The use of plant extracts as insecticides against vector insects serves as a perfect alternative to conventional methods.This study was carried out to assess the chemical composition and efficacy of Chromolaena odorat...The use of plant extracts as insecticides against vector insects serves as a perfect alternative to conventional methods.This study was carried out to assess the chemical composition and efficacy of Chromolaena odorata L.and Ocimum gratissimum L.in the control of adult houseflies.C.odorata and O.gratissimum were extracted with cold water and applied at four concentrations(5,10,40 and 100%v/v)in different bioassays(contact,fumigant and feeding-deterrent).A synthetic insecticide(Lambdacyhalothrin)and an untreated control were included in the treatments.The treatments were arranged in a completely randomized design with three replicates.The phytochemical compositions of the tested plant extracts were determined via gas chromatography‒mass spectrometry(GC‒MS).Mortality data were recorded at the stipulated times(1,2,4,6,8 and 24 h),and the means were separated via Duncan’s multiple range test at a 5%probability.GC‒MS revealed different chemical compounds,and eugenol,n-hexadecanoic acid,caryophyllene,phytol,humulene,9,12,15-octadecatrienoic acid,(Z,Z,Z)-,squalene,and stigmasterol compounds,among others,were identified as active insecticidal compounds.The tested plant extracts were effective against the studied insects,which suggested synergistic action of the observed natural chemicals in the plant extracts used.Moreover,the two plant extracts did not kill the studied insects faster than the synthetic insecticide did,but 100%mortality was observed after 12 h of exposure to the plant extracts.The mode of application and concentration played a significant role in the toxicity of the plant extracts,with the feeding mode of application resulting in greater toxicity effects than the fumigant and contact bioassays at the highest concentration.However,O.gratissimum exhibited better insecticidal control than C.odorata extracts did.Therefore,the use of crude plant extracts as insecticides could serve as substitutes for lambdachyalothrin in the control of houseflies,especially in animal rearing facilities and in the human population.展开更多
文摘The use of plant extracts as insecticides against vector insects serves as a perfect alternative to conventional methods.This study was carried out to assess the chemical composition and efficacy of Chromolaena odorata L.and Ocimum gratissimum L.in the control of adult houseflies.C.odorata and O.gratissimum were extracted with cold water and applied at four concentrations(5,10,40 and 100%v/v)in different bioassays(contact,fumigant and feeding-deterrent).A synthetic insecticide(Lambdacyhalothrin)and an untreated control were included in the treatments.The treatments were arranged in a completely randomized design with three replicates.The phytochemical compositions of the tested plant extracts were determined via gas chromatography‒mass spectrometry(GC‒MS).Mortality data were recorded at the stipulated times(1,2,4,6,8 and 24 h),and the means were separated via Duncan’s multiple range test at a 5%probability.GC‒MS revealed different chemical compounds,and eugenol,n-hexadecanoic acid,caryophyllene,phytol,humulene,9,12,15-octadecatrienoic acid,(Z,Z,Z)-,squalene,and stigmasterol compounds,among others,were identified as active insecticidal compounds.The tested plant extracts were effective against the studied insects,which suggested synergistic action of the observed natural chemicals in the plant extracts used.Moreover,the two plant extracts did not kill the studied insects faster than the synthetic insecticide did,but 100%mortality was observed after 12 h of exposure to the plant extracts.The mode of application and concentration played a significant role in the toxicity of the plant extracts,with the feeding mode of application resulting in greater toxicity effects than the fumigant and contact bioassays at the highest concentration.However,O.gratissimum exhibited better insecticidal control than C.odorata extracts did.Therefore,the use of crude plant extracts as insecticides could serve as substitutes for lambdachyalothrin in the control of houseflies,especially in animal rearing facilities and in the human population.
