Efficacy of Melia azedarach L. extract on the malarial vector Anopheles stephensi Liston (Diptera: Culicidae)

Methanolic extracts of leaves and seeds from the chinaberry tree, Melia azedarach L. (Meliaceae) was tested against mature and immature mosquito vector Anopheles stephensi Liston (Diptera) under laboratory condition. The extract showed strong larvicidal, pupicidal, adulticidal, antiovipositional activity, repellency and biting deterency. The M. azedarach seed and leaf extracts were used to determine their effect on A. stephensi adults and their corresponding oviposition and consequent adult emergence in comparison with the control. The seed extracts showed high bioactivity at all doses, while the leaf extracts proved to be active, only in the higher dose. Results obtained from the laboratory experiment showed that the seed extracts suppressed the pupal and adult activity of A. stephensi even at low dose. In general, first and second instar larvae were more susceptible to both leaves and seed extracts. Clear dose-response relationships were established with the highest dose of 2% plant extract evoking 96% mortality. Entire development of A. stephensi was inhibited by M. azedarach treatment. Less expensive (less than 0.50 US dollars per 1 kg seed), naturally accruing bio-pesticide could be an alternative for chemical pesticides.     

Effects of Dysoxylum malabaricum Bedd. (Meliaceae) extract on the malarial vector Anopheles stephensi Liston (Diptera: Culicidae)

In recent years, use of environmentally friendly and biodegradable natural insecticides of plant origin have received renewed attention as agents for disease vector control. Methanol extracts of leaves from the Indian white cedar Dysoxylum malabaricum Bedd. (Meliaceae) were tested against mature and immature Anopheles stephensi Liston (Diptera) mosquitoes under laboratory conditions. The extract showed strong larvicidal, pupicidal, adulticidal, and antiovipositional activity. The maximum leaf extract concentration tested in this study was 4%, which produced pronounced effects. In general, first and second instars were more susceptible to leaf extract than older insects. Clear dose-response relationships were established, with the highest dose of 4% plant extract causing 97% mortality of first instars.     

The use of Eucalyptus tereticornis Sm. (Myrtaceae) oil (leaf extract) as a natural larvicidal agent against the malaria vector Anopheles stephensi Liston (Diptera: Culicidae)

Secondary metabolites obtained from the indigenous plants with proven mosquito control potential can be used as an alternative to synthetic insecticides under the integrated vector control. The essential oil extract from the forest redgum, Eucalyptus tereticornis Sm. (Myrtaceae) was tested against mature and immature mosquito vector Anopheles stephensi Liston (Diptera) under laboratory condition. The extract showed strong larvicidal, pupicidal and adulticidal activity. The leaf oil extracts showed high bioactivity at high doses. Results obtained from the laboratory experiment showed that the leaf extracts suppressed the pupal and adult activity of Anopheles stephensi at higher doses. In general, first and second instar larvae were more susceptible to all treatments. Clear dose -response relationships were established with the highest dose of 160ppm plant extract evoking almost 100% mortality. The results obtained suggest that, in addition to their medicinal activities, E. tereticornis can also serve as a natural mosquitocide.     

Bioefficacy of Aristolochia tagala Cham. against Spodoptera litura Fab. (Lepidoptera: Noctuidae)

Bioefficacy of leaf and root extracts of Aristolochia tagala Cham. at different concentrations was evaluated at room temperature against Spodoptera litura Fab. Effects on feeding, larvicidal and pupicidal activities and larval–pupal duration were studied. Higher antifeedant activity (56.06%), lethal concentration for feeding inhibition (3.69%), larvicidal (40.66%), pupicidal (28%), total mortality (68.66%) and prolonged larval–pupal duration (12.04–13.08 days) were observed in ethyl acetate leaf extract at 5.0% concentration. Dose dependant effect of test extracts was observed. This plant could be used to isolate active principles and to develop a new botanical formulation in pest management programmes.     

Potential of crude seed extract of celery, Apium graveolens L., against the mosquito Aedes aegypti (L.) (Diptera: Culicidae).

