Control of phlebotomine sandflies in confined spaces using diffusible repellents and insecticides

The control of phlebotomine sandflies (Diptera: Psychodidae), the vectors
of leishmaniasis, is directed mostly against adults as larvae develop in unknown or inaccessible
habitats. In the current study we tested geraniol, a natural plant-derived product,
as a space repellent and the synthetic pyrethroid prallethrin as a diffusible insecticide.
Geraniol was dispersed in the air using diffusers with an electric fan and prallethrin was
evaporated using electrically heated evaporators. Both substances were tested in inhabited
bedrooms and in tents. Geraniol failed to effect significant reductions in the numbers
of either Phlebotomus papatasi Scopoli in rooms or Phlebotomus sergenti Parrot
in tents. In laboratory experiments, geraniol proved ineffective in preventing sandflies
from feeding. By contrast, prallethrin was highly effective in reducing the number of
sandflies in rooms as well as in tents. Exposure of sandflies to prallethrin in laboratory
experiments caused 97% mortality rates. Both prallethrin and, to a lesser extent, geraniol
reduced the number of Culex mosquitoes captured in tents. Electric liquid-vaporizers
with 1.5% prallethrin are highly effective in protecting people from sandfly bites in
confined spaces and may be useful in combating cutaneous leishmaniasis.