Evaluation of two Neem seed kernel extracts againstLiriomyza trifolii (Burg.) (Dipt. Agromyzidae) (original) (raw)
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Systemic effects of a neem insecticide on Liriomyza huidobrensis larvae
Phytoparasitica, 1997
In an effort to expand the spectrum of larvicides effective against the pea leafminer, Liriomyza huidobrensis (Blanchard), we studied the effects of a neem-based insecticide (Neemix-45) on the development of the leafminer under laboratory conditions. Bean plants were treated with a soil drench of 1, 5, 10 or 25 ppm azadirachtin or by dipping leaves in 1 or 15 ppm azadirachtin at various times before or during the development of the leafminer. Treating the plants with the neem insecticide before exposure to egg-laying adults had a greater effect on inhibiting the development of pupae and adult eclosion than treatment at the 1st-instar larval stage. The systemic effects from a soil drench had a greater adverse effect on pupation and adult eclosion than leaf dipping. Drenching plants with 1 ppm azadirachtin 24 h before exposure to adults had a greater effect (0% adult eclosion) than leaf dipping at the same time period and concentration (15.6% adult eclosion). Similar results were obtained when drenching plants infested with 1st-instar larvae with 1 ppm azadirachtin (11.7% eclosion) vs dipping leaves at the same time period and concentration (44.7% eclosion).
Phytoparasitica, 1976
The effect of Neem on the development of Boarmia (Ascotis) selenaria Schiff. was investigated. Young leaves of avocado were treated in the laboratory with varying concentrations of Neem seed kernel suspensions or with emulsions of some Neem oil products, and offered to larvae of different size. Furthermore, avocado plants in flower pots were sprayed with Neem suspensions and the residues allowed to age in different locations. Leaves from the different treatments were offered to larvae of various sizes in laboratory tests and tl~t larval weight, pupation rate and mortality were recorded. 0.3% Neem was highly effective on laboratory-treated leaves. A negative correlation was found between the concentration of the Neem suspensions on the one hand and the rate of growth and pupation on the other hand. No activity was found with the emulsion of either Neem extractive or Neem oil obtained from Neem kernels after extraction. In larvae kept for four days on avocado leaves treated with 0.3% Neem suspension, the growth and pupation rate was nearly as low as in larvae fed on treated leaves throughout their life span. The experiment with Neem-sprayed plants kept at different locations indicated the following order of activity of the residues: laboratory ~ shade > sun.
Laboratory studies were conducted to investigate the toxic, growth-inhibiting and antifeedant/deterrent effects of neem derivatives on spotted bollworm and its effects on the parasitism potential and adult emergence of Trichogramma chilonis. Neem oil at 1, 1.5 and 2 % and neem seed water extract at 3 % concentrations not only significantly killed more spotted bollworm larvae but also reduced the number of surviving larvae that pupated. However, neem oil and neem seed water extract at 1 % did not affect adult emergence in the tested insect. Neem oil at 1.5 and 2 % and neem seed water extract at 3 % significantly reduced the number of larvae on treated leaves. Percentage parasitism of bollworm eggs by T. chilonis was significantly reduced when they were placed on leaves treated with 2 % neem oil, Polytrin-C ® (40 % profenofos + 4 % cypermethrin) and 3 % neem seed water extract, but adult emergence of T. chilonis was not affected by any of the neem treatments. Similarly, the F1 progeny parasitized the bollworm untreated eggs normally and the emergence of F2 progeny was not affected by neem treatments. However, Polytrin-C ® significantly reduced parasitism of the bollworm eggs by T. chilonis and adult emergence of the parasitoid.
Pesticide Science, 1993
The activity of two neem extracts, AZT and NEEM-AZAL (containing 30 and 3 mg azadirachtin ml-' 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; LC,, 0.54 pg AZ ml-l) than either neem extract against a laboratory strain of P. xylostella (FS). The LC,, 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 pg AZ ml-l) 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 pg AZ ml-l) 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 pg AZ m1-l. In medium-volume (MV, 200 litre ha-') and ultra-low-volume (c. 1 litre ha-') spray bioassays on Brussels sprout, AZT gave 1 6 9 2 % and 88-100% mortality respectively (Wellcome strain) at rates approximating to 1-20 g AZ ha-'. 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.
Pesticide Science, 1993
The activity of two neem extracts, AZT and NEEM-AZAL (containing 30 and 3 mg azadirachtin ml-' 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; LC,, 0.54 pg AZ ml-l) than either neem extract against a laboratory strain of P. xylostella (FS). The LC,, 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 pg AZ ml-l) 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 pg AZ ml-l) 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 pg AZ m1-l. In medium-volume (MV, 200 litre ha-') and ultra-low-volume (c. 1 litre ha-') spray bioassays on Brussels sprout, AZT gave 1 6 9 2 % and 88-100% mortality respectively (Wellcome strain) at rates approximating to 1-20 g AZ ha-'. 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.
