Challenges to using neem (Azadirachta indica var. sianensis Valenton) in Thailand

The use of botanical insecticides based on the neem seed (Azadirachta indica var.siamensis Valeton) shows strong potential in the fight against important agricultural pests. Unfortunately, its use in rural Thailand is extremely limited. This study examines the efficacy of neem extracts processed under rural conditions; identifies factors that influence local farmers’ adoption of neem products; and proposes recommendations to promote the use of neem insecticides. The principal findings are: in field trials conducted under typical rural conditions, neem did not adequately control major pests of yard-long beans (Vigna sesquipedalis); and intensity of vegetable production, knowledge of neem insecticides and availability and accessibility of neem products strongly influence farmers’ adoption of neem products for pest control.     

The effect of neem (Azadirachta indica A. Juss) oil on oviposition, development and reproductive potentials of Sesamia calamistis Hampson (Lepidoptera: Noctuidae) and Eldana saccharina Walker (Lepidoptera: Pyralidae)

Abstract 1 The effect of different treatments of neem oil (0, 0.075, 0.1 and 0.15 mL/plant) and their persistence (0, 5 and 10 days after application; DAA) on the oviposition behaviour and the bionomics of the noctuid Sesamia calamistis and the pyralid Eldana saccharina were tested in laboratory and greenhouse experiments. 2 For most variables, no difference was found between DAA, showing that the treatments had a long‐term effect, and pooled analyses across DAA were performed. Compared with the control (0 mL/plant), mean reductions due to neem in numbers of egg batch and eggs laid were 70 and 88% for S. calamistis and 50 and 49% for E. saccharina, respectively, but no differences were found among neem concentrations. 3 For both species, larval and pupal development time was shortest in the control and longest with the highest oil concentration. Immature survival, larval weight and fecundity were highest in the control and similar in the neem treatments. 4 No differences were found in sex ratios. Egg viability was highest in the control (approximately 87%) and lowest (72%) with the highest oil concentration. As a result of lower fecundity and longer developmental time, on average, the intrinsic rates of increase in the neem treatments were 30% lower than in the control. 5 In view of the low oviposition rates, immature survival, fecundity and egg viability in the neem treatments, and the relatively high persistence of neem oil, it can be expected that the reduction in densities of the two borers species in the field will be considerable.     

Evaluation of neem (Azadirachta indica) seed and ginger (Zingiber officinale) as potential control agents of yam (Dioscorea rotundata Poir.) tuber rot fungi

Yam is an important crop which serves as a source of income to small-holder farmers as well as a foreign exchange earner. Among the constraints faced by yam farmers are pests and diseases, especially deterioration caused by microbes during storage. Since over dependence on pesticides is being discouraged, neem seed and ginger extracts were evaluated as potential control agents against rot-causing fungi. The study was conducted in the Spanish laboratory, at the Faculty of Agriculture, University for Development Studies, Nyankpala Campus. Isolations were made from rotted yam tubers sampled from the Tamale Central market with potato dextrose agar (PDA) as the growth medium. Growth inhibition of the isolates was determined by growing pure cultures on PDA plates amended with 2?ml each of ethanol and aqueous extracts of neem seed and ginger as well as carbendazim. A pathogenicity test proved that Aspergillus flavus, A. niger, A. ochraceus and Penicillium digitatum isolated from the rotted tubers were responsible for the rot. A. niger had a significantly higher (p?<?0.05) occurrence (40%) than the others. Growth inhibitions by carbendazim and ethanol extracts of neem seed and ginger were comparable but significantly higher (p?<?0.05) than the aqueous extracts of neem seed and ginger as well as the control. However, the aqueous extracts of neem seed and ginger had a significantly higher (p?<?0.05) inhibition than the control. For instance, growth inhibition of A. niger by carbendazim, ethanol neem seed and ginger extracts were 70.5, 69.6 and 65.5%, respectively, while inhibition by aqueous neem seed and ginger extracts were 33.9 and 24.8%, respectively. Since aqueous extracts of neem seed and ginger significantly inhibited (p?<?0.05) growth of the rot-causing fungi, they can be used as surface protectants of stored tubers.     

