Larvicidal and repellent potential of Moringa oleifera against malarial vector,Anopheles stephensi Liston(Insecta:Diptera:Culicidae)

Objective:To evaluate the larvicidal and pupicidal potential of the methanolic extracts from Moringa oleifera(M.oleifera) plant seeds against malarial vector Anopheles stephensi(A.stephensi) mosquitoes at different concentrations(20,40,60,80 and 100 ppm).Methods:M.oleifera was collected from the area of around Bharathiar University,Coimbatore.The dried plant materials were powdered by an electrical blender.From each sample,100 g of the plant material were extracted with 300 mL of methanol for 8 h in a Soxhlet apparatus.The extracts were evaporated to dryness in rotary vacuum evaporator to yield 122 mg and 110 mg of dark greenish material(residue) from Arcang amara and Ocimum basilicum,respectively.One gram of the each plant residue was dissolved separately in 100 mL of acetone(stock solution) from which different concentrations, i.e.,20,40,60,80 and 100 ppm were prepared.Results:Larvicidal activity of M.oleifera exhibited in the first to fourth instar larvae of the A.stephensi,and the LC_(50) and LC_(90) values were 57.79 ppm and 125.93 ppm for the first instar,63.90 ppm and 133.07 ppm for the second inslar,72.45 ppm and 139.82 ppm for the third instar,78.93 ppm and 143.20 ppm for the fourth instar,respectively. During the pupal stage the methanolic extract of M.oleifera showed that the LC_(50),and LC_(90) values were 67.77 ppm and 141.00 ppm,respectively.Conclusions:The present study indicates that the phytochemicals derived from M.oleifera seeds extracts are effective mosquito vector control agents and the plant extracts may be used for further integrated pest management programs.

Mosquito larvicidal and ovicidal properties of Eclipta alba(L.) Hassk(Asteraceae) against chikungunya vector,Aedes aegypti(Linn.)(Diptera:Culicidae)

Objective:The present study deals with the investigation of larvicidal and ovicidal activities of benzene,hexane,ethyl acetate,methanol and chloroform leaf extract of Eclipta alba（E.alba） against dengue vector,Aedes aegypti（Ae.Aegypti）.Methods:Twenty five earlyⅢinstar larvae of Ae.aegypti was exposed to various concentrations（50-300 ppm） and was assayed in the laboratory by using the protocol of WHO 2005;the 24 h LC50 values of the E.alba leaf extract was determined by Probit analysis.For ovicidal activity,slightly modified method of Su and Mulla was performed.The ovicidal activity was determined against Ae.aegypti to various concentrations ranging from 100-350 ppm under the laboratory conditions.The egg hatch rates were assessed 48 h post treatment.Results:The LC50 values of benzene,hexane,ethyl acetate,methanol and chloroform extract of E.alba against early third instar larvae of Ae.aegypti were 151.38,165.10, 154.88,127.64 and 146.28 ppm,respectively.Maximum larvicidal activity was observed in the methanol extract followed by chloroform,benzene,ethyl acetate and hexane extract.No mortality was observed in control.Among five solvent tested the methanol extract was found to be most effective for ovicidal activity against Ae.aegypti.The methanol extracts exerted 100%mortality （zero hatchability） at 300 ppm.Conclusions:From the results it can be concluded the crude extract of E.alba was an excellent potential for controlling Ae.aegypti mosquito.

Exploration of larvicidal and adult emergence inhibition activities of Ricinus communis seed extract against three potential mosquito vectors in Kolkata,India

Objective:To determine the larvicidal and adult emergence inhibition activities of castor （Ricinus communis） seed extract against three potential mosquito vectors Anopheles stephensi（An. slephensi）,Culex quinquefasciatus（Cx.quinquefasciatus） and Aedes albopictus（Ae.albopictus） in India.Methods:The R.communis seed extract was tested,employing WHO procedure,against fourth larval instars of the three mosquito species for 24 h and larval mortalities were recorded at various concentrations（2-64μg/mL）:the 24 h LC50 values of the R.communis seed extract were determined following Probit analysis.The larval killing,antipupation and adult emergence inhibition rates of the test extract,using a single concentration of 2μLC50,were studied at different time periods（24-72 h）:the extract toxicity was tested against a fish.Oreochromis niloticus（O.niloticus）.Results:The R.communis seed extract exhibited larvicidal effects with 100%killing activities at concentrations 32-64μg/mL,and with LC50 values 7.10.11.64 and 16.84μg/mL for Cx.quinquefasciatus,An.stephensi and Ae.albopictus larvae,respectively. When the larvae were treated with the extract at a single concentration of 2×LC50,significant differences were observed,compared to control groups,in rate of pupation（P【0.001） as well as in adult formation（P【0.001）.Conclusions:The present findings suggest that the R.communis seed extract provided an excellent potential for controlling An.stephensi,Cx.quinquefasciatus and Ae. albopictus mosquito vectors.

