Evaluation of the larvicidal efficiency of stem,roots and leaves of the weed,Parthenium hysterophorus (Family: Asteraceae) against Aedes aegypti L.

ObjectiveTo assess the larvicidal potential of various extracts prepared from the stem, roots and leaves of Parthenium hysterophorus (P. hysterophorus) against 3rd and 4th instars of Aedes aegypti (Ae. aegypti).MethodsThe extracts from each part were prepared with four solvents; petroleum ether, hexane, acetone and diethyl ether. Each part was dried, powdered and soaked in different solvents, separately, for five days. The crude extracts thus formed were concentrated using rotary evaporator and stored as stock solution of 1 000 mg/L.ResultsAll the extracts prepared from the leaves were found ineffective against both the instars causing only 10%-40% mortality. Against 3rd instars, the hexane and petroleum ether extracts prepared from the stem of P. hysterophorus were found effective exhibiting LC₅₀ values of 379.76 and 438.57 mg/L, respectively. Likewise the hexane and petroleum ether extracts from the Parthenium roots resulted in LC₅₀ values of 432.38 and 562.50 mg/L, respectively, against 4th instars of Ae. aegypti revealing their larvicidal potential. It was further found that the hexane extracts, whether from roots or stem, were 13-28% more effective than the petroleum ether extracts. The qualitative phytochemical study of the effective extracts from the stems and roots showed the presence of alkaloids, saponins, terpenoids and flavonoids in different combinations.ConclusionsOur investigations demonstrated the potential of P. hysterophorus roots and stems against Ae. aegypti larvae and their benefits as new types of mosquito larvicides. Variety of types and levels of active constituents in each kind of extract may be responsible for the variability in their potential against Ae. aegypti. Further research is needed to identify these components.     

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

ObjectiveTo 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).MethodsThe larvicidal activity was assayed against three mosquito species at various concentrations ranging from (50-450 ppm) under the laboratory conditions. The LC₅₀ and LC₉₀ value of the O. thymiflorus leaf extract was determined by Probit analysis.ResultsThe 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.ConclusionsThe 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.     

Adulticidal properties of Pithecellobium dulce (Roxb.) Benth. (Family: Fabaceae) against dengue vector,Aedes aegypti (Linn.) (Diptera: Culicidae)

To examine the toxicity of mosquito adulticidal activity of different solvent leaf and seed extracts of Pithecellobium dulce (P. dulce) against dengue vector, Aedes aegypti (Ae. aegypti).MethodsAdulticidal efficacy of the crude leaf and seed extracts of P. dulce with five different solvents like benzene, hexane, ethyl acetate, methanol and chloroform was tested against the five to six day old adult female mosquitoes of Ae. aegypti. The adult mortality was observed after 24 h under the laboratory conditions.ResultsAmong the tested solvents the maximum efficacy was observed in the leaf and seed methanol extract. The LC₅₀ and LC₉₀ values of P. dulce leaf and seed extract against adults of Ae. aegypti were 218.64, 257.99 mg/L and 426.05, 507.73 mg/L, respectively. No mortality was observed in controls. The Chi-square values were significant at P<0.05 level.ConclusionsFrom the results it can be concluded the crude extract of P. dulce leaf and seed was an excellent potential for controlling dengue vector mosquito, Ae. aegypti.     

Clerodendron inerme Gaertn. plant as an effective natural product against dengue and filarial vector mosquitoes

