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.     

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.     

Evaluation of antibacterial activity of selected medicinal plant extracts from south India against human pathogens

ObjectiveThe present study was to evaluate the antibacterial properties of 21 crude extracts from leaf and flower of Aristolochia indica (A. indica), Cassia angustifolia (C. angustifolia), leaf of Catharanthus roseus (C. roseus), Diospyros melanoxylon (D. melanoxylon), Dolichos biflorus (D. biflorus), Gymnema sylvestre (G. sylvestre) and Justicia procumbens (J. procumbens).MethodsThe ethyl acetate, acetone and methanol extract of medicinal plants were evaluated against Gram-positive Bacillus cereus (B. cereus) and Gram-negative bacteria Aeromonas hydrophila (A. hydrophila), Enterobacter aerogenes (E. aerogenes), Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) by using well diffusion assay and minimum inhibitory concentration (MIC).ResultsThe crude plant extracts demonstrated broad spectrum activity against all bacteria. The highest inhibitory zone was observed in leaf methanol extract of A. indica against E. aerogenes (25 mm), and E. coli (20 mm), flower methanol extract of C. angustifolia against B. cereus (22 mm) and leaf acetone extract of G. sylvestre against B. cereus (22mm). The MIC values of leaf methanol extract of A. indica against K. pneumonia (22.6μg/ml), and flower extract showed against E. coli (MIC: 24.2μg/ml), leaf ethyl acetate extract of C. angustifolia against K. pneumoniae (MIC: 28.4μg/ml). Acetone ethyl acetate and methanol extracts of D. melanoxylon and D. biflorus showed the lowest MIC activity value of >30 μg/ml against all tested pathogens.ConclusionThe antibacterial activity could be confirmed in most species used in traditional medicine in South India. Nevertheless, traditional knowledge might provide some leads to elucidate potential candidates for future development of new antibiotic agents.     

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.     

Laboratory and field trial of developing medicinal local Thai plant products against four species of mosquito vectors

Oils of Syzygium aromaticum (clove) and Zanthoxylum limonella (makaen), widely used essential oils for dental caries or flavoring of food in Thailand, were prepared as 10 experimental repellent products in gel or cream form against Aedes aegypti, Culex quinquefasciatus, and Anopheles dirus under laboratory conditions, using the human-arm-in-cage method. Two products that gave the longest-lasting complete protection were selected to examine their repellency against a variety of mosquito species under field conditions. In laboratory tests, 0.1 g of each product was applied to 3x10 cm of exposed area on a volunteer's forearm, while in field trials, 1.0 g was applied to each volunteer's leg (from knee to ankle). In the laboratory, the gel dosage form contained 20% clove oil (Gel B) or 10% clove plus 10% makaen oil mixture (Gel E) were promising plant-based repellents against three mosquito species and gave significantly longer complete protection times of 4-5 hours than all other developing products. Therefore, their efficacy in the field was evaluated. Under field conditions, Gel E showed complete protection for 4 hours and gave 95.7% repellency after 5 hours application, whereas Gel B and 20% deet (di-methyl benzamide) provided only 86.8 and 82.7% repellency after treatment, respectively against Ae. aegypti, daytime-biting mosquitos. For nighttime-biting, the 3 repellents under development yielded equally excellent (average 97.1%) repellency for 5 hours against the predominant Cx. quinquefasciatus and Mansonia uniformis, but they gave 89.0% repellency against Cx. tritaeniorhynchus and Cx. gelidus. This finding demonstrated the effectiveness of Gel B and Gel E products for possible use by low-income rural communities against various mosquito species.     

Chemical composition and larvicidal activities of the essential oil of Zanthoxylum armatum DC (Rutaceae) against three mosquito vectors

BACKGROUND & OBJECTIVES: In view of the recently increased interest in developing plant origin insecticides as an alternative to chemical insecticide, this study was undertaken to assess the larvicidal potential of the essential oil from the seeds of Zanthoxylum armatum DC [syn. Z. alatum Roxb] (Rutaceae) against three medically important species of mosquito vectors, Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus. METHODS: Essential oil was hydro distilled in the laboratory from the seeds obtained from the market and the chemical constituents of the oil were determined using GC/GC-MS. Bioefficacy of the essential oil was evaluated under laboratory conditions using III instar mosquito larvae. RESULTS: Among the three mosquito species tested, Cx. quinquefasciatus was the most sensitive (LC50 = 49 ppm) followed by Ae. aegypti (LC50 = 54 ppm) and An. stephensi (LC50 = 58 ppm). GC-MS analysis of the oil revealed at least 28 compounds, consisting mainly of oxygenated monoterpenes (75%) and monoterpenes (22%). Linalool though constituted a major part (57%), failed to produce any appreciable mortality when tested alone. INTERPRETATION & CONCLUSION: From the results it can be concluded that the larvae of the three mosquito species were susceptible to the essential oil composition. Such findings would be useful in promoting research aiming at the development of new agent for mosquito control based on bioactive chemical compounds from indigenous plant sources as an alternative to chemical larvicides.     

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.     

