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: In order to make experimental studies comparable and statistically meaningful, the article recommends the following formula: per cent control = 100(X - Y)/X, which eliminates errors due to deaths in the control sample which were not due to the insecticide.
Abstract: There are several statistical methods used in biology (entomology) for computing the effectiveness of an insecticide, based on relating the number of dead insects in the treated plat to the number of live ones in the untreated plat. In order to make experimental studies comparable and statistically meaningful, the article recommends the following formula: per cent control = 100(X - Y)/X, where X = % living in the untreated check sample and Y = % living in the treated sample. Calculation using this method eliminates errors due to deaths in the control sample which were not due to the insecticide. An example based on treatments of San Jose scale includes computation of probable errors for X and Y, and the significance of the difference between the two counts. Common biometric convention holds that when the difference between the results of two experiments is greater than three times its probable error, the results are significant and due to the treatment applied.
11,700 citations
"Larvicidal activity of neem oil (Az..." refers methods in this paper
...The percent corrected mortality was calculated using Abbott's formula [13] and Log probit analysis was used to determine the median lethal concentration (LC50)/90% lethal concentration (LC90) of the formulation....
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TL;DR: In the context of agricultural pest management, botanical insecticides are best suited for use in organic food production in industrialized countries but can play a much greater role in the production and postharvest protection of food in developing countries.
Abstract: Botanical insecticides have long been touted as attractive alternatives to synthetic chemical insecticides for pest management because botanicals reputedly pose little threat to the environment or to human health. The body of scientific literature documenting bioactivity of plant derivatives to arthropod pests continues to expand, yet only a handful of botanicals are currently used in agriculture in the industrialized world, and there are few prospects for commercial development of new botanical products. Pyrethrum and neem are well established commercially, pesticides based on plant essential oils have recently entered the marketplace, and the use of rotenone appears to be waning. A number of plant substances have been considered for use as insect antifeedants or repellents, but apart from some natural mosquito repellents, little commercial success has ensued for plant substances that modify arthropod behavior. Several factors appear to limit the success of botanicals, most notably regulatory barriers and the availability of competing products (newer synthetics, fermentation products, microbials) that are cost-effective and relatively safe compared with their predecessors. In the context of agricultural pest management, botanical insecticides are best suited for use in organic food production in industrialized countries but can play a much greater role in the production and postharvest protection of food in developing countries.
2,996 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: Les substances derivees du «neem», efficaces contre les insectes sont examines (influence sur le comportement de fixation, the ponte, the prise de nourriture, the metamorphose, the fecondite, the fitners) ainsi que les capacites potentielles des insecticides extraits du neem pour le controle des insectes nuisibles and leurs effets sur les animaux.
Abstract: Les substances derivees du «neem», efficaces contre les insectes sont examines (influence sur le comportement de fixation, la ponte, la prise de nourriture, la metamorphose, la fecondite, la fitners) ainsi que les capacites potentielles des insecticides extraits du neem pour le controle des insectes nuisibles et leurs effets sur les animaux a sang chaud et sur l'homme
1,595 citations
Journal Article•
TL;DR: Examples of phytochemicals evaluated against mosquitoes as general toxicants, growth and reproduction inhibitors, repellents and ovipositional deterrents are given.
Abstract: A review on the reported uses of chemicals derived from botanical sources is presented, along with the part of the plant used for extraction, the mosquito species studied and the bioactivity observed for 344 plant species. Examples of phytochemicals evaluated against mosquitoes as general toxicants, growth and reproduction inhibitors, repellents and ovipositional deterrents are given. The effects of mosquito species and life stage specificity, solvents used for extraction, phototoxic activity and the geographical source from where the plant compounds are derived are discussed.
735 citations
Book•
01 Jan 1995
TL;DR: The tree and its characteristics biologically active ingredients effects on viruses and organisms neem products for pest management and practical results of neem applications against arthropod pests, and probability of development of resistance toxicity of neems to vertebrates and side effects on beneficial and other non-target organisms as discussed by the authors.
Abstract: The tree and its characteristics biologically active ingredients effects on viruses and organisms neem products for pest management and practical results of neem applications against arthropod pests, and probability of development of resistance toxicity of neem to vertebrates and side effects on beneficial and other non-target organisms various uses of neem products economic, socioeconomic and policy considerations, and neem in sociocultural life in South Asia other meliaceous plants containing ingredients for pest management and other purposes register of scientific and common names. (Part contents).
414 citations