Toxicity of copper (II) metal complexes with amino acids ligands: A study of activity in Aedes aegypti larvae

The larval control of Aedes aegypti has been done mainly by insecticides, which cause resistance and environmental contamination and have a high-cost development and application. The need for alternative solutions to problems caused by synthetic insecticides has led to studies to find new, active, and less toxic compounds, such as metallo-insecticides. In the present study, the toxic activity of Cu(II) - complexes with the amino acids tryptophan, histidine, methionine, and taurine in Ae. aegypti larvae were evaluated. The Cu(II) - histidine complex showed no toxicity. For the Cu(II) - tryptophan and Cu(II) - methionine complexes, the mortality percentages ranged from 3.16% to 46.55% and 5.46% to 12.42%, respectively. Cu(II) - taurine presented 100% mortality in 24 h at the lowest concentration tested (50 mg L-1, ppm). Considering the concentration range of 50 to 1000 mg L-1 and 24 h of exposure of the larvae to the metal complexes, the series of decreasing toxicity is Cu(II) - taurine > Cu(II) - tryptophan > Cu(II) - methionine > Cu(II) - histidine. From these studies, the Cu (II) - taurine complex can be a candidate to be used as an alternative and less toxic insecticide, low-cost for control of Ae.aegypti larvae.