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Objective: To 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)., Methods: The 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 (LC(50) and LC(90)) 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 of N. nucifera, seed ethyl acetate and methanol extract of P. nigrum against the larvae of An. stephensi (LC(50) = 34.76, 24.54 and 30.20 ppm) and against Cx. quinquefasciatus (LC(50) = 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., 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., (Copyright © 2011 Hainan Medical College. Published by Elsevier B.V. All rights reserved.)

Background & Objectives: Mosquitoes transmit serious human diseases, causing millions of deaths every year and the development of resistance to chemical insecticides resulting in rebounding vectorial capacity. Plants may be alternative sources of mosquito control agents. The present study assessed the role of larvicidal activities of hexane, chloroform, ethyl acetate, acetone, and methanol dried leaf and bark extracts of Annona squamosa L., Chrysanthemum indicum L., and Tridax procumbens L. against the fourth instar larvae of malaria vector, Anopheles subpictus Grassi and Japanese encephalitis vector, Culex tritaeniorhynchus Giles (Diptera: Culicidae)., Methods: Larvicidal activities of three medicinal plant extracts were studied in the range of 4.69 to 1000 mg/l in the laboratory bioassays against early 4 th instar larvae of An. subpictus and Cx. tritaeniorhynchus. The mortality 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 respective species., Results: All plant extracts showed moderate effects after 24 h of exposure; however, the highest toxic effect of bark methanol extract of A. squamosa, leaf ethyl acetate extract of C. indicum and leaf acetone extract of T. procumbens against the larvae of An. subpictus (LC 50 = 93.80, 39.98 and 51.57 mg/l) and bark methanol extract of A. squamosa, leaf methanol extract of C. indicum and leaf ethyl acetate extract of T. procumbens against the larvae of Cx. tritaeniorhynchus (LC50 =104.94, 42.29 and 69.16 mg/l) respectively., Interpretation & Conclusions: Our data suggest that the bark ethyl acetate and methanol extract of A. squamosa, leaf ethyl acetate and methanol extract of C. indicum, acetone and ethyl acetate extract of T. procumbens have the potential to be used as an ecofriendly approach for the control of the An. subpictus, and Cx. tritaeniorhynchus.

The aim of this study was to investigate the larvicidal potential of the hexane, chloroform, ethyl acetate, acetone, methanol, and aqueous leaf extracts of Nelumbo nucifera Gaertn. (Nymphaeaceae) and synthesized silver nanoparticles using aqueous leaf extract against fourth instar larvae of Anopheles subpictus Grassi and Culex quinquefasciatus Say (Diptera: Culicidae). Nanoparticles are being used in many commercial applications. It was found that aqueous silver ions can be reduced by aqueous extract of plant parts to generate extremely stable silver nanoparticles in water. The results recorded from UV-vis spectrum, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared support the biosynthesis and characterization of silver nanoparticles. Larvae were exposed to varying concentrations of plant extracts and synthesized silver nanoparticles for 24 h. All extracts showed moderate larvicidal effects; however, the maximum efficacy was observed in crude methanol, aqueous, and synthesized silver nanoparticles against the larvae of A. subpictus (LC(50) = 8.89, 11.82, and 0.69 ppm; LC(90) = 28.65, 36.06, and 2.15 ppm) and against the larvae of C. quinquefasciatus (LC(50) = 9.51, 13.65, and 1.10 ppm; LC(90) = 28.13, 35.83, and 3.59 ppm), respectively. These results suggest that the leaf methanol, aqueous extracts of N. nucifera, and green synthesis of silver nanoparticles have the potential to be used as an ideal eco-friendly approach for the control of the A. subpictus and C. quinquefasciatus. This is the first report on the mosquito larvicidal activity of the plant extracts and synthesized nanoparticles.

