Potential of the Ethanol Extract of Aerial Parts of Diplazium esculentum (Retz) SW. AS Larvicide against Anopheles gambiae Giles and Culex quinquefasciatus Say

Abstract

Plant products have been tested as insecticides against mosquitoes as they are promising candidates to replace conventional insecticides. This study was carried out to evaluate the larvicidal potential of ethanol extract of the aerial parts of Diplazium esculentum against Anopheles gambiae and Culex quinquefasciatus. Ethanol extract of the aerial parts of D. esculentum was screened for its phytochemical constituents and used for larvicidal assay. A stock solution of the extract (5 g in 100 ml of water) was prepared. From the stock solution, 0.45, 0.60, 0.75, 0.90 and 1.05% w/v concentrations of the extract were obtained for the study. Each concentration of the extract had 3 replicates. The control was also replicated. Twenty (20) third instar larvae each of Anopheles gambiae and Culex quinquefasciatus were separately exposed to each extract concentration for a duration of 48 hours. 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. Mortality of larvae exposed to the extract increased with increased concentration and exposure time. This study revealed a differential susceptibility of larvae of the two mosquito species to the extract as evident by the 24 h LC50 values obtained which were 0.355 and 2.468% w/v for An. gambiae and Cx. quinquefasciatus respectively. Exposure of An. gambiae larvae to the extract resulted in 100% mortality even with the least concentration of 0.45% w/v after 48 hours exposure period while the highest concentration of extract (1.05% w/v) resulted in 53.33% mortality of Cx. quinquefasciatus larvae, after an exposure period of 48 hours. Results obtained from this study suggest that the aerial parts of D. esculentum if further explored would be useful in the control of An. gambiae and Cx. quinquefasciatus.