Phytochemical composition and larvicidal properties of plants used for mosquito control in Kwale County, Kenya

Abstract

The present study determined phytochemical constituents and larvicidal activities of Tagetus minuta L., Adansonia digitata Linn., Ocimum suave, Plectranthus barbatus A., Azadirachta indica A. Juss., Lantana camara L. Phytochemical analysis established that saponins were present in all the plants. Alkaloids and flavonoids were present in 83% of all the extracts. Tannins and sterols were found in 67% of the plants. Terpenoids were present in 33% of the plants while glycosides were present in 16% of the plants. Larvicidal activity was tested on 4th instar larva of Aedes aegypti. At the concentration of 1mg/ml, all the extracts exhibited 100% larval mortality except aqueous extract of L. camara that killed 90% of the larvae. In aqueous extracts, T. minuta extract was most active with LD50 of 0.61 and LD95 0f 2.256. Acetone extracts of T. minuta and hexane extract of was O. suave were most active as they caused 100% larval mortality at all tested concentrations thus LD50 and LD95 could not be determined for these extracts. These findings indicate that the selected plants have larvicidal activity. More studies are needed to evaluate the activities of the plants against other types of mosquito larvae and for possible development of larvicides that are safe to use and environment friendly.