Extraction of total phenolic content from Azadirachta indica or (neem) leaves: Kinetics study

The objective of this work is to put forth the optimization and kinetics of total phenolic compounds extraction from Azadirachta indica leaves in a stirred batch extraction. Various experiential extraction parameters have been studied for maximum extraction of the total phenolic compounds. The maximum yield of total phenolic compounds was found to be 10.80?mg?g^?1 of dried neem powder under the optimized conditions. The extraction kinetics behavior followed first-order kinetics with diffusion coefficient ranged from 1.8?×?10^?12 to 3.2?×?10^?12?m² s^?1 for all sets. Activation energy (E_a) value for the extraction of the total phenolic compounds was found to be 22.87?kJ?mol^?1. The kinetic expression model developed by Spiro and Siddique showed a good agreement with the experimental outcomes. The obtained results can be used to scale up the operations for industrial purposes.     

A survey of die-back disease of neem in Tamil Nadu,India and PCR-based confirmation of the isolates

A survey of die-back disease of neem was done in different agro climatic regions of Tamil Nadu, India using Global Positioning System (GARMIN 12). Twigs of Azadirachta indica (Neem) infected with die-back were collected from different regions of Tamil Nadu, India and they were further analyzed to determine the pathogen. Phomopsis azadirachtae the causal organism was isolated on malt extract agar from die-back infected neem twigs. They were identified by conventional and molecular methods. Phomopsis genus specific primers (5.8S r-DNA) were then used for the confirmation of P. azadirachtae – the causative agent of die-back of neem by Polymerase chain reaction (PCR). Studies revealed the amplification of expected 141bp DNA in P. azadirachtae isolated from the diseased trees of different regions of Tamil Nadu confirming the causal organism of die-back of neem. Studies revealed a very high incidence of die-back in most of the places of Tamil Nadu. Hand held GPS was used in the study which would help in continuous monitoring of the diseased trees.     

Study of die back disease incidence of neem in Karnataka,India and PCR based identification of the isolates

A disease survey of die back of neem was done in different agroclimatic regions of Karnataka, India using Global Positioning System (GARMIN 12). Twigs of Azadirachta indica (Neem) infected with die back were collected from different regions of Karnataka, India and they were further analysed to determine the pathogen. Phomopsis azadirachtae the causal organism was isolated on malt extract agar from die back infected neem twigs. They were identified by conventional and molecular methods. Phomopsis genus specific primers (5.8S r-DNA) were then used for the detection of P. azadirachtae, the causative agent of die back of neem by polymerase chain reaction (PCR). Studies revealed the amplification of expected 141 bp DNA in P. azadirachtae isolated from the diseased trees of different regions of Karnataka indicating the causal organism of die back disease on neem. Studies revealed a very high incidence of die back in most of the places of Karnataka. This is the first report on disease incidence of die back of neem. Hand held GPS was used in the study which helps in continuous monitoring of the diseased trees.     

Studies on plant gums. Proteases in neem (Azadirachta indica) gum

Proteolytic activity was detected in neem (Azadirachta indica) exudate gum when tested with casein and albumin as substrates. The enzyme activity was separated into two fractions by chromatography on TEAE-cellulose after EDTA treatment. Both the enzyme fractions were fairly stable to high temperatures and wide range of pH conditions. The pH optima were found to be around 6.5. Phenylmethyl sulphonylfluoride inhibited the activity of both the fractions. EDTA, Β-mercaptoethanol, tosylamide phenylethylchloromethylketone, tosyllysine chloroimethylketone,p-chloromercuribenzoate and dithiobis-2-nitrobenzoie acid did not affect the activity of the two enzyme fractions. The two fractions had no hydrolytic action on a variety of synthetic substrates tested.     

