Effects of neem (Azadirachta indica) seed kernel extracts from different solvents on the carmine spider mite,Tetranychus cinnabarinus

Extracts of neem (Azadirachta indica A. Juss) seed kernels prepared from various solvents affected the behavior and fecundity of the carmine spider mite,Tetranychus cinnabarinus (Boisd.). Bean leaf discs freshly sprayed with different concentrations of the extracts strongly repelled the females from the treated leaves and egg-laying was reduced. On the basis of EC 50s for both parameters, the order of effectiveness of the extracts was pentane > chloroform >n-butanol > acetone > methanol > H₂ 0 (inactive). The activity decreased with increasing dielectric constant of the extracting solvent. The chloroform and butanol extracts in the original solvents were phytotoxic. Bean leaf discs 7 days after spraying with the pentane and acetone extracts, still caused mortality and reduction in fecundity of adult females, but no repellency. The acetone and the pentane extracts sprayed directly on adult female mites on bean leaf discs, caused repellency and reduction of fecundity and also mortality of adults.     

effects of neem(Azadirachta indica) seed kernel extracts from different solvents on the predacious mitePhytoseiulus persimilis and the phytophagous miteTetranychus cinnabarinus

The effects of neem seed kernel extracts from different solvents on the predacious mitePhytoseiulus persimilis Athias-Henriot and the phytophagous miteTetranychus cinnabarinus (Boisd.) were compared. All extracts were much more toxic to the latter pest than to the former. Using the respective LC₅₀ for the two species, the toxicity index (LC₅₀ Phytoseiulus/LC₅₀ Tetranychus) was found to be 3 for the methanol, 4 for the ethanol, 23 for the acetone, and 58 for the pentane extract. The order of toxicity of the extracts (pentane > acetone > ethanol > methanol) was valid only forT. cinnabarinus. The EC₅₀s for reduction of fecundity were rather close for the two species.     

Activity of neem (Azadirachta indica A. Juss) seed kernel extracts against the mustard aphid,Lipaphis erysimi

An aqueous, an ethanolic and a hexane extract obtained from neem(Azadirachta indica A. Juss) seed kernels were tested for insecticidal activity against the mustard aphid,Lipaphis erysimi Kalt. The hexane extract, which exhibited a much higher activity than the two other extracts, had an LC50 of 0.674%. When the hexane extract was partitioned with ethanol, the ethanol-soluble fraction had an LC₅₀ of 0.328%, whereas the ethanol-insoluble part showed no activity even at 1%. Column chromatography of the ethanol-soluble fraction yielded eight compounds: nimbin, epinimbin, desacetylnimbin, salannin, desacetyl-salannin, azadirachtin and two unidentified compounds — a salannin derivative and a nonterpenoid. Of these, only five could be tested. Nimbin and epinimbin exhibited no toxicity at 0.3%, whereas salannin, a salannin derivative and the non-terpenoid gave LC₅₀ values of 0.055, 0.096 and 0.104%, respectively.     

Molluscicidal effects of neem (Azadirachta indica) extracts on edible tropical land snails

The effects of 350, 500 and 700 mg kg(-1) of crude extracts of neem, Azadirachta indica A Juss, on edible tropical land snails Archachatina marginata and Limicolaria aurora (Jay) were determined and compared with control using pawpaw, Carica papaya L as bait. Responses were measured through normal feeding, cessation of food intake, cessation of crawling, mucus secretion, lack of response to mechanical stimuli (mortality) and decomposition. Results showed no effects on the controls or snails exposed to neem seed oil extract. Crude extracts of bark, root and leaf of neem at 500 and 700 mg kg(-1) produced mortality after exposure for 48 h for L aurora and 72 h for A marginata.     

Effects of neem (Azadirachta indica) extracts onLeptocorisa chinensis under choice and no-choice conditions

Two extracts from neem (Azadirachta indica A. Juss. (Meliaceae)) seeds, azadirachtin and oil, and a mixture of neem oil and abamectin, were tested on second-instar nymphs of the rice bugLeptocorisa chinensis (Dallas) (Hemiptera: Alydidae). To clarify the effect of spraying coverage on bioefficacy of test materials, experiments were conducted under choice and no-choice conditions in field cages. In a choice test, treatment with the mixture of neem oil and abamectin was most effective in reducing the survival ofL. chinensis, followed by azadirachtin at 60 ppm, 30 ppm and 3% neem oil, whereas all treatments except neem oil caused 100% mortality within 3 weeks in a no-choice test. When second-instar nymphs had choices of treated and untreated plants within a treatment, no differences in yield and sum of dead and stained grains were found between those two choices, indicating that nymphs neither caused significant reduction in yield nor reduced the quality of untreated plants. Regardless of treatment, the difference in overall yield between treated and untreated plants under choice conditions was not statistically significant (P>0.05). Our results indicate that neem-based formulations, used alone or in combination with abamectin, have the potential to be integrated into the existing programs to control the rice bug. http://www.phytoparasitica.org posting Aug. 28, 2005.     