Crude seed extract of celery, Apium graveolens, was investigated for anti-mosquito potential, including larvicidal, adulticidal, and repellent activities against Aedes aegypti, the vector of dengue haemorrhagic fever. The ethanol-extracted A. graveolens possessed larvicidal activity against fourth instar larvae of Ae. aegypti with LD50 and LD95 values of 81.0 and 176.8 mg/L, respectively. The abnormal movement observed in treated larvae indicated that the toxic effect of A. graveolens extract was probably on the nervous system. In testing for adulticidal activity, this plant extract exhibited a slightly adulticidal potency with LD50 and LD95 values of 6.6 and 66.4 mg/cm2, respectively. It showed repellency against Ae. aegypti adult females with ED50 and ED95 values of 2.03 and 28.12 mg/cm2, respectively. It also provided biting protection time of 3 h when applied at a concentration of 25 g%. Topical application of the ethanol-extracted A. graveolens did not induce dermal irritation. No adverse effects on the skin or other parts of the body of human volunteers were observed during 3 mo of the study period or in the following 3 mo, after which time observations ceased. A. graveolens, therefore, can be considered as a probable source of some biologically active compounds used in the development of mosquito control agents, particularly repellent products.     

The toxicity and biological effect of Pedalium murex L. extracts on the tobacco cutworm,Spodoptera litura (Fabr.) larvae

Petroleum ether, acetone, water and aqueous extract of Pedalium murex L. (Pedalaceae) leaves, root and fruit were tested against fourth instar larvae of the tobacco cutworm, Spodoptera litura (Fabr.) under laboratory conditions using leaf dip method. Larval mortality; larval, pupal and adult periods; pupal weight, pupation and adult emergence; larval and pupal deformities of S. litura were recorded. All the tested solvent extracts of P. murex were effective against S. litura life stages by causing mortality in a dose dependent manner. However, the efficacy was more significant with respect to acetone (leaf and root) and petroleum ether (root) at higher concentrations (0.8%) which leads to 100% larval mortality. The water and aqueous extracts of root caused 86.6 and 88.0% larval mortality respectively at 4% concentration. Among the plant parts tested, root had more importance followed by leaf and fruit. Plant extracts extended the larval, pupal and adult periods; reduced the pupal weight, pupal and adult emergence and caused larval–pupal deformities. Total life time was highly prolonged in acetone extracts of P. murex root. Though all the extracts were found to have insecticide activity, acetone and petroleum ether extracts of P. murex root can be used as an effective alternative to modern synthetic insecticides. Bioactive principles from these extracts can be isolated, identified and integrated in S. litura management.     

Evaluation of extracts and oils of tick-repellent plants from Sweden

Abstract. Leaves of Myrica gale Linnaeus (Myricaceae), Rhododendron tomentosum (Stokes) H. Harmaja (formerly Ledum palustre Linnaeus: Ericaceae) and Artemisia absinthium Linnaeus (Asteraceae) were extracted with organic solvents of different polarities and the essential oils of leaves were obtained by steam distillation. The extracts or oils were tested in the laboratory for repellency against host-seeking nymphs of Ixodes ricinus Linnaeus (Acari: Ixodidae). Rhododendron tomentosum oil, 10%, diluted in acetone, exhibited 95% repellency; R. tomentosum and A. absinthium extracts in ethyl acetate, > 70% repellency; A. absinthium extract in hexane, approximately 62% repellency; and M. gale oil, 10%, approximately 50% repellency on I. ricinus nymphs. Compounds in the leaf extracts or in the oils were collected by solid phase microextraction (SPME) and identified by gas chromatography-mass spectrometry (GC-MS) and/or MS. Characteristic volatiles detected from oil or extract of M. gale were the monoterpenes 1,8-cineole, alpha-terpineol, 4-terpineol and thujenol; and of R. tomentosum myrcene and palustrol. Characteristic volatiles from leaf extracts of A. absinthium were sabinene, oxygenated monoterpenes, e.g. thujenol and linalool, and geranyl acetate. Each plant species synthesized numerous volatiles known to exhibit acaricidal, insecticidal, 'pesticidal' and/or arthropod repellent properties. These plants may be useful sources of chemicals for the control of arthropods of medical, veterinary or agricultural importance.     

Chemical composition and anti-mosquito potential of rhizome extract and volatile oil derived from Curcuma aromatica against Aedes aegypti (Diptera: Culicidae).