In recent years, use of environment friendly and biodegradable natural insecticides of plant origin have received renewed attention as agents for vector control because they are rich in bioactive chemicals, active against a limited number of species including specific target insects, and biodegradable. The present study was carried out to evaluate the adulticidal, repellent, and larvicidal activity of crude hexane, ethyl acetate, and methanol extracts of eight plants, viz. Aristolochia indica L., Cassia angustifolia Vahl, Diospyros melanoxylon Roxb., Dolichos biflorus L., Gymnema sylvestre (Retz) Schult, Justicia procumbens L., Mimosa pudica L., and Zingiber zerumbet L., were tested against adult and early fourth instar larvae of Culex gelidus Theobald and Culex quinquefasciatus Say (Diptera: Culicidae). The effective adult mortality was observed in methanol extract of A. indica, ethyl acetate extract of D. biflorus, and ethyl acetate and hexane extract of Z. zerumbet against C. gelidus and C. quinquefasciatus (LD(50) =37.75, 78.56, 129.44, 86.13, 80.06, 112.42, 53.83, and 46.61; LD(90) =166.83, 379.14, 521.50, 289.83, 328.18, 455.72, 181.15, and 354.50 ppm, respectively). Complete protections for 150 min were found in hexane and methanol extract of A. indica and Z. zerumbet at 1,000 ppm against mosquito bites. The highest larval mortality was found in the hexane extract of Z. zerumbet, ethyl acetate extract of D. biflorus, and methanol extracts of A. indica against C. gelidus (LC(50) =26.48, 33.02, and 12.47 ppm; LC(90) =127.73, 128.79, and 62.33 ppm) and against C. quinquefasciatus (LC(50) =69.18, 34.76, and 25.60 ppm; LC(90) =324.40, 172.78, and 105.52 ppm), respectively, after 24 h. The plant extracts are potential to be used as an ideal eco-friendly approach for the control of the Japanese encephalitis vector, C. gelidus, and lymphatic filariasis vector, C. quinquefasciatus.

Mosquitoes transmit serious human diseases, causing millions of deaths every year. Natural products of plant origin with insecticidal properties have been used in recent years for control of a variety of pest insects and vectors. The present study was based on assessments of the larvicidal activity to determine the efficacies of hexane, chloroform, ethyl acetate, acetone and methanol extracts of ten medicinal plants tested against fourth instar larvae of malaria vector, Anopheles stephensi Liston and lymphatic filariasis vector, Culex quinquefasciatus Say (Diptera: Culicidae). The larvicidal activity was assessed by the procedure of WHO with some modification. The highest larval mortality was found in leaf acetone of Adhatoda vasica, bark ethyl acetate of Annona squamosa, methanol leaf and flower of Cassia auriculata, leaf ethyl acetate of Hydrocotyle javanica, methanol leaf and seed of Solanum torvum and leaf hexane extracts of Vitex negundo against the fourth instar larvae of An. stephensi and Cx. quinquefasciatus. The calculated LC90 for acetone, ethyl acetate, methanol and hexane extracts of dried leaf and bark of A. vasica, A. squamosa, S. torvum, and V. negundo were in the range of 70.38-210.68 ppm. Our results suggest that the leaf methanol extract of S.torvum and bark ethyl acetate extract of A. squamosa from Southern India have the potential for use to control mosquitoes. Therefore, this study provides the larvicidal activity against An. stephensi and Cx. quinquefasciatus of plant extracts.

In recent times, there were considerable efforts made to promote the use of environmentally friendly and biodegradable natural insecticides and repellents, particularly from botanical sources. The present study explored the effects of crude leaf ethyl acetate, acetone, and methanol extracts of Aegle marmelos (L.) Correa ex Roxb, Andrographis lineata Wallich ex Nees., Andrographis paniculata (Burm.f.) Wallich ex Nees., Cocculus hirsutus (L.) Diels, Eclipta prostrata L., and Tagetes erecta L. on repellent activity against Culex tritaeniorhynchus Giles. The maximum repellent activity was observed at 500 ppm in methanol extracts of A. marmelos, ethyl acetate extracts of A. lineata, C. hirsutus, and E. prostrata and the mean complete protection time ranged from 120 to 150 min with the different extracts tested. The ethyl acetate extract of A. lineata showed 100% repellency in 120 min; acetone extracts of A. marmelos and C. hirsutus and methanol extract of T. erecta showed complete protection in 90 min at 250 ppm, respectively. These results suggest that the leaf extracts of A. marmelos, A. lineata, and C. hirsutus have the potential to be used as an ideal eco-friendly approach for the control of the C. tritaeniorhynchus. Therefore, this study provides first report on the repellent activity against Japanese encephalitis, C. tritaeniorhynchus of plant extracts from Southern India.

