Field evaluation of an insecticide formulated with active ingredients acting on larval and adult stages of Lutzomyia longipalpis

JUAN LW; GOULD IT; SALOMÓN OD; MOLINA J; ALZOGARAY RA; ZERBA EN

Puerto Iguazú

Simposio; VIII International Symposium on Phlebotomine Sandflies; 2014

Instituto Nacional de Medicina Tropical

In Argentina, the American tegumentary leishmaniasis (ATL) is endemic, with wild enzootic cycles, while visceral leishmaniasis (VL) is urban. VL is more severe because it can affect internal organs with high fatality. Since 2006, this disease is an emerging phenomenon of public health importance. The most practical way of prevention is to control the insect vector, phlebotomines sand flies from genus Lutzomyia, by application of residual insecticides, and dogs treatment with veterinary formulations. Recently, insecticide treated nets were introduced with controversial results. The application of insecticides in phlebotomines cities foci could be an important vector control tactic to reduce urban transmission. With the objective to develop a new control alternative, we evaluated a formulation containing the pyrethroid insecticide permethrin (10%) and the insect growth regulator pyriproxyfen (2%). According studies performed at our laboratory, permethrin is effective on adult L. longipalpis. Pyriproxyfen is an larvicide that disrupts metamorphosis of immature stages of sand fly, preventing it from reaching the adult stage. The trial was carried out in the city of Puerto Iguazú, Misiones, Argentina, in March-April, 2014. Three dwellings with presence of L. longipalpis, all of them with poultry houses, were selected. Before applying the formulation, population level of sand fly were monitored for two days with CDC type traps. The formulation was emulsified in water and applied in two dwellings (TP and Chan). The third house (Ct) was untreated (control). The application was performed during sunset using a hand pulverizer. Application covered the interior of houses and surroundings to a distance of three meters. One week before the application, the average of number of adults sand flies catched by the traps were 13 and 22 in the houses TP and Chan, respectively. Just before the treatment, the flies catched during two days were 21 and 11, respectively. One month after the treatment, no flies were catched in TP and just one in Chan. In the control house, more than 50 sandflies were catched in all cases. This succesfull result could be attributed to the complementary effects of the insecticides applied: permethrin against adults insects and pyriproxyfen against larvaes present in soil.