Article

Early Evening Questing and Oviposition Activity by the Culex (Diptera: Culicidae) Vectors of West Nile Virus in Northeastern North America

Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA.
Journal of Medical Entomology (Impact Factor: 1.82). 04/2007; 44(2):211-4. DOI: 10.1603/0022-2585(2007)44[211:EEQAOA]2.0.CO;2
Source: PubMed

ABSTRACT To determine whether the Culex (Diptera: Culicidae) mosquitoes that transmit West Nile virus (family Flaviviridae, genus Flavivirus, WNV) in the northeastern United States seek hosts and oviposit contemporaneously, we recorded when these mosquitoes attacked caged birds and when they deposited eggs. They traversed oviposition sites most frequently approximately 2 h after astronomical sunset, and eggs generally were deposited at that time. Although they most frequently approached avian hosts approximately 2 h after sunset during midsummer, they are more opportunistic during mid- to late fall. Because the Culex mosquitoes that serve as the main vectors of West Nile virus in the northeastern United States quest for hosts and seek to oviposit well after sunset, insecticidal aerosols would be most effective when applied at that time.

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    • "The olfactometer was made of Perspex glass with internal diameter of 10 and 120 cm length from the release chamber to treatment/control chambers at the two arms. The experiment was done between 18:00 h and 20:00 h using a group of 20 gravid mosquitoes for each replicate because maximum nocturnal oviposition activity was observed in the first 2 h after the sunset and majority of the egg deposition occurred during the first 4 h (Reddy et al., 2007). In a dimly lit room, mosquitoes were aspirated and released in the releasing chamber of the olfactometer. "
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    • "Predictions for longer time scales (years or season to season) have indicated that suboptimal habitats may be chosen as the end of the suitable oviposition season is approached (Edgerly et al., 1998) and that timely rainfall can synchronize mosquito populations through oviposition (Shaman et al., 2002, 2005; Shaman & Day, 2007). For finely grained time scales, i.e. daily and hourly, it has been demonstrated that light plays a major role, inhibiting oviposition when continuous in laboratory settings (Suleman & Shirin, 1981) and delaying oviposition time in the field (Macdonald et al., 1981; Reddy et al., 2007). Similar inhibitory effects on oviposition at fine-grained temporal scales have been shown for strong winds and heavy rainfall (de Meillon et al., 1967). "
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