Non-target organism acute toxicity testing of methionine, a novel mosquito larvicide

Mosquito larvicides are an effective means of source reduction, controlling the population size so that the number of adult females that are present to bite and potentially spread pathogenic organisms is decreased. The toxicity of methionine, an essential amino acid, as a larvicide has been demonstrated against four mosquito species in three genera, Anopheles, Culex and Aedes. For all pesticides, including bio-pesticides like methionine, it is important to examine the potential for toxicity to non-target organisms. The aim of our study was to determine the potential impact of methionine applied as a mosquito larvicide on non-target organisms. Acute toxicity assays are currently in progress in accordance with the U.S. Environmental Protection Agency guidelines with the honey bee (Apis mellifera), daphnids (Daphnia magna) and the fathead minnow (Pimephales promelas). Preliminary results with honey bee larvae and daphnid neonates suggest that the doses required to kill mosquito larvae do not result in adverse effects on these non-target organisms. Therefore, methionine may provide a valuable addition to a mosquito integrated pest management program.