Mosquito control is facing a threat because of the emergence of resistance to synthetic insecticides. Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. The purpose of the present study was to assess the effect of leaf ethyl acetate, acetone and methanol extracts of Aegle marmelos (L.) Correa ex Roxb (Rutaceae), Andrographis lineata Wallich ex Nees. (Acanthaceae), Andrographis paniculata (Burm.f.) Wall. ex Nees. (Acanthaceae), Cocculus hirsutus (L.) Diels (Menispermaceae), Eclipta prostrata L. (Asteraceae) and Tagetes erecta L. (Compositae) on ovicidal and oviposition-deterrent activities against Culex tritaeniorhynchus Giles (Diptera: Culicidae). The percentage of egg hatching in methanol extracts of Andrographis lineata, Cocculus hirsutus and T. erecta were 16, 12 and 16 exerted at 500 ppm, respectively. The percentage of effective oviposition repellency was 97.77 at 500 ppm and the lowest repellency was 42.06 at 31.25 ppm in methanol and acetone extracts of Andrographis lineata and Andrographis paniculata, respectively. The oviposition activity index values revealed that the solvent plant extracts have deterrent effect, and they caused a remarkable negative response resulting in oviposition of very few eggs. These results suggest that the leaf solvent plant extracts have the potential to be used as an ideal ecofriendly approach for the control of the Culex tritaeniorhynchus.

The purpose of the present study was to assess the effect of leaf hexane and chloroform extracts of Aegle marmelos, Andrographis lineata, Andrographis paniculata, Cocculus hirsutus, Eclipta prostrata, and Tagetes erecta on repellent, ovicidal, and oviposition-deterrent activities against Culex tritaeniorhynchus Giles (Diptera: Culicidae). The repellent action of the plant extracts tested varied depending on the plant species, part, solvent used in extraction, and the extract dose. The hexane extract of A. paniculata was more effective in exhibiting the repellent action against the mosquito as compared with A. lineata extract. Complete protections for 150 min were found in hexane extract of A. paniculata at 500 ppm against mosquito bites. Mean percent hatchability of the ovicidal activity was observed 24 h after treatment. The percent hatchability was inversely proportional to the concentration of extract and directly proportional to the eggs. No hatchability was observed with hexane, and chloroform extracts of A. lineata, A. paniculata, and hexane extract of T. erecta were exerted at 1,000 ppm. The percentage of effective oviposition repellency were 95.90, 94.75, 95.04, 90.58, 87.93, 87.14, 94.82, 95.71, 92.26, 90.58, 83.35, and 78.16 at 500 ppm, and the lowest repellency was 69.93, 53.06, 64.81, 70.06, 51.82, 54.54, 48.31, 66.71, 68.82, 61.85, 34.84, and 39.53 at 31.25 ppm in hexane and chloroform extracts of A. marmelos, A. lineata, A. paniculata, C. hirsutus, E. prostrata, and T. erecta, respectively. The oviposition activity index values revealed that the solvent plant extracts have deterrent effect, and they caused a remarkable negative response resulting in oviposition of very few eggs. These results clearly reveal that the hexane extracts of A. marmelos and A. paniculata served as a potential repellent, ovicidal, and oviposition deterrent against Japanese encephalitis vector, C. tritaeniorhynchus.

