Repellent,larvicidal and adulticidal activities of essential oil from Dai medicinal plant Zingiber cassumunar against Aedes albopictus

Zingiber cassumunar is an important plant used in traditional medicine and as a natural mosquito re-pellent.However,the compounds responsible for the repellent activity of the plant are still unknown.The aim of the study is to identify the components of Z.cassumunar essential oil that show repellent activity against Aedes albopictus.We also evaluated the larvicidal and adulticidal activities of Z.cassumunar essential oil against Ae.albopictus.In-cage mosquito repellent experiments showed that Z.cassumunar essential oil possessed moderate repellent activity with a minimum effective dose(MED)of 0.16±0.01 mg/cm^(20,compared to reference standard N,N-diethyl-3-methylbenzamide(DEET,0.03±0.01 mg/cm^(20).Bioassay-guided fractionation identified the major active compound of Z.cassumunar essential oil as(-)-terpinen-4-ol(1)(MED:0.19±0 mg/cm^(20).We also found that Z.cassumunar essential oil showed moderate larvicidal activity against first instar larvae of Ae.albopictus with a LC50(50%lethal concentration)of 44.9 mg/L after 24 h.Fumigation bioassays showed that Z.cassumunar essential oil exhibits moderate adulticidal activity against Ae.albopictus with a LC50 of 5.44%,while(-)-terpinen-4-ol showed significant adulticidal activity with a LC50 of 2.10%after 24 h.This study verifies that the Z.cassumunar essential oil has mosquito repellent activity,and that(-)-terpinen-4-ol is mainly responsible for this activity.Furthermore,this study provides scientific support for the folk usage of Z.cassumunar essential oil as mosquito repellent and indicates that Z.cassumunar essential oil and(-)-terpinen-4-ol can be used as plant-derived repellents and insecticides for mosquito control.

Repellent Activity of Extracts of Wild Rice Species against Panonychus citri and Aphis citricola in Associated with Esterase Isoenzyme in Insests

Six species of wild rice with different ecophenotypes including Oryza grandiglumis （E6-1, E6-3 / 6-4）, O. minuta （E13-9, E13-13）, O. officinalis（E15-8, E15-13）, O. punctata （E16-1, E16-3, E16-13）, O. granulata（E7-4）, and O. latifolia（101392, E9-1, E9-10） were extracted with methnol and the repellent activity of the extracts against the two insects Aphis citricola and Panonychus citri were studied. The extracts of O. officinalis E15-8 showed higher repellent rate to the two insects than those of the other species. The repellent rates of the extracts of E15-8 to P. citriand A. citricola were 83.26% and 87.86% at 5×10^4 μg/mL in 24 h and 87.95% and 82.43% in 48 h, respectively. The extracts of O. officinalis E15-8 had the effect of inhibition to the esterase of the two insects.

Phenological stage effect on phenolic composition and repellent potential of Mentha pulegium against Tribolium castaneum and Lasioderma serricorne

Objective:To elucidate for the first time the phenological stage effect on polyphenol,flavonoid and proanthocyanidin contents of pennyroyal(Mentha pulegium)as well as their antioxidant capacities and insecticidal potentials against Tribolium castaneum and Lasioderma serricorne.Methods:Crude methanol extracts from pennyroyal(Mentha pulegium)aerial parts were evaluated for their anti radical,reducing power activities and repellent potentials against selected coleopteran insects during different phenological stages.Results:Phenolic contents of pennyroyal aerial parts and their antioxidant effects were significantly dependent on maturity stage of the plant.The maximum of phenol production was reached during the full flowering stage.Apigenin was the major phenol in Mentha pulegium with an amount of6.01 mg/g of dry vegetable matter during this period.Nevertheless,at fructification stage,the highest antioxidant activity was not related to high phenolic content.The repulsive effect of pennyroyal extract showed that Lasioderma serricorne was more susceptible to pennyroyal extract than Tribolium castarneum with corresponding median repellent dose values of 0.124and 0.006 mg/mL respectively.Moreover,great differences in insect repulsion depending on extract concentrations,exposure time and developmental stage was observed.For the lowest concentration(0.125 mg/mL),the repellent effect against Tribolium reached its maximum(90%)during the fructification stage(after 24 h of exposure)while this repellent effect was 80%during the vegetative stage.Conclusions:Due to the strong insecticidal potential of pennyroyal extracts,this study highlights the therapeutic properties of this plant and encourages its use as a safer,environmental-friendly and efficient insecticide in food industry.