Crude rhizome extracts and volatile oils of Curcuma aromatica were evaluated for chemical composition and anti-mosquito potential, including larvicidal, adulticidal, and repellent activities against the Aedes aegypti mosquito. Chemical identification achieved by GC/MS analysis revealed that xanthorrhizol, 1H-3a, 7-methanoazulene and curcumene at 35.08 and 13.65%, 21.81 and 30.02%, and 13.75 and 25.71%, were the main constituents in hexane extracts and volatile oils, respectively. Volatile oil of Cu. aromatica possessed a significantly higher larvicidal activity against the 4th instar larvae of Ae. aegypti than that of hexane extracts, with LC50 values of 36.30 and 57.15 ppm, respectively. In testing for adulticidal activity, on the other hand, hexane-extracted Cu. aromatica (LC50: 1.60 microg/mg female) was found to be slightly more effective against female Ae. aegypti than volatile oil (LC50: 2.86 microg/mg female). However, the repellency of these two products against Ae. aegypti adult females differed significantly. The hexane-extracted Cu. aromatica, with a median complete protection time of 1 h (range = 1-1.5 h) when applied at a concentration of 25%, appeared to have significantly higher repellency than that of distillate oil (0.5 h, range = 0-0.5 h). The different results obtained from both products of Cu. aromatica were probably due to variety in quantity and type of active ingredients as well as the biological and physiological characteristics that differed between both developmental stages of mosquitoes, larvae, and adults.     

非嗜食植物提取物对桔全爪螨产卵的驱避性测定

The oviposition repellency of the alcohol extracts from 50 species of non-preferable plants and azadirachtin against citrus red mite ( Panonychus cirri ) was determined using laboratory bioassays. In choice tests, the extracts from 42 of the 50 plant species and 1% azadirachtin (2000×) significantly reduced oviposition 1d after treatment.The repellency effect of the extracts from the 42 plant species was better than that of azadirachtin. Mikania micrantha extract had the best result, with an Interference Index of Population Control (IIPC) of 0.087 1 d after treatment, and significantly reduced oviposition for 9 d, while the extracts from Sesbania cannabina, Allium tuberosum , Paederia scandens , Duranta erecta and Dicranopteris pedata also had good effects, with an oviposition repellency of over 70 % 1 d after treatment, and significantly reduced oviposition for 4 - 6 d. The effect became weaker as time went on. None of the extracts showed significant oviposition attraction.     

Larvicidal and insect growth regulator effect of α-amyrin acetate from Catharanthus Roseus Linn against the malaria vector Anopheles Stephensi Liston (Diptera: Culicidae)

Vector control is a serious concern in developing countries. Over the past two decades, phytochemicals have received progressively more attention as insecticide alternatives, and they have recently become the focus in the concept of integrated vector control. α-Amyrin acetate, the n-hexane fraction of acetone extract from the leaves of Catharanthus roseus , was evaluated for its larvicidal, pupicidal and fecundity effects as well as insect growth regulator activity against the malaria vector Anopheles stephensi Liston. The highest concentration of 1 p.p.m. produced 100% mortality in first to second instars and 94% mortality in third and fourth instars. In addition, the duration of larval instars and the total developmental time were prolonged, while female longevity and fecundity were markedly decreased. The suppression of pupation and adult emergence was probably due to its action similar to juvenile hormone analogs in combination with growth regulator activity and toxicity, which reduced the overall performance of the malaria vector An. stephensi .     

Evaluation of common cocklebur Xanthium strumarium leaf extract as post‐harvest grain protectant of black gram against pulse beetle Callosobruchus chinensis (Coleoptera: Bruchidae) and isolation of crude compound

The pulse beetle Callosobruchus chinensis L. is considered the most important stored grain pest of black gram Vigna mungo Hepper in Bangladesh and other tropical and subtropical countries. Bioactive compounds derived from plants can be used to control of the pulse beetle as a potential alternative to synthetic insecticides. Therefore, aqueous extracts of common cocklebur Xanthium strumarium L. leaf was examined for insecticidal properties against C. chinensis. The extracts showed toxicity, repellent properties, inhibited fecundity and adult emergence of the insects, and protected grains. Insect mortality was accounted highest (72.6%) with 4% extract at 4 days after treatment. The beetles showed highest repellency rate (58.0%) with 4% concentration at 1 hour exposure; however insect repellency decreased with time. The beetles exerted the lowest fecundity and grain damage and produced the lowest number of offspring when they were reared on grains treated with 4% extract. The insecticidal compounds present in common cocklebur leaf were extracted in chloroform and ethanol, and isolated by thin layer chromatography (TLC) and spectral studies (¹H‐NMR and IR), which identified the presence of aromatic ester, n‐hexyl salicylate or o‐hydroxy‐n‐hexyl‐benzoate and a long‐chain ketone. Therefore, naturally occurring X. strumarium and its derivatives may be potential components for integrated management of C. chinensis.     

