The development of plant-derived products to control Bemisia tabaci Genn.(Hemiptera:Aleyrodidae)is an urgent need for production of horticultural crops.Plant extracts and essential oils of several species of the genus...The development of plant-derived products to control Bemisia tabaci Genn.(Hemiptera:Aleyrodidae)is an urgent need for production of horticultural crops.Plant extracts and essential oils of several species of the genus Eugenia(Myrtaceae)have shown insecticidal activity.In southern Mexico,leaf extracts from Eugenia winzerlingii showed nematicidal effect but its insecticidal properties have not been explored.Therefore,the objective of this study was to evaluate the insecticidal effect of aqueous and organic extracts from E.winzerlingii leaves on B.tabaci egg,nymph and adult stages,and else to explore its nursery propagation.Then,extracts of this species were obtained by maceration with different polarity solvents.Bioassays were carried out on Capsicum chinense leaves.Mortality assays showed that aqueous and total crude ethanol(TCE)extracts necrosed the eggs(LC50=0.21%w/v and 4.68 mg/mL,respectively),whereas hexane,ethyl acetate(ETA),residual ethanol and TCE extracts affected the nymphs(LC50=0.25-4.85 mg/mL).In adults,oviposition inhibition by free choice assay indicated that TCE and ETA extracts had major activity(EC50=14.62 and 27.86μg/cm2,respectively).On other hand,the sexual and vegetative propagation of E.winzerlingii showed that this species can be easily cultivated by seeds.In conclusion,extracts of E.winzerlingii leaves are highly effective in controlling B.tabaci.TCE extract,in particular,was toxic to three stages of B.tabaci.This plant could be a potential alternative to develop a novel botanical insecticide to manage this destructive pest.展开更多
The angoumois grain moth, Sitotroga cerealella （Olivier）, is one of the most serious stored grain pests around the world. In attempts to reduce the losses caused by the moth and to suppress its populations, the fumi...The angoumois grain moth, Sitotroga cerealella （Olivier）, is one of the most serious stored grain pests around the world. In attempts to reduce the losses caused by the moth and to suppress its populations, the fumigant activities, behavioral influence and ovipositional inhibition of garlic （Allium sativum） essential oil and its two major components, diallyl disulfide and diallyl trisulfide, were investigated against the adult grain moth. Their effects on reduction in survival of first instar larvae to adult emergence were also evaluated. Results showed that these three materials （garlic essential oil, diallyl disulfide and diallyl trisulfide） had significant fumigant activity with 50% lethal concentration values at 1.33, 0.99, and 1.02/zL/L air space, respectively; meanwhile, the three materials possessed high behavioral deterrent activities against adults in the Y-tube olfactometer. When applied to rice grains, these materials reduced adult longevity and inhibited oviposition, with ovipositional inhibition above 70% at a concentration of 1.5uL/25 g in either no-choice or two-choice tests. In short, the study showed that both diallyl disulfide and diallyl trisulfide, like garlic essential oil, acted as fitrnigants, produced behavioral deter- rence and inhibited oviposition against angoumois grain moth. Our work here indicates that diallyl disulfide and diallyl trisulfide may serve as potential alternatives for grain protectants since both of them can be prepared easily from readily available chemicals.展开更多
文摘The development of plant-derived products to control Bemisia tabaci Genn.(Hemiptera:Aleyrodidae)is an urgent need for production of horticultural crops.Plant extracts and essential oils of several species of the genus Eugenia(Myrtaceae)have shown insecticidal activity.In southern Mexico,leaf extracts from Eugenia winzerlingii showed nematicidal effect but its insecticidal properties have not been explored.Therefore,the objective of this study was to evaluate the insecticidal effect of aqueous and organic extracts from E.winzerlingii leaves on B.tabaci egg,nymph and adult stages,and else to explore its nursery propagation.Then,extracts of this species were obtained by maceration with different polarity solvents.Bioassays were carried out on Capsicum chinense leaves.Mortality assays showed that aqueous and total crude ethanol(TCE)extracts necrosed the eggs(LC50=0.21%w/v and 4.68 mg/mL,respectively),whereas hexane,ethyl acetate(ETA),residual ethanol and TCE extracts affected the nymphs(LC50=0.25-4.85 mg/mL).In adults,oviposition inhibition by free choice assay indicated that TCE and ETA extracts had major activity(EC50=14.62 and 27.86μg/cm2,respectively).On other hand,the sexual and vegetative propagation of E.winzerlingii showed that this species can be easily cultivated by seeds.In conclusion,extracts of E.winzerlingii leaves are highly effective in controlling B.tabaci.TCE extract,in particular,was toxic to three stages of B.tabaci.This plant could be a potential alternative to develop a novel botanical insecticide to manage this destructive pest.
文摘The angoumois grain moth, Sitotroga cerealella （Olivier）, is one of the most serious stored grain pests around the world. In attempts to reduce the losses caused by the moth and to suppress its populations, the fumigant activities, behavioral influence and ovipositional inhibition of garlic （Allium sativum） essential oil and its two major components, diallyl disulfide and diallyl trisulfide, were investigated against the adult grain moth. Their effects on reduction in survival of first instar larvae to adult emergence were also evaluated. Results showed that these three materials （garlic essential oil, diallyl disulfide and diallyl trisulfide） had significant fumigant activity with 50% lethal concentration values at 1.33, 0.99, and 1.02/zL/L air space, respectively; meanwhile, the three materials possessed high behavioral deterrent activities against adults in the Y-tube olfactometer. When applied to rice grains, these materials reduced adult longevity and inhibited oviposition, with ovipositional inhibition above 70% at a concentration of 1.5uL/25 g in either no-choice or two-choice tests. In short, the study showed that both diallyl disulfide and diallyl trisulfide, like garlic essential oil, acted as fitrnigants, produced behavioral deter- rence and inhibited oviposition against angoumois grain moth. Our work here indicates that diallyl disulfide and diallyl trisulfide may serve as potential alternatives for grain protectants since both of them can be prepared easily from readily available chemicals.
