Repellence and insecticidal activity mediated by necrosis in Aedes aegypti mosquitoes exposed to thymol

Abstract

The mosquito Aedes aegypti is a major threat to public health because it spreads several arboviruses. Since this insect is an anthropophilic mosquito that has evolved to thrive in urban settings and is common in Brazil and other tropical nations, controlling its population growth is difficult. The two basic methods of control are eradicating its breeding grounds and applying pesticides. There have been reports of pesticide resistance emerging as well as DEET's potential danger for people, particularly youngsters. Therefore, research has been done to find novel insecticides and repellents. In this way, the goal of this research was to assess thymol's insecticidal and repellent activities in Ae. aegypti. Bioassays were performed with eggs, larvae and adults exposed to different concentrations of thymol. The findings demonstrated that thymol has insecticidal effect in both the immature and adult phases, eliminating the larvae in 24 hours. In addition, necrosis was observed in hemocytes, without alteration in the production of nitric oxide by the insects. When evaluating repellency, thymol showed 99.5% of landing inhibition. This leads to the conclusion that thymol can be employed as an active component in the formulation of insecticides and repellents for the Ae. aegypti mosquito.