Acaricidal Activity of Boenninghausenia sessilicarpa Against Panonychus citri

Acaricidal activity of Boenninghausenia sessilicarpa against Panonychus cirri was tested in the laboratory. Four solvents were used to prepare crude extracts, petroleum ether, chloroform, ethyl acetate, and ethanol, among which ethanol was the most effective one. The results suggested that ethanol extracts of B. sessilicarpa had eminent acaricidal and ovicidal activities. Concentrated extracts were prepared using petroleum ether, chloroform, ethyl acetate, or distilled water as solvent. Mite mortality rates in the concentrated extracts by petroleum ether, chloroform, or distilled water were significantly lower than those by ethyl acetate. The LC50 values of eggs and female mites were 0.7639 and 1.1033 mg mL^-1, respectively. After liquid chromatography and thin layer chromatography, the concentrated extracts were separated into 14 groups of fractions and further tests for their acaricidal and ovicidal activities were conducted. Fraction 2 was found to possess higher acaricidal and ovicidal activities. The mortality of eggs and adult mites were 85.83 and 63.07%, respectively. Moreover, fraction 2 showed moderate oviposition inhibition effect （0.8795） against P. citri when the used dose was higher than 2.5 mg mL^-1

Mosquitocidal activity of indigenenous plants of Western Ghats,Achras sapota Linn.(Sapotaceae)and Cassia auriculata L.(Fabaceae)against a common malarial vector,Anopheles stephensi Liston(Culicidae:Diptera)

Objective:To evaluate the mosquito larvicidal,ovicidal,pupicidal and repellent activities of hexane,diethyl ether,dichloromethane,acetone and methanol extracts of Indian medicinal plants,Achras sapota(A.sapota)and Cassia auriculata(C.auriculata)at different concentrations against Anopheles stephensi(An.stephensi),a malarial vector.Methods:Twenty five early third instar larvae of An.stephensi were exposed to various concentrations(30-210 mg/L)of plants extracts and were assayed in the laboratory by using the protocol of WHO 2005;then after 24 h LC_(50) values of the A.sapota and C.auriculata leaf extract was determined by probit analysis.The ovicidal activity was tested with the extracts ranging from 50-350 mg/L.The pupicidal activity was recorded after 24 h of exposure to the extract.The repellent efficacy was determined against mosquito species at two different concentrations 1.5 and 3.0 mg/cm^(2) under laboratory conditions.Results:Among the five different extracts tested against the An.stephensi,methanol extract of A.sapota proved to be an more effective solvent extract in almost all the parameters studied than C.auriculata.Conclusions:It is inferred that the leaf extract of A.sapota and C.auriculata could be used in vector control programme.

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.

Mosquito larvicidal and ovicidal properties of Pithecellobium dulce(Roxb.)Benth.(Fabaceae)against Culex quinquefasciatus Say(Diptera:Culicidae)

Objective:To assess the larvicidal and ovicidal potential of the crude hexane,benzene,chloroform,ethyl acetate and methanol solvent extracts from the medicinal plant,Pithecellobium dulce(P.dulce)against filariasis vector mosquito,Culex quinquefasciatus(Cx.quinquefasciatus).Methods:Twenty five early third instar larvae of Cx.quinquefasciatus were exposed to various concentrations and were assayed in the laboratory by using the protocol of W HO(2005).The larval mortality was observed after 24 h of treatment.The ovicidal activity was determined against Cx.quinquefasciatus mosquito eggs to various concentrations ranging from 100-750 mg/L under the laboratory conditions.Results:The methanol extract of the leaves and seed of P.dulce was the most effective against the larvae with LCs0 and LCgo values 164.12 mg/L,214.29 mg/L,289.34 mg/L and 410.18 mg/L being observed after 24 h of exposure.The efficacy of methanol was followed by that of the ethyl acetate,chloroform,benzene and hexane extracts.The mean percent hatchability of the egg rafts were observed after 48 h of treatment.About 100%mortality was observed at 500 mg/L for leaf and 750 mg/L for seed methanol extracts of P.dulce.Conclusions:From the results,it can be concluded that the larvicidal and ovicidal effect of P.dulce against Cx.quinquefasciatus make this plant product promising as an alternative to synthetic insecticide in mosquito control programs.

