Efficacy of microencapsulated insecticides against the sandfly, Phlebotomus papatasi Scopoli

The baseline and residual activity of micro-encapsulated insecticides was assessed on a sandfly colony originating in the Jordan Valley, Israel. Lethal doses were calculated for formulations of the pyrethroids permethrin and cypermethrin and the organophosphates diazinon and chlorpyrifos. Cypermethrin was found to be more toxic than permethrin and chlorpyrifos was more toxic than diazinon. Accordingly, the residual activity of chlorpyrifos and cypermethrin was tested after 1 and 4 wk exposure of impregnated filter papers under three environmental conditions: Jerusalem-indoors, Jerusalem-outdoors and semi-arid conditions. The results showed that environmental and climatic conditions play a major role in the persistence of toxicity of micro-encapsulated insecticides. A significant loss of toxicity for both compounds was noted after 4 wk of exposure under semi-arid conditions.