Azadirachta indica A. Juss (neem) as a contraceptive: An evidence-based review on its pharmacological efficiency

BackgroundAzadirachta indica A. Juss. is an Indian medicinal plant with innumerable pharmacological properties. Studies have proven that the phytochemicals from neem possess remarkable contraceptive abilities with limited knowledge on its mechanism of action.PurposeThe present review aims to summarize the efficiency of A. indica treatment as a contraceptive.MethodsThe Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines were used. Published scientific articles on antifertility, antispermatogenic, antiovulation, hormone altering, contraceptive, and abortifacient activities of A. indica were collected from reputed Journals from 1980 to 2020 using electronic databases. Specific keywords search was completed to collect numerous articles with unique experiment design and significant results. This was followed by the selection of the requisite articles based on the criteria designed by the authors. Data extraction was based on the common research elements included in the articles.ResultsA total of 27 studies were considered for reviewing, which included key pharmacological investigations. In the beginning, authors evaluated a number of publications on the contraceptive properties of A. indica, in which it was revealed that most of the publications were made between 2005 and 2009. All the collected articles were categorised and reviewed as antifertility, antispermatogenic, antiovulation, hormone altering, contraceptive, and abortifacient. Authors also assessed studies based on the plant parts used for pharmacological evaluations including leaves, seeds, stem-bark, and flowers. The article was primarily divided into different sections based on the previous works of authors on phytochemistry and pharmacological review articles.ConclusionAlthough A. indica is not reported with the complete alleviation of reproductive system in both male and female animal models, studies have proven its efficacy as a contraceptive. Extracts and phytochemicals from neem neither reduced the libido nor retarded the growth of secondary sexual characters, thus indicating only a temporary and reversible contraceptive activity. However, there is a dearth for clinical studies to prove the efficacy of A. indica as a herbal contraceptive.     

Bacillus thuringiensis and neem seed oil (Azadirachta indica) effects on the potato tuber moth Phthorimaea operculella zeller in the field and stores

A comparative evaluation for the efficacy of Bacillus thuringiensis and neem seed oil on Phthorimaea operculella has been carried out in the field and store. These two preparations were almost equally effective on the potato tuber moth infestation. The percentage of infestation was reduced through successive application of either preparations in the field up to harvest. No synergism was observed upon using combination of the two preparations. In the store, neem seed oil (500 ppm) was highly protective and was as effective as sevin. A combination of both neem and B.t. (Delfin) significantly protects the tubers. This suggests the possible use of either neem seed oil or B.t. in combating the insect pest in the field or during storage.     

Field evaluation of the efficacy of neem oil (Azadirachta indica A. Juss) and Beauveria bassiana (Bals.) Vuill. in cotton production

Neem oil (Azadirachta indica A. Juss) alone and combined with the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin (isolate Bb11) was applied to control cotton pests. The efficacy of these treatments was compared with that of synthetic insecticides applied either in a calendar‐based application or in the ‘Lutte Etagée Ciblée’ (LEC) strategy, consisting of using first calendar‐based (half‐dose) applications followed by threshold‐based treatments. The experiment was carried out in collaborative research with farmers in three cotton agro‐ecological zones differing in rainfall, pest prevalence, and farming practices. The neem oil and neem oil‐Bb11 treatments required 2 to 6 applications, while conventional and LEC received 6 to 8 applications. The percentage of damaged reproductive organs in plots treated with neem oil and neem oil plus Bb11 was higher than that recorded under the conventional and LEC strategy, with exception of the zone with the highest rainfall; this resulted in yields being 25% and 39% lower, respectively. Yields in the biopesticide plots were 26–42% higher and in the conventional and LEC plots 44–59% higher than those in the control plots that received only water. Overall, the LEC regime scored best, both in yield and profitability. The incidence of natural enemies was highest in the control and in the plots treated with biopesticides. Although the use of entomopathogen Bb11 and neem oil avoids many problems associated with the application of synthetic insecticides, their efficacy needs to be enhanced by improved formulation or by combining them with other pesticides.     

