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.

Chemical Composition, Larvicidal and Adult Emergence Inhibition Activities of Balanites aegyptiaca Del. Seed and Aristolochia albida Duch. Root Extracts against Malaria Vector, Anopheles gambiae Giles

Background: Anopheles gambiae is enemy number one of mankind in Africa and particularly in Cameroon due to its ability of transmitting malaria which is the deadliest disease in this part of the world. Synthetic insecticides have been used to control malaria vectors but they have negative effects on non-target organisms and are environmentally unfriendly. Control of mosquitoes at larval stages using phytochemicals is currently the leading tool to reduce the mosquito population and so the reduction of malaria transmission rates. Therefore, the present study was to evaluate the phytochemical contents, larvicidal and adult emergence inhibition activities of Balanites aegyptiaca seed and Aristolochia albida root solvents extracts against Anopheles gambiae larvae. Methods: The World Health Organization standard protocols were followed for the different bioassays. Concentrations ranging from 500 - 2000 ppm for larvicidal and 500 - 1500 ppm for IGRs were used. Results: Both plants showed the presence of alkaloids, flavonoids, saponins, tannins, phenols, terpenoids and oils except the absence of phenols in Aristolochia albida. The larvicidal activity of Aristolochia albida extracts showed that hexane and methanol fractions were the most active killing relatively all exposed larvae with the LC50 values of 420.1 and 453 ppm, respectively. The same observation was made in hexane fraction from Balanites aegyptiaca (LC50 = 588 ppm). The insect growth inhibitory activity of Aristolochia albida extracts proved that hexane and methanol fractions relatively caused a 100% inhibition in the mosquito development, recording the EI50 values of 482.4 and 555.6 ppm, respectively. The same trend was observed with Balanites aegyptiaca hexane fraction registering better EI50 of 623.9 ppm. Conclusions: Our findings demonstrate that Balanites aegyptiaca seed and Aristolochia albida seed extracts are rich in phytochemicals capable of killing mosquito larvae and disrupting mosquito larval development. This could contribute to the control of mosquito populations and improved management of malaria.

Larvicidal efficacy of monoterpenes against the larvae of Anopheles gambiae

Objective:To evaluate the larvicidal efficacy of eight volatile components of essential oils against 3rd instar larvae of Anopheles gambiae s.s.Methods:Larvicidal effects of each compound were evaluated in both laboratory and semi-field trials.Stock solution was prepared and serial dilutions were made in six concentrations for each compound.A total of 20 larvae were exposed to larvicides for each replicate and monitored at intervals of 12,24,48 and 72 h.Larvae monitoring was done on basis of dead and live larvae in all intervals.Results:All assayed compounds were larvicides and presented varying degrees of larval toxicity,with LC50 values ranging from 1.28 to 1 938.92 mg/L depending on the treatment time(12,24,48 or 72 h).(-)-Perillyl alcohol presented the strongest larvicidal activity towards Anopheles gambiae larvae,with LC_(50) values of 73.60,18.36,1.72 and1.28 mg/L after 12,24,48 and 72 h of exposure,respectively.The next strongest were(-)-isopulegol(LC_(50)= 135.10,49.39,34.39 and 20.22 mg/L) and(-)-carvone epoxide(LC_(50)= 168.86,124.74,80.84 and 23.46 mg/L).After 12,24 and 48 h of treatment,hydroxydihydrocarvone was the least toxic compound,with LC_(50) values of 1 938.92,1 172.18 and 401.03 mg/L,respectively.Conclusions:The data obtained in this study suggest that all evaluated monoterpenes,especially(-)-perillyl alcohol,have remarkable larvicidal effects and may be considered as potential sources for the development of suitable natural larvicides for mosquito management programs.Further small-scale field trials should be conducted.