The adulticidal and larvicidal effect of indigenous plant extracts were investigated against the adult cattle tick Haemaphysalis bispinosa Neumann, 1897 (Acarina: Ixodidae), sheep fluke Paramphistomum cervi Zeder, 1790 (Digenea: Paramphistomatidae), fourth instar larvae of malaria vector, Anopheles subpictus Grassi and Japanese encephalitis vector, Culex tritaeniorhynchus Giles (Diptera: Culicidae). The aim of this study was to evaluate the toxic effect of leaf hexane, chloroform, ethyl acetate, acetone and methanol extracts of Annona squamosa L., Centella asiatica (L.) Urban, Gloriosa superba L., Mukia maderaspatensis (L.) M.Roem, Pergularia daemia (Forsk.) Chiov. and Phyllanthus emblica L. were exposed to different concentrations. All plant extracts showed moderate toxic effect on parasites after 24h of exposure; however, the highest mortality was found in leaf hexane extract of A. squamosa, methanol extracts of G. superba and P. emblica against H. bispinosa (LC(50)=145.39, 225.57 and 256.08ppm); methanol extracts of C. asiatica, G. superba, P. daemia and P. emblica against P. cervi (LC(50)=77.61, 60.16, 59.61, and 60.60ppm); acetone, ethyl acetate extracts of A. squamosa, methanol extract of C. asiatica, acetone extracts of G. superba, ethyl acetate, hexane and methanol extracts of P. daemia against A. subpictus (LC(50)=17.48, 18.60, 26.62, 18.43, 34.06, 13.63, and 50.39ppm); and chloroform, ethyl acetate extracts of A. squamosa, ethyl acetate extract of P. daemia, ethyl acetate and methanol extracts of P. emblica against C. tritaeniorhynchus (LC(50)=63.81, 60.01, 31.94, 69.09, and 54.82ppm), respectively. These results demonstrate that methanol extracts of C. asiatica, G. superba, P. daemia and P. emblica extracts may serve as parasites control even in their crude form.

The present study was based on assessments of the antiparasitic activities to determine the efficacies of acetone, chloroform, ethyl acetate, hexane, and methanol dried leaf, flower, and seed extracts of Achyranthes aspera L., Anisomeles malabarica (L.) R. Br., Gloriosa superba L., Psidium guajava L., Ricinus communis L., and Solanum trilobatum L. tested against the larvae of cattle tick Rhipicephalus (Boophilus) microplus (Canestrini 1887) (Acari: Ixodidae), sheep internal parasite Paramphistomum cervi (Zeder 1790) (Digenea: Paramphistomatidae) at 2,000 ppm and fourth instar larvae of Anopheles subpictus Grassi and Culex tritaeniorhynchus Giles (Diptera: Culicidae) at 1,000 ppm. All plant extracts showed moderate effects after 24 h of exposure; however, the highest parasite mortality was found in the leaf ethyl acetate extract of A. aspera, leaf methanol extract of A. malabarica, flower methanol extract of G. superba, and leaf methanol extract of R. communis against the larvae of R. microplus (LC(50) = 265.33, 95.97, 153.73, and 181.49 ppm; LC(90) = 1,130.18, 393.88, 1,794.25, and 1,829.94 ppm); leaf acetone and chloroform of A. malabarica, flower acetone extract of G. superba, and leaf chloroform and methanol of R. communis against the adult of P. cervi (LC(50) = 108.07, 106.69, 157.61, 69.44, and 168.24 ppm; LC(90) = 521.77, 463.94, 747.02, 256.52, and 809.45 ppm); leaf ethyl acetate extract of A. aspera, leaf chloroform extract of A. malabarica, flower methanol of G. superba, and leaf methanol extract of R. communis against the larvae of A. subpictus (LC(50) = 48.83, 135.36, 106.77, and 102.71 ppm; LC(90) = 225.36, 527.24, 471.90, and 483.04 ppm); and leaf ethyl acetate extract of A. aspera, leaf chloroform extract of A. malabarica, flower methanol extract of G. superba, and leaf methanol extract of R. communis against the larvae of C. tritaeniorhynchus (LC(50) = 68.27, 95.98, 59.51, and 93.94 ppm; LC(90) = 306.88, 393.83, 278.99, and 413.27 ppm), respectively. These results suggest that the leaf ethyl acetate extract of A. aspera, leaf acetone and chloroform extract of A. malabarica, flower methanol extract of G. superba, and leaf methanol extract of R. communis have the potential to be used as an ideal eco-friendly approach for the control of the R. microplus, P. cervi, A. subpictus, and C. tritaeniorhynchus. Therefore, this study provides the first report on the larvae and adult parasitic activity of crude solvent extracts, indigenous plants consumed by the natives in southern India.

