Discriminating concentrations for three insecticides used in public health, in Lutzomyia longipalpis experimental strain from Colombia

Abstract

Introduction: In Colombia, periurban populations of Lutzomyia longipalpis, vector of the causative agent of visceral leishmaniasis in the upper and middle valley of the Magdalena River, may be exposed to insecticide applications with different purposes. Thus, it is important to begin a susceptibility surveillance of this species to insecticides.
Objective: To determine indicators of susceptibility to three insecticides habitually used in public health, such as malathion, deltamethrin and lambda-cyhalothrin in an experimental strain of L. longipalpis.
Materials and methods: We used the method proposed by the Centers for Disease Control and Prevention. Groups of 10 to 15 unfed females were exposed to different concentrations of the insecticides using 250 ml glass bottles as test chambers. Mortality was registered every five minutes for an hour. Diagnostic concentrations and lethal times for each insecticide were calculated.
Results: In the evaluated L. longipalpis strain, the diagnostic concentrations and times were 75 μg/ml and 25 minutes for malathion, 10 μg/ml and 35 minutes for deltamethrin, and 15 μg/ml during 30 minutes for lambda-cyhalothrin.
Conclusions: Baseline data over mortality response to three insecticides were established in a susceptibility strain of L. longipalpis vector. These indicators will allow establishing comparisons with populations of L. longipalpis exposed regularly or sporadically to chemical control measures to detect changes in their resistance to these insecticides.