Cytotoxic and antiproliferative effects induced by a non terpenoid polar extract of A. indica seeds on 3T6 murine fibroblasts in culture

Neem oil is a natural product obtained from the seeds of the tree Azadirachta indica. Its composition is very complex and the oil exhibits a number of biological activities. The most studied component is the terpenoid azadirachtin which is used for its insecticidal and putative antimicrobial properties. In this report we investigate the biological activity of partially purified components of the oil obtained from A. indica. We show that the semi-purified fractions have moderate to strong cytotoxicity. However, this is not attributable to azadirachtin but to other active compounds present in the mixture. Each fraction was further purified by appropriate extraction procedures and we observed a differential cytotoxicity in the various sub-fractions. This led us to investigate the mode of cell death. After treatment with the oil fractions we observed positivity to TUNEL staining and extensive internucleosomal DNA degradation both indicating apoptotic death. The anti-proliferative properties of the neem oil-derived compounds were also assayed by evaluation of the nuclear PCNA levels (Proliferating Cell Nuclear Antigen). PCNA is significantly reduced in cells treated with a specific fraction of neem oil. Finally, our results strongly suggest a possible involvement of the mitochondrial pathway in the apoptotic death.     

The neem limonoids azadirachtin and nimbolide induce cell cycle arrest and mitochondria-mediated apoptosis in human cervical cancer (HeLa) cells

Abstract

Limonoids from the neem tree (Azadirachta indica) have attracted considerable research attention in recent years owing to their potent antioxidant and anti-proliferative effects. The present study was designed to investigate the cellular and molecular mechanisms by which azadirachtin and nimbolide exert cytotoxic effects in the human cervical cancer (HeLa) cell line. Both azadirachtin and nimbolide significantly suppressed the viability of HeLa cells in a dose-dependent manner by inducing cell cycle arrest at G0/G1 phase accompanied by p53-dependent p21 accumulation and down-regulation of the cell cycle regulatory proteins cyclin B, cyclin D1 and PCNA. Characteristic changes in nuclear morphology, presence of a subdiploid peak and annexin-V staining pointed to apoptosis as the mode of cell death. Increased generation of reactive oxygen species with decline in the mitochondrial transmembrane potential and release of cytochrome c confirmed that the neem limonoids transduced the apoptotic signal via the mitochondrial pathway. Altered expression of the Bcl-2 family of proteins, inhibition of NF-κB activation and over-expression of caspases and survivin provide compelling evidence that azadirachtin and nimbolide induce a shift of balance toward a pro-apoptotic phenotype. Antioxidants such as azadirachtin and nimbolide that can simultaneously arrest the cell cycle and target multiple molecules involved in mitochondrial apoptosis offer immense potential as anti-cancer therapeutic drugs.     

Somatic embryogenesis and plant regeneration of neem (Azadirachta indica A. Juss.)

Somatic embryos were initiated with mature seeds of neem (Azadirachta indica A. Juss.) when cultured on Murashige and Skoog's medium supplemented with thidiazuron (TDZ). Regeneration occurred via somatic embryogenesis: direct embryo formation and through an intermediary callus phase. TDZ was very effective and induced somatic embryogenesis across a wide range of concentrations (1–50 μm). However, somatic embryogenesis was accompanied by callus formation at concentrations of 20 μm and above. Cell suspension cultures were established with the TDZ-induced callus and groups of large cell clumps were formed within 2–3 weeks. Plants were regenerated from both directly formed somatic embryos and somatic embryos derived from cell suspensions plated on semisolid medium devoid of growth regulators. Regenerated plantlets continued to grow after transfer to a greenhouse environment and were similar phenotypically to zygotic seedlings. This simple regeneration system may be beneficial for mass propagation of selected elite clones of neem. Received: 13 May 1997 / Revision received: 13 November 1997 / Accepted: 2 December 1997     

Evaluation of neem (Azadirachta indica L.) products for the control of root-knot nematode of chilli pepper (Capsicum annum L.)

