Bioactivity of Sphaeranthus indicus leaf extracts on the aquatic stages of Aedes aegypti and Culex quinquefasciatus mosquitoes

Abstract

The prevalence of mosquito-borne diseases is increasing due to urbanization and climate change. Synthetic insecticides have resulted in resistance, and alternative control methods are needed. This study evaluated hexane, chloroform, and methanol extracts from Sphaeranthus indicus leaves for their efficacy against the larvae, pupae and eggs of Aedes aegypti and Culex quinquefasciatus mosquitoes. The plant materials were coarsely powdered and sequentially extracted in hexane, chloroform, and methanol using a Soxhlet apparatus, followed by filtration and concentration under reduced pressure with a rotary vacuum evaporator. In the case of Ae. aegypti, the hexane extract exhibited notable toxicity against all three examined stages. The LC₅₀ values for larval mortality, pupal lethality, and ovicidal activity were determined to be 81.83 ppm, 86.13 ppm, and 63.2 ppm, respectively. Similarly, for Cx. quinquefasciatus, the hexane extract showed efficacy with LC₅₀ values of 81.23 ppm for larval mortality, 93.24 ppm for pupal lethality, and 75.2 ppm for ovicidal activity. Following the hexane extract, the chloroform and methanol extracts demonstrated moderate larvicidal and pupicidal activity against both mosquito species, but they exhibited limited effectiveness against ovicidal activity. These findings suggest the potential use of natural extracts as supplementary control measures against mosquito vectors.