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.     

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 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.     

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.     

Larvicidal activity of Persea americana Mill. against Aedes aegypti

ObjectiveTo evaluate the toxicity of the ethanol and hexane extracts of the different parts of Persea americana Mill. (P. americana) toward third and fourth instars larvae of Aedes aegypti (Ae. aegypti) and to characterize the ethanol extract by qualitative phytochemical analysis.MethodsThe seeds, peels and pulp of P. americana were processed for crude extraction using 95% ethanol and n-hexane. Crude extracts were bio-assayed for larvicidal activity against Ae. aegypti following the World Health Organization standard bioassay method. The mortality was observed at 24 h and 48 h after treatment and data were subjected to probit analysis to determine lethal concentrations (LC₅₀ and LC₉₀). The ethanol extract was characterized by phytochemical analysis.ResultsBoth the hexane and ethanol extracts from the different parts of P. americana exhibited evidence of larvicidal toxicity. The hexane extract from the seeds exhibited the highest toxicity with LC₅₀ and LC₉₀ values of 9.82 mg/L and 22.19 mg/L, respectively, while the ethanol seed extract exhibited LC₅₀ of 16.48 mg/L and LC₉₀ 45.77 mg/L, respectively. This was closely followed by the ethanol extract of the peels with an LC₅₀ of 10.35 mg/L and LC₉₀ of 26.29 mg/L. The pulp extracted with ethanol also yielded great larvicidal toxicity with LC₅₀ of 21.32 mg/L and LC₉₀ of 59.45 mg/L. Results of the phytochemical analysis of the ethanol seed extract indicated presence of alkaloids, tannins, saponins, unsaturated steroids and triterpenoids, flavonoids (leucoanthocyanins), fats and oils.ConclusionsBoth the hexane and ethanol extracts of P. americana showed promising potential as an alternative source of a more sustainable, non-toxic and environmentally friendly solution for the control of dengue vector, Ae. aegypti.     

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

ObjectiveTo evaluate the larvicidal and repellent activities of ethyl acetate and methanol extracts of Acacia concinna (A. concinna), Cassia siamea (C. siamea), Coriandrum sativum (C. sativum),Cuminum cyminum (C. cyminum), Lantana camara (L. camara), Nelumbo nucifera (N. nucifera) Phyllanthus amarus (P. amarus), Piper nigrum (P. nigrum) and Trachyspermum ammi (T. ammi) against Anopheles stephensi (An. stephensi) and Culex quinquefasciatus (Cx. quinquefasciatus).MethodsThe larvicidal activity of medicinal plant extracts were tested against early 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.ResultsAll 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 of 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 after 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.ConclusionsThese 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 activity of Dregea volubilis and Bombax malabaricum leaf extracts against the filarial vector Culex quinquefasciatus

ObjectiveTo analyze the larvicidal activity of two plant leaf powder and leaf-extracts, Dregea volubilis and Bombax malabaricum against Culex quinquefasciatus.MethodsThe 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 post-exposure. LC₅₀ and LC₉₀ values were calculated at different time intervals for third instar larvae.ResultsAll 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 LC₅₀ 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.ConclusionsThe results have shown potential and eco-friendly use of both plant extracts against larva of Culex quinquefasciatus for the first time.     

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.     

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

ObjectiveTo explore the larvicidal and pupicidal activity of Euphorbia hirta (E. hirta) leaf extract and Bacillus sphaericus (B. sphaericus) against the malarial vector, Anopheles stephensi (An. stephensi).MethodsThe 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.ResultsThe 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.ConclusionsThese results suggest methanol leaf extracts of E. hirta and B. sphaericus have potential to be used as an ideal eco-friendly 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 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.     

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.     

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

ObjectiveTo investigate the potentiality of mosquitocidal activity of Gliricidia sepium (G. sepium) (Jacq.) (Leguminosae).MethodsTwenty 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 hatchability 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.ResultsResults 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 LC₉₀ value was recorded to be 231.98 ppm. Ovicidal activity of ethanol extract was assessed by assessing the egg hatchability. Highest concentration of both solvent extracts exhibited 100% ovicidal activity. Similarly, pupae exposed to different concentrations 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 hatchability was recorded above 50 ppm (100% egg mortality) in the experimental group. Statistically significant pupicidal activity was recorded from 75 ppm concentration.ConclusionsFrom 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, fraction 3 possess a novel and active principle which could be responsible for those biological activities.     

Larvicidal activity of Wrightia tinctoria R. BR. (Apocynaceae) fruit and leaf extracts against the filarial vector Culex quinquefasciatus Say (Diptera: Culicidae)

ObjectiveTo determine the larvicidal activity of crude aqueous and petroleum ether extracts of Wrightia tinctoria fruits and leaves against the filarial vector, Culex quinquefasciatus.MethodsThe larvicidal activity was evaluated at concentrations of 0.06%, 0.12%, 0.25%, 0.50% and 1.00%. Larval mortality was observed for 24 and 48 h.ResultsAmong the plant parts tested, aqueous fruit extract exhibited highest larvicidal activity followed by aqueous leaf extract with LC₅₀ values of 0.17% and 0.09%; 0.21% and 0.11% after 24 and 48 h respectively.ConclusionsFurther investigations are needed to elucidate this activity against a wide range of all stages of mosquito species and also the active ingredient(s) of the extract responsible for larvicidal activity should be identified.     