Chemical composition and larvicidal activity of leaf essential oil from Clausena anisata (Willd.) Hook.f.ex Benth (Rutaceae) against three mosquito species

Objective:To determine the mosquito larvicidal activity of leaf essential oil and their chemical constituents from Clausena anisata（C.anisata）（Willd.） Hook.f.ex Benth.against Culex quinquefasciatus,Aedes aegypti and Anopheles Stephensi.Methods:Essential oil was obtained by hydro-distillation and the chemical composition of the leaf essential oil was analyzed using gas chromatography—mass spectrometry.The mosquitoes were reared in the vector control laboratory and twenty lateⅢinstar larvae of three mosquito species were exposed to based on the wide range and narrow range tests,essential oil was tested at 50.100.150,200 and 250 ppm and each compound was tested at various concentration（5-75 ppm） and were assayed in the laboratory by using the protocol of WHO 2005:the 24 h LC50 values of the C.anisata leaf essential oil and their major compounds were determined following Probit analysis.Results:The oil contained were mainlyβ-pinene（32.8%）,sabinene（28.3%）,germacrene-D（12.7%）,estragole （6.4%） and linalool（5.9%）.The essential oil from the leaves of C.anisata exhibited significant larvicidal activity,with 24 h LC50 values of 140.96,130.19 and 119.59 ppm.respectively.The five pure constituents extracted from the C.anisata leaf essential oil were also tested individually against three mosquito larvae.The LC50 values ofβ-pinene,sabinene,germacrene-D,estragole and linalool appeared to be most effective against Anopheles stephensi(LC50-23.17,19.67,16.95. 11.01,35.17 ppm) followed by Aedes aegypti(LC50-27.69,21.20,18.76,12.70,38.64 ppm) and Culex quinquefasciatus(LC50-32.23,25.01.21.28,14.01,42.28).Conclusions:The essential oil of C. anisata contains five major compounds and has remarkable larvicidal properties,which may be considered as a potent source for the production of natural larvicides.

Larvicidal and repellent activities of Sida acuta Burm.F.(Family:Malvaceae) against three important vector mosquitoes

Objective:To determine the larvicidal and repellent activities of Sida acuta Burm.F.（Family: Malvaceae）extract against Culex quinquefasciatus,Aedes aegypti and Anopheles stephensi. Methods:Twenty five late III instar larve of three mosquito species were exposed to various concentrations（15-90 mg/L） and were assayed in the laboratory by using the protocol of WHO 2005:the 24 h LC50 values of the Sida acuta leaf extract was determined following Probit analysis. The repellent efficacy was determined against three mosquito species at three concentrations viz.,1.0,2.5 and 5.0 mg/cm2 under the laboratory conditions.Results:Results showed varying degree of larvicidal activity of crude extract of Sida acuta against three important mosquitoes with LC50 values ranging between 38 to 48 mg/L.The crude extract had strong repellent action against three species of mosquitoes as it provided 100%protection against Anopheles stephensi for 180 min followed by Aedes aegypti（150 min） and Culex quinquefasciatus（120 min）.Conclusions: From the results it can be concluded the crude extract of Sida acuta was an excellent potential for controlling Culex quinquefasciatus,Aedes aegypti and Anopleles stephensi mosquitoes.

