Residual Efficacy of Insecticides Sprayed on Different Types of Surfaces Against Leishmaniasis and Filariasis Vectors in Egypt.

Determination of the residual activity of insecticides is an essential component in the selection of an appropriate insecticide for indoor residual spraying operations. This report presents the results of a laboratory study to evaluate the residual bio-efficacy of four insecticides sprayed on the most common house-wall surfaces that occur in Egypt (wood, mud, and cement) against Phlebotomus papatasi (Scopoli, 1786) (Diptera: Psychodidae) and Culex pipiens Linnaeus, 1758 (Diptera: Culicidae). In total, 28,050 P. papatasi females and 31,275 Cx. pipiens females were subjected to the WHO cone bioassay. Effective and extended control (≥80% mortality) was produced by lambda-cyhalothrin on indoor wood and cement surfaces. Lambda-cyhalothrin effectively controlled (>80% mortality) P. papatasi and Cx. pipiens for 10 and 12 wk postspray on wood surfaces, respectively. Deltamethrin effectively controlled Cx. pipiens for 8 wk on indoor wood, mud, and cement surfaces. Indoor and outdoor-kept surfaces treated with permethrin and malathion provided negligible efficacy against P. papatasi and Cx. pipiens. Phlebotomus papatasi was better able to survive bioassay exposure than Cx. pipiens against all insecticides investigated. The role surfaces might play in inhibiting IRS-based vector control endeavors in rural areas in developing countries was highlighted in this study. The current insecticide labeling system that includes both sand flies with mosquitoes under the same dosage category should be revised periodically.

Mosquitoes and the Environment in Nile Delta Villages with Previous Rift Valley Fever Activity.

Egypt is affected by serious human and animal mosquito-borne diseases such as Rift Valley fever (RVF). We investigated how potential RVF virus mosquito vector populations are affected by environmental conditions in the Nile Delta region of Egypt by collecting mosquitoes and environmental data from 3 key governorates before and after 2012 seasonal flooding. We found that environmental effects varied among species, life stages, pre- and postflood groupings, and geographic populations of the same species, and that mosquito community composition could change after flooding. Our study provides preliminary data for modeling mosquitoes and mosquito-borne diseases in the Nile Delta region.