SUSCEPTIBILITY OF LUTZOMYIA-LONGIPALPIS (DIPTERA, PSYCHODIDAE) TO SELECTED INSECTICIDES IN AN ENDEMIC FOCUS OF VISCERAL LEISHMANIASIS IN VENEZUELA

A field population of Lutzomyia longipalpis from La Rinconada, Lara St ate, an endemic focus of visceral leishmaniasis in Venezuela, was test ed for susceptibility to organochlorine (DDT 2%), carbamate (propoxur 0.01%), organophosphate (malathion 2%, fenitrothion 1%, and pirimiphos methyl 1%), and pyrethroid (deltamethrin 0.06%, lambdacyhalothrin 0.0 6%, and permethrin 0.2%) insecticides. Susceptibility to the insectici des tested was evaluated in the field population of L. longipalpis and compared with a laboratory reference strain. The (LT95) to propoxur a nd malathion insecticides for the field population was lower than the LT95 for the laboratory reference strain, demonstrating high susceptib ility to these compounds. A low level of resistance at LT50 (<3-fold) was found for fenitrothion, pirimiphos methyl, and permethrin insectic ides, but no resistance was detected at LT95. No significant resistanc e at the LT50 and LT95 was detected for the pyrethroids deltamethrin a nd lambdacyhalothrin. The susceptibility levels of L. longipalpis to t he insecticides tested are discussed in view of a future control progr am against endophilic vectors of leishmaniases based on the use of pes ticides.