Larvicidal and repellent activity of medicinal plant extracts from Eastern Ghats of South India against malaria and filariasis vectors

Objective:To evaluate the larvicidal and repellent activities of ethyl acetate and methanol extracts of Acacia concinna（A.concinna）,Cassia siamea（C.siamea）.Conundrum sativum（C. sativum）,Cuminum cyminum（C.cyminum）,Lantana camma（L.camara）,Nelumbo nucifera （N.nucifera） Phyllanlhus amarus（P.amarus）.Piper nigrum（P.nigrum） and Trachyspermum ammi（T.ammi） against Anopheles stephensi（An.stephensi） and Culex quinquefasciatus（Cx. quinquefasciatus）.Methods:The larvicidal activity of medicinal plant extracts were tested against earl) fourth-instar larvae of malaria and filariasis vectors.The mortality was observed 24 h and 48 h after treatment,data were subjected to probit analysis to determine the lethal concentrations(LC50 and LC90) to kill 50 and 90 per cent of the treated larvae of the tested species. The repellent efficacy was determined against two mosquito species at five concentrations（31.25. 62.50.125.00.250.00,and 500.00 ppm） under the laboratory conditions.Results:All plant extracts showed moderate effects after 24 h and 48 h of exposure;however,the highest activity was observed after 24 h in the leaf methanol extract ol N.nucifera.seed ethyl acetate and methanol extract of P.nigrum against the larvae of An.Stephensi(LC50 = 34.76.24.54 and 30.20 ppm) and against Cx.quinquefasciatus(LC50= 37.49.43.94 and 57.39 ppm),respectively.The toxic effect of leaf methanol extract of C.siamea,seed methanol extract of C.cyminum,leaf ethyl acetate extract of N.nucifera.leaf ethyl acetate and methanol extract of P.amarus and seed methanol extract of T.ammi were showed 100%mortality against An.stephensi and Cx.quinquefasciatus alter 48 h exposer.The maximum repellent activity was observed at 500 ppm in methanol extracts of N. nucifera.ethyl acetate and methanol extract of P.nigrum and methanol extract of T.ammi and the mean complete protection time ranged from 30 to 150 min with the different extracts tested. Conclusions:These results suggest that the leaf and seed extracts of C.siamea.N.nucifera.P. amarus.P.nigrum and T.ammi have the potential to be used as an ideal ecofriendly approach for the control of the An.stephensi and Cx.quinquefasciatus.

Larvicidal and repellent properties of some essential oils against Culex tritaeniorhynchus Giles and Anopheles subpictus Grassi(Diptera:Culicidae)

Objective:To investigate the larvicidal and repellent properties of essential oils from various parts of four plant species Cymbopogan citrates,Cinnamomum zeylanicum,Rosmarinus of ficinalis and Zingiber of ficinale against Culex tritaeniorhynchus（Cx.tritaeniorhynchus） and Anopheles subpictus（An.subpktus）.Methods:Essential oils were obtained by hydro-distillation method.The mosquitoes were reared in the vector control laboratory and twenty five late third ins tar larvae of Cx.tritaeniorhynchus and An.subpictus were exposed to based on the wide range and narrow range test,essential oil tested at various concentrations ranging from 25 to 250 ppm.The larval mortality was observed after 24 h under the laboratory conditions.The repellent efficacy was determined against two mosquito species at three concentrations viz., 1.0,2.5 and 5.0 mg/cm2 under laboratory conditions.Results:Results showed all the four plant essential oil produced significant larval mortality against two mosquito species.However,the highest larvicidal activity was observed in the essential oil from Zingiber of ficinale against Cx. tritaeniorhynchus and An.subpktus with the LC50 and LC90 values as 98.83,57.98 ppm and 186.55, 104.23 ppm,respectively.All the four essential oil shows significant repellency against Cx. tritaeniorhynchus than An.subpktus.Among four essential oil tested the highest repellency was observed in Zingiber of ficinale,a higher concentration of 5.0 mg/cm2 provided 100%protection up to 150 and 180 min against Cx.tritaeniorhynchus and An.subpktus,respectively.Conclusions: In this work,it can be concluded that four essential oils which were distilled from Cymbopogan citrates,Cinnamomum zeylanicum,Rosmarinus of ficinalis and Zingiber of ficinale showed promising larvicidal and repellent agent against Cx.tritaeniorhynchus and An.subpktus.

