Toxicity Of Azadirachtin Research Articles

INSECTICIDAL AND OXIDATIVE EFFECTS OF AZADIRACHTIN ON THE MODEL ORGANISM Galleria mellonella L. (LEPIDOPTERA: PYRALIDAE).

The insecticidal effects, specifically, changes in hemolymph total protein and malondialdehyde (MDA) levels, and antioxidant enzyme activities of azadirachtin (AZA) given to the wax moth, Galleria mellonella L. (Lepidoptera: Pyralidae) larvae via force feeding were investigated. Bioassays showed that the LD50 and LD99 (lethal dose) values of AZA were 2.1 and 4.6 μg/larva, respectively. Experimental analyses were performed with five doses of AZA (0.5, 1, 1.5, 2, and 3 μg/larva). Total protein level in larval hemolymph increased at all AZA doses at 24 h whereas a considerable decrease was observed at 2 and 3 μg/larva doses, and only an increase displayed at 1.5 μg/larva at 72 h. The level of MDA increased at 2 and 3 μg/larva doses at 24 h compared with controls. This trend was also observed at 1.5, 2, and 3 μg/larva doses at 72 h and MDA levels were lower when compared with those of 24 h at all doses except for 1.5 μg/larva dose. Catalase activity decreased at 1, 1.5, and 2 μg/larva doses at 24 h whereas increased at all doses except for 0.5 μg/larva at 72 h compared with controls. AZA led to a decline in superoxide dismutase activity at all experimental doses at 24 and 72 h except for 3 μg/larva doses at 72 h. An increase in glutathione-S-transferase (GST) activity was evident at all AZA doses at 24 h. AZA displayed 68% decline in GST activity at 72 h post treatments when compared to 24 h. Consequently, We infer that the toxicity of AZA extends beyond its known actions in molting processes to redox homeostasis.

EVALUATION OF ENVIRONMENTAL SAFE NATURAL COMPOUNDS IN CONTROLLING COTTON LEAFWORM Spodoptera littoralis.

The toxicity of azadirachtin, pyridalyl and quercetin compounds were evaluated against the immature stages of the cotton leafworm, Spodoptera littoralis, field strain andlaboratory susceptible strain.The results showed that azadirachtin was the most potent tested compound flowed by pyridalyl and the least one was quercetin. Azadirachtin at 15.0 ppm achieved 30.4% mortality of treated egg masses, while pyridalyl and quercetin at the same concentration caused 28.8% and 21.2% mortality of treated egg masses, for lab strain, respectively, while field strain at the same concentration caused 23.4%; 20.4% and 16.4% mortality of treated egg masses respectively. The toxicity of tested compounds were evaluated against 2nd and 4th larval instar of S. littoralis, cleared that the toxicity of the tested compounds increased with increasing the exposure time, decreased by increasing the stage of larval instars. The larvae stop eating after two days of treatment. Also, the tested compounds shows no pupal mortality after 24; 48, and 72 hrs of treatment, but significantly increased percentages of deformed of adults. Results proved that the three natural compounds (azadirachtin, pyridalyl and quercetin), are potentially potent for control of S. littoralis, as antifeeding. Generally, natural compounds, will produce a new trend to increase toxicity of the newly hatched larvae of S. littoralis, enhance the role of beneficial insects. These compounds could be used in the IPM programmes, in order to minimize the negative effects of conventional insecticides on environment components and to protect the natural enemies.

Effect of azadirachtin of neemix-4.5 on SWR/J mice

Inbred normal SWR/J male and female mice, 8–10 weeks old and weighing 22.55–26.72 g, were used throughout the study. A total of 100 males and 100 females were used and were divided into 20 groups, 10 animals in each group. Azadirachtin of neemix-4.5, a commercial botanical pesticide derived from the neem tree, orally administered to male and female SWR/J mice at a dose level 9.0 mg/kg (1/10 LD 50) for different treatment periods (2, 4, 6, 8 or 11.5 weeks) has produced signs of toxicity, mortality and changes in body and tissue weights of both sexes at almost all treated periods used in the present study. Moreover the oral administration of this dose level for 11.5 weeks has also resulted in some histopathological changes in the livers, kidneys and testes of treated animals compared with the control group, and the degree of these changes ranged from mild to severe in these organs of treated males. However, conflicting results have been reported concerning the toxicity of azadirachtin in mammalian species using different formulations of neem-based pesticides. It appears, therefore, that the toxicity produced by neemix-4.5 in the present study may be due to factors other than azadirachtin in this formulation.

