Toxicity of Macroalgae Extracts to Larvae of the Northern House Mosquito

The continuous use of synthetic insecticides to suppress mosquito larvae has detrimental impacts on the environment and human health. Finding novel and target-specific bio-insecticides has become crucial. Here, the larvicidal and genotoxic activities of different extracts from Ulva lactuca and Turbinaria ornata toward Culex pipiens larvae were investigated. The macroalgae thalli were subjected to various solvent extractions followed by phytochemical quantification, larvicidal testing on C. pipiens larvae, genotoxic evaluation through comet assays, and compound characterization by gas chromatography–mass spectrometry. The methylene chloride extract from U. lactuca displayed the highest toxicity with LC50 = 30.99 ppm, followed by the acetone extract from T. ornata, with LC50 = 52.09 ppm after 72 h. U. lactuca exhibited the maximum contents of total alkaloids, total flavonoids, total terpenoids, total phenols, and total tannins with the methanol extract, while the acetone extract from T. ornata exhibited the maximum contents of total alkaloids, total flavonoids, total terpenoids, and total phenols. The methylene chloride extract of U. lactuca and the acetone extract of T. ornata caused significant DNA damage in larva body cells. Thus, the methylene chloride extract from U. lactuca and the acetone extract from T. ornata showed promising potential as environmentally friendly larvicides against C. pipiens larvae.