Effect of Pb, Cd and Cu on survival and development of Culex quinquefasciatus (Diptera: Culicidae)

The present research aimed to determine the lowest levels of three heavy metals (Pb, Cd and Cu) to which the larvae of Southern House Mosquito, Culex quinquefasciatus are susceptible in water. The study also aimed to investigate the effects of these heavy metals on the development of Cx. quinquefasciatus at concentrations set by Pakistan Environmental Protection Agency (Pak-EPA) as permissible levels for liquid industrial effluents. The 2nd instar larvae of Cx. quinquefasciatus were exposed to different concentrations of Pb, Cd and Cu and their effects on oviposition preference, egg hatching rate and larval development were studied. The LC50 values of Pb, Cd and Cu were 12.6, 6.3 and 2.6 ppm, respectively. Gravid female mosquito adults deposited a significantly lower number of egg rafts in containers containing 0.50 ppm Pb or 1.0 ppm Cu in water. Each of the heavy metals in water resulted in significantly (p < 0.05) lower egg hatching rate, prolonged time to pupation, lower pupation rate, prolonged time to adult emergence, lower adult emergence rate and higher female to male ratio. It is concluded that the 2nd instar larvae of Cx. quinquefasciatus are susceptible to Pak-EPA permissible levels of Pb, Cd and Cu in municipal and liquid industrial effluents.