Abstract

LARVICIDAL EFFECTS OF ETHANOLIC EXTRACT OF FLOWERS (BUDS AND CALYX) OF TAGETES ERECTA AND ITS CHLOROFORM AND PETROLEUM ETHER SOLUBLE FRACTIONS AGAINST THE LARVAE OF AEDES AEGYPTI

S. Hannah Catherine Raj and Dr. N. Shettu*

ABSTRACT

The mosquito-borne diseases, dengue fever, malaria, encephalitis, yellow fever, chikungunya, filariasis, are causing havoc in many countries, and loss in terms of human lives is irreversible. Aedes aegypti the primary vector for dengue fever, dengue haemorrhagic fever and yellow fever is widespread over large areas of the tropics and subtropics; and is reported to infect more than 100 million people every year in more than 110 countries in the tropics. Application of chemical insecticides, though undesirable, is still the major tool adopted globally for mosquito control but has reflected in various drawbacks. In the current era, research is focused on natural products to combat these disease transmitting vectors and a recent emphasis has been placed on plant material. Plants enriched with phytochemicals are reported to possess insecticidal properties particularly larvicidal. In the present study larvicidal activity of ethanol extract, petroleum ether and chloroform fractions of buds and calyx of Tagetes erecta was tested against Aedes aegypti. The fresh flowers of T. erecta were extracted in cold with ethanol and after concentration, the ethanol extract was fractionated with chloroform and petroleum ether to afford a brownish syrupy suspension of ethanol extract petroleum ether soluble fraction and chloroform soluble fraction. The larvicidal effect of ethanol extract and their solvent fractions were determined by the standard procedure of WHO against different instars of Aedes aegypti. The larval mortality rate of T. erecta was entirely time and dose
dependent. It can be concluded that the flowers of T. erecta are very effective natural
larvicide and could be useful against Aedes aegypti.

Keywords: Tagetes erecta, Aedes aegypti, Larvicidal effect.