Professor Vanderbilt University Nashville, Tennessee
The overuse of insecticides has led to the emergence of resistant mosquito populations across the globe. Therefore, effective vector control strategies require the development of new insecticides. Here, we investigate the larvicidal properties of an emerging class of insecticide known as photosensitive insecticides (PSIs). PSIs generate reactive oxygen species (ROS) in response to light and the broad toxicity of these ROS decreases the likelihood that resistance will evolve against PSIs. This makes PSIs a promising new vector control strategy though little is known about their larvicidal efficiency across the mosquito lineage. Here, we investigated the toxicity of two candidate PSIs – Rose Bengal (RB) and Methylene Blue (MB) – against A. gambiae and A. aegypti larvae. We found that when larvae had more time to ingest the PSI before a photoperiod, PSIs were more toxic against both A. gambiae and A. aegypti. Additionally, co-incubation of the PSIs with food increased the larval lethality of both MB and RB – suggesting that larval feeding plays a large role in determining PSI toxicity. Furthermore, under our laboratory conditions MB was more toxic than RB. Further investigation into the larvicidal efficiency of PSIs – and the factors that affect their toxicity – will provide a better understanding of how PSIs can be used to control mosquito populations that are resistant to other insecticides.