Effect of Environmental Temperature on the Ability ofCulex pipiens(Diptera: Culicidae) to Transmit West Nile Virus

Abstract

Environmental temperature can affect the ability of mosquitoes to transmit an arbovirus. However, results of various studies indicate that these effects are not consistent among viruses or mosquito species, and there is no information available on the effect of environmental temperature on the ability of North American mosquito species to transmit West Nile (WN) virus. We evaluated the effect of incubation temperature (18, 20, 26, or 30 degrees C) on the ability of Culex pipiens L. derived from specimens collected during the outbreak in New York in 1999 to transmit a strain of WN virus obtained from a crow that died during this outbreak. Although mosquitoes fed on the same viremic chickens, infection rates were directly related to subsequent incubation temperatures. In mosquitoes held at 30 degrees C, virus was recovered from nearly all mosquitoes tested, disseminated infections were detected as early as 4 d after the infectious blood meal, and >90% of all mosquitoes had a disseminated infection 12 or more days after the infectious blood meal. In contrast, for mosquitoes held at 18 degrees C, disseminated infections were not detected until 25 d after the infectious blood meal, and even after 28 d, <30% contained a disseminated infection. Results for mosquitoes held at 20 and 26 degrees C were intermediate for both infection and dissemination rates. The effect of environmental temperature should to be considered when evaluating the vector competence of these mosquitoes and modeling risk of WN virus transmission in nature.

An Update on the Potential of North American Mosquitoes (Diptera: Culicidae) to Transmit West Nile Virus

“…Holding mosquitoes for longer periods of time increased dissemination, and thus transmission rates for Cx. pipiens (Dohm et al 2002). Therefore, studies may need to be conducted that evaluate mosquitoes after a longer period of extrinsic incubation.…”

“…Therefore, studies may need to be conducted that evaluate mosquitoes after a longer period of extrinsic incubation. Likewise, environmental temperatures are known to inßuence vector competence for arboviruses in general, and WNV in particular (Jupp 1974, Cornel et al 1993, Dohm et al 2002. Therefore, additional studies are needed to determine the impact of environmental temperature on the ability of North American mosquitoes to transmit WNV.…”

Climate change impacts on West Nile virus transmission in a global context

“…However, it was shown that the replication cycle is completed more quickly in mosquitoes at higher temperatures [38,39], while a clear association was found between extreme heat and outbreak intensity in humans [4,18,22,35,[40][41][42][43]. At the same time, it is important to note that, in some cases, extremely high temperatures begin to slow down mosquito activity.…”

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

“…Ornithophagic species within the genus Culex are important vectors and responsible for zoonotic WNV transmission among birds (Molaei et al 2006). Culex in California are quiescent or diapause during cold winter months (Nelms et al 2013a,b), and low temperatures hinder WNV replication within the overwintering mosquito hosts (Dohm et al 2002, Reisen et al 2006b). Nevertheless, researchers in New York State documented American Crow (Corvus brachyrhynchos; hereafter "crow") mortality during February and March of 2005 (Dawson et al 2007).…”