COMPARATIVE REPELLENCY OF COMMERCIAL FORMULATIONS OF DEET, PERMETHRINAND CITRONELLAL AGAINST THE MOSQUITO AEDES-AEGYPTI, USING A COLLAGEN MEMBRANE TECHNIQUE COMPARED WITH HUMAN ARM TESTS

A collagen membrane technique, based on the membrane blood-feeding sys tem of Cosgrove et al. (1994), was used to compare repellents against Aedes aegypti mosquitoes. Repellency was defined in terms of inhibitio n of probing (ED50 and ED90) after 5 min exposure. A direct comparison was made with repellency from probing after 5 min on five male volunt eers. Four repellent products were compared with technical DEET as the standard. The liquid formulations tested were: Autan(R) (20% deet; Ba yer); Repel Plus(R) (20% deer plus 0.05% permethrin; Boots); permethri n (Zeneca) and citronellal (Sigma). Membrane and arm tests gave simila r results. Deet formulations required less active compound than citron ellal for the same degree of repellency. Pure deer and Autan gave simi lar results, dose for dose. Permethrin was highly repellent at very lo w doses, but Repel Plus did not enhance the immediate repellency of de et. A technique using the same membrane system was developed to evalua te persistence of Autan, which declined to 75% after 1 h against Ae. a egypti, and to about 50% after 2-4 h.