dry, or semipermanent, that is, that become dry with a low probability, aquatic habitats (Hinman 1935), which include crab holes (Mogi et al 1984), treeholes, bamboo stumps (Sota et al 1994), leaf axils, pitcher plants and artiÞcial containers (Toma and Miyagi 1981), and wetlands (Chambers et al 1979). Adults have been observed feeding predominantly on reptiles and amphibians (Miyagi et al 2010), a pattern conÞrmed by mosquito bloodmeal analysis (Fyodorova et al 2006, Hamer et al 2009, Tamashiro et al 2011. Species are gonotrophically concordant, with eggs oviposited in clutches that form ßoating rafts (Hinman 1935;Dampf 1943;Chapman 1964Chapman , 1970Miyagi et al 2010).…”

West Nile Virus Activity in a Winter Roost of American Crows (Corvus brachyrhynchos): Is Bird-To-Bird Transmission Important in Persistence and Amplification?

“…The transmission cycle of WNV is dependent upon competent mosquito vectors and susceptible birds intersecting within a permissive environment (Campbell et al 2002, Marra et al 2004, Allan et al 2009, Hamer et al 2009, Egizi et al 2014. Ornithophagic species within the genus Culex are important vectors and responsible for zoonotic WNV transmission among birds (Molaei et al 2006).…”