Toxicity of azadirachtin to larvae and adults of <i>Tribolium castaneum</i> (Herbst)

Key words: Azadirachtin; Azadirachta indica ; LC 50 ; Tribolium castaneum ; larva; adult; residual exposure Univ. j. zool. Rajshahi Univ. Vol.22, 2003. pp. 47-53

Biological studies of azadirachtin and its derivatives against polyphagous pest, Spodoptera litura

Azadirachtin-A (Aza-A, figure 1) was subjected to a variety of synthetic transformations and the antifeedant activity and toxicity of the azadirachtin derivatives were assessed against second instar larvae Spodoptera litura on castor leaves in comparison with the crude material containing 9.14% Aza-A, as well as relatively pure 91% Aza-A. A probable mechanism for the base initiated fragmentation of the diketocarbonate into a decalin fragment and a spiroketal moiety has been proposed. Figure 1. Structure of Azadirachtin-A. The present study indicates that the combination of insect toxicity and antifeedancy of azadirachtin provides good crop protection.

The effects of azadirachtin on the parasitic mite, Varroa jacobsoni and its host honey bee (Apis mellifera)

SUMMARYWe conducted a series of experiments under laboratory conditions to evaluate the feasibility of using a neem-based (Azadirachta indica) insecticide to control varroa (Varroa jacobsoni). The experiments included studies of anti-feeding effects of azadirachtin, the active ingredient of neem-based insecticides, on adult worker honey bees (Apis mellifera); toxicity of azadirachtin to adult workers, worker larvae and associated mites; and the effects of azadirachtin on female V. jacobsoni reproduction. Both commercially formulated and purified azadirachtin were used in the experiments. The results of adult feeding experiments showed that azadirachtin significantly reduced syrup consumption by worker bees (P < 0.05) and exhibited a dose response in mortality: with an oral LC50 of 10.87 μg/ml in mite-free bees, 13.69 μg/ml in mite-infested bees, and 41.87 μg/ml for associated mites. The topical LC50 of azadirachtin was 12.53 μg/ml in mite-free bees, 12.31 μg/ml in mite-infested bees, and 35.43 μg/ml in the associated mites. The results of larval feeding experiments showed that worker larvae were more sensitive to azadirachtin than adult worker bees: exhibiting an LC50 of 180.92 μg/ml to purified azadirachtin and 100.13 μg/ml to formulated azadirachtin. More than 90% of treated, normal-appearing, white prepupae and pupae showed precocious and abnormal pigmentation on their mouthparts and other appendages. LC50‘s of topical applications of formulated azadirachtin were 104.91, 99.12 and 171.37 μg/ml for mite-free worker larvae, mite-inoculated larvae and associated mites, respectively. In addition, feeding host larvae with azadirachtin significantly reduced the fecundity of mother mites (P < 0.001) as well as egg hatching rate (P < 0.001). However, more research is needed to evaluate the reproductive effects of azadirachtin on drones, queens, and varroa under hive conditions.

Effects of Azadirachtin on Different Strains of German Cockroach (Dictyoptera: Blattellidae)

Technical grade azadirachtin (11.46% [AI]) was tested for its toxicity to insecticide-resistant and -susceptible strains of German cockroach, Blattella germanica (L.), by injection and diet incorporation. The effect of azadirachtin was dose dependent. The LC50 and LC90 for 3 strains ranged between 2.49 and 2.56 μg per insect and 6.49 and 6.92 μg per insect, respectively. Incorporation of Azadirachtin in food pellets resulted in LT50s of 22, 23, and 22 d for Dursban-R, CSMA, and Baygon-R strains, respectively. No significant differences were observed in toxicity of Azadirachtin to either insecticide-resistant or susceptible strains. The body weight of German cockroaches varied with time depending upon the dose administered. The roaches injected with 2 and 3 μg of Azadirachtin showed a continuous weight reduction. The toxicity of Azadirachtin to German cockroaches may be associated with an altered feeding behavior and a disruption of endocrinal events.

Repellency and Toxicity of Azadirachtin and Neem Concentrates to Three Stored-Product Beetles

Repellency and toxicity of azadirachtin (98% AZA, which contains 98% azadirachtin) and 3 neem extracts (48, 23, and 7% AZA) to 3 stored-product insects, the rusty grain beetle, Cryptolestes ferrugineus (Stephens), the rice weevil, Sitophilus oryzae (L.), and the red Aour beetle, Tribvlium castaneum (Herbst), were investigated in the laboratory. Each test material repelled all 3 species in a standard repellency test using a food preference apparatus. Significant negative correlations were found between insect settling response and extract concentrations. T. castaneum was more sensitive to the repellent action of neem than the other 2 species. The test materials were also toxic to the 3 pest species, with C. ferrugineus being the most susceptible. Six-week LC50 values for 48, 23, and 7% AZA for C. ferrugineus were 18.8, 37.0, and 127.3 ppm, respectively. The F1 adults of all 3 insect species in almost all treatments were significantly reduced compared with controls. This reduction was significantly dose dependent. The relationship between bioactivity of neem materials and their azadirachtin content was established and is discussed. We confirmed that azadirachtin was largely responsible for both repellent (behavioral) and toxic (physiological) actions of neem on stored-product insects. However, the neem extracts are slightly more active than pure azadirachtin when applied at equivalent azadirachtin concentrations, indicating that azadirachtin is not the only active compound in neem.