Jatropha curcas L: Phytochemical, antimicrobial and larvicidal properties

Objective: To evaluate antimicrobial activities as well as the phytochemical and lavicidal properties of different parts of Jatropha curcas L.(J. curcas) growing in Mauritius.Methods: Determination of the presence of phytochemicals in the crude plants extracts by test tube reactions. Disc diffusion method and microdilution method were used to detect the antimicrobial sensitivity and activity(minimal inhibitory concentration). The crude solvent extracts were also tested on the larvae of two insects, Bactrocera zonata and Bactrocera cucurbitae(Diptera, Tephritidae).Results: The antimicrobial activities were significantly dependent for the different crude plant extracts on the thirteen microorganisms tested. For the Gram-positive bacteria, the crude ethyl acetate extract was more efficient compared to the Gram-negative bacteria with both solvents being effective. The crude ethyl acetate extract of J. curcas bark and mature seed oil showed the highest efficacy. The highest mortality percentage was observed after 24 h for both Diptera flies with(66.67 ± 2.89)% of Bactrocera cucurbitae larvae killed by ethyl acetate extract of J. curcas bark.Conclusions: This paper compared the different J. curcas plant sections with respect to the effectiveness of the plant as a potential candidate for new pharmaceuticals. The larvicidal effect was also studied in order to demonstrate the dual purpose of the plant.

Mosquito larvicidal and pupicidal activity of Euphorbia hirta Linn.(Family:Euphorbiaceae) and Bacillus sphaericus against Anopheles stephensi Liston.(Diptera:Culicidae)

Objective:To explore the larvicidal and pupicidal activity of Euphorbia hirta（E.hirta） leaf extract and Bacillus sphaericus（B.sphaericus） against the malarial vector.Anopheles siephensi（An. stephensi）.Methods:The larvicidal and pupicidal activity was assayed against An.stephensi at various concentrations ranging from（75-375 ppm） under the laboratory as well as field conditions. The LC50 and LC90 value of the E.hirta leaf extract was determined by probit analysis.Results: The plant extract showed larvicidal effects after 24 h of exposure;however,the highest larval mortality was found in the methanol extract of E.hirta against the first to fourth instars larvae and pupae of values LC50=137.40,172.65,217.81,269.37 and 332.39 ppm;B.sphaericus against the first to fourth instars larvae and pupae of values LC50= 44.29,55.83,68.51,82.19 and 95.55 ppm, respectively.Moreover,combined treatment of values of LC50= 79.13,80.42,86.01,93.00 and 98.12 ppm,respectively.No mortality was observed in the control.Conclusions:These results suggest methanol leaf extracts of E.hirta and B.sphaericus have potential to be used as an ideal ecofriendly approach for the control of the malarial vector.An.stephensi as target species of vector control programs.This study provides the first report on the combined mosquito larvicidal and pupicidal activity of this plant crude extract and bacterial toxin against An.stephensi mosquitoes.

Larvicidal activity of Dregea volubilis and Bombax malabaricum leaf extracts against the filarial vector Culex quinquefasciatus

Objective:To analyze the larvicidal activity of two plant leaf powder and leaf-extracts, Dregea volubilis and Bombax malabaricum against Culex quinquefasciatus.Methods:The larvicidal bioassay was done for powdered leaves of Dregea volubilis and Bombax malabaricum individually and their methanol extracts against first-,second-,third- and fourth-instar larval forms of Culex quinquefasciatus.Mortality rate was recorded after 24,48 and 72 h of postexposure. LC50 and LG90 values were calculated at different time intervals for third instar larvae. Results:All the graded concentration（0.1%,0.2%,0.3%,0.4%,0.5%） of powdered leaves showed significant（P 【0.05） larval mortality.The mortality rate was higher in 50 ppm doses of methanolic extracts of both the plants against Culex quinquefaciatus.The corresponding 【C50 values were 56.97 ppm and 48.85 ppm,respectively after 24 h of exposure.There is no mortality of non-target organism such as Chironomous circumdatus,Oreochromis niloticus niloticus and Diplonichus annulatum within 72 h of post exposure to 0.1%,0.2%,0.3%crude powdered leaves and methanolic extracts of both the two individual plants under the laboratory condition.The results of preliminary qualitative phytochemical analysis of both the plants revealed the presence of many bioactive principles such as steroids,tannins,flavonoids,triterpenoids,saponins,etc. that may be responsible for their bio-control potentiality.Conclusions:The results have shown potential and eco-friendly use of both plant extracts against larva of Culex quinquefasciatus for the first time.