Larvicidal efficacy of Aloe barbadensis and Cannabis sativa against the malaria vector Anopheles stephensi (Diptera: Culicidae)

Anopheles stephensi is the primary vector of malaria, an endemic disease in India. An effort to control An. stephensi larvae by leaf extracts of Aloe barbadensis (Liliaceae) and Cannabis sativa (Moraceae) was made under laboratory conditions. A carbon tetrachloride extract of A. barbadensis was the most effective of all the extracts tested for larvicidal activity against the anopheline larvae, with LC₅₀ 15.58 and 8.04 p.p.m. after 24 and 48 h of exposure, respectively. Thus, the leaf extract of A. barbadensis has active components that could be useful as a larvicide of ecocongenial nature against malaria vectors.     

Oral administration of Eclipta alba leaf aqueous extract enhances the non-specific immune responses and disease resistance of Oreochromis mossambicus

Immunostimulatory effects of the oral administration of the medicinal plant, Eclipta alba leaf extracts was studied in tilapia, Oreochromis mossambicus. For this purpose, fish were fed for 1, 2 or 3 weeks with diets containing E. alba leaf aqueous extract at 0, 0.01, 0.1 or 1% levels. After each week, non-specific humoral (lysozyme, antiprotease and complement) and cellular (myeloperoxidase content, production of reactive oxygen and nitrogen species) responses and disease resistance against Aeromonas hydrophila were determined. The results indicated that E. alba aqueous extract administered as feed supplement significantly enhanced most of the non-specific immune parameters tested. Among the humoral responses, lysozyme activity significantly increased after feeding with aqueous extract for 1, 2 or 3 weeks. No significant modulation was noticed in all the cellular responses tested after 3 weeks of feeding, while reactive oxygen species production and myeloperoxidase content showed significant enhancement after 1 week of feeding with aqueous extract. When challenged with A. hydrophila after 1, 2 or 3 weeks of feeding, the percentage mortality was significantly reduced in the treated fish. The highest dose of 1% gave better protection than the other doses with the relative percentage survival (RPS) values of 64, 75 and 32 after feeding for 1, 2 and 3 weeks respectively. The results indicate that dietary intake of E. alba aqueous leaf extract enhances the non-specific immune responses and disease resistance of O. mossambicus against A. hydrophila.     

Growth inhibitory and antifeedant activity of extracts from Melia dubia to Spodoptera litura and Helicoverpa armigera larvae

The growth inhibitory activity and deterrency of Melia dubia (Meliaceae) extracts to Spodoptera litura and Helicoverpa armigera were investigated. Artificial diet bioassays using neonate larvae of both S. litura and H. armigera indicated that dichloroethane (DCE) and methanol (Me) extracts of M. dubia inhibited growth in a dose dependent manner. DCE and Me-5II fractions also resulted in 50% deterrency at concentrations of 22.5 and 16.8 micrograms/cm2 respectively against S. litura larvae in a leaf disc-choice test. The DCE-5 fraction was found to be more toxic to larvae (LC50 of 0.65%) than the Me-5II (LC50 of 0.8%), 72 hr after topical application. Both fractions lack contact toxicity, but the deterrent effect persisted for at least 60 hr under laboratory conditions. Although salannin was isolated from the DCE fraction to show antifeedant activity, the physico-chemical characteristics of the active fractions DCE-5 and Me-5II were not identical with either salannin or azadirachtin.     

Plant essential oils: a substitute for conventional insecticides against Tribolium species (Coleoptera: Tenebrionidae)-achievements and challenges

Abstract

The literature on efficacy of plant essential oils and their constituents for the management of Tribolium spp. (T. castaneum and T. confusum), instigating infestation of a variety of stored grains and their products is reviewed here. Both species caused significant losses in the diverse food grains and their products through infestation. Essential oils of higher plants showed potential activity in the management of these infestation driven losses. Researchers have found that essential oils and their chemical constituents have significant toxicity against both the species of Tribolium via different modes of action like repellent, insecticidal, ovicidal, larvicidal, pupicidal, ovipositional and feeding deterrent actions. Concerning repellency and in vivo bioassays, few studies have been done with the essential oils against T. confusum, thus, more investigations are required to find the repellent agents against this insect. There are some essential oil-based botanical insecticides which have been proved effective for the protection of food grains from both beetles during storage. These botanical insecticides also exhibited behaviour altering properties against both beetles, thus, reducing the problem of pest resistance which is a problem with conventional insecticides. Therefore, essential oils-based botanical insecticides may be preferred option than conventional insecticides for protecting stored grains and their products against Tribolium infestation.     

Evaluation of certain insecticides on nettings for their efficacy and wash resistance against mosquito species

Five insecticides (Bifenthrin, Deltamethrin, Etofenprox, Permethrin and Lamda cyhalothrin) recommended by WHO, at their recommended dose were compared for their efficacy and wash resistance through bioassay against mosquito vectors, Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi. Etofenprox treated nettings exhibited better knockdown and mortality than the other insecticides. The order of efficacy of the insecticides treated nettings was Etofenprox > or = Deltamethrin > Lambda cyhalothrin > Permethrin > Bifenthrin.     

