Larvicidal Activity of Extracts from the Artemisia arborescens L. Plant and Hyrtios erectus Sponge Against the Culex pipiens Mosquito (Diptera: Culicidae) and Toxicological Assessment on Danio rerio Zebrafish Embryos as Non-Target Organism

There is a growing need for eco-friendly methods to control disease-carrying insects. The present study aimed to investigate the larvicidal activity of methanolic extracts and their various fractions from a plant, <i>Artemisia arborescens</i> L., and a marine sponge, <i>Hyrtios erectus</i>, against the mosquito, <i>Culex pipiens</i> L. Crude methanolic extracts of <i>A. arborescens</i> and <i>H. erectus</i> were prepared by maceration and successive fractionation were obtained using the liquid-liquid partition of crude extracts. The larvicidal activity of the extracts and their fractions was determined according to the WHO standard method. The results revealed that the <i>n</i>-hexane fraction of <i>A. arborescens</i> exhibited the highest larvicidal activity (LC₅₀ 346.74 μg/mL), exceeding the efficacy of the crude extract and other fractions. Furthermore, the sponge's <i>n</i>-hexane (LC₅₀ 68.39 μg/mL), chloroform (LC₅₀ 63.03 μg/mL), and <i>n</i>-butanol (LC₅₀ 71.23 μg/mL) fractions showed a significant 3.9 to 4.5 times increase in the larvicidal potency compared to its crude extract (LC₅₀ = 280.74 μg/mL). The safety of the sponge extracts was tested in the embryos of zebrafish as a non-target organism. In this regard, the crude methanolic extract and <i>n</i>-butanol fraction exhibited weak toxicity and chloroform fraction showed no detectable toxicity. This study suggests the <i>H. erectus</i> sponge as a source for developing safe natural substitutes for use in the battle against <i>Cx. pipiens</i> mosquito, which may help in reducing the spread of mosquito vectors and mosquito-borne diseases.