A comparative study of the ovicidal and larvicidal activities of aqueous and ethanolic extracts of pawpaw seeds Carica papaya(Caricaceae) on Heligmosomoides bakeri

Objective:To assess the ovicidal and larvicidal activities of aqueous and ethanolic extracts of pawpaw seeds Carica papaya（Caricaceae） on the eggs and first stage larvae（L1） of Heligmosomoides bakeri.Methods:Eggs of this parasite were obtained from experimentally infested mice（Mus musculus） and larvae were from eggs after incubation at 25℃for about 72 hours.The eggs and larvae were exposed to ten different concentrations（0.125,0.25,0.375,0.5, 0.75,1.0,1.25,1.75,2.25 and 2.75 mg/mL） of both aqueous and ethanolic extracts respectively for 72 hours.Distilled water and 0.05%ethanol used as placebo and negative control,respectively. Results:Placebo and negative control group all showed average 92%embryonnation,98%egg hatching and 2%larval mortality,and did not affect development and larval survival.The extracts inhibited embryonic development,egg hatching and larval survival.In general,the ovicidal and larvicidal activities increased with increasing concentration of different extracts.The aqueous extract was found to be more potent on eggs than on larvae.At 2.75 mg/mL,only 8%of eggs embryonnated and 50%hatched to L1 vs 57%embryonic development and 79%hatching occurred in the ethanolic extract.However,this later extract was more efficient in preventing larval development producing 96%mortality as against 68%with the aqueous extract.Conclusions: These results shows the ovicidal and larvicidal properties of aqueous and ethanolic pawpaw seeds extracts.

Mosquito larvicidal properties of Ficus henghalensis L.(Family:Moraceae) against Culex tritaeniorhynchus Giles and Anopheles subpictus Grassi(Diptera:Culicidae)

Objective:To determine the larvicidal efficacy of different solvent leaf extract of Ficus benghalensis（F.benghalensis） against Culex tritaeniorhynchus（Cx.tritaeniorhynchus） and Anopheles subpictus（An.subpictus）.Methods:Twenty five early third instar larvae of Cx. tritaeniorhynchus and An.subpictus were exposed to various concentrations and were assayed in the laboratory by using the protocol of WHO 2005.The larval mortality was observed after 24 h of treatment.Results:Among three solvent extracts tested the maximum efficacy was observed in the methanol extract.The LC50 and LC90 values of F.benghalensis against early third instar of Cx. tritaeniorhynchus and An.subpictus were 100.88.159.76 ppm and 56.66.85.84 ppm.respectively. No mortality was observed in controls.The chi-square values were significant at P【0.05 level. Conclusions:From the results it can be concluded the crude extract of F.benghalensis was an excellent potential for controlling Cx.tritaeniorhynchus and Art.subpictus mosquito larvae.

Biosynthesis of silver nanoparticles by using mangrove plant extract and their potential mosquito larvicidal property

Objective:To identify the larvicidal activities of silver nano particles synthesised with Rhizophora mucronata（R.mucronata） leaf extract against the larvae of Aedes aegypti（Ae.aegypti） and Culex quinquefasciatus（Cx.quinquefasciatus）.Methods:In vitro larvicidal activities such as LC50 and LC90 were assessed for the Ae.aegypti and Cx.quinquefasciatus larval species.Further, characterisation such as UV,XRD,FTIR and AFM analysis were carried out for the synthesised silver nano particles.Results:The LC50 value of the synthesised silver nano particle was identified as 0.585 and 0.891 mgg/L for Ae.aegypti and Cx.quinquefasciatus larvae respectively. Further,the LG90 values are also identified as 2.615 and 6.291 mg/L for Ae.aegypti and Cx. quinquefasciatus species respectively.The synthesised silver nanoparticles have maximum absorption at 420 nm with the average size of 60-95 nm.The XRD data showed 20 intense values with various degrees such as 37.10°,47.66°,63.97°and 70.01°.The FTIR data showed prominent peaks in（3 426.89,2 925.49,2 869.56,2 346.95,1 631.49,1 031.73,669.18 and 455.12） different ranges.Conclusions:The biosynthesis of silver nanoparticles with leaf aqueous extract of R. mucronata provides potential source for the larvicidal activity against mosquito borne diseases.