Crop Protection, 2003
In greenhouse (Khartoum, Sudan), the effect of NeemAzal-T/Ss (NA, at 20 g a. i. ha À1 ) on mortality of third instar nymphs of Jacobiasca lybica was not significantly different from that of Omethoate at 200 g a. i. ha À1 . Neem oil (at 0.2 g a. i. ha À1 ) was less effective. In two semi-field tests, numbers of J. lybica and potato yield were negatively correlated. The percentage yield losses were equal in both years. Two field experiments conducted in potato, using a VLV-technique with weekly treatments of 20 l ha À1 , showed similar mortality by NA and fenvalerate (20% EC at 140 g a. i. ha À1 ) in J. lybica and Bemisia tabaci. In Aphis gossypii, fenvalerate exerted a stronger effect (84%) than NA (77%). Potato yield was highest in NA and fenvalerate, lower in neem kernel water extract (NKWE; with 2-5 g a. i. ha À1 ), and equal to water treatment in neem oil (NO). In three similar field experiments in eggplant (aubergines), fenvalerate reduced J. lybica, B. tabaci and A. gossypii by 92%, 70% and 82%, respectively, followed by NA (86%, 61% and 78%). NO and NKWE were less effective. Eggplant yield was highest following NA-treatment, fenvalerate having a lower yield in one of the experiments. NO and NKWE increased the yield in only one of the three experiments. In eggplant, the frequency of stenophagous antagonists of the homopterous pests was affected negatively by fenvalerate, resulting in an unfavourable prey/ predator ratio. The neem preparations induced only mild reduction of the antagonists, producing a favourable prey/predator ratio. Based on availability, the effects on pests, beneficials, and on yield, the use of NKWE may be recommended for plant protection in vegetables in the Sudan. Optimal concentrations, in excess of 2-5 g a. i. ha À1 , as used here, and new formulations remain to be studied. r
International Journal of Agriculture and Rural Development
Different neem (Azadirachta indica L.) extracts (leaf and seed) and seed oils were tested against English grain aphid (Sitobion avenae F.) with a neonicotinoid, imidacloprid on wheat. All neem oils and neem seed kernel extract proved comparatively more effective in laboratory bioassay studies, with LC 50 values ranging from 0.34 to 1.10%. In field-cage experiment, neem seed oil-hexane was statistically similar with imidacloprid followed by neem seed oil-expeller and neem seed kernel extract, while neem seed oil-ethanol was at par with imidacloprid. On the basis of cumulative insect days in field trials, neem seed oilexpeller proved as effective as imidacloprid in controlling the aphids, while except neem seed cake extract, all other treatments were statistically at par with imidacloprid. Non-significant differences were found in the population of mummified aphids between control and neem seed kernel extract, neem leaf extract, neem seed oil-hexane, neem seed cake extract and neem seed oil-expeller. There existed non-significant differences in all treatments regarding aphid predators. Maximum increase in wheat yield (7.28 q/ha) was observed in neem seed kernel extract treated plots followed by those of imidacloprid (7.23 q/ha). Application of imidacloprid resulted in maximum cost-benefit ratio (1:1.34) followed by that of neem seek kernel extract 5% (1:1.31). If the additional cost of loss of beneficial organisms and environmental risks posed by the application of synthetic insecticides is considered, the cost-benefit ratio of neem seed kernel extract may be comparable to that of imidacloprid and may be used against wheat aphids.
2014
Laboratory bioassays were carried out to study the insecticidal, antifeedant, developmental, and reproductive effects of three commercial neem oil-based formulations (Pure Neem Oil, Azatrol, and Triple Action Neem) on Spodoptera eridania when used at recommended concentrations. Neemderived insecticides significantly reduced the food intake of all instars tested, often limiting the feeding activity on neem-treated leaf areas to a fraction of that occurring on controls, in both choice and no-choice bioassay tests. Pure neem oil, followed by Azatrol, demonstrated up to 96% antifeedant activity against larvae; consequently, both biopesticides are effective antifeedants. A two-day feeding period on leaves treated independently with pure neem oil and Azatrol induced the prolongation of the second larval instars by 4.5 and 2.7 days, and by 2.4 and 1.3 days for fourth larval instars, respectively. Mortality and pupal ecdysis of S. eridania were also negatively impaired by neem-based biopesticides, with the greatest efficacy attributable for pure neem oil. When administered orally, commercial formulations induced significant reduction in longevity by 0.8-4.1 days, and fecundity of adults was significantly reduced compared to those fed on untreated diet.