ObjectiveTo investigate insecticidal properties of organic solvent extracts of Clerodendron inerme (C. inerme) leaves against larval stages of Aedes aegypti (Ae. aegypti) and Culex quinquefasciatus (Cx. quinquefasciatus) mosquito species.MethodsThe sundried leaf powder of C. inerme was subjected for extraction using organic solvents viz. methanol, chloroform, petroleum ether and hexane extract, and were tested against third/fourth instar larvae of Ae. aegypti and Cx. quinquefasciatus species in accordance with WHO standard methods. Experiments were conducted in four replicates with control group containing water alone and positive control group containing respective solvent (dimethylsulfoxide/acetone) used for dissolving the extracts.ResultsAmong the four solvent extracts, hexane extract has effective growth disruptive activity against Ae. aegypti, and showed positive tests for presence of four groups of phytochemical constituents viz. tanin, phytosteriod, terpenoid and cardiac glycoside. The hexane extract was tested against field collected filarial vector Cx. quinquefasciatus larvae for growth disruptive activity. Adult emergence inhibition values for 50 percent suppression (EI₅₀) of the tested population for methanol, chloroform, petroleum ether and hexane extracts treated against third instar larvae of Ae. aegypti were found to be 37.45, 14.79, 2.56 and 1.96 mg/L respectively, while hexane extract treated against Cx. quinquefasciatus was found to be equally effective with EI₅₀ value of 3.74 mg/L. Hexane extract treated against fourth instar larvae of Ae. aegypti and Cx. quinquefasciatus showed EI₅₀ values of 8.07 and 19.55 mg/L respectively in comparison with that of standard insect growth regulator methoprene demonstrating EI₅₀ value of 0.05 mg/L. Besides, the hexane extract was also found to possess toxic effect against non-target organism Gambusia affinis (a bio-control agent), however, the lethal concentration (LC₅₀=172.7 mg/L for 24 h) against Gambusia affinis was much higher in comparison with that of tested concentrations against Ae. aegypti and Cx. quinquefasciatus.ConclusionsWe conclude from the present investigation that the hexane extract of C. inerme has positive implications for its consideration in integrated control of dengue/filarial vectors due to their ecological distinctness in comparison with non-target organism and further due to ecofriendly nature of the extract in terms of easy biodegradability.     

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

ObjectiveThe 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).MethodsTwenty five early III instar 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.ResultsThe 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.ConclusionsFrom the results it can be concluded the crude extract of E. alba was an excellent potential for controlling Ae. aegypti mosquito.     

Mosquito larvicidal efficay of Acorus calamus extracts against Aedes aegypti L. larvae

ObjectiveTo evaluate the larvicidal activity of petroleum ether and ethyl alcohol extracts of Acorus calamus (A. calamus).MethodsPetroleum ether and ethyl alcohol extracts were extracted from plant materials through soxhlet extraction process and its efficacy was determined through bioassay method. Extracts were evaluated further for the determination of their LC₅₀ and LC₉₀ values. Observation of mortality response was assessed after 24 h.ResultsPetroleum ether and ethyl alcohol extracts of A. calamus produced 99% and 96% mortality at 125 mg/L respectively. Petroleum ether extract exhibited LC₅₀ at 57.32 mg/L, LC₉₀ at 120.13 mg/L, while ethyl alcohol extract exhibited LC₅₀ at 64.22 mg/L, LC₉₀ at 130.37 mg/L.ConclusionsPresent study indicated that A. calamus carries huge potential as a mosquito larvicide. This potential could be exploited for the development of safer and effective botanical mosquito larvicidal tool for the management of Aedes aegypti.     

Effect of niloticin,a protolimonoid isolated from Limonia acidissima L. (Rutaceae) on the immature stages of dengue vector Aedes aegypti L. (Diptera: Culicidae)

The aim of the present study was to evaluate the mosquitocidal activity of fractions and a compound niloticin from the hexane extract of Limonia acidissima L. leaves on eggs, larvae and pupae of Aedes aegypti L. (Diptera: Culicidae). In these bioassays, the eggs, larvae and pupae were exposed to concentrations of 2.5, 5.0, 7.5 and 10.0 ppm for fractions and 0.5, 1.0, 1.5 and 2.0 ppm for compound. After 24 h, the mortality was assessed and the LC₅₀ and LC₉₀ values were calculated for larvae and pupae. Per cent ovicidal activity was calculated for eggs after 120 h post treatment. Among the sixteen fractions screened, fraction 8 from the hexane extract of L. acidissima generated good mosquitocidal activity against Ae. aegypti. The LC₅₀ and LC₉₀ values of fraction 8 were 4.11, 8.04 ppm against Ae. aegypti larvae and 4.19, 8.10 ppm against Ae. aegypti pupae, respectively. Further, the isolated compound, niloticin recorded strong larvicidal and pupicidal activities. The 2 ppm concentration of niloticin showed 100% larvicidal and pupicidal activities in 24 h. The LC₅₀ and LC₉₀ values of niloticin on Ae. aegypti larvae were 0.44, 1.17 ppm and on pupae were 0.62, 1.45 ppm, respectively. Niloticin presented 83.2% ovicidal activity at 2 ppm concentration after 120 h post treatment and niloticin exhibited significant growth disruption and morphological deformities at sub lethal concentrations against Ae. aegypti. The structure of the isolated compound was identified on the basis of single XRD and spectral data (¹H NMR and ¹³C NMR) and compared with literature spectral data. The results indicate that niloticin could be used as a potential natural mosquitocide.     