Chilli pepper is an important vegetable in the diet of Ghanaians but there are some constraints militating against increased production notable among which is nematode infestation. A study was therefore carried out at the plant house of the Faculty of Agriculture, University for Development Studies, Nyankpala to investigate the efficacy of neem products against root-knot nematode of chilli pepper (Capsicum annum L.). The treatments which included 20 g neem leaf powder, 20 g neem cake, 20 g neem seed powder and control were arranged in a completely randomised design with four replications. Neem products significantly reduced (p < 0.05) nematode population, with 20 g of neem leaf powder recording the highest reduction. Similarly, plants treated with neem leaf powder produced a significantly lower (p < 0.05) number of root galls compared to the other treatments. Neem leaf powder could be used as a nematicide for nematodes control as a replacement for synthetic nematicides.     

Toxicity of insecticides to obliquebanded leafroller, Choristoneura rosaceana, larvae and adults exposed previously to neem seed oil

Adult and sixth instar obliquebanded leafroller, Choristoneura rosaceana (Harris), exposed previously as fifth instar larvae to sub-lethal concentrations of neem, Azadirachta indica A. Juss., seed oil contained in artificial diet were more susceptible to topically applied pyrethroid, carbamate and organophosphate insecticides than C. rosaceana reared on control diets. Increased susceptibility to insecticides did not result from reduced vigour, as measured by reductions in adult or larval weights, but is instead correlated with previously demonstrated reductions in detoxication enzyme activities. The modest increases in susceptibilities, not exceeding ca. 4.5-fold, for C. rosaceana exposed to neem were achieved with subjects from a susceptible laboratory colony; a larger response could be expected for resistant field populations having elevated detoxication enzyme levels. Neem-based insecticides could be useful tools for the management of orchard pests that have developed resistance to synthetic neurotoxins. These findings also contribute to a better understanding of the numerous physiological changes that occur in larval Lepidoptera following exposure to neem extracts.     

Limonoids and Flavonoids from the Flowers of Azadirachta indica var. siamensis,and Their Melanogenesis‐Inhibitory and Cytotoxic Activities

A new limonoid, 7‐O‐acetyl‐7‐O‐debenzoyl‐22‐hydroxy‐21‐methoxylimocinin ( 2 ), and two new flavonoids, 3′‐(3‐hydroxy‐3‐methylbutyl)naringenin ( 7 ) and 4′‐O‐methyllespedezaflavanone C ( 9 ), along with nine known compounds, including two limonoids, 1 and 3 , and seven flavonoids, 4 – 6, 8 , and 10 – 12 , were isolated from a MeOH extract of the flowers of Azadirachta indica A.Juss. var. siamensis Valeton (Siamese neem tree; Meliaceae). The structures of new compounds were elucidated on the basis of extensive spectroscopic analysis and comparison with literature data. All of these compounds were evaluated for their melanogenesis‐inhibitory activities in B16 melanoma cells induced with α‐melanocyte‐stimulating hormone (α‐MSH). Compound 2 (16.9% melanin content at 30 μM ), 6‐deacetylnimbin ( 3 ; 49.6% melanin content at 100 μM ), and kaempferide ( 10 ; 41.7% melanin content at 10 μM ) exhibited inhibitory effects with no, or almost no, toxicity to the cells (81.0–111.7% cell viability). In addition, evaluation of their cytotoxic activities against HL60, A549, AZ521, and SK‐BR‐3 human cancer cell lines, isoazadironolide ( 1 ), 4′‐O‐methyl‐8‐prenylnaringenin ( 5 ), euchrestaflavanone A ( 8 ), 9 , and 3‐methoxy‐3′‐prenylnaringenin ( 12 ) revealed potent cytotoxicities against one or more cell lines with IC₅₀ values in the range of 4.5–9.9 μM .     