Larvicidal and adulticidal potential of medicinal plant extracts from south India against vectors

ObjectiveTo determine the larvicidal and adulticidal activities of hexane, ethyl acetate and methanol extracts of Momordica charantia (M.charantia), Moringa oleifera(M. oleifera), Ocimum gratissimum (O. gratissimum), Ocimum tenuiflorum (O. tenuiflorum), Punica granatum(P. granatum) and Tribulus terrestris (T. terrestris) against Culex gelidus (Cx. gelidus) and Culex quinquefasciatus (Cx. quinquefasciatus).MethodsBioassay test was carried out by WHO method for determination of larvicidal and adulticidal activity against mosquitoes.ResultsAll plant extracts showed moderate larvicidal and adulticidal activities, however the effective larval mortality was found in the leaf ethyl acetate and methanol extract of O. gratissimum and bark methanol extract of M. oleifera against Cx.gelidus with LC₅₀ values of 39.31, 66.28, and 21.83 μg/mL respectively, and methanol extract of O. gratissimum, O. tenuiflorum and P. granatum against Cx. quinquefasciatus with LC₅₀ values of 38.47, 24.90 and 67.20 μg/mL, respectively. The adult exposed for 1 h and mortality was recorded at 24 h recovery period. Above 90% mortality was found in the ethyl acetate and methanol extract of all experimental plants at the concentrations of 500 μg/mL.ConclusionsThe present results suggest that the medicinal plant extracts provided an excellent potential for controlling Cx. gelidus and Cx. quinquefasciatus.     

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.     

Effect of leaf essential oil of Coccinia indica on egg hatchability and different larval instars of malarial mosquito Anopheles stephensi

ObjectiveTo assess the larvicidal and egg hatching inhibition property of the leaf essential oil of Coccinia indica (C. indica) against Anopheles stephensi (An. stephensi).MethodsThe larvicidal potential of C. indica leaf essential oil was evaluated against 1st, 2nd, 3rd and 4th instars larvae of An. stephensi using WHO protocol. The 24h LC₅₀ and LC₉₀ values of the essential oil were determined following probit analysis. The egg hatching inhibition activity was also tested at 10, 20, 40, and 60 mg/L. The IC₅₀ value of essential oil was determined against eggs of An. stephensi.ResultsThe essential oil extracted from C. indica possessed excellent larvicidal and egg hatching inhibition activity against An. stephensi. The bioassays showed LC₅₀-LC₉₀ of 54.3-140.3, 65.5-155.6, 86.8-180.7 and 95.3-192.6 for 1st, 2nd, 3rd, and 4th larval instars, respectively. The 50% egg hatching inhibition concentration (IC₅₀) was noted at 16.5 mg/L.ConclusionsThe present finding suggest that the C. indica leaf essential oil provided an excellent potential for controlling An. stephensi mosquito at earlier stage of their life cycle.     

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.     

Adulticidal activity of Pithecellobium dulce (Roxb.) Benth. against Culex quinquefasciatus (Say)

ObjectiveTo determine the adulticidal efficacy of different solvent leaf and seed extracts of Pithecellobium dulce (P. dulce) against Culex quinquefasciatus (Cx. quinquefasciatus).MethodsSucrose-fed and blood starved mosquitoes were released into the tube, and the mortality effects of the extracts were observed every 10 min for 3 h exposure period. At the end of 1, 2, and 3 h exposure periods, the mosquitoes were placed in the holding tube. Cotton pads soaked in 10% sugar solution with vitamin B complex were placed in the tube during the holding period of 24 h. Mortality of the mosquitoes was recorded after 24 h.ResultsAmong five solvent extracts tested, the maximum efficacy was observed in the methanol extract of leaves of P. dulce. The LC₅₀ and LC₉₀ values of P. dulce leaves and seeds against Cx. quinquefasciatus were 234.97, 309.24 ppm and 464.86, 570.80 ppm, 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 that the crude extract of P. dulce has excellent potential for controlling filariasis vector mosquito, Cx. quinquefasciatus. This is the first report on the mosquito adulticidal activity of the reported P. dulce plant.     

In vitro antiplasmodial effect of ethanolic extracts of traditional medicinal plant Ocimum species against Plasmodium falciparum

ObjectiveTo identify the possible antiplasmodial compounds from leaf, stem, root and flower extracts of Ocimum canum (O. canum), Ocimum sanctum (O. sanctum) and Ocimum basilicum (O. basilicum).MethodsThe O. canum, O. sanctum and O. basilicum were collected from Ramanathapuram District, Tamil Nadu and the extraction was carried out in ethanol. The filter sterilized extracts (100, 50, 25, 12.5, 6.25 and 3.125 μg/mL) of leaf, stem, root and flower extracts of O. canum, O. sanctum and O. basilicum were tested for antiplasmodial activity against Plasmodium falciparum (P. falciparum). The potential extracts were also tested for their phytochemical constituents.ResultsThe leaf extract of O. sanctum showed excellent antiplasmodial activity (IC₅₀ 35.58 μg/mL) followed by leaf extract of O. basilicum (IC₅₀ 43.81 μg/mL). The leaf extract of O. canum, root extracts of O. sanctum and O. basilicum, the stem and flower extracts of all the three tested Ocimum species showed IC₅₀ values between 50 and 100 μg/mL. Statistical analysis reveals that, significant antiplasmodial activity (P <0.01) was observed between the concentrations and time of exposure. The chemical injury to erythrocytes was also carried out and it shows that, there were no morphological changes in erythrocytes by the ethanolic extract of O. canum, O. sanctum and O. basilicum. The in vitro antiplasmodial activity might be due to the presence of alkaloids, glycosides, flavonoids, phenols, saponins, triterpenoids, proteins, resins, steroids and tannins in the ethanolic extracts of tested plants.ConclusionsThe ethanolic leaf extracts of O. sanctum possess lead compounds for the development of antiplasmodial drugs.