Potency of Ethanol Extract and Fractions of the Leaf of <i>Annona muricata</i> against <i>Aedes aegypti</i> Larvae

Abstract

Annona muricata L. is a plant commonly used in Southern Nigeria, for nutritional and medicinal purposes. This study was
carried out to determine the larvicidal potentials of ethanol extract and fractions of the leaf of A. muricata. The ethanol leaf
extract was subjected to phytochemical screening using standard protocol. The leaf crude extract and fractions (i.e., ethyl
acetate and n-hexane) were used for larvicidal assay. The stock solution (5g each in 100ml of water) was prepared. From the
stock solution 0.15, 0.30, 0.45, 0.60 and 0.75_ %w/v concentrations of extract and fractions were prepared and each
concentration of the extract and fractions had 5 replicates. The control (100ml water and larval nutrient only) was also
replicated . Twenty (20), third instar, larvae of Aedes aegypti were exposed to each extract concentration and fractions and
their controls. Larval nutrient was added to each experimental set up. Observations were made after 24 and 48 hours exposure
period. Phytochemical screening revealed the presence of some plant metabolites (alkaloids, saponins, tannins etc).
Mortality of larvae exposed to the extract and fractions increased with increased in extract concentration and exposure time.
This study revealed a differential potency of the extract and fractions used and a difference in susceptibility of larvae to the
extract and fractions as evident by the 48hLC values obtained. Exposure of larvae to 0.75_ %w/v of ethanol extract and ethyl 50
acetate fraction resulted in 100 _% mortality after 48 hours exposure period. Probit analysis gave 48hr_LC₅₀ values of 0.33
and 0.24_ %w/v for ethanol extract and ethyl acetate fraction, respectively. The n-hexane fraction was the least potent with
48h_LC₅₀ value of 0.5461%w/v. Results obtained from this study suggest that the leaf extract and fractions of A. muricata
hold potential as larvicides against Ae. aegypti. Its active ingredient should be isolated, characterized and formulated for use
in larval habitats.

Keywords: Potency, Extract, Fractions, Annona muricata, Aedes aegypti