Health + Life Science Alliance Heidelberg Mannheim

The main goal of the project was to establish a standardized method for testing the lethality and behavioral alterations induced by a broad panel of pesticides on mosquito larvae. The method was designed and optimized using three agrochemicals that –based on previous research conducted by the Crocker group – are known to affect the behavior of Drosophila larvae at sublethal concentrations. Using the pipeline developed here, the team managed to observe similar sublethal behavioral alterations triggered by these molecules on Anopheles stephensi larvae, and reported their results in https://www.science.org/doi/10.1126/science.ado0251.

The next phase of the project consists in scaling up this method to systematically compare the effects of all the insecticides available through Sigma-Aldrich (a total of 309 different molecules) on two different isolates of the malaria vector Anopheles gambiae. One isolate was collected from a natural reserve in Kenya and therefore is highly susceptible to agrochemicals, while the other one was collected from a farming region in Côte d'Ivoire, and has been reported to be highly resistant to organophosphates and pyrethroids. The team expects to complete this phase of the project soon, but preliminary data indicates that the Côte d'Ivoire strain shows a much broader resistance profile than previously expected, with lower sensitivity to molecules mechanistically unrelated to pyrethroids and organophosphates. At the same time, this strain appears to be more susceptible to ~5% of the insecticides in this library. Thus, the methods developed in this project open up the possibility of efficiently screening for molecules capable of effectively controlling populations of resistant mosquitoes in malaria-endemic regions.