Larvicidal Effect of Some Plant Extracts Against Anopheles Arabiensis Patton (Diptera: Culicidae) Under Laboratory Condition In Ethiopia
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Date
2019-06-03
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Addis Ababa University
Abstract
Despite the availability of control interventions, malaria remains as a major public health problem in Ethiopia. The emergence and spread of malaria vector resistance to insecticide is limiting the efficacy of current control interventions. Natural plant products have a vital role to resolve this problem. In this study larvicidal activities of Artemisia annua L. (Asteraceae), Calpurnia aurea (Aiton) (Fabaceae) Clausena anisata (Wild) Hook. F.ex. Benth (Rutaceae), Datura stramonium L. (Solanaceae) and Ricinus communis L. (Euphorbiaceae) ethanol and methanol leaf extracts were evaluated against Anopheles arabiensis larvae under laboratory conditions. Larvicidal bioassay was conducted in three replicates per treatment each with a total of 25 3rd instar An. arabiensis larvae at different concentrations ranging from 50-300 ppm. The larval mortality were observed after 24 hours and percentage mortality were recorded. LC50 and LC90 were also determined using log probit analysis. Furthermore, methanol extract of C. aurea was subjected to bioassay guided column chromatographic fractionation and seven fraction were tested for their larvicidal activities. Qualitative secondary metabolite screening was also conducted for the crude extract of test plants. All the plant crude extracts were found to have a potential larvicidal activity against 3rd instar An. arabiensis larvae. The highest larvicidal activity was observed in methanol crude extract of C. aurea with 100% larval mortality at 300 ppm and lowest LC50 of 84.85 ppm and LC90 of 192.29 ppm. Ethanol crude extract of R. communis also achieved 93.33% larval mortality at 300 ppm with the LC50 and LC90 of 134.52 ppm and 304.67 ppm, respectively. The lowest larvicidal activity was observed in methanol extracts of A. annua with 68% larval mortality at 300 ppm. Fraction F1 and F3 leaf methanol extracts of C. aurea showed an excellent larvicidal activities with mortality of 100% and 98.66 % at 250 ppm and LC50 of 62.51 and 82.33 ppm, respectively after 24 hours exposures while F5-F6 showed no larvicidal activity in all test concentrations. Besides, methanol extract of C. aurea showed the presence of alkaloids, flavonoids, phenol, terpenoids, tannin and saponin. The present study revealed that column chromatographic F1 and F3 of methanol extract of C. aurea exerted a remarkable larvicidal activity against An. arabiensis and thus these can be used for botanical mosquito insecticide development. Further study need to be conducted to identify the active ingredients in the column chromatographic fractions of F1-F3 of methanol extracts of C. aurea and their mode of actions.
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Keywords
Anopheles Arabiensis, Larvicide, Plant Extract, Column Chromatography