Larvicidal activity of Xenorhabdus and Photorhabdus bacteria against Aedes aegypti and Aedes albopictus

Objective: To evaluate the efficacy of symbiotic bacteria, Xenorhabdus indica, Xenorhabdus stockiae, Photorhabdus luminescens subsp. akhurstii and Photorhabdus luminescens subsp. hainanensis as a larvicide against Aedes aegypti and Aedes albopictus. Methods: Larvae(L3-L4) of Aedes aegypti and Aedes albopictus were given 2 m L of a suspension 107-108 CFU/m L of each symbiotic bacterium. Distilled water and Escherichia coli ATCC襅25922 were used as the control. The mortality rate of the larval mosquitoes was observed at 24, 48, 72 and 96 h. The experiment was performed in triplicates. Results: The larvae of both Aedes species started to die at 24 h exposure. Aedes aegypti showed the highest mortality rate(87%-99%), 96 h after exposure to Xenorhabdus stockiae(b NBP22.2_TH). The mortality rate of Aedes albopictus was between 82% and 96% at 96 h after exposure to Xenorhabdus indica(b KK26.2_TH). Low effectiveness of distilled water and Escherichia coli ATCC襅25922 were observed in both Aedes larvae, with a mortality rate of 2% to 12%. Conclusions: The study confirms the oral toxicity of Xenorhabdus and Photorhabdus bacteria against Aedes spp. Xenorhabdus stockiae and Xenorhabdus indica may be an alternative agent for control Aedes spp. This is basic information for further study on the mechanism of action on Aedes larvae or application to control mosquito larvae in the community.

Larvicidal efficacy of plant extracts and isolated compounds from Annonaceae and Piperaceae against Aedes aegypti and Aedes albopictus

The Aedes(Ae.)aegypti and Ae.albopictus mosquitoes are vectors of epidemiologically relevant arboviruses in the public health context,such as the dengue,Zika and chikungunya viruses.Among the alternatives to synthetic insecticides for the control of these vectors,the use of natural plant products deserves attention.This review summarizes findings on the larvicidal potential of plant extracts on Ae.aegypti and Ae.albopictus,as well as the potential of isolated compounds from plants of the Annonaceae and Piperaceae families against these vectors.Descriptors related to larvicidal activity of plant extracts and isolated compounds in Aedes spp.in the Web of Science database were used,for plant extracts considering publications between 2000 and 2019.A total of 859 articles were analyzed for plant extracts and estimates of lethal concentration values(LC50 and LC90).In the end,95 articles that presented the larvicidal potential of 150 plant species from 52 families were analyzed.The two families most studied for this activity were Fabaceae and Asterace Aedes.The plant families with the best LC50 values against mosquitoes were Piperaceae and Annonaceae.Larvicidal activity of 50 acetogenins has already been identified on Ae.aegypti,and 29 of them presented LC50 below 10μg/mL,as well as the larvicidal activity of 8 compounds isolated from Piperaceae.Therefore,plants of these two families are promising for the development of commercial botanical larvicides in the form of extracts and isolated substances,as well as the production via organic synthesis of the most active compounds.

Phytochemical, Anti-oxidant, Larvicidal, and Antimicrobial Activities of Castor(Ricinus communis) Synthesized Silver Nanoparticles