Evaluation of Andrographis paniculata Burm.f. (Family:Acanthaceae) extracts against Culex quinquefasciatus (Say.) and Aedes aegypti (Linn.) (Diptera:Culicidae)

ObjectiveTo investigate the larvicidal and ovicidal efficacy of different extracts of Andrographis paniculata (A. paniculata) against Culex quinquefasciatus (Cx. quinquefasciatus) Say and Aedes aegypti (Ae. aegypti) L. (Diptera: Culicidae).MethodsLarvicidal efficacy of the crude leaf extracts of A. paniculata with five different solvents like benzene, hexane, ethyl acetate, methanol and chloroform was tested against the early third instar larvae of Cx. quinquefasciatus and Ae. aegypti. The ovicidal activity was determined against two mosquito species to various concentrations ranging from 50-300 ppm under the laboratory conditions.ResultsThe benzene, hexane, ethyl acetate, methanol and chloroform leaf extract of A. paniculata was found to be more effective against Cx. quinquefasciatus than Ae. aegypti. The LC₅₀ values were 112.19, 137.48, 118.67, 102.05, 91.20 ppm and 119.58, 146.34, 124.24, 110.12, 99.54 ppm respectively. Among five tested solvent, methanol and ethyl acetate crude extract was found to be most effective for ovicidal activity against two mosquito species. The extract of methanol and ethyl acetate exerted 100% mortality at 200 ppm against Cx. quinquefasciatus and at 250 ppm against Ae. aegypti.ConclusionsFrom the results it can be concluded the crude extract of A. paniculata was a potential for controlling Cx. quinquefasciatus and Ae. aegypti mosquitoes.     

Evaluation of larvicidal and pupicidal activity of Morinda citrifolia L. (Noni) (Family: Rubiaceae) against three mosquito vectors

ObjectiveTo evaluate the mosquito larvicidal and pupicidal activity against three important medically mosquito vector such as malarial vector, Anopheles stephensi (An. stephensi), dengue vector, Aedes aegypti (Ae. aegypti) and filarial vector Culex quinquefasciatus (Cx. quinquefasciatus).MethodsMorinda citrifolia (M. citrifolia) leaf was collected in and around Alleppy districts, Kerala, India. M. citrifolia leaf was washed with tap water and shade dried at room temperature. An electrical blender powdered the dried plant materials (leaves). From the leaf, 1 kg powdered was macerated with 3.0 L of methanol sequentially for a period 72 h and filtered. The crude plant extracts were evaporated to dryness in rotary vacuum evaporator. The larvicidal and pupicidal activity was assayed at various concentrations ranging from (100–500 ppm) under the laboratory as well as field conditions. The LC₅₀and LC₉₀value of the M. citrifolia leaf extract was determined by Probit analysis.ResultsThe plant extract showed larvicidal and pupicidal effects after 24 and 48 hrs of exposure; All larval instars and pupae have considerably moderate mortality; however, the highest larval and pupal mortality was methanolic extract of M. citrifolia observed in three mosquito vectors at 48 h. The LC₅₀and LC₉₀of M. citrifolia against the first to fourth instar larvae and pupae against mosquito vectors. An. stephensi had values of LC₅₀=146.08, 159.07, 172.16, 185.08 and 202.68 ppm and LC₉₀=322.12, 363.48, 388.56, 436.51 and 513.56 ppm, respectively. The Ae. aegypti had values of LC₅₀=181.27, 210.40, 229.80, 256.73 and 292.01 ppm and LC₉₀=407.99, 485.65, 534.14, 624.16 and 756.79 ppm, respectively. The Cx. quinquefasciatus had values of LC₅₀=226.70, 256.97, 290.05, 316.33 and 358.11 ppm and LC₉₀=560.35, 652.07, 733.03, 797.09 and 875.25 ppm, respectively at 24 h.ConclusionsThe results of the leaf extract of M. citrifolia are promising as good larvicidal and pupicidal activity against the mosquito vector, An. stephensi, Ae. aegypti, Cx. quinquefasciatus. This is a new eco-friendly approach for the control of vector control programs. Therefore, this study provides first report on the larvicidal and pupicidal activities against three species of mosquito vectors of this plant extract from India.     

