Larvicidal, Ovicidal, Oviposition Deterrence and Emergence Inhibition Activity of Selected Sudanese Plants Against Anopheles Arabiensis and Culex Quinquefasciatus

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Abd Alla Musa Ali, Elimam
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Malaria and Filariases are prevalent in Sudan , the control of these diseases depends largely on preventive measures against mosquito vectors . Previous control efforts targeting all stages of mosquitoes, but has focused almost on adult (flying stage) control, by using conventional insecticides . The present study aimed to investigate, the potential larvicidal activity, and its subsequent effects upon egg hatching, adult emergence inhibition and oviposition deterrent activity of aqueous leaves extract of five selected indigenous plant against Anopheles arabiensis (the main vector of malaria in Sudan) and Culex quinquefasciatus (the main vector of Filariasis) as biological control . Laboratory experiment were conducted as follows : The larvicidal activity of each plant extract was studded against 2nd, 3rd and 4th instars larvae of each mosquito . The larval mortality was observed after 24 hours . The adult emergence inhibition activity was tested by exposing 3rd instar larvae of each mosquito to different concentration of each plant extract . The oviposition deterrent activity was tested by using three different concentration of extract that cause high, moderate and low larvae mortality in the larvicidal experiment . The results obtained were : It was found that the three plants Euphorbia hirta Umlebien, Sonchus oleraceous Molita and Eclipta prostrata Tamr Elganm have not shown any larvicidal activity against both mosquito species studied, up to a concentration as high as 10000ppm of the extract . The plant Calotropis procera (Ushar) and Ricinus communis (Khirwi) showed high level of toxicity against both mosquitoes larvae . The pupal stage was not affected till a concentration of 10000 ppm . In all cases 2nd instar was more susceptible than 3rd instar and the later was more susceptible than 4th instar . The extracts of C. procera was more potent than that of R. communis against the two species of mosquito. Culex quinquefasciatus was more susceptible than Anopheles arabiensis with respect to C. procera, and Anopheles arabiensis was more susceptible than Culex quinquefasciatus with respect to R. communis . Both plants showed remarkable effect on egg hatching and larval development. Eggs were found more susceptible than 3rd and 4th instar larvae . The concentration that cause 50% of adult emergence inhibition (EI50) was less than that cause 50% larvae mortality ( LC50 ) . The leaves extract of both plants showed 100% oviposition deterrent and effective repellence against both mosquitoes at different larvicidal concentration (high, moderate and low) when there is a choice of control (treated – control ) . But the avoidance of eggs laying was not shown when the control was not offered (treated water only), with the observation on that maximum of eggs laying was preferred in the low larvicidal concentration . In all cases at high larvicidal concentration the eggs laying was avoided or at least reduced to very low number by female mosquito . The results suggest that the leaves extract of C. procera and R. communis possess remarkable larvicidal, adult emergence inhibitor, ovicidal and oviposition deterrent properties against An. Arabiensis and Culex quinquefasciatus, and might be used as natural biocides for mosquito control
Larvicidal, ovicidal, oviposition deterrence, emergence inhibition activity, Sudanese plants, Anopheles arabiensis,Culex quinquefasciatus