Larvicidal and irritant activities of hexane leaf extracts of Citrus sinensis against dengue vector Aedes aegypti L.

Objective:To assess the larvicidal and irritant activities of the hexane extracts of leaves of Citrus sinensis(C.sinensis)against the early fourth instars and female adults of Aedes aegypti(Ae.aegypti).Methods:The larvicidal potential of the prepared leaf extract was evaluated against early fourth instar larvae of Ae.aegypli using WHO protocol.The mortality counts were made after 24 h and LC_(50)and LG_(50)values were calculated.The efficacy of extract as mosquito irritant was assessed by contact irritancy assays.Extract-impregnated paper was placed on a glass plate over which a perspex funnel with a hole on the top was kept inverted.Single female adult,3-day old unfed/blood-fed,was released inside the funnel.After 3 min of acclimatization time,the time taken for the first take-off and total number of flights undertaken during 15 min were scored.Results:The citrus leaf extracts from hexane possessed moderate larvicidal efficiency against dengue vector.The bioassays resulted in an LC_(50)and LC_(90)value of 446.84 and 1370.96 ppm,respectively after 24 h of exposure.However,the extracts were proved to be remarkable irritant against adults Ae.aegypti,more pronounced effects being observed on blood-fed females than unfed females.The extract-impregnated paper was thus proved to be 7-11 times more irritable as compared with the control paper.Conclusions:The hexane extracts from C.sinensis leaves are proved to be reasonably larvicidal But remarkably irritant against dengue vector.Further studies are needed to identify the possible role of extract as adulticide,oviposition deterrent and ovicidal agent.The isolation of active ingredient from the extract could help in formulating strategies for mosquito control.

Mosquito larvicidal properties of Orthosiphon thymiflorus(Roth)Sleesen.(Family:Labiatae)against mosquito vectors,Anopheles stephensi,Culex quinquefasciatus and Aedes aegypti(Diptera:Culicidae)

Objective:To determine the mosquito larvicidal activities of hexane,chloroform,ethyl acetate, acetone and methanol leaf extract of Orthosiphon thymiflorus（O.thymiflorus） against Anopheles stephensi（An.stephensi）,Culex quinquefasciatus（Cx.quinquefasciatus） and Aedes aegypti （Ae.aegypti）.Methods:The larvicidal activity was assayed against three mosquito species at various concentrations ranging from（50-450 ppm） under the laboratory conditions.The LC50 and LC90value of the O.thymiflorus leaf extract was determined by Probit analysis.Results:The LC50 values of hexane,chloroform,ethyl acetate,acetone and methanol extract of O.thymiflorus third instar larvae of An.stephensi were LC50= 201.39,178.76,158.06,139.22 and 118.74 ppm; Cx.quinquefasciatus were LC50=228.13,209.72.183.35,163.55 and 149.96 ppm and Ae.aegypti were LC50=215.65,197.91,175.05,154.80 and 137.26 ppm,respectively.Maximum larvicidal activity was observed in the methanolic extract followed by acetone,ethyl acetate chloroform and hexane extract.The larval mortality was observed after 24 h exposure.No mortality was observed in control.Conclusions:The present results suggest that the effective plant crude extracts have potential to be used as an ideal eco-friendly approach for the control of mosquito vectors.This study provides the first report on the larvicidal activity of this plant crude solvent extract of against An.stephensi,Cx.quinquefasciatus and Ae.aegypti mosquitoes.

Efficacy of larvicidal and pupicidal activity of Catharanthus roseus aqueous and solvent extracts against Anopheles stephensi Liston and Culex quinquefasciatus Say (Diptera: Culicidae)