Anopheles subpictus and Culex tritaeniorhynchus have developed resistance to various synthetic insecticides, making its control increasingly difficult. Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. The leaf acetone, chloroform, ethyl acetate, hexane, and methanol extracts of Aegle marmelos (Linn.) Correa ex Roxb, Andrographis lineata Wallich ex Nees., Andrographis paniculata (Burm.f.) Wall. ex Nees., Cocculus hirsutus (L.) Diels, Eclipta prostrata L., and Tagetes erecta L. were tested against fourth-instar larvae of malaria vector, A. subpictus Grassi and Japanese encephalitis vector, C. tritaeniorhynchus Giles (Diptera: Culicidae). All plant extracts showed moderate larvicidal effects after 24 h of exposure at 1,000 ppm; however, the highest larval mortality was found in leaf ethyl acetate of A. marmelos, E. prostrata, hexane, methanol of A. paniculata and C. hirsutus against the larvae of A. subpictus (LC(50) = 167.00, 78.28, 67.24, 142.83 ppm; LC(90) = 588.31, 360.75, 371.91, and 830.01 ppm) and against the larvae of C. tritaeniorhynchus (LC(50) = 99.03, 119.89, 88.50, 105.19 ppm; LC(90) = 479.23, 564.85, 416.39, and 507.86 ppm), respectively. These results suggest that the leaf hexane extract of A. paniculata and ethyl acetate extract of E. prostrata have the potential to be used as an ideal eco-friendly approach for the control of the A. subpictus and C. tritaeniorhynchus. Therefore, this study provides first report on the mosquito larvicidal activity of plant extracts against vectors from Southern India.

The present study explored the effects of crude leaf acetone, chloroform, hot water, methanol, petroleum ether (60-80 degrees C), and water extracts of Calotropis procera (Ait) R. Br., Canna indica L., Hibiscus rosa-sinensis Linn., Ipomoea carnea Jacq. spp. fistulosa Choisy, and Sarcostemma brevistigma Wight that were selected for investigating larvicidal potential against second and fourth instar larvae of the laboratory-reared mosquito species, Culex quinquefasciatus Say, in which the major lymphatic filariasis was used. All plant extracts showed moderate larvicidal effects after 24 h of exposure at 1,000 ppm; however, the highest larval mortality was found in leaf acetone, chloroform, methanol, and petroleum ether of C. indica (LC(50) = 29.62, 59.18, 40.77, and 44.38 ppm; LC(90) = 148.55, 267.87, 165.00, and 171.91 ppm) against second instar larvae (LC(50) = 121.88, 118.25, 69.76, and 56.31 ppm; LC(90) = 624.35, 573.93, 304.27, and 248.24 ppm) and against fourth instar larvae and acetone, hot water, methanol, and petroleum ether extracts of I. carnea (LC(50) = 61.17, 41.07, 41.82, and 39.32 ppm; LC(90) = 252.91, 142.67, 423.76, and 176.39 ppm) against second instar larvae (LC(50) = 145.37, 58.00, 163.81, and 41.75 ppm; LC(90) = 573.30, 181.10, 627.38, and 162.63 ppm) and against fourth instar larvae of C. quinquefasciatus, respectively. These results suggest that the acetone, methanol extracts of C. indica and hot water, petroleum ether extracts of I. carnea have the potential to be used as an ideal eco-friendly approach for the control of the major lymphatic filariasis vector, C. quinquefasciatus.

Mosquito control is facing a threat due to the emergence of resistance to synthetic insecticides. Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. The acetone, chloroform, ethyl acetate, hexane, methanol and petroleum ether extracts of leaf, flower and seed of Cassia auriculata L., Leucas aspera (Willd.), Rhinacanthus nasutus KURZ., Solanum torvum Swartz and Vitex negundo Linn. were tested against fourth instar larvae of malaria vector, Anopheles subpictus Grassi and Japanese encephalitis vector, Culex tritaeniorhynchus Giles (Diptera: Culicidae). The larval mortality was observed after 24 h of exposure. All extracts showed moderate larvicidal effects; however, the highest mortality was found in leaf petroleum ether, flower methanol extracts of C. auriculata, flower methanol extracts of L. aspera and R. nasutus, leaf and seed methanol extracts of S. torvum and leaf hexane extract of V. negundo against the larvae of A. subpictus (LC(50) = 44.21, 44.69, 53.16, 41.07, 35.32, 28.90 and 44.40 ppm; LC(90) = 187.31, 188.29, 233.18, 142.66, 151.60, 121.05 and 192.11 ppm, respectively) and against the larvae of C. tritaeniorhynchus (LC(50) = 69.83, 51.29, 81.24, 71.79, 44.42, 84.47 and 65.35 ppm; LC(90) = 335.26, 245.63, 300.45, 361.83, 185.09, 351.41 and 302.42 ppm, respectively). These results suggest that the leaf petroleum ether, flower methanol extracts of C. auriculata, leaf and seed methanol extracts of S. torvum and leaf hexane extract of V. negundo have the potential to be used as an ideal eco-friendly approach for the control of the A. subpictus and C. tritaeniorhynchus. This is the first report on the mosquito larvicidal activity of the medicinal plant extracts.

