Biological Evaluation of the Susceptibility of Aedes aegypti Larvae to Household Insecticides

Abstract

Vector-borne diseases (VBDs) are a serious problem worldwide. In Paraguay, the most important are Dengue, Zika and Chikungunya, caused by viral agents transmitted by the Aedes aegypti mosquito. Insecticides are a fundamental tool for the control of this vector; however, their continuous and excessive use can generate resistance in mosquito populations. The objective of this research was to determine the susceptibility of A. aegypti larvae to pyrethroid insecticides for domestic use (cypermethrin and lambdacyhalothrin). Water samples containing mosquito larvae were collected from the downtown area of the city of Encarnación, Department of Itapúa. The insecticides used were "Mapex" (cypermethrin 25% v/v) and "Newtrine" (lambdacyhalothrin 2.5% w/v). The tests were carried out in duplicate in addition to the control. Solutions were prepared according to the manufacturer's instructions, where the larvae were exposed for a certain time to the insecticides. The data were recorded and analyzed, obtaining a mortality rate of 91% in larvae exposed to cypermethrin and 100% in those treated with lambdacyhalothrin, indicating its efficacy. The values of R²=0.6709 and R²= 0.9138 indicated a positive correlation between the variables mortality and time. A. aegypti larvae in the area are susceptible to the pyrethroid insecticides cypermethrin and lambdacyhalothrin, providing initial evidence of mortality to these insecticides for domestic use and providing a basis for monitoring and controlling the resistance of these vectors.