Impact of pyrethroid-impregnated curtains on Phlebotomus papatasi sandflies indoors at Khartoum, Sudan

Laboratory and field investigations were made in an endemic focus of cutaneous leishmaniasis in Khartoum State, Sudan, to evaluate the effects of permethrin-impregnated curtains on the human-biting activity, nocturnal activity and resting behaviour of the vector sandfly Phlebotomus papatasi (Diptera: Psychodidae) indoors. Laboratory bioassays showed that curtains impregnated with 0.5, 1.0 or 1.5 g/m2 permethrin all gave 100% mortality within 24h of exposure of P. papatasi for 3 min. Under natural field conditions, the biting activity indoors and the resting density of P. papatasi were significantly reduced (P<0.001 and P=0.036, respectively) in rooms provided with permethrin-impregnated curtains as compared to control rooms left without curtains or fitted with unimpregnated curtains. No significant difference was found between the numbers of nocturnally active P. papatasi collected in rooms provided with impregnated curtains and rooms left without curtains or provided with unimpregnated curtains (P=0.377). Evidently P. papatasi was not repelled by these doses of permethrin on curtains, but the survival rate of sandflies collected from test rooms provided with permethrin-impregnated curtains was significantly reduced (P=0.036). We conclude that use of permethrin-impregnated curtains may provide a good control method for P. papatasi and other endophilic and/or endophagic sandfly vectors of leishmaniasis.