Synthesis and biological activities of(E)-β-farnesene analogues containing 1,2,3-thiadiazole

In order to discover novel compounds with high-activity to control aphid,a series of novel（E）-β-farnesene analogues containing 1,2,3-thiadiazole were designed and synthesized,and their structures were confirmed by IR,^1H NMR,^13C NMR,and HRMS（ESI）.The stability of representative compounds was studied by HPLC and -1H NMR techniques.Repellent activity results indicated that compounds 8h and 8j displayed 60.3%and 62.0%repellent rates,respectively.The aphicidal bioassay results showed that most analogues exhibited considerable aphicidal activity against Myzus persicae.Especially,analogues 81,8s and 8t exhibited high activity with LC50 values of 33.4 μg/mL,50.2 μg/mL and 61.8 μg/mL,respectively,which were higher than the lead compound（E）-β-farnesene,but lower than commercial insecticide pymetrozine with a LC50 of 7.1 μg/mL

Mosquito repellent potential of Pithecellobium dulce leaf and seed against malaria vector Anopheles stephensi(Diptera:Culicidae)

Objective:To determine the repellent properties of hexane,benzene,ethyl acetate,chloroform and methanol extract of Pithecellobium dulce(P.dulce)leaf and seed against Anopheles stephensi(An.stephensi).Methods:Repellent activity assay was carried out in a net cage(45 cm×30 cm×25 cm)containing 100 blood starved female mosquitoes of An.stephensi.This assay was carried out in the laboratory conditions according to the WHO 2009 protocol.Plant crude extracts of P.dulce were applied at 1.0,2.5,and 5.0 mg/cm^(2) separately in the exposed fore arm of study subjects.Ethanol was used as the sole control.Results:In this study,the applied plant crude extracts were observed to protect against mosquito bites.There were no allergic reactions experienced by the study subjects.The repellent activity of the extract was dependent on the concentration of the extract.Among the tested solvents,the leaf and seed methanol extract showed the maximum efficacy.The highest concentration of 5.0 mg/cm^(2) leaf and seed methanol extract of P.dulce provided over 180 min and 150 min protection,respectively.Conclusions:Crude extracts of P.dulce exhibit the potential for controlling malaria vector mosquito An.stephensi.

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.

Alstonia boonei De Wild oil extract in the management of mosquito(Anopheles gambiae),a vector of malaria disease

Objective:To evaluate the insecticidal potential of Alstonia boonei(A.boonei)oils and derivatives against different life stages of a malaria vector,Anopheles gambiae.Methods:The leaf,stem bark and root bark of A.boonei were collected from an open field and air dried before being blended to fine powder.Oils from this plant were extracted by cold extraction and were prepared at different concentrations.Contact toxicity of A.boonei was tested against the larvae and pupae of the insect while smoke toxicity of the plant materials in form of mosquito coil was tested against the adult insect.Results:Alstodine recorded the highest insect mortality rate and the order of susceptibility of the life stages of the insect to the plant was pupae<adult<larvae.Alstodine recorded the highest repellant activity(100%)after 4-5 h of application.However,all the treatments achieved high repellency(above 70%)after 6-7 h of application compared with the control.The formulated mosquito coil(smoke)of A.boonei oil extracts and derivatives showed high rate of protectability as they achieved above 55%protection.Moreover,alstodine(83.22%)showed the greatest smoke toxicity effect on the insect as it recorded almost the same percentage protection as the positive control(Raid synthetic insecticide)which recorded 83.56%protection.Conclusions:This present study has proven A.boonei oil extracts and derivatives as a potential botanical insecticide which could serve as a new thoroughfare of mosquito control.Moreover,the order of effectiveness of the plant can be arranged thus:alstodine>alstonine>stem bark extract>leaf extract>root bark extract.

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.

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.