Objective: To investigate the larvicidal and pupicidal activities of aqueous, ethyl acetate and methanol extracts of Catharanthus roseus ( C. roseus ) against malaria and filariasis vectors. Methods: The larvicidal and pupicidal activities of C. roseus leaf extracts were tested against the fourth instar larvae and pupae of Anopheles stephensi ( An. stephensi ) and Culex quinquefasciatus ( Cx. quinquefasciatus ). The mortality was observed after 24 and 48 h post the treatment. The data were subjected to probit analysis to determine the lethal concentrations (LC 50 and LC 90 ) at which 50% and 90% of the treated larvae or pupae of the tested species were killed. Results: The larval and pupal mortality were observed after 24 and 48 h of exposure of aqueous, ethyl acetate and methanol extracts of C. roseus ; no mortality was observed in the control group. The LC 50 values against the fourth-instar larvae of An. stephensi were 68.62 and 72.04 mg/mL for the aqueous extract, 82.47 mg/mL for the ethyl acetate extract, and 78.80 and 86.64 mg/mL for the methanol extract, while the aqueous, ethyl acetate and methanol extracts had LC 50 values of 85.21, 76.84 and 94.20 mg/mL against the fourth-instar larvae of Cx. quinquefasciatus . The aqueous, ethyl acetate and methanol extracts had LC 50 values of 118.08, 182.47 and 143.80 mg/mL against the pupae of An. stephensi and 146.20, 226.84 and 156.62 mg/mL against the pupae of Cx. quinquefasciatus , respectively. Conclusions: The aqueous and methanol extracts of C. roseus leaves had an excellent potential to control the malarial vector An. stephensi and filariasis vector Cx. quinquefasciatus .

Evaluation of larvicidal activity of medicinal plant extracts against three mosquito vectors

Objective:To evaluate the mosquito larvicidal activity of plant extracts.Methods:The hexane,chloroform,ethyl acetate,acetone,and methanol leaf,flower and seed extracts of Abrus precatorius（A.precatorius）,Croton bonplandianum（C.bonplandianum）,Cynodon dactylon （C.dactylon）,Musa paradisiaca（M.paradisiaca） and Syzygium aromaticum（S.aromaticum） were tested against fourth instar larvae of Anopheles vagus（An.vagus）,Armigeres subalbatus （Ar.subalbatus） and Culex vishnui（Cx.vishnui）.Results:The highest larval mortality was found in seed ethyl acetate extracts of A.precatorius and leaf extracts of C.bonplandianum, flower chloroform and methanol extracts of M.paradisiaca,and flower bud hexane extract of S. aromaticum against An.vagus with LC50 values of 19.31,39.96,35.18,79.90 and 85.90μg/mL;leaf ethyl acetate and methanol extracts of C.dactylon,flower methanol extract of M.paradisiaca, flower bud methanol extract of S.aromaticum against Ar.subalbatus with LC50 values of 21.67, 32.62,48.90 and 78.28μg/mL,and seed methanol of A.precatorius,flower methanol extract of M.paradisiaca,flower bud hexane extract of S.aromaticum against Cx.vishnui with LC50 values of 136.84,103.36 and 149.56μg/mL,respectively.Conclusions:These results suggest that the effective plant crude extracts have the potential to be used as an ideal ecofriendly approach for the control of disease vectors.This study provides the first report on the larvicidal activity of crude solvent extracts of different mosquitoes.

Larvicidal,ovicidal and pupicidal activities of Gliricidia sepium(Jacq.)(Leguminosae) against the malarial vector,Anopheles stephensi Liston(Culicidae:Diptera)

Objective:To investigate the potentiality of mosquitocidal activity of Gliricidia sepium（C.sepium） （Jacq.）（Leguminosae）.Methods:Twenty five early third instar larvae of Anopheles stephensi （An.stephensi） were exposed to various concentrations（50-250 ppm） and the 24 h LC50 values of the G.sepium extract was determined by probit analysis.The ovicidal activity was determined against An.stephensi to various concentrations ranging from 25-100 ppm under laboratory conditions.The eggs hatchabilily was assessed 48 h post treatment.The pupicidal activity was determined against An.stephensi to various concentrations ranging from 25-100 ppm.Mortality of each pupa was recorded after 24 h of exposure to the extract.Results:Results pertaining to the experiment clearly revealed that ethanol extract showed significant larvicidal,ovicidal and pupicidal activity against the An.stephensi.Larvicidal activity of ethanol extracts of G.sepium showed maximum mortality in 250 ppm concentration（96.0±2.4）%.Furthermore,the LC50 was found to be 121.79 and the LC50 value was recorded to be 231.98 ppm.Ovicidal activity of ethanol extract was assessed by assessing the egg hatchabilily.Highest concentration of both solvent extracts exhibited 100%ovicidal activity.Similarly,pupae exposed to different concentratioiLs of ethanol extract were found dead with 58.10%adult emergence when it was treated with 25 ppm concentration.Similarly,18.36（n=30;61.20%）;21.28（70.93） and 27.33（91.10） pupal mortality was recorded from the experimental pupae treated with 50,75 and 100 ppm concentration of extracts. Three fractions have been tested for their larvicidal activity of which the Fraction 3 showed the LC50 and LC90 values of 23.23 and 40.39 ppm.With regard to the ovicidal effect fraction 3 showed highest ovicidal activities than the other two fractions.Furthermore,there were no hatchabilily was recorded above 50 ppm（100%egg mortality） in the experimental group.Statistically significant pupicidal activity was recorded from 75 ppm concentration.Conclusions:From the results it can be concluded the crude extract of G.sepium is an excellent potential for controlling An.stephensi mosquito.It is apparent that,iraction 3 possess a novel and active principle which could be responsible for those biological activities.