The acetone, chloroform, ethyl acetate, hexane and methanol extracts of peel and leaf extracts of Citrus sinensis, Ocimum canum, Ocimum sanctum and Rhinacanthus nasutus were tested against fourth instar larvae of malaria vector, Anopheles subpictus Grassi, Japanese encephalitis vector, Culex tritaeniorhynchus Giles (Diptera: Culicidae) and feeding deterrence to nymphs of cotton pest, Aphis gossypii Glover (Homoptera: Aphididae). The larval and nymph mortality were observed after 24 h of exposure. All extracts showed moderate larvicidal and nymphicidal effects; however, the highest mortality was found in peel chloroform extract of C. sinensis, leaf ethyl acetate extracts of O. canum and O. sanctum and leaf chloroform extract of R. nasutus against the larvae of A. subpictus (LC(50) = 58.25, 88.15, 21.67 and 40.46 ppm; LC(90) = 298.31, 528.70, 98.34 and 267.20 ppm), peel methanol extract of C. sinensis, leaf methanol extract of O. canum, ethyl acetate extracts of O. sanctum and R. nasutus against the larvae of C. tritaeniorhynchus (LC(50) = 38.15, 72.40, 109.12 and 39.32 ppm; LC(90) = 184.67, 268.93, 646.62 and 176.39 ppm), peel hexane extract of C. sinensis, leaf methanol extracts of O. canum and R. nasutus and leaf ethyl acetate extract of O. sanctum against the nymph of A. gossypii (LC(50) = 162.89, 80.99, 73.27 and 130.19 ppm; LC(90) = 595.40, 293.33, 338.74 and 450.90 ppm), respectively. These results suggest that the peel methanol extracts of C. sinensis and O. canum, ethyl acetate leaf extract of O. sanctum and leaf chloroform and ethyl acetate extract of R. nasutus have the potential to be used as an ideal eco-friendly approach for the control of the A. subpictus, C. tritaeniorhynchus and A. gossypii.

This study investigates the larvicidal potential of indigenous plant extracts from commonly used medicinal herbs as an environmentally safe measure to control the filarial vector, Culex quinquefasciatus Say (Diptera: Culicidae). The early fourth-instar larvae of C. quinquefasciatus, reared in the laboratory, were used for larvicidal assay with water, hot water, acetone, chloroform, and methanol leaf, stem-bark, and flower extracts of Acacia arabica Willd. Sans, Cedrus deodara Roxb, Hibiscus rosa-sinensis L., Mangifera indica L., Nerium indicum Mill., Nicotiana tabacum Linn., Pongamia pinnata (L.) Pierre, and Solanum nigrum Linn. All plant extracts showed moderate larvicidal effects after 24 h of exposure at 1,000 ppm; however, the highest larval mortality was found in stem-bark hot water, acetone, and methanol extracts of C. deodara (LC50 = 133.85, 141.60, and 95.19 ppm, LC90 = 583.14, 624.19, and 639.99 ppm) and leaf hot water, acetone, methanol, and chloroform extracts of N. tabacum (LC50 = 76.27, 163.81, 83.38, and 105.85 ppm, LC90 = 334.72, 627.38, 709.51, and 524.39 ppm) against the larvae of C. quinquefasciatus, respectively. This is an ideal ecofriendly approach for the control of lymphatic filariasis vector, C. quinquefasciatus.

The larvicidal activity of a petroleum ether extract of Zingiber officinale Roscoe (Zingiberaceae) was evaluated against Aedes aegypti L. and Culex quinquefasciatus Say (Diptera). Bioassay-guided fractionation led to the isolation of 4-gingerol (1), (6)-dehydrogingerdione (2) and (6)-dihydrogingerdione (3); the latter has not previously been reported from Z. officinale. The structures were established from infrared (IR), ultraviolet (UV), (1)H-nuclear magnetic resonance (NMR), (13)C-NMR and mass spectral data. Following a 24 h exposure, compounds 1-3 exhibited larvicidal activities against fourth instar larvae of A. aegypti (LC(50) 4.25, 9.80, 18.20 ppm) and C. quinquefasciatus (LC50 5.52, 7.66, 27.24 ppm), respectively. The results show that the most effective compound was 4-gingerol.