Evaluation of larvicidal activity of the aerial extracts of a medicinal plant,Ammannia baccifera (Linn) against two important species of mosquitoes,Aedes aegypti and Culex quinquefasciatus

ObjectiveTo analyze the larvicidal effect of the aerial extracts of Ammannia baccifera on two important mosquito species, Aedes aegypti and Culex quinquefasciatus.MethodsThe larval mortality of fourth instar larvae of A. aegypti and C. quinquefasciatus after 24h and 48h of treatment were observed separately in control 50, 100, 150, 200, 250, 300, 350, 400, 450 and 500 mg/L concentrations of the aerial extracts (methanol, ethyl acetate, chloroform) of A. baccifera.ResultsBased on the probit analysis, the 24h and 48h aerial methanol extract of A. baccifera LC₅₀value of C. quinquefasciatus was found to be in 164.00 mg/L and 107.00 mg/L and LC₉₀values for C. quinquefasciatus was found be in 310.00 and 261.00 mg/L. The 24h and 48h aerial part of methanol extract of A. baccifera LC₅₀value of A. aegypti was found be in 226.00 mg/L and 186.00 mg/L and LC₉₀values was found be in 476.00 and 309.00 mg/L.ConclusionsThe results indicate that the A. baccifera could be effectively used for the control of mosquito larvae and the possibility of exploiting for the development of commercial larvicides a plant widely occurring in India.     

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

ObjectiveTo 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).MethodsIn 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.ResultsThe LC₅₀ value of the synthesised silver nano particle was identified as 0.585 and 0.891 mg/L for Ae. aegypti and Cx. quinquefasciatus larvae respectively. Further, the LC₉₀ 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 2θ 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.ConclusionsThe biosynthesis of silver nanoparticles with leaf aqueous extract of R. mucronata provides potential source for the larvicidal activity against mosquito borne diseases.     

Mosquitocidal properties of Morinda citrifolia L. (Noni) (Family: Rubiaceae) leaf extract and Metarhizium anisopliae against malaria vector,Anopheles stephensi Liston. (Diptera: Culicidae)

ObjectiveTo evaluate the mosquito larvicidal and pupicidal activity of the ethanolic extracts from Morinda citrifolia (M. citrifolia) plant and entomopathogenic fungi Metarhizium anisopliae (M. anisopliae) against malaria vector, Anopheles stephensi (An. stephensi).MethodsM. citrifolia leaves were collected in and around Alleppy districts, Kerala, India. M. citrifolia leaf was washed with tap water and shade dried at room temperature. An electrical blender powdered the dried plant leaves. A total of 500 g leaf powder was macerated with 1.5 L of ethanol sequentially for a period of 72 h and filtered. The crude plant extracts were evaporated to dryness in rotary vacuum evaporator. The larvicidal and pupicidal activity was assayed at various concentrations ranging from 100 to 500 mg/L under the laboratory conditions. The LC₅₀ and LC₉₀ values of the M. citrifolia leaf extract and M. anisopliae fungi were determined by Probit analysis.ResultsThe plant extract showed larvicidal and pupicidal effects after 24 and 48 h of exposure; all larval instars and pupae have considerably moderate mortality; however, the highest larval and pupal mortality appeared in combined treatment at 24 and 48 h. The LC₅₀ and LC₉₀ values of M. citrifolia and M. anisopliae and their combined treatment against the first to fourth instars larvae and pupae of the malaria vector were assessed. M. citrifolia had values of LC₅₀=202.47, 95.75, 57.52, 18.30 and 97.78 mg/L; LC₉₀=384.37, 482.91, 631.22, 757.55 and 944.96 mg/L at 48 h. M. anisopliae had values of LC₅₀=1.40, 3.99, 5.56, 8.77 and 11.49%; LC₉₀=13.84, 17.62, 22.20, 25.71 and 30.78% at 48 h; Combined treatment had values of LC₅₀=3.71, 16.73, 29.71, 40.60 and 138.10 mg/L; LC₉₀=122.29, 150.15, 156.90, 211.99 and 806.67 mg/L at 48 h, respectively.ConclusionsThe plant and the fungi are promising larvicidal and pupicidal agents against malaria vector, An. stephensi. This is a new eco-friendly approach for the control of vector. Therefore, this study provides first report on the combined treatment of this plant extract and fungi from India.     