Response ofTearias Insulana boisd. larvae to neem (Azadirachta Indica a. juss) Kernel extract

The effect of Neem on the development ofEarias insulana Boisd. was investigated. Different concentrations of an aqueous extract of Neem kernels were incorporated in a semi-synthetic diet and larval growth, pupation rate and mortality of larvae were recorded. Neem was highly effective against 7-8- and 12-day-old larvae at all concentrations ranging between 0.075 and 1%. The systemic activity of Neem was investigated by standing cotyledons of a glandless cotton strain with their petioles in different concentrations of Neem. After 72 hours feeding at all concentrations tested, larval weight was about half that on the untreated leaves.     

Biological activity of neem seed kernel extracts and synthetic azadirachtin against larvae of Plutella xylostella L

The activity of two neem extracts, AZT and NEEM-AZAL (containing 30 and 3 mg azadirachtin ml^?1 respectively) and synthetic azadirachtin (AZ) against second-instar larvae (L2) of Plutella xylostella L. was examined using leafdip bioassays. On Chinese cabbage, AZ was significantly (P <0.05) less toxic (3 to 4-fold; LC₅₀ 0.54 μg AZ ml^?1) than either neem extract against a laboratory strain of P. xylostella (FS). The LC₅₀ values for AZT against the FS and another laboratory strain (Wellcome) were not significantly different on Chinese cabbage. The activity of AZT against the FS and Wellcome strains was similar on Chinese cabbage and Brussels sprout. AZT was significantly less toxic (3-fold) on Brussels sprout against an acylurea-resistant field strain (Sawi) when compared with the FS strain on Chinese cabbage. Larval mortality (at day 13) was found to increase with increasing exposure time of P. xylostella (FS) larvae to AZT-treated Chinese cabbage, although there was little difference in mortality between 48 and 120 h exposure. When AZT, NEEM-AZAL and AZ were applied at a dose (1 μg AZ ml^?1) which gave end-point mortalities between 50 and 90% (at day 13), all treatments delayed the development of a proportion of surviving larvae but no morphogenetic abnormalities were observed in larvae which reached pupation. Evidence for antifeedant (reduced weight gain) and repellant effects (choicechamber) for AZT were observed with L2 P. xylostella (Wellcome) on Chinese cabbage. AZT was also shown to have ovicidal activity against P. xylostella (Wellcome) at relatively high dose ranges (10-1000 μg AZ ml^?1) as well as some contact activity (FS strain) in topical bioassays. In residual bioassays on glass with adults of the hymenopteran endo-larval parasitoid of P. xylostella, Diadegma semiclausum (Ichneumonidae), AZT showed little or no activity at rates up to 1000 μg AZ ml^?1. In medium-volume (MV, 200 litre ha^?1) and ultra-low-volume (c. 1 litre ha^?1) spray bioassays on Brussels sprout, AZT gave 16-92% and 88-100% mortality respectively (Wellcome strain) at rates approximating to 1-20 g AZ ha^?1. The residual activity of AZT and NEEM-AZAL against P. xylostella (FS) on Brussels sprout (MV spray) was observed to decrease appreciably after three days, the decline in activity being particularly marked for NEEM-AZAL.     

Efficacy of neem plant (Azadirachta indica) extracts in the control of Trogoderma granarium,a pest of stored groundnuts

Journal of Plant Diseases and Protection - Petroleum ether extracts of leaves and kernels of the neem plant, Azadirachta indica A. Juss, mixed at varied dosages of 0, 50, 150, 250, 350 and 500...     