Aberrations caused by neem oil odour in green leafhopper feeding on rice plants

Using an electronic device and a lignin-specific dye, the feeding behaviour of the green leafhopper,Nephotettix virescens (Distant), (Homoptera: Cicadellidae) was monitored on rice plants kept in an arena permeated with the odour of neem (Azadirachta indica A. Juss) seed oil. The garlicky odour of neem oil disrupted the normal feeding behaviour of the leafhopper. Phloem feeding byN. virescens on rice plants kept in an arena permeated with odour of 6, 12, or 25% neem oil was significantly reduced compared with that on control plants kept in an arena with paraffin oil or 1.66% aqueous Teepol solution. Reduced intake from phloem was associated with a significant increase in the insect's probing frequency and an increase in durations of salivation and xylem ingestion.

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Alterations du comportement sur riz de Nephotettix virescens, dues à l'odeur d'essence de neem (Azadirachta indica)

Résumé De nombreux essais en plein champ à l'I.R.R.I. ont révélé une réduction du T.V. (tungro virus) transmis par (Nephotettix virescens) sur des parcelles de riz sensible non-traitées, entourées de parcelles pulvérisées périodiquement avec de l'essence de graines de neem (Azadirachta indica).L'essence de neem a une forte odeur d'ail, perceptible à distance. Nous avons examiné l'effet de l'odeur d'essence de neem sur le comportement alimentaire deN. verescens, grâce à un dispositif électronique et un colorant spécifique de la lignine. Sur du riz maintenu dans une enceinte imprégnée d'odeur d'essence de neem, nous avons constaté une diminution de la consommation de phloème, une augmentation significative de la fréquence des piqûres et une augmentation de temps de salivation et d'absorption de xylème. Ces altérations du comportement alimentaire provoquées par l'odeur d'essence de neem peuvent expliquer la diminution de la fréquence du T.V. spécifique du phloème dans des champs de riz non-traités, entourés de champs pulvérisés avec de l'essence de neem.

     

In vitro screening of systemic fungicides against Phomopsis azadirachtae,the incitant of die-back of neem

Abstract

Phomopsis azadirachtae Sateesh, Bhat & Devaki is the causal organism of die-back of neem (Azadirachta indica A.Juss.) which is, presently, a major crippling disease of neem in India. Six systemic fungicides such as Bavistin (carbendazim), Contaf (hexaconazole), Beam (tricyclazole), Fuji-one (isoprothiolane) Roko (thiophanate methyl) and Downymil (metalaxyl) were evaluated against P. azadirachtae under in vitro conditions. Colony diameter, mycelial dry weight, pycnidial formation and the germ tube length of the pathogen were the parameters studied. The results indicated that carbendazim was the most effective in inhibiting the growth followed by thiophanate methyl. Among the different concentrations tested, carbendazim at 0.25 ppm and thiophanate methyl at 0.75 ppm were optimum for controlling the growth of the pathogen. Both these fungicides can be utilized for the control of die-back of neem.     

Studies on plant gums. Role of calcium in polysaccharide-protein interaction in the neem (Azadirachta indica) gum

The partial removal of tightly bound Ca²⁺ from dialysed neem (Azadirachta indica) gum, resulted in the release of a basic protein from a highly anionic polysaccharide-protein complex as evidenced by chromatographic studies on TEAE-cellulose. Complete removal of Ca²⁺ caused, in addition, the release of a minor heteropolysaccharide which was found in association with the basic protein. These processes were reversed on the addition of Ca²⁺. The gum, in addition, contained a protein-rich component accounting for 35% protein and 7.5% total carbohydrate. This component behaved as a distinct entity during ion-exchange chromatography of the native gum solutions, or which were either partially or completely depleted of bound Ca²⁺.