Larvicidal and repellent activity of tetradecanoic acid against Aedes aegypti (Linn.) and Culex quinquefasciatus (Say.) (Diptera:Culicidae)

ObjectiveTo investigate the larvicidal and repellent efficacy of tetradecanoic acid against Aedes aegypti (Ae. aegypti) L. and Culex quinquefasciatus (Cx. quinquefasciatus) Say (Diptera: Culicidae).MethodsLarvicidal efficacy of tetradecanoic acid was tested at various concentrations against the early third instar larvae of Ae. aegypti and Cx. quinquefasciatus. The repellent activity was determined against two mosquito species at three concentrations viz., 1.0,2.5 and 5.0 ppm under the laboratory conditions.ResultsThe tetradecanoic acid was found to be more effective against Cx. quinquefasciatus than Ae. aegypti larvae. The LC₅₀ values were 14.08 ppm and 25.10 ppm, respectively. Tetradecanoic acid showed lesser repellency against Ae. aegypti and Cx. quinquefasciatus. The highest repellency was observed in higher concentration of 5.0 mg/cm² provided 100% protection up to 60 and 90 min against Ae. aegypti and Cx. quinquefasciatus respectively.ConclusionsFrom the results it can be concluded the tetradecanoic acid is a potential for controlling Cx. quinquefasciatus and Ae. aegypti mosquitoes.     

Adulticidal activity of Ageratum houstonianum Mill. (Asteraceae) leaf extracts against three vector mosquito species (Diptera: Culicidae)

ObjectiveTo determine the intrinsic toxicity of hexane, ethyl acetate and methanol crude extracts of Ageratum houstonianum leaves against adult Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus mosquitoes.MethodsBioassay was performed in 2-day-old laboratory reared unfed adult female mosquitoes by topical application at concentrations of 0.01, 0.05, 0.10, 0.25 and 0.50 μg/mg female adult mosquito.ResultsAedes aegypti was found to be more susceptible to ethyl acetate and hexane extracts with LD₅₀ value of 0.10 μg/mg, and both Anopheles stephensi and Culex quinquefasciatus were susceptible to methanol extract with LD₅₀ values of 0.12 μg/mg female adult mosquito.ConclusionsThe results show promising adulticidal activity on topical application and further studies followed by in-depth laboratory and field bioassays are needed to screen, isolate and purify bioactive phytochemical constituents or compounds.     

Bioactivity of sea grass against the malarial fever mosquito Culex quinquefasciatus

ObjectiveTo identify the larvicidal activity of the seagrass extracts against Culex quinquefasciatus (Cx. quinquefasciatus)MethodsSeagrass extracts, Halodule pinifolia (H. pinifolia), Cymodocea serrulata (C. serrulata) and Thalasia testudinum (T. testudinum) were dissolved in dimethylsulfoxide to prepare a graded series of concentration. Batches of 25 early 4th instars larvae of Cx. quinquefasciatus were transferred to 250 mL enamel bowl containing 199 mL of distilled water and 1 mL of plant extracts (0.01 mg−0.1 mg). After 24 h the mortality rate was identified with the formulae [(% of test mortality − % of control mortality)/(100 − % of control mortality)]×100. Each experiment was conducted with three replicates and a concurrent control group. A control group consisted of 1 mL of dimethylsulfoxide and 199 mL of distilled water only.ResultsThe root extract of H. pinifolia showed maximum larvicidal activity with minimum concentration of extract of LC₅₀ value of (0.614±0.006) μg/mL with lower confidence limit-upper confidence limit value of (0.052–0.072) and LC₉₀ value of 0.9120 μg/mL followed by leaf extract of C. serrulata LC₅₀ value of (0.074±0.008) μg/mL and LC₉₀ value of 0.1487 μg/mL. T. testudinum leaf extract showed LC₅₀ value of (0.082±0.006) μg/mL. The regression equation of root and leaf extract of H. pinifolia for 4 th instar larvae of Cx. quinquefasciatus were Y=5.229+1.36x (R²=0.993) and Y=2.369+1.21x (R²=0.878) respectively and analysis of variation was significant at P<0.05 level. The result of the preliminary phytochemical constituents showed the presence of saponin, steroids, terpenoid, phenols, protein and sugars.ConclusionsFrom the present study the ethanolic extracts of seagrass of H. pinifolia possess lead compound for development of larvicidal activity.     

