Evaluation of different formulations of deltamethrin in comparison with permethrin for impregnation of netting

Five formulations of deltamethrin and one of permethrin were impregnated into cotton and nylon netting and tested for their efficacy and persistence in killing Anopheles gambiae Giles which were attempting to penetrate the netting in search of blood meals. Emulsifiable concentrates persisted better than wettable powders of deltamethrin, and all the deltamethrin formulations performed better than permethrin, even though the latter was applied at an eight times higher dose. The insecticidal effect of both compounds persisted better on nylon than on cotton; it was adversely affected by repeated washing.