Antioxidant and Antimicrobial Activity in Some Indian Herbal Plants: Protective Effect against Free Radical Mediated DNA Damage

Indian herbal plant species Lantana indica, Adhatoda vasica, Pandanus furcatus, Tylophora indica and Centella asiatica, traditionally used in ethno medicines to treat common infections and various disorders, have been studied for their antimicrobial and antioxidant activity. The methanolic extracts of the plant leaves exhibited significant and dose-dependent antioxidant activities in DPPH radical scavenging, ferric ion reducing and phosphomolybdate assays. These leaf extracts showed antimicrobial activity against selected Gram +ve and Gram ?ve bacterial strains. A. vasica and L. indica extracts possessed maximum antioxidant and antimicrobial activity, respectively. The activities could be correlated to phenolics and flavonoid content of the leaf extracts which ranged from 30.25 to 91.98 mg GAE g^?1 dw leaf extract and 2.67 to 96.45 mg RE g^?1 dw leaf extract respectively. The aqueous extracts of plant leaves significantly protected the DNA damage against the oxidative damage caused by hydroxyl radicals.     

Immunostimulatory effect of Tinospora cordifolia Miers leaf extract in Oreochromis mossambicus

Immunostimulatory effect of leaf extract of T. cordifolia on (i) specific immunity (antibody response), (ii) non-specific immunity (neutrophil activity) and (iii) disease resistance against Aeromonas hydrophila was investigated in O. mossambicus. Ethanol and petroleum ether extracts of the leaves were used. Both ethanol and petroleum ether extracts administered at doses of 0.8, 8 or 80 mg/kg body weight, prolonged the peak primary antibody titres upto one to three weeks. Ethanol extract at the dose of 8 mg/kg and petroleum ether extract at the doses of 0.8 or 8 mg/kg enhanced the secondary antibody response. All the doses of ethanol extract significantly enhanced neutrophil activity. Fish injected with petroleum ether or ethanol extract at a dose of 8 mg/kg were protected against experimental infection with virulent A. hydrophila. The results indicates the potential of T. cordifolia leaf extracts for use as an immunoprophylactic to prevent diseases in finfish aquaculture.     

Efficacy of two tropical plant extracts for the control of mosquitoes

The larvicidal activity of seed and leaf extracts of Calophyllum inophyllum and leaf extract of Rhinacanthus nasutus on the juveniles of Culex quinquefasciatus , Anopheles stephensi and Aedes aegypti was determined. Ethyl acetate (EA) soluble fractions of C. inophyllum and petroleum ether (PE) fraction of R. nasutus extracts showed very high larvicidal activity. Irrespective of the species of the mosquitoes tested, at concentrations ranging from 3.91 to 9.39 ppm, 9.04 to 35.49 ppm and 13.21 to 28.92 ppm of the active fractions of seed and leaf extracts of C. inophyllum and the leaf extract of R. nasutus , respectively, killed 50% of the treated larvae. The fractions also interfered with adult emergence. Exposure of the mosquitoes at any stage of their larval development to less than 0.86, 5.49 and 6.81 ppm of the active fractions of seed and leaf extracts of C. inophyllum and the leaf extract of R. nasutus , respectively, inhibited 50% of the treated larvae from emerging as adults. Experiments under laboratory and semi-field conditions showed that the activity of the extracts persisted for up to 10 days.     

Laboratory evaluation of methanolic extract of Atlantia monophylla (Family: Rutaceae) against immature stages of mosquitoes and non-target organisms

Methanolic extracts of the leaves of Atlantia monophylla (Rutaceae) were evaluated for mosquitocidal activity against immature stages of three mosquito species, Culex quinquefasciatus, Anopheles stephensi, and Aedes aegypti in the laboratory.Larvae of Cx. quinquefasciatus and pupae of An. stephensi were found more susceptible, with LC50 values of 0.14 mg/l and 0.05 mg/l, respectively. Insect growth regulating activity of this extract was more pronounced against Ae. aegypti, with EI50 value 0.002 mg/l. The extract was found safe to aquatic mosquito predators Gambusia affinis, Poecilia reticulata, and Diplonychus indicus, with the respective LC50 values of 23.4, 21.3, and 5.7 mg/l. The results indicate that the mosquitocidal effects of the extract of this plant were comparable to neem extract and certain synthetic chemical larvicides like fenthion, methoprene, etc.