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1.
Resistance in Spodoptera litura (Fabricius) has been attributed to enhanced detoxification of insecticides by increased levels of esterases, oxidases and/or glutathione S-transferases. Enzyme inhibiting insecticide synergists can be employed to counter increased levels of such enzymes in S. litura. Dihydrodillapiole induced synergism of pyrethroid toxicity was examined in the laboratory-reared third instar larval population of S. litura collected in Delhi (susceptible), and Guntur (resistant) region of Andhra Pradesh, India. The Guntur population was found to be 7.04 and 10.19 times resistant to cypermethrin and lambdacyhalothrin, respectively. The activity of cypermethrin, lambdacyhalothrin and profenophos against susceptible and resistance populations of S. litura, was gradually increased when used along with a plant-derived insecticide synergist dihydrodillapiole. The α-naphthyl acetate hydrolysable esterase activity in Delhi population was less as compared to the Guntur population. Resistance associated esterases in Delhi population were inhibited by pre-treatment with dihydrodillapiole. The esterase level in insect was instantly reduced initially, sustained for about 3 h and equilibrated at 4 h post treatment. The esterase activity of Guntur population was increased to 1.28 μmoles/mg/min at 2 h post treatment and subsequently reduced to lower than 0.70 μmoles at 4-12 h post treatment. The variation in esterase activity is suggestive of its homeostatic regulation in test populations. Dihydrodillapiole thus caused significant reduction of resistance in S. litura to cypermethrin, lambda cyhalothrin and profenophos.  相似文献   

2.
Four extracts of Arisaema erubescens tubers by acetic acetal (AAE), benzinum (BZE), n-butanol (NBE) and chloroform (CFE) were obtained to evaluate their molluscicidal activities against the snail Oncomlania hupensis. The responses of choline esterase (ChE), alkaline phosphatase (ALP), esterase (EST), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) to the extracts (NBE) were also investigated. In the four extracts (AAE, BZE, NBE and CFE), NBE showed the highest toxicity on the snails after 48 h exposure. NBE also showed the time- and concentration-dependent effect, for example, the LC90 values of the NBE were decreased from 365.5 mg/L (24 h) to 36.4 mg/L (96 h). At the end of exposure to NBE (LC50 concentration), the activities of ChE and ALP in snail tissues (cephalopodium and liver) decreased significantly. Isozyme electrophoresis profiles indicated that responses of isozymes (EST, SOD and GSH-Px) to NBE were more intense in liver than in cephalopodium. After 72 h exposure to NBE, the EST activity in snail liver decreased and some enzyme bands (EST1 and EST4) disappeared. But the activities of SOD 1 and GSH 2 in liver increased after 48 h exposure. The results indicated that NBE was the highest toxic component in the four extracts. The decline of the detoxification ability and the oxidative damage in snail tissues might be the main reason for the molluscicidal activities.  相似文献   

3.
An enzyme that possesses the glutathione S-transferase (GST) activity was found in the rice leaffolder moth, Cnaphalocrocis medinalis. The enzyme was purified to homogeneity for the first time by ammonium sulfate fractionation and affinity chromatography. The resultant enzyme revealed a single band with a molecular mass of 24 kDa by SDS-polyacrylamide gel electrophoresis under reduced conditions. When assayed with 1-chloro-2,4-dinitrobenzene, a universal substrate for GST, the purified GST had an optimum pH at 8.0, and was fairly stable at pH 3-10 and at temperatures below 50 °C. The enzyme was also able to conjugate glutathione to 4-hydroxynonenal, a cytotoxic lipid peroxidation product. The present GST was inhibited by fenitrothion, permethrin, and deltamethrin, suggesting that the GST could be involved in metabolizing these organophosphorus and pyrethroid insecticides.  相似文献   