In vitro larvicidal potential against Anopheles stephensi and antioxidative enzyme activities of Ginkgo biloba,Stevia rebaudiana and Parthenium hysterophorous

Objective:To investigate in vitro larvicidal and antioxidant enzymes potential of the medicinal plants Ginkgo biloba（G.biloba）,Stevia rebaudiana（S.rebaudiana） and Parthenium hysterophorous（P.hysterophorous） against Anopheles stephensi（An.stephensi） 4th instars larvae. Methods:For evaluation of larvicidal potential,the ethanolic,methanolic and dichloromethane leaves extracts of three different plants were used in dose-dependent experiments in two media, while the antioxidant enzymes activities were investigated using four different methods viz., superoxide dismutase,peroxidase,ascorbate and catalase.Results:An.stephensi has developed resistance to various synthetic insecticides,making its control increasingly difficult.The comparative performance of ethanolic extracts（65%-90%） was found better than the methanolic extract（70%-87%） and dichloromethane extract（60%-70%）.Among the three plants extracts tested in two media,S.rebaudiana exhibited higher larvicidal activity with LC50（24 h） in methanolic extract than P.hysterophorous and G.biloba.G.biloba and P.hysterophorous exhibited the strongest antioxidative enzymes activity and S.rebaudiana were less active and no significant difference was observed.Conclusions:These three plants exhibit larvicidal potential and can be further used for vector control alternative to synthetic insecticide due to eco-friendly and diseases control,furthermore these plant species have potent antioxidative enzyme activities, therefore,making them strong natural candidate particularly for diseases which are caused due to free radicals.

Larvicidal efficacy of crude and fractionated extracts of Dracaena loureiri Gagnep against Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Anopheles minimus mosquito vectors

Objective:To evaluate the larvicidal efficacy of crude and fractionated extracts of Dracaena loureiri endocarp against Aedes aegypti,Aedes albopictus,Culex quinquefasciatus,and Anopheles minimus mosquitos.Methods:Larvicidal activity was tested according to World Health Organization standard protocol.The third-stage larvae of each mosquito species were exposed to various concentrations of Dracaena loureiri crude extract and six groups of Dracaena loureiri fractionated extracts(RC-DT 009-014).Larval mortality rates were observed after 24 h and48 h of exposure.Then,a computerized probit analysis of the mortality data was performed to determine lethal concentration 50(LC_(50))and lethal concentration 90 values.Results:Anopheles minimus larvae(24-h LC_(50)77.88 mg/L)had the highest susceptibility to crude extract,whereas others(Aedes aegypti,24-h LC_(50)224.73 mg/L;Aedes albopictus,24-h LC_(50)261.75 mg/L;and Culex quinquefasciatus,24-h LC_(50)282.86 mg/L)were significantly less susceptible.The most effective groups of fractionated extracts were RC-DT 012 and RC-DT 013.The mosquito species most susceptible to fractionated extracts was Culex quinquefasciatus,with 24-h LC_(50)values of 0.66 and 0.94 mg/L for RC-DT 012 and RC-DT 013,respectively.Conclusions:The larvicidal activity of fractionated extracts is more effective than that of crude extract against all tested mosquito species.For the most effective alternative larvicide,purification and a phytochemical constituent analysis must be performed.