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, Artemisia arborescens L., and a marine sponge, Hyrtios erectus, against the mosquito, Culex pipiens L. Crude methanolic extracts of A. arborescens and H. erectus 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 n-hexane fraction of A. arborescens exhibited the highest larvicidal activity (LC50 346.74 μg/mL), exceeding the efficacy of the crude extract and other fractions. Furthermore, the sponge’s n-hexane (LC50 68.39 μg/mL), chloroform (LC50 63.03 μg/mL), and n-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 n-butanol fraction exhibited weak toxicity and chloroform fraction showed no detectable toxicity. This study suggests the H. erectus sponge as a source for developing safe natural substitutes for use in the battle against Cx. pipiens mosquito, which may help in reducing the spread of mosquito vectors and mosquito-borne diseases.