Mosquitocidal properties of Solanum trilobatum L. (Solanaceae) leaf extracts against three important human vector mosquitoes (Diptera: Culicidae)

ObjectiveTo determine the larvicidal and pupicidal activites of Solanum trilobatum (S. trilobatum) leaf extracts against Aedes aegypti (Ae. aegypti), Culex quinquefasciatus (Cx. quinquefasciatus) and Anopheles stephensi (An. stephensi).MethodsThe larvicidal and pupucidal was determined at five different concentrations of 50, 100, 150, 200 and 250 ppm. Percentage of larval mortality was assessed after 48 h.ResultsMethanol extracts of S. trilobatum was found to be more susceptible against the larvae of Ae. aegypti, Cx. quinquefasciatus and An. stephensi at 250 ppm with a LC₅₀ value of 125.43, 127.77 and 116.64 ppm respectively. Leaf methanol extracts of S. trilobatum also exhibited pupicidal and adult emergence properties.ConclusionsThese results suggested that the leaf extracts of S. trilobatum showed potential to be used as an ideal ecofriendly approach for the control of the Ae. Aegypti, Cx. quinquefasciatus and An. stephensi.     

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

ObjectiveTo investigate the larvicidal and pupicidal activities of aqueous, ethyl acetate and methanol extracts of Catharanthus roseus (C. roseus) against malaria and filariasis vectors.MethodsThe 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 (LC₅₀ and LC₉₀) at which 50% and 90% of the treated larvae or pupae of the tested species were killed.ResultsThe 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 LC₅₀ 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 LC₅₀ 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 LC₅₀ 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.ConclusionsThe 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

ObjectiveTo evaluate the mosquito larvicidal activity of plant extracts.MethodsThe 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).ResultsThe 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 85.90 μg/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 78.28 μg/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 149.56 μg/mL, respectively.ConclusionsThese 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 activity of essential oil and methanol extract of Nepeta menthoides against malaria vector Anopheles stephensi

ObjectiveTo investigate the larvicidal activity of essential oil and methanol extract of the Nepeta menthoides (N. menthoides) against main malaria vector, Anopheles stephensi (An. stephensi).MethodsThe essential oil of plant was obtained by Clevenger type apparatus and the methanol extract was supplied with Percolation method. Larvicidal activity was tested by WHO method. Twenty five fourth-instar larvae of An. stephensi were used in the larvicidal assay and four replicates were tested for each concentration. Five different concentrations of the oil and extract were tested for calculation of LC₅₀ and LC₉₀ values.ResultsThe LC₅₀ and LC₉₀ values were determined by probit analysis. LC₅₀ was 69.5 and 234.3 ppm and LC₉₀ was 175.5 and 419.9 ppm for the extract and essential oil respectively.ConclusionsAccording to the results of this study methanolic extract of plant exhibited more larvicidal activity than essential oil. This could be useful for investigation of new natural larvicidal compounds.     

Larvicidal efficacy of Catharanthus roseus Linn. (Family: Apocynaceae) leaf extract and bacterial insecticide Bacillus thuringiensis against Anopheles stephensi Liston.

ObjectiveTo explore the larvicidal activity of Catharanthus roseus (C. roseus) leaf extract and Bacillus thuringiensis (B. thuringiensis) against the malarial vector Anopheles stephensi (An. stephensi), when being used alone or together.MethodsThe larvicidal activity was assayed at various concentrations under the laboratory and field conditions. The LC₅₀ and LC₉₀ values of the C. roseus leaf extract were determined by probit analysis.ResultsThe plant extract showed larvicidal effects after 24 h of exposure; however, the highest larval mortality was found in the petroleum ether extract of C. roseus against the first to fourth instars larvae with LC₅₀=3.34, 4.48, 5.90 and 8.17 g/L, respectively; B. thuringiensis against the first to fourth instars larvae with LC₅₀=1.72, 1.93, 2.17 and 2.42 g/L, respectively; and the combined treatment with LC₅₀=2.18, 2.41, 2.76 and 3.22 g/L, respectively. No mortality was observed in the control.ConclusionsThe petroleum ether extract of C. roseus extract and B. thuringiensis have potential to be used as ideal eco–friendly agents for the control of An. stephensi in vector control programs. The combined treatment with this plant crude extract and bacterial toxin has better larvicidal efficacy against An. stephensi.