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 <i>Ulva lactuca</i> and <i>Turbinaria ornata</i> toward <i>Culex pipiens</i> larvae were investigated. The macroalgae thalli were subjected to various solvent extractions followed by phytochemical quantification, larvicidal testing on <i>C. pipiens</i> larvae, genotoxic evaluation through comet assays, and compound characterization by gas chromatography-mass spectrometry. The methylene chloride extract from <i>U. lactuca</i> displayed the highest toxicity with LC₅₀ = 30.99 ppm, followed by the acetone extract from <i>T. ornata</i>, with LC₅₀ = 52.09 ppm after 72 h. <i>U. lactuca</i> 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 <i>T. ornata</i> exhibited the maximum contents of total alkaloids, total flavonoids, total terpenoids, and total phenols. The methylene chloride extract of <i>U. lactuca</i> and the acetone extract of <i>T. ornata</i> caused significant DNA damage in larva body cells. Thus, the methylene chloride extract from <i>U. lactuca</i> and the acetone extract from <i>T. ornata</i> showed promising potential as environmentally friendly larvicides against <i>C. pipiens</i> larvae.