Prospects of Using Ethanolic Extracts of the Leaf and Seeds of Picralima nitida in the Control of Culex quinquefasciatus and Aedes aegypti Larvae

Picralima nitida is a medicinal plant used for the treatment of various ailments in Southern Nigeria. This study was aimed at evaluating the prospects of using ethanol leaf and seed extracts of Picralima nitida in the control of Culex quinquefasciatus and Aedes aegypti, at their larval stages. Fourth instar larvae of test organisms were exposed in static bioassays to the crude extracts of P. nitida. Concentrations tested were 0.15 – 0.75 %w/v, at exposure periods of 24, 48 and 72 hours. At the end of assays (72 hr), the highest concentration (0.75 % w/v) of the ethanol leaf extract of P. nitida resulted in 48.00 and 50.40% mortality of larvae of Cu. quniquefasciatus and Ae. aegypti, respectively. At the same exposure period (72hr) the ethanol seed extract (0.75 %w/v) resulted in larval mortality of 74.40 and 60.80 % for Cu. quinquefasciatus and Ae aegypti, respectively. The 72h LC50 values obtained from probit analysis revealed that larvae of Cu. quinquefasciatus were more susceptible to the seed extract than larvae of Ae. aegypti, with 72 h LC50 values of 0.500 and 0.650 % w/v, respectively. Phytochemical (qualitative) screening of the leaves and seeds of Pnitida detected the presence of alkaloids, cardiac glycosides, saponins and terpenes. In addition, flavonoids and tannins were detected in the seeds. This preliminary investigation has revealed that the leaves and seeds of Pintida hold larvicidal potential. Their formulation as alternatives to synthetic larvicides should therefore be considered.