Pesticidal activity of Rivina humilis L.(Phytolaccaceae)against important agricultural polyphagous field pest,Spodoptera litura(Fab.)(Lepidoptera:Noctuidae)

Objective:To evaluate the pesticidal activity of antifeedant,oviposition deterrent,ovicidal and larvicidal activities of benzene,dichloromethane,diethylether,ethylacetate and methanol extracts of Rivina humilis at different concentrations against agricultural polyphagous pest Spodoptera litura(Lepidoptera:Noctuidae)(S.litura).Methods:Antifeedant activities of the selected plant extract were studied as described by Isman et al.(1990),with slight modifications.For oviposition deterrent activity,ten pairs of(adult moths)S.litura were subjected in five replicates.After 48 h,the numbers of eggs masses laid on treated and control leaves were recorded and the percentage of oviposition deterrence was calculated.The ovicidal activity was determined against the eggs of S.litura.Twenty five early fourth instar larvae of S.litura were exposed to various concentrations and was assayed by using the protocol of Abbott’s formula(1925);the 24 h LC_(50)values of the Rivina humilis leaf extract was determined by probit analysis.Results:All the extracts showed moderate antifeedant activitiy;however,significant antifeedant,ovicidal,oviposition deterrent and larvicidal activities were observed in methanol extract.Conclusions:This study showed that the selected plant can be a potent source of natural antifeedant,oviposition deterrent,ovicidal and larvicidal activities against field pest S.litura.

Bioefficacy of Caesalpinia bonducella extracts against tobacco cutworm,Helicoverpa armigera(Hub.)(Lepidoptera:Noctuidae)

Objective:To evaluate the antifeedant,oviposition deterrent,ovicidal and larvicidal activities of benzene,dichloromethane,diethylether,ethyl acetate and methanol extracts of Indian medicinal plant,Caesalpinia bonducella(C.bonducella)at different concentrations against Lepidopteran agricultural field pest Helicoverpa armigera(Lepidoptera:Noctuidae).Methods:Antifeedant activities of the selected plant extract were studied using leaf disc no-choice method and oviposition deterrent,ovicidal and larvicidal activities were also assessed by adapting the standard protocols.Results:The antifeedant activity of C.bonducella showed significant antifeedant activity in methanol extract.Oviposition deterrency is higher in methanol extract than the other solvent extracts.Similarly,maximum egg mortality was observed in methanol leaf extract of C.bonducella Lethal concentration,LC_(50)value of benzene,diethylether,dichloromethane,ethyl acetate and methanol extract of C.bonducella were 470.02,469.00,465.47,460.52 and 443.87 mg/L respectively.The Chi-square values are significant at P<0.05 level.Among five solventextracts,the methanol extract was responsible for strong lethal activity observed against selected pest species.Conclusions:Results of this study show that the selected Indian medicinal plant C.bonducella could be a potent source of natural antifeedant,oviposition deterrent,ovicidal and larvicidal agent against the field pest Helicoverpa armigera.