Objective Castor possesses the medicinal properties. Hence, castor extract has the reducing power agent was used in nanoparticles synthesis. Extract of castor also produces secondary metabolites （phenolics, reducing agent） and exhibits anti-oxidant property, which was used as larvicide and antimicrobial agent. In the present study the silver nanoparticles （AgNPs） were synthesized using aqueous leaf extract of castor. Methods The synthesized AgNPs were characterized with UV-visible spectroscopy and transmission electron microscopy （TEM）. The phenolics, reducing sugar and total sugar were evaluated performing Folin-Ciocalteu reagent method, DNS method and Phenol-sulphuric acid method. Anti-oxidant activity of synthesized nanoparticles was evaluated using DPPH assay. The larvicidal activity of synthesized AgNPs was evaluated against the third instar of Anopheles stephensi and Aedes aegypti. The mortality was observed after 24 h by probit analysis. Further, the antimicrobial activity was reported against Staphylococcus aureus （Gram positive） and Pseudomonas aeruginosa （Gram negative）. Results The UV spectra showed maximum absorbance at 445 nm and TEM analysis indicated spherical shape of nanoparticles with average size of 8.96 nm. The synthesized nanoparticles also possessed anti-oxidant potentials. Thus, it could be used as potential free radical scavenger. The larvae of A. stephensiwere found more susceptible to AgNPs than larvae of A. aegyptL Conclusion Due to the medicinal properties and reducing power activity, in the present study AgNPs have been synthesized using the aqueous leaves extract of castor and access their phytochemical, anti-oxidant, larvicidal and antimicrobial properties.

Evaluations of larvicidal activity of medicinal plant extracts to Aedes aegypti （Diptera： Culicidae） and other effects on a non target fish

A preliminary study was conducted to investigate the effects of the extracts of 112 medicinal plant species, collected from the southern part of Thailand, on Aedes aegypti. Studies on larvicidal properties of plant extracts against the fourth instar larvae revealed that extracts of 14 species showed evidence of larvicidal activity. Eight out of the 14 plant species showed 100% mosquito larvae mortality. The LC50 values were less than 100μg/mL （4.1μg/ mL-89.4μg/mL）. Six plant species were comparatively more effective against the fourth instar larvae at very low concentrations. These extracts demonstrated no or very low toxicity to guppy fish （Poecilia reticulata）, which was selected to represent most common non-target organism found in habitats ofAe. aegypti, at concentrations active to mosquito larvae. Three medicinal plants with promising larvicidal activity, having LC50 and LC50 values being 4.1 and 16.4 μg/mL for Mammea siamensis, 20.2 and 34.7 μg/mL forAnethum graveolens and 67.4 and 110.3μg/mL forAnnona muricata, respectively, were used to study the impact of the extracts on the life cycle ofAe. aegypti. These plants affected pupal and adult mortality and also affected the reproductive potential of surviving adults by reducing the number of eggs laid and the percentage of egg hatchability. When each larval stage was treated with successive extracts at the LC50 value, the first instar larvae were found to be very susceptible to A. muricata and the second instar larvae were found to be susceptible to A. graveolens, while the third and fourth instar larvae were found to be susceptible to M. siamensis. These extracts delayed larval development and inhibited adult emergence and had no adverse effects on P. reticulata at LC50 and LC50 values, except for the M. siamensis extract at its LC50 value.

Mosquito larvicidal properties of Impatiens balsamina(Balsaminaceae)against Anopheles stephensi,Aedes aegypti and Culex quinquefasciatus(Diptera:Culicidae)

Objective:To assess the larvicidal potential of the crude benzene,chloroform,ethyl acetate and methanol solvent extracts of the medicinal plant Impatiens balsamina against Anopheles stephensi(An.stephensi),Aedes aegypti(Ae.aegypti)and Culex quinquefasciatus(Cx.quinquefasciatus).Methods:Twenty five third instar larvae of An.stephensi,Ae.aegypti and Cx.quinquefasciatus were exposed to various concentrations and were assayed in the laboratory by using the protocol recommended by WHO.The larval mortality was observed after 24 h of treatment.Results:Among extracts tested,the highest larvicidal activity was observed in leaf methanol extract of Impatiens balsamina against An.stephensi,Ae.aegypti and Cx.quinquefasciatus with the LC_(50)and LC_(90)values 98.04,119.68,125.06 and 172.93,210.14,220.60 mg/L,respectively.Conclusions:From the results it can be concluded that the larvicidal effect of Impatiens balsamina against An.stephensi,Ae.aegypti and Cx.quinquefasciatus make this plant product promising as an alternative to synthetic insecticide in mosquito control programs.

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 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.

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.

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.

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.