A screening for larvicidal activity of plant extracts with some known medicinal attributes could lead to the discovery of new agents for pest and vector control. In the backdrop of recent revival of interest in developing plant-based insecticides, the present study was carried out to evaluate the larvicidal properties in three medicinal plants growing abundantly in the region of Chitheri Hills, Dharmapuri District, India. Antifeedant and larvicidal activity of the acetone, chloroform, ethyl acetate, hexane and methanol leaf extracts of Ocimum canum, Ocimum sanctum and Rhinacanthus nasutus were studied against fourth instar larvae of Spodoptera litura (Lepidoptera: Noctuidae), Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae). The larval mortality was observed after 24 h of exposure. All extracts showed moderate larvicidal effects; however, the highest larval mortality was found in methanol extract of O. canum, R. nasutus and acetone extract of O. sanctum against the larvae of S. litura (LC(50) = 36.46, 68.08 and 68.84 ppm), against A. aegypti (LC(50) = 99.42, 94.43 and 81.56 ppm) and against C. quinquefasciatus (LC(50) = 44.54, 73.40 and 38.30 ppm), respectively. This is an ideal eco-friendly approach for the control of the agricultural pest, S. litura, and medically important vectors, A. aegypti and C. quinquefasciatus.

The acetone, chloroform, ethyl acetate, hexane and methanol leaf extracts of Acalypha indica, Achyranthes aspera, Leucas aspera, Morinda tinctoria and Ocimum sanctum were studied against the early fourth-instar larvae of Aedes aegypti L and Culex quinquefasciatus Say. The larval mortality was observed after 24 h exposure. All extracts showed moderate larvicidal effects; however, the highest larval mortality was found in the ethyl acetate extract of A. aspera. In the present study, bioassay-guided fractionation of A. aspera led to the separation and identification ofa saponin as a potential mosquito larvicidal compound, with LC50 value of 18.20 and 27.24 ppm against A. aegypti and C. quinquefasciatus, respectively. 1H NMR, 13C NMR and mass spectral data confirmed the identification of the active compound. This is the first report on the mosquito larvicidal activity of the saponin from the ethyl acetate extract of A. aspera. This study investigates the potential of crude extracts from commonly used medical herbs in India as an environmentally safe measure to control the vector of dengue and lymphatic filariasis.

Abstract  The purpose of the present study was to assess the effect of leaf hexane and chloroform extracts of Aegle marmelos, Andrographis lineata, Andrographis paniculata, Cocculus hirsutus, Eclipta prostrata, and Tagetes erecta on repellent, ovicidal, and oviposition-deterrent activities against Culex tritaeniorhynchus Giles (Diptera: Culicidae). The repellent action of the plant extracts tested varied depending on the plant species, part, solvent used in extraction, and the extract dose. The hexane extract of A. paniculata was more effective in exhibiting the repellent action against the mosquito as compared with A. lineata extract. Complete protections for 150 min were found in hexane extract of A. paniculata at 500 ppm against mosquito bites. Mean percent hatchability of the ovicidal activity was observed 24 h after treatment. The percent hatchability was inversely proportional to the concentration of extract and directly proportional to the eggs. No hatchability was observed with hexane, and chloroform extracts of A. lineata, A. paniculata, and hexane extract of T. erecta were exerted at 1,000 ppm. The percentage of effective oviposition repellency were 95.90, 94.75, 95.04, 90.58, 87.93, 87.14, 94.82, 95.71, 92.26, 90.58, 83.35, and 78.16 at 500 ppm, and the lowest repellency was 69.93, 53.06, 64.81, 70.06, 51.82, 54.54, 48.31, 66.71, 68.82, 61.85, 34.84, and 39.53 at 31.25 ppm in hexane and chloroform extracts of A. marmelos, A. lineata, A. paniculata, C. hirsutus, E. prostrata, and T. erecta, respectively. The oviposition activity index values revealed that the solvent plant extracts have deterrent effect, and they caused a remarkable negative response resulting in oviposition of very few eggs. These results clearly reveal that the hexane extracts of A. marmelos and A. paniculata served as a potential repellent, ovicidal, and oviposition deterrent against Japanese encephalitis vector, C. tritaeniorhynchus. [ABSTRACT FROM AUTHOR]

