Acute toxicity of mosquito pesticides on weed biological control agents in south Florida, USA

Mosquito pesticides effectively control vectors of human disease but have numerous unintended consequences. These may include adversely affecting non-target species such as weed biological control agents. Acute toxicity of two mosquito pesticides, naled and permethrin, was studied on three biological control agents released against invasive weeds in south Florida. These were the biological control agentOxyops vitiosaof melaleuca,Melaleuca quinquenervia,the agentNeomusotima conspurcatalisfor Old World climbing fern,Lygodium microphyllum, and the agentLilioceris chenifor air potatoDioscorea bulbifera. We calculated LD(50)values for both pesticides on early and late instars for each herbivore species. The air potato herbivore,L. cheniwas the most sensitive species tested and all three species were more sensitive to the pesticide permethrin than naled. These results indicate that even low concentrations of these products can have a detrimental effect on these weed biological control agents. The unintended consequences of mosquito adulticide applications should be considered when evaluating biological control agent impacts.