Effects of Washing on Insecticidal Efficiency of Long-lasting Perma Nets Against Culex quinquefasciatus (Say) in Khartoum State (Sudan)

Abstract

This research entitled: The effects of washing on insecticidal efficiency of long-lasting Perma Nets against Culex quinquefasciatus (Say) in Khartoum State (Sudan); aimed to investigate the effect of washing of Perma Nets on the relative knock down and mortality of newly emerged females of Cx. quinquefasciatus before washing of the bed nets and after one, five, ten, fifteen, and twenty washes respectively. Wild populations of this species of mosquitoes were used for this investigation. No susceptibility tests were conducted to investigate the susceptibility of the wild Cx. quinquefasciatus population to the deltamethrin (the insecticide by which Perma Nets were impregnated by the manufacturers). Immature stages of Culex mosquitoes were scooped from breeding sites at Khartoum Bus Terminal then transferred to the laboratory where they were reared in order to perform bio assay tests. Three Deltamethrin long- lasting impregnated nets were washed manually. Six bioassay tests were conducted for each net (according to the number of washes). Four plastic cones were fixed over each net then ten females of the reared adult mosquitoes were transferred to each cone using a mouth aspirator. In order to isolate the control cone from being in contact with the net; a white paper with non impregnated net were set over the net before fixing the fifth cone and transferring the mosquitoes to it. The exposure time was three minutes. The female mosquitoes were then aspirated from the cones and transferred to the labeled paper cups. The number of knocked down individuals was calculated after an hour. The number of dead mosquitoes was recorded after 24 hours