Neem (Azadirachta indica) seed kernel extracts and azadirachtin as oviposition deterrents against the melon fly (Bactrocera cucurbitae) and the oriental fruit fly (Bactrocera dorsalis)

Neem(Azadirachta indica A. Juss.) seed kernel (NSK) extracts,viz., NSK aqueous suspension (NSKS), ethanolic extract of NSK (EtOH. NSK), hexane extract of NSK (neem oil), ethanolic extract of the hexane extract (EtOH. oil) and acetone extract of deoiled NSK powder (Acet. DNSKP) at 1.25-20% concentrations, and pure azadirachtin at 1.25-10 ppm, were evaluated as oviposition deterrents toBactrocera cucurbitae (Coq.) andB. dorsalis Hendel. NSKS at ≥5% under choice test conditions, and at all concentrations (≥1.25%) in no-choice tests significantly deterred oviposition in both species. Similarly, EtOH. NSK was significantly active at all the concentrations tested for both species in choice and no-choice tests. However, with neem oil and EtOH. oil sensitivities of the two species differed considerably. Both extracts deterred oviposition byB. cucurbitae at all the concentrations tested under both choice and no-choice test conditions. On the other hand, withB. dorsalis, neem oil was significantly deterrent only at 20% in both test regimes and at 5% and 20% for EtOH. oil under choice and no-choice test conditions, respectively. Acet. DNSKP significantly deterred oviposition by both species at all concentrations tested. Azadirachtin failed to deter oviposition in either species.     

Effect of a neem seed kernel suspension onTelenomus remus,an egg parasite ofSpodoptera litura

Laboratory tests showed that a 2% neem (Azadirachta indica A. Juss) seed kernel suspension (NSKS) in water sprayed onSpodoptera litura (F.) eggs before or after parasitization did not adversely affect the emergence of the egg parasiteTelenomus remus Nixon. When sprayed on eggs before parasitization, the treatment did not repel the parasite. The treatment accelerated the development of the parasite but significantly reduced the longevity of its adult. When parasitized eggs were treated, NSKS significantly increased the adult parasite longevity. Thus, a schedule of NSKS sprays can be integrated withT. remus for the control of the tobacco caterpillar,S. litura, in tobacco nurseries.     

The antifeedant effect of neem seed kernel extract and azadirachtin on nymphs ofEyprepocnemis plorans

Acridids belonging to different species and families exhibit large differences in their response to neem components. In this context the antifeedant effect of a methanolic neem seed kernel extract (NSKE) and of azadirachtin (AZA) on fourth-instar nymphs of the acrididEyprepocnemis plorans Charpentier (Saltatoria:Acrididae) was investigated. Nymphs were offered either saccharose-impregnated filter paper disks or leaves of broad beans, treated with neem components. The amount of substrate consumed was determined by weighing the filter paper or by measuring the leaf area. On filter paper both NSKE and AZA were highly active down to the 10⁻⁴% treatment. In the leaf treatment, however, AZA was definitely more active than NSKE, with 100% deterrence at 10⁻⁴% and 10⁻²%, respectively. The methanolic NSKE was somewhat more active than the commercial preparation ‘Neemark’.     

The different effects of two preparations of neem (Azadirachta indica) and of Sumicidin® on the aphid predator Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae)

Journal of Plant Diseases and Protection - Greenhouse experiments were conducted at Khartoum (Sudan) with the aphid predator Hippodamia variegata, two botanical and one synthetic insecticides: neem...     

Efficacy of diflubenzuron and neem seed kernel suspension against the tobacco caterpillar,spodoptera litura,in tobacco nurseries

Nursery tests showed that aqueous sprays of a 25% diflubenzuron (DFB) W.P. at 0.007%, 0.009%, 0.011% and 0.013% a.i., a 2% neem seed kernel suspension (NSKS) in water and a combination of 1% NSKS plus 0.0035% DFB protected tobacco seedlings from tobacco caterpillar (Spodoptera litura [F.]) damage up to 9 days after spraying. Weekly treatments in a bulk nursery with 0.009% DFB and 2% NSKS commencing 4 weeks after germination and continued for 7 weeks, offered significant protection and significantly reducedS. litura larval population compared with an unprotected nursery.     

Influence of carrier solvent on the efficacy of neem (Azadirachta indica A. Juss) seed oil applied for the control of Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)

Journal of Plant Diseases and Protection - The influence of four carrier-solvents (acetone, ethanol, petroleum ether and hexane) on the efficacy of neem (Azadirachta indica A. Juss) seed oil...     

