The use of garlic (Alliumsativa) and lemon peel (Citrus limom) extracts as Culex pipiens larvacides: Persistence and interaction with an organophosphate resistance mechanism

There is a growing interest in the use of botanical pesticides to reduce the use of chemical pesticides and also to avoid problems with insecticide resistance. We present here data from bioassays on Culex pipiens mosquito larvae using raw garlic and lemon peel extracts made by simply crushing material in water. Both garlic and lemon were toxic to mosquitoes. Garlic was more persistent than lemon, with no significant differences in kill between fresh and approximately 4.5 day old treatments. The addition of food to the bioassays increased toxicity to both lemon and garlic and represent the situation in the field more closely, where food will be available to the larva. A mosquito strain resistant to organophosphate insecticides was significantly less susceptible to the lemon extract which suggests that using natural extracts as larvacides will not necessarily side-step problems posed by some existing mechanisms of resistance to synthetic compounds.