Mosquitocidal properties of Oxystelma esculentum(Asclepiadaceae)-Indian medicinal plant tested against Ades aegypti(Linn.)(Diptera:Culicidae)

Objective:To evaluate the mosquitocidal activities of various solvent extract of Oxystelma esculentum(O.esculentum)against the medically important dengue vector mosquito,Aedes aegypti(Ae.aegypti)L.Methods:A total of 25 early third instar larvae of Ae.aegypti were exposed to various concentrations(60-300 mg/L)and were assayed in the laboratory by using the protocol of World Health Organization,2005;the 24 h LC_(50) values of the O.esculentum leaf extract was determined by probit analysis.The ovicidal activity was determined against the freshly laid eggs of Ae.aegypti to various concentrations ranging from 50-300 mg/L under laboratory conditions.The pupicidal activity was determined against pupae of Ae.aegypti to various concentrations ranging from 70-280 mg/L after 24 h of exposure to the concern extract.The repellent efficacy was determined against adult female mosquito species at 1.0,2.0 and 3.0 mg/cm^(2) under laboratory conditions.Results:The LC_(50) value of methanol extract of O.esculentum against 3rd instar larvae of Ae.aegypti was 125.82 mg/L.The same extract showed 100%egg mortality at 250 mg/L and also pupicidal activity observed against the pupae of Ae.aegypti at 280 mg/L.Conclusions:The present results suggest that the O.esculentum leaf extracts provided an excellent,potential phytopesticide for controlling Ae.aegypti mosquito.

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.

Chemical composition and laboratory investigation of Melissa officinalis essential oil against human malarial vector mosquito,Anopheles stephensi L.(Diptera:Culicidae)

Objective:To decide the larvicides,ovicidal,pupicidal and repellent activity of Melissa officinalis(M.officinalis)chemical compositions against important mosquito Anopheles stephensi(An.stephensi)(Diptera:Culicidae).Methods:A chemical constituent of 24 compounds was identified in the oils of M.officinalis compounds representing to 98.73%.A total of 253rd instar larvae of An.stephensi were showed to a variety of concentrations(30-300 mg/L)in laboratory by means of utilizing the standard procedure portrayed by World Health Organization(2005).The larvae were exposed for 24 h and mortalities were subjected to probit analysis.The ovicidal activity was strong-minded against An.stephensi mosquito to a variety of concentrations ranging from 15-90 mg/L under the laboratory circumstances.The repellent activity of M.officinalis chemical compositions tested at concentrations of 0.75 and 1.50 mg/cm^(2)was evaluated in a net cage(45 cm×45 cm×40 cm)including 100 blood starving female mosquitoes of An.stephensi using the methods of World Health Organization(1996).Results:The LC_(50)and LC_(90)values of citronellal compound against An.stephensi larvae were 85.44 and 159.73 mg/L,respectively.Mean percent hatchability of the ovicidal action was observed 48 h post-treatment.Similarly,the citronellal compound and other compositions were found to be mainly effective against eggs of An.stephensi.Citronellal compound exerted 45,60,75 and 90 mg/L against An.stephensi,respectively.The repellent activity of citronellal compound was contained to be mainly effective and the maximum action was observed at 0.75 and 1.50 mg/cm^(2)concentrations giving 100%protection up to 210 min against An.stephensi.Conclusions:This current study was undertaken to evaluate the larvicidal,ovicidal,repellent potential of compounds from the M.officinalis essential oil against An.stephensi.This is initial statement on the mosquito larvicidal,ovicidal and repellent activity of M.officinalis chemical compositions.