Production of desert locust feeding deterrents from in vitro cultured neem (Azadirachta indica)

Callus was initiated from cotyledon, hypocotyl and shoot tip explants of neem seedlings (Azadirachta indica A. Juss.) that were cultured on Murashige and Skoog (MS) agar medium supplemented with MS vitamins, casein hydrolysate, indole-3-acetic acid and benzylamino purine. Shoots regenerated from hypocotyl-derived callus only. Mature 10-12-week-old callus regenerated both shoots and somatic embryos (SEm). The antifeedant activity of different types of callus, leaves and SEm was determined with larvae of the desert locust Schistocerca gregaria in a no-choice feeding bioassay. In vitro tissue-cultured neem had antifeedant properties against the desert locust. To the best of our knowledge the antifeedant activity of neem somatic embryos extracts is reported here for the first time.     

Comparison of anti-feedant and insecticidal activity of nimbin and salannin photo-oxidation products with neem (Azadirachta indica) limonoids

Photo-oxidation of the neem limonoids nimbin and salannin with UV light in the presence of oxygen gives two isomeric lactone products per limonoid, nimbinolide and isonimbinolide, and salanninolide and isosalanninolide, respectively. When compared in insect tests with the important limonoids of neem seeds, azadirachtin, nimbin and salannin, isonimbinolide and isosalanninolide show activity greater than that of nimbin or salannin and in some respects show activity approaching that of azadirachtin. The photo-oxidation products were tested for anti-feedant activity and toxicity against larvae of three species of Lepidoptera, Spodoptera littoralis (Boisd), Spodoptera frugiperda (FE Smith) and Helicoverpa armigera (Hübner) and nymphs of the locusts Schistocerca gregaria (Forsk?l) and Locusta migratoria (L).     

The residual effect of a neem seed kernel extract sprayed on fodder beet against larvae ofSpodoptera littoralis

The residual effect of a dried methanolic extract of neem (Azadirachta indica A. Juss) seed kernels was investigated with larvae of the Egyptian cotton leafworm,Spodoptera littoralis (Boisd.), in field trials. Fodder beet was sprayed with 1% emulsions of the extract. The treated leaves were collected from the field 1, 3, 5 and 9 days after spraying and offered to the larvae for 48 h. Survival and mean weight of the larvae were recorded 2, 4, 6, 9 and 11 days from the start of exposure to the residues, and rate of pupation was calculated. The extract had a strong antifeedant effect and an intense insect growth-regulating (IGR) effect in field-treated leaves, especially with the 1- and 3-day-old residues. A positive correlation was found between the age of the residues and the mean percent of live larvae, larval weight and pupation rate of the larvae.     

Effects of two different neem products on different stages of Nezara viridula (L.) (Heteroptera, Pentatomidae)

In this study, the effects of two different commercial neem insecticides (NeemAzal T/S and Neem Oil) were determined on different stages of Nezara viridula (L.) (Heteroptera: Pentatomidae) under laboratory conditions. Neem Azal and Neem Oil were applied at concentrations of 0.5 % and 2 %, respectively. Mortality was recorded after 3, 7 and 14 days for nymphs and adults; 7 and 14 days for old (4-day-old) eggs; and 14 days for newly laid (one-day-old) eggs. Both products have no significant effect on adults and newly laid eggs. However Neem Oil was found to be more effective than NeemAzal T/S on nymphs and on old laid eggs after 7 and 14 days. It can be concluded that both neem products have potential for insecticidal efficacy (approximately 60 %) against nymphs of N. viridula. at concentrations recommended by manufacturers for registered pests.     

Effects of two different neem products on different stages of Nezara viridula (L.) (Heteroptera, Pentatomidae)

In this study, the effects of two different commercial neem insecticides (NeemAzal T/S and Neem Oil) were determined on different stages of Nezara viridula (L.) (Heteroptera: Pentatomidae) under laboratory conditions. Neem Azal and Neem Oil were applied at concentrations of 0.5 % and 2 %, respectively. Mortality was recorded after 3, 7 and 14 days for nymphs and adults; 7 and 14 days for old (4-day-old) eggs; and 14 days for newly laid (one-day-old) eggs. Both products have no significant effect on adults and newly laid eggs. However Neem Oil was found to be more effective than NeemAzal T/S on nymphs and on old laid eggs after 7 and 14 days. It can be concluded that both neem products have potential for insecticidal efficacy (approximately 60 %) against nymphs of N. viridula. at concentrations recommended by manufacturers for registered pests.