Abstract  Mosquito control is facing a threat due to the emergence of resistance to synthetic insecticides. Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. The acetone, chloroform, ethyl acetate, hexane, methanol and petroleum ether extracts of leaf, flower and seed of Cassia auriculata L., Leucas aspera (Willd.), Rhinacanthus nasutus KURZ., Solanum torvum Swartz and Vitex negundo Linn. were tested against fourth instar larvae of malaria vector, Anopheles subpictus Grassi and Japanese encephalitis vector, Culex tritaeniorhynchus Giles (Diptera: Culicidae). The larval mortality was observed after 24 h of exposure. All extracts showed moderate larvicidal effects; however, the highest mortality was found in leaf petroleum ether, flower methanol extracts of C. auriculata, flower methanol extracts of L. aspera and R. nasutus, leaf and seed methanol extracts of S. torvum and leaf hexane extract of V. negundo against the larvae of A. subpictus (LC50 = 44.21, 44.69, 53.16, 41.07, 35.32, 28.90 and 44.40 ppm; LC90 = 187.31, 188.29, 233.18, 142.66, 151.60, 121.05 and 192.11 ppm, respectively) and against the larvae of C. tritaeniorhynchus (LC50 = 69.83, 51.29, 81.24, 71.79, 44.42, 84.47 and 65.35 ppm; LC90 = 335.26, 245.63, 300.45, 361.83, 185.09, 351.41 and 302.42 ppm, respectively). These results suggest that the leaf petroleum ether, flower methanol extracts of C. auriculata, leaf and seed methanol extracts of S. torvum and leaf hexane extract of V. negundo have the potential to be used as an ideal eco-friendly approach for the control of the A. subpictus and C. tritaeniorhynchus. This is the first report on the mosquito larvicidal activity of the medicinal plant extracts. [ABSTRACT FROM AUTHOR]

Abstract  The acetone, chloroform, ethyl acetate, hexane and methanol extracts of peel and leaf extracts of Citrus sinensis, Ocimum canum, Ocimum sanctum and Rhinacanthus nasutus were tested against fourth instar larvae of malaria vector, Anopheles subpictus Grassi, Japanese encephalitis vector, Culex tritaeniorhynchus Giles (Diptera: Culicidae) and feeding deterrence to nymphs of cotton pest, Aphis gossypii Glover (Homoptera: Aphididae). The larval and nymph mortality were observed after 24 h of exposure. All extracts showed moderate larvicidal and nymphicidal effects; however, the highest mortality was found in peel chloroform extract of C. sinensis, leaf ethyl acetate extracts of O. canum and O. sanctum and leaf chloroform extract of R. nasutus against the larvae of A. subpictus (LC50 = 58.25, 88.15, 21.67 and 40.46 ppm; LC90 = 298.31, 528.70, 98.34 and 267.20 ppm), peel methanol extract of C. sinensis, leaf methanol extract of O. canum, ethyl acetate extracts of O. sanctum and R. nasutus against the larvae of C. tritaeniorhynchus (LC50 = 38.15, 72.40, 109.12 and 39.32 ppm; LC90 = 184.67, 268.93, 646.62 and 176.39 ppm), peel hexane extract of C. sinensis, leaf methanol extracts of O. canum and R. nasutus and leaf ethyl acetate extract of O. sanctum against the nymph of A. gossypii (LC50 = 162.89, 80.99, 73.27 and 130.19 ppm; LC90 = 595.40, 293.33, 338.74 and 450.90 ppm), respectively. These results suggest that the peel methanol extracts of C. sinensis and O. canum, ethyl acetate leaf extract of O. sanctum and leaf chloroform and ethyl acetate extract of R. nasutus have the potential to be used as an ideal eco-friendly approach for the control of the A. subpictus, C. tritaeniorhynchus and A. gossypii. [ABSTRACT FROM AUTHOR]