4.
Rhyzopertha dominica causes extensive damage to stored wheat grains. α-Amylase, the major insect digestive enzyme, can be an attractive candidate to control the insect damage by inhibiting the enzyme through α-amylase inhibitors. R. dominica α-amylase (RDA) was purified to homogeneity by differential ammonium sulphate fractionation, Sephadex G-25 and Sephadex G-100 column chromatography. The homogenous α-amylase has a molecular weight of 52 kDa. The pH optima was 7.0 and temperature optima was 40 °C. Activation energy of RDA was 3.9 Kcal mol−1. The enzyme showed high activity with starch, amylose and amylopectin whereas dextrins were the poor substrates. The purified enzyme was identified to be α-amylase on the basis of products formed from starch. The enzyme showed Km of 0.98 mg ml−1 for starch as a substrate. Citric acid, oxalic acid, salicylic acid, HgCl2, tannic acid and α-amylase inhibitors from wheat were inhibitors whereas; Ca2+ and Mg2+ were the activators of RDA. Ki values calculated from Dixon graphs with salicylic acid, citric acid, oxalic acid and wheat α-amylase inhibitors were 6.9, 2.6-8.2, 3.2 mM and 0.013-0.018 μM, respectively. The Lineweaver-Burk plots with different inhibitors showed mixed type inhibition. Wheat α-amylase inhibitor showed mainly competitive inhibition with some non-competitive behaviour and other inhibitors showed mainly non-competitive inhibition with some un-competitive behaviour. Feeding trials with salicylic acid, citric acid, oxalic acid and wheat α-amylase inhibitor showed significant effect of salicylic acid and oxalic acid along with wheat α-amylase inhibitor in controlling the multiplication of R. dominica.  相似文献   

5.
Properties of the phenoloxidase (PO) from adult of Gastrolina depressa Baly (Coleoptera: Chrysomelidae) as well as effects of some metal ions and inhibitors on the activity of PO purified by (NH4)2SO4 were determined. The optimal pH and temperature of the enzyme for the oxidation of catechol were determined to be at pH 7.5 and at 40 °C, respectively. The kinetic parameters for the oxidation of L-DOPA and catechol by the PO were 15.01 and 9.17 mM, respectively. The PO activity was strongly inhibited by Zn2+ and Cu2+, different to Mg2+ slightly. Both ascorbic acid and cysteine exhibited competitive inhibition and the inhibitory constants (Ki) were determined to be 2.22 mM and 0.40 mM, respectively.  相似文献   

6.
The biological effects of two important medicinal plants, Artemisia annua L. and Achillea millefolium (L.) (viz, mortality, growth, and feeding indices as well as enzyme and non-enzymatic activities) were studied on small white Pieris rapae L a deleterious pest of cruciferous plants under controlled conditions (16:8 h L:D at 25 ± 1 °C and 65 ± 5% RH). The LC50 and LC25 values were 9.387% and 3.645% for A. annua L. and 4.19% and 1.69% for A. millefolium (L.), respectively. At the lowest concentration (0.625%), the deterrency was 29.826% and 44.185% for A. annua L. and A. millefolium (L.), respectively. Feeding indices were variously affected with changes in a number of parameters and an increase in larval and pupal duration. The activity level of alkaline phosphatase increased sharply while alanin and aspartate aminotransferases showed a sharp decrease. For non-enzymatic compounds, the amount of glucose and uric acid increased, but total protein and cholesterol decreased. These results indicate that these two medicinal plants might possess potential secondary metabolites that may be useful for controlling potential insect pests.  相似文献   

