The toxicity of yeast encapsulated curcumin on Anopheles gambiae mosquito larvae

Mosquitoes transmit deadly diseases, so there is a pressing need to implement strategies that control mosquito populations. However, the overuse of insecticides has widely selected for resistant mosquitoes, and thus, new control strategies are needed. One underexplored option is photosensitive insecticides (PSIs), which are chemicals that when activated by light, kill mosquitoes via oxidative damage. Although PSIs are toxic to mosquitoes, they are also toxic to aquatic microorganisms. Therefore, we investigated whether yeast encapsulation of PSIs could be used to kill mosquitoes while leaving microorganisms unharmed. To study this, we first encapsulated curcumin into yeast. We then treated Anopheles gambiae larvae with the yeast encapsulated curcumin and found that, following photoactivation, the yeast encapsulated curcumin was lethal to larvae, and that it was more lethal than non-encapsulated curcumin. We then added the yeast encapsulated curcumin to E. coli cultures and exposed them to light. We found that the yeast encapsulated curcumin did not kill E. coli but non-encapsulated curcumin did. These data show that yeast encapsulation makes curcumin more toxic to larvae while having a minimal effect on the surrounding microbes.