Insecticidal Effect of Ethnobotanical Plant Extracts Against Anopheles Arabiensis (Diptera: Culicidae) Under Laboratory Condition

Abstract

Background: The emergence and spread of resistant strains of malaria vectors to chemical insecticides are becoming major problem for malaria vector management. Natural plant products play a vital role to resolve the current challenge of malaria control.Objective: The current study was conducted to evaluate insecticidal effect of ethnobotanical plant extracts against the primary malaria vector, Anopheles arabiensis in Northwestern Ethiopia.Methods: Primarily, ethnobotanical plants used for Anopheles mosquito control was surveyed in Dangur district, Northwestern Ethiopia. Insecticide susceptible strains of Anopheles arabiensis mosquito were reared in insectary of tropical and infectious diseases research center, Assosa university. The larvicidal and adulticidal potentials of frequently used plant extracts against susceptible strains of laboratory colony were evaluated.Result: A total of fifteen plants were identified as ethnobotanical plants helping the local people for mosquito control. Azadirachta indica, Ocimum lamiifolium, Ocimum americanum, Moringa olifiera leaf, and Moringa olifiera seed species of local plants were found to be frequently used to kill and/or repel mosquitoes in the study district. All the plant extracts were found to have potential larvicidal activity against 4th instar larvae of An. arabiensis and only ethanol and methanol extract of A. indica and O. lamiifolium were found to have potential adulticidal effect against adult of An. arabiensis. The highest larvicidal activity was observed in ethanol extract of A. indica with 95% larval mortality and lowest LC50 of 40.73 ppm and LC90 of 186.66 ppm. The highest adulticidal activity was observed in methanol extract of A. indica with 75% adult mortality at 300 ppm and lowest LC50 of 106.65ppm and LC90 of 1293ppm. The lowest larvicidal and adulticidal activity was observed in methanol extracts of O. lamiifolium with 63.35% larval mortality and leaf extract of M. olifiera with 50% adult mortality at 300 ppm, respectively.Conclusion: ethanol extract of A. indica exerted a remarkable larvicidal effect against An. arabiensis and thus it can be used for botanical mosquito insecticide development.