7.
A natural compound plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) was isolated from the leaves of Plumbago auriculata and found to inhibit the enzyme, 8-amino-7-oxononanoate synthase (AONS, also known as 7-keto-8-aminopelargonate synthase, KAPAS) an IC50 of 2.1 μM in vitro. Biotin supplement significantly rescued the plant injury caused by the plumbagin treatment, and this result confirmed the target site, AONS. Foliar application of 1000 ∼ 2000 μg/mL plumbagin in a greenhouse condition showed lethal activity against eight species of weeds, containing three grass species of Sorghum bicolor, Echinochloa crus-galli, Digitaria sanguinalis and five broad leaf species of Solanum nigrum, Aeschynomene indica, Abutilon avicennae, Xanthium strumarium, Calystegia japonica. Field trial of foliar application with plumbagin 2000 μg/mL have successfully controlled 10 ∼ 15 leaf-stages and 2 ∼ 3 m vine lengths of Sicyos angulatus at the natural habitats around riparian zone in the Nam-Han River in Korea. Visual symptom of desiccation might be induced by the physiological cellular leakage which was significantly dose dependent on the plumbagin treatment regardless of light.  相似文献   

8.
Recovery study was performed at regular intervals to establish the time course of 50% and 100% recovery in neurotransmitter enzyme (acetylcholinesterase, AChE, EC 3.1.1.7) and locomotor behaviour response of mosquito fish, Gambusia affinis exposed to lethal concentration (20.49 mg L−1) of an organophosphorous pesticide, monocrotophos (MCP) for 96 h. In vitro AChE activity studies indicated that MCP could cause 50% inhibition (I50) at 10.2 × 10−5 M. A positive correlation was observed between brain AChE activity and swimming speed during the recovery study. Also, the recovery response of the antioxidant enzymes superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6) and glutathione reductase (GR, EC 1.6.4.2) as well as lipid peroxidation (LPO) as biomarkers of oxidative stress were assessed in viscera of G. affinis. The results showed that the MCP besides its inhibitory effect on target enzyme AChE activity and induction in antioxidant enzyme activities as a characteristic of oxidative stress, which can be used as biomarkers in the pesticide contaminated aquatic streams.  相似文献   

9.
A hydrophilic form of acetylcholinesterase (AChE) was purified from N-methyl carbamate susceptible (SA) and highly N-methyl carbamate-resistant (N3D) strains of the green rice leafhopper (GRLH), Nephotettix cincticeps Uhler. Both of purified AChE from SA and N3D strains displayed the highest activities toward acetylthiocholine (ATCh) at pH 8.5. In the SA strain, the optimum concentrations for ATCh, propionylthiocholine (PTCh), and butyrylthiocholine (BTCh) were about 1 × 10−3, 2.5 × 10−3, and 1 × 10−3 M, respectively. However, in the N3D strain, substrate inhibition was not identified for ATCh, PTCh, and BTCh to 1 × 10−2 M. The Km value in the SA strain was 51.1, 39.1, and 41.6 μM and that in the N3D strain was 91.8, 88.1, and 85.2 μM for ATCh, PTCh, and BTCh, respectively. The Km value in the N3D strain indicated about 1.80-, 2.25-, and 2.05-fold lower affinity than that of the SA strain for ATCh, PTCh, and BTCh, respectively. The Vmax value in the SA strain was 70.2, 30.5, and 4.6 U/mg protein and that in the N3D strain was 123.0, 27.0, and 14.5 U/mg protein for ATCh, PTCh, and BTCh, respectively. The Vmax value in the N3D strain was 1.75- and 3.15-fold higher for ATCh and BTCh than that in the N3D strain. However, it was 1.13-fold lower for PTCh. The increased activity of AChE in the N3D strain is due to the qualitatively modified enzyme with a higher catalytic efficiency. The bimolecular rate constant (ki) for propoxur was 27.1 × 104 and 0.51 × 104 M−1 min−1 in the SA and N3D strain and that for monocrotophos was 0.031 × 104 and 2.0 × 104 M−1 min−1 in the SA and N3D strain. AChE from the N3D strain was 53-fold less sensitive than SA strain to inhibition by propoxur. In contrast, AChE from the N3D strain was 65-fold more sensitive to inhibition by monocrotophos than AChE from the SA strain. This indicated negatively correlated cross-insensitivity of AChE to propoxur and monocrotophos.  相似文献   

10.
The toxicity and physiological (enzyme and nutritional indices) effect of Dysoxