Larvicidal activity of neem oil (Azadirachta indica) formulation against mosquitoes
TL;DR: The neem oil formulation was found effective in controlling mosquito larvae in different breeding sites under natural field conditions and may prove to be an effective and eco-friendly larvicide, which could be used as an alternative for malaria control.
Abstract: Background
Mosquitoes transmit serious human diseases, causing millions of deaths every year. Use of synthetic insecticides to control vector mosquitoes has caused physiological resistance and adverse environmental effects in addition to high operational cost. Insecticides of botanical origin have been reported as useful for control of mosquitoes. Azadirachta indica (Meliaceae) and its derived products have shown a variety of insecticidal properties. The present paper discusses the larvicidal activity of neem-based biopesticide for the control of mosquitoes.
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TL;DR: The formulated neem oil nanoemulsion of 31.03 nm size was found to be an effective larvicidal agent and may be a good choice as a potent and selective larvicide for Cx.
Abstract: BACKGROUND: Nanoemulsion composed of neem oil and non-ionic surfactant Tween 20, with a mean droplet size ranging from 31.03 to 251.43 nm, was formulated for various concentrations of the oil and surfactant. The larvicidal effect of the formulated neem oil nanoemulsion was checked against Culex quinquefasciatus.
RESULTS: O/W emulsion was prepared using neem oil, Tween 20 and water. Nanoemulsion of 31.03 nm size was obtained at a 1:3 ratio of oil and surfactant, and it was found to be stable. The larger droplet size (251.43 nm) shifted to a smaller size of 31.03 nm with increase in the concentration of Tween 20. The viscosity of the nanoemulsion increased with increasing concentration of Tween 20. The lethal concentration (LC50) of the nanoemulsion against Cx. quinquefasciatus was checked for 1:0.30, 1:1.5 and 1:3 ratios of oil and surfactant respectively. The LC50 decreased with droplet size. The LC50 for the ratio 1:3 nanoemulsions was 11.75 mg L−1.
CONCLUSION: The formulated nanoemulsion of 31.03 nm size was found to be an effective larvicidal agent. This is the first time that a neem oil nanoemulsion of this droplet size has been reported. It may be a good choice as a potent and selective larvicide for Cx. quinquefasciatus. Copyright © 2011 Society of Chemical Industry
255 citations
TL;DR: Issues associated with the present-day vector control strategies and state opportunities are raised with a focus on ongoing research and recent advances to enable to sustain the gains achieved so far.
Abstract: Malaria is one of the most common vector-borne diseases widespread in the tropical and subtropical regions. Despite considerable success of malaria control programs in the past, malaria still continues as a major public health problem in several countries. Vector control is an essential part for reducing malaria transmission and became less effective in recent years, due to many technical and administrative reasons, including poor or no adoption of alternative tools. Of the different strategies available for vector control, the most successful are indoor residual spraying and insecticide-treated nets (ITNs), including long-lasting ITNs and materials. Earlier DDT spray has shown spectacular success in decimating disease vectors but resulted in development of insecticide resistance, and to control the resistant mosquitoes, organophosphates, carbamates, and synthetic pyrethroids were introduced in indoor residual spraying with needed success but subsequently resulted in the development of widespread multiple insecticide resistance in vectors. Vector control in many countries still use insecticides in the absence of viable alternatives. Few developments for vector control, using ovitraps, space spray, biological control agents, etc., were encouraging when used in limited scale. Likewise, recent introduction of safer vector control agents, such as insect growth regulators, biocontrol agents, and natural plant products have yet to gain the needed scale of utility for vector control. Bacterial pesticides are promising and are effective in many countries. Environmental management has shown sufficient promise for vector control and disease management but still needs advocacy for inter-sectoral coordination and sometimes are very work-intensive. The more recent genetic manipulation and sterile insect techniques are under development and consideration for use in routine vector control and for these, standardized procedures and methods are available but need thorough understanding of biology, ethical considerations, and sufficiently trained manpower for implementation being technically intensive methods. All the methods mentioned in the review that are being implemented or proposed for implementation needs effective inter-sectoral coordination and community participation. The latest strategy is evolution-proof insecticides that include fungal biopesticides, Wolbachia, and Denso virus that essentially manipulate the life cycle of the mosquitoes were found effective but needs more research. However, for effective vector control, integrated vector management methods, involving use of combination of effective tools, is needed and is also suggested by Global Malaria Control Strategy. This review article raises issues associated with the present-day vector control strategies and state opportunities with a focus on ongoing research and recent advances to enable to sustain the gains achieved so far.
226 citations
Cites background from "Larvicidal activity of neem oil (Az..."
...stephensi larvae in tanks and pits, and 100% reduction was found (Dua et al. 2009)....
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...Larvicidal activity of the emulsified neem oil formulation was observed against late instars of A. stephensi larvae in tanks and pits, and 100% reduction was found (Dua et al. 2009)....
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TL;DR: Key neem pesticidal components, their active functional ingredients along with recent strategies on employing nanocarriers, to provide controlled release of the active ingredients and to improve their stability and sustainability are discussed.
Abstract: Over the years, extensive use of commercially available synthetic pesticides against phytophagous insects has led to their bioaccumulation in the environment causing increased resistance and reduction in soil biodiversity. Further, 90% of the applied pesticides enter the various environmental resources as a result of run-off, exposing the farmers as well as consumers of the agricultural produce to severe health issues. Therefore, growing attention has been given toward the development of alternate environmentally friendly pesticides/insecticides that would aid an efficient pest management system and also prevent chronic exposures leading to diseases. One such strategy is, the use of neem plant's (Binomial name: Azadirachta indica) active ingredients which exhibit agro-medicinal properties conferring insecticidal as well as immunomodulatory and anti-cancer properties. The most prominent constituent of neem is azadirachtin, which has been established as a pivotal insecticidal ingredient. It acts as an antifeedant, repellent, and repugnant agent and induces sterility in insects by preventing oviposition and interrupting sperm production in males. This review discusses, key neem pesticidal components, their active functional ingredients along with recent strategies on employing nanocarriers, to provide controlled release of the active ingredients and to improve their stability and sustainability.
183 citations
Cites background from "Larvicidal activity of neem oil (Az..."
...Even though the neem oil formulations employed were costlier than the synthetic larvicides, neem oil was more effective for preventing pest resistance (Dua et al., 2009)....
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...Neem oil formulations at Frontiers in Plant Science | www.frontiersin.org 3 May 2017 | Volume 8 | Article 610 different concentrations were evaluated againstAedes, Anopheles, and Culex mosquitoes (Dua et al., 2009)....
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TL;DR: Overall, neem cake can be proposed as an eco-friendly and low-cost source of chemicals to build newer and safer control tools against mosquito vectors.
Abstract: Mosquitoes (Diptera: Culicidae) represent an important threat to millions of people worldwide, since they act as vectors for important pathogens, such as malaria, yellow fever, dengue and West Nile. Control programmes mainly rely on chemical treatments against larvae, indoor residual spraying and insecticide-treated bed nets. In recent years, huge efforts have been carried out to propose new eco-friendly alternatives, with a special focus on the evaluation of plant-borne mosquitocidal compounds. Major examples are neem-based products (Azadirachta indica A. Juss, Meliaceae) that have been proven as really effective against a huge range of pests of medical and veterinary importance, including mosquitoes. Recent research highlighted that neem cake, a cheap by-product from neem oil extraction, is an important source of mosquitocidal metabolites. In this review, we examined (i) the latest achievements about neem cake metabolomics with special reference to nor-terpenoid and related content; (ii) the neem cake ovicidal, larvicidal and pupicidal toxicity against Aedes, Anopheles and Culex mosquito vectors; (iii) its non-target effects against vertebrates; and (iv) its oviposition deterrence effects on mosquito females. Overall, neem cake can be proposed as an eco-friendly and low-cost source of chemicals to build newer and safer control tools against mosquito vectors.
106 citations
TL;DR: This is the first report concerning larvicidal toxicity of NSO against A. albopictus and ovideterrence against Culicidae in the field and the chance to use chemicals from the NSO EA fraction seems promising, since they are effective at lower doses, if compared to synthetic products currently marketed, and could be an advantageous alternative to build newer and safer mosquito control tools.
Abstract: Neem seed oil (NSO) of Azadirachta indica (Meliaceae) contains more than 100 determined biologically active compounds, and many formulations deriving from them showed toxicity, antifeedancy and repellence against a number of arthropod pests. However, it is widely known that botanical products can differ in their chemical composition and bioactivity, as function of the production site and production process. We used high-performance thin layer chromatography (HPTLC) to investigate differences in chemical constituents of NSOs from three production sites. HPTLC analyses showed several differences in chemical abundance and diversity among NSOs, with special reference to limonoids. Furthermore, the three NSOs and their fractions of increasing polarities [i.e. ethyl acetate (EA) fraction and butanol (BU) fraction] were evaluated for larvicidal toxicity and field oviposition deterrence against the Asian tiger mosquito, Aedes albopictus, currently the most invasive mosquito worldwide. Results from bioactivity experiments showed good toxicity of NSOs and EA fractions against A. albopictus fourth instar larvae (with LC50 values ranging from 142.28 to 209.73 ppm), while little toxicity was exerted by BU fractions. A significant effect of the production site and dosage was also found and is probably linked to differences in abundance of constituents among samples, as highlighted by HPTLC analyses. NSOs and EAs were also able to deter A. albopictus oviposition in the field (effective repellence values ranging from 98.55 to 70.10 %), while little effectiveness of BU fractions was found. Concerning ovideterrent activity, no difference due to the production site was found. This is the first report concerning larvicidal toxicity of NSO against A. albopictus and ovideterrence against Culicidae in the field. The chance to use chemicals from the NSO EA fraction seems promising, since they are effective at lower doses, if compared to synthetic products currently marketed, and could be an advantageous alternative to build newer and safer mosquito control tools.
93 citations
Cites background from "Larvicidal activity of neem oil (Az..."
...Many formulations deriving from neem seeds show antifeedancy, fecundity suppression, ovicidal and larvicidal activity, insect growth regulation and/or repellence against insect pests, even at low dosages (Dua et al. 2009; Egho 2012)....
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...indica oil showed an excellent larvicidal potential against different mosquito genera, including Aedes, Anopheles and Culex, also under field conditions (Dua et al. 2009)....
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...…Giles (LC50=11 ppm) (Okumu et al. 2007), while LC50 of an industrial neem oil formulation (i.e. neem oil coformulated with polyoxyethylene ether, sorbitan dioleate and epichlorohydrin) againstA. stephensi,C. quinquefasciatus and A. aegypti were 1.6, 1.8 and 1.7 ppm respectively (Dua et al. 2009)....
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...Many formulations deriving from neem seeds show antifeedancy, fecundity suppression, ovicidal and larvicidal activity, insect growth regulation and/or repellence against insect pests, even at low dosages (Dua et al. 2009; Egho 2012)....
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...Noticeably, emulsified formulations of A. indica oil showed an excellent larvicidal potential against different mosquito genera, including Aedes, Anopheles and Culex, also under field conditions (Dua et al. 2009)....
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References
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TL;DR: It is indicated that Neem Azal impairs hormone control of oogenesis and exerts a cytotoxic effect on both follicular cells and oocytes of the Asian malaria vector A. stephensi.
Abstract: Secondary metabolites of the neem tree (Azadirachta indica A. Juss., Meliaceae) exhibit a wide range of biological activities in insects. However, few studies have addressed the effects of neem extracts or compounds in arthropods of medical importance. In this study, a laboratory strain of Anopheles stephensi was used to assess the effects of a commercial formulation (Neem Azal® (NA)), containing azadirachtin A at 34%, on blood feeding, oviposition and oocyte ultrastructure. Oral administration of Neem Azal® to A. stephensi females through artificial blood meals did impair blood intake and oviposition in a concentration dependent manner. Similar results were obtained on females, which had consumed Neem Azal® in sucrose solution before taking a blood meal of plain blood. Neem treated females displayed a delay in oocyte development in both the phase of vitellogenesis and the phase of choriogenesis. The ultrastructural studies on ovaries from Neem Azal® treated females revealed distinct structural modifications indicative of: (i) a complete block of oogenesis, (ii) impairment of vitellogenesis and vitelline envelope formation, (iii) a severe degeneration of follicle cells. In agreement with results obtained in other insects, this study indicates that Neem Azal® impairs hormone control of oogenesis and exerts a cytotoxic effect on both follicular cells and oocytes of the Asian malaria vector A. stephensi.
95 citations
TL;DR: The gonotrophic cycle of female Anopheles was impaired by exposure to volatiles of neem, (Azadirachta indica), reetha, and garlic, but not to castor seeds and cotton seed oil, while vitellogenesis was impaired irreversably by long-term exposure to neem odor and some extracts.
Abstract: The gonotrophic cycle of female Anopheles was impaired by exposure to volatiles of neem, (Azadirachta indica), reetha, (Sapindus mukorossi), and garlic, (Allium sativum), but not to castor seeds and cotton seed oil. A brief exposure to contact or volatile extracts from neem suppressed rather than inhibited oviposition. Complete inhibition of oviposition was observed by exposure of mosquitoes to neem oil and 1 fraction containing volatile components. Vitellogenesis was impaired irreversably by long-term exposure to neem odor and some extracts. The effect of volatiles on oviposition seems to be regulated by absorption through the cuticle, although passage through the spiracles could not be excluded.
85 citations
TL;DR: Neem-based insecticides are being investigated as alternatives to synthetic insecticides for the control of forest insect pests in Canada and neither formulation caused significant mortality or antifeedant effects after a 28-day exposure.
58 citations
Journal Article•
TL;DR: Neem oil is an indigenous product and a low-cost alternative for personal protection against sand fly bites and against Phlebotomus papatasi it repelled sand flies for about 7 h in the laboratory.
Abstract: The repellent action of neem oil was evaluated against sand flies under laboratory and field conditions. Concentrations of 2% neem oil mixed in coconut or mustard oil provided 100% protection against Phlebotomus argentipes throughout the night under field conditions; against Phlebotomus papatasi it repelled sand flies for about 7 h in the laboratory. Neem oil is an indigenous product and a low-cost alternative for personal protection against sand fly bites.
56 citations
"Larvicidal activity of neem oil (Az..." refers background in this paper
...Many of these derived products have antifeedancy, ovicidal activity, fecundity suppression besides insect growth regulation and repellency against insects [5-10]....
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TL;DR: Applications of neem, Azadirachta indica (Meliaceae), to rice‐fields were evaluated with the dual objective of controlling the culicine mosquito vectors of Japanese encephalitis virus (JEV) and enhancing the grain yield.
Abstract: Applications of neem, Azadirachta indica (Meliaceae), to rice-fields were evaluated with the dual objective of controlling the culicine mosquito vectors of Japanese encephalitis virus (JEV) and enhancing the grain yield. Since crude neem products deteriorate under improper storage conditions, a laboratory bioassay was developed to screen neem cake powder against mosquito larvae, Culex quinquefasciatus. Only samples of neem giving over 90% bioassay mortality were used in field trials. When good quality neem cake powder was applied at the dose of 500 kg/ha, either alone or coated over urea, there was a striking reduction in the abundance of late instar culicine larvae and pupae. Only fourteen pupae were obtained over a period of 13 weeks in neem cake powder treated plots, and four in those treated with neem coated urea, compared with 101 in control plots. Both treatments were significantly less than the control, but on par with one another. In another field trial, neem cake coated urea was tested at 500 and 250 kg neem/ha in combination with water management practices. No reduction in efficacy was noted at the lower dose. Larval abundance in plots under water management alone did not differ significantly from the controls, but was significantly reduced when water management was combined with neem products. Two stable formulations, 'Neemrich-I' (lipid rich) and 'Neemrich-II' (azadirachtin rich), also gave good suppression of immature culicines. All the treatments with neem also gave higher grain yield than the control.(ABSTRACT TRUNCATED AT 250 WORDS)
46 citations