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

ObjectiveTo determine the larvicidal and adult emergence inhibition activities of castor (Ricinus communis) seed extract against three potential mosquito vectors Anopheles stephensi (An. stephensi), Culex quinquefasciatus (Cx. quinquefasciatus) and Aedes albopictus (Ae. albopictus) in India.MethodsThe R. communis seed extract was tested, employing WHO procedure, against fourth larval instars of the three mosquito species for 24 h and larval mortalities were recorded at various concentrations (2-64 μg/mL); the 24 h LC₅₀ values of the R. communis seed extract were determined following Probit analysis. The larval killing, antipupation and adult emergence inhibition rates of the test extract, using a single concentration of 2 μ LC₅₀, were studied at different time periods (24-72 h); the extract toxicity was tested against a fish, Oreochromis niloticus (O. niloticus).ResultsThe R. communis seed extract exhibited larvicidal effects with 100 % killing activities at concentrations 32-64 μg/mL, and with LC₅₀ values 7.10, 11.64 and 16.84 μg/mL for Cx. quinquefasciatus, An. stephensi and Ae. albopictus larvae, respectively. When the larvae were treated with the extract at a single concentration of 2×LC₅₀, significant differences were observed, compared to control groups, in rate of pupation (P<0.001) as well as in adult formation (P<0.001).ConclusionsThe present findings suggest that the R. communis seed extract provided an excellent potential for controlling An. stephensi, Cx. quinquefasciatus and Ae. albopictus mosquito vectors.     

Screening for larvicidal activity in some Thai plants against four mosquito vector species

Ninety-six ethanolic extracts from various parts of 84 Thai plant species were tested for their larvicidal activity against Aedes aegypti mosquitoes. Extracts from Rhinacanthus nasutus, Derris elliptica, Trigonostemon reidioides, Homalomena aromatica, Stemona tuberosa and Acorus calamus possessed high larvicidal activity, with LC50 values between 16.0 and 48.2 mg/l. Petroleum ether (PE) and methanol (MeOH) extracts were tested for their larvicidal activity against 4 mosquito vector species. The PE extract of R. nasutus exhibited larvicidal effects against Ae. aegypti, Culex quinquefasciatus, Anopheles dirus and Mansonia uniformis with LC50 values between 3.9 and 11.5 mg/l, while the MeOH extract gave LC50 values of between 8.1 and 14.7 mg/l. D. elliptica PE extract showed LC50 values of between 11.2 and 18.84 mg/l and the MeOH extract exhibited LC50 values between 13.2 and 45.2 mg/l.     

Evaluation of EMD vaporizers and bioallethrin vaporizing mats against mosquito vectors.

Different Electric-Mat-Device (EMD) vaporizers and bioallethrin impregnated mats were evaluated for the knockdown and mortality in the adults of Culex quinquefasciatus, Anopheles stephensi and Aedes aegypti. Percentage knockdown of 80-100 was recorded throughout the test period of 11 hours. However, the percentage mortality observed was not appreciable in all types of EMD vaporizers. Device "A" was found to be effective only against Ae. aegypti. Devices "C" and "D" showed moderate effects against An. stephensi and Ae. aegypti. Only device "B" was found to give appreciable mortality in all three vector mosquito species compared to other devices which may be attributed to the uniform release rate (2 mg/hour) of bioallethrin.     

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.     

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.     

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.     

In vitro antiplasmodial activity of ethanolic extracts of South Indian medicinal plants against Plasmodium falciparum

ObjectiveTo explore the antiplasmodial potential ofCatharanthus roseus L (C. roseus), Coccinea grandis (C. grandis), Thevetia peruviana (T. peruviana), Prosopis juliflora (P. juliflora), Acacia nilotica (A. nilotica), Azadirachta indica (A. indica) (Abr. Juss) and Morinda pubescens (M. pubescens).MethodsThe C. roseus L, C. grandis, T. peruviana, P. juliflora, A. nilotica, A. indica (Abr. Juss) and M. pubescens were collected from Ramanathapuram District, Tamil Nadu, India and the extraction was carried out in ethanol. The filter sterilized extracts (100, 50, 25, 12.5, 6.25 and 3.125 μg/mL) were tested for antiplasmodial activity against Plasmodium falciparum. The phytochemical constituents in the potential extracts were also detected.ResultsOf the selected plants species, the bark extract of A. indica (Abr. Juss) showed excellent antiplasmodial activity (IC₅₀ 29.77 μg/mL) followed by leaf extract of A. indica (Abr. Juss) (IC₅₀47.20 μg/mL) and leaf extract of C. roseus L (IC₅₀49.63 μg/mL). The leaf, bark and flower extracts of P. juliflora showed IC₅₀values of more than 100 μg/mL. Statistical analysis reveals significant antiplasmodial activity (P<0.01) between the concentrations and time of exposure. Additionally, no chemical injury was found in the erythrocytes incubated with the ethanolic extract of all the tested plants. The in vitro antiplasmodial activity might be due to the presence of alkaloids, glycosides, carbohydrates, flavonoids, phenols, saponins, triterpenoids, proteins and tannins in the ethanolic extracts of the tested plants.ConclusionsThe ethanolic bark extracts of A. indica (Abr. Juss) possess lead compounds for the development of antiplasmodial drugs.     

Recombinant larvicidal bacteria with markedly improved efficacy against culex vectors of west nile virus

An urgent need exists for new agents to control mosquito vectors of disease. Mosquito larvicides based on the bacteria Bacillus thuringiensis subsp. israelensis (Bti) or B. sphaericus (Bs) are effective in many habitats, but use is limited by their high cost. Moreover, mosquito resistance evolves rapidly to Bs where it is used intensively. The efficacy of these bacteria is due to a binary protein (BsB) in Bs and four proteins (Cry4A, Cry4B, Cry11A, and Cyt1A) in Bti. Here we report the use of cyt1A promoters and a 5' mRNA stabilizing sequence to synthesize high levels of Bs2362 binary toxin in Bti strains. The recombinant BtiIPS-82/BsB showed high potency against fourth instars of Culex quinquefasciatus, a vector of West Nile virus, being 21-fold as potent as BtiIPS-82, and 32-fold as potent as Bs2362. Similar improved efficacy was obtained against larvae of Cx. tarsalis. Moreover, BtiIPS-82/BsB suppressed resistance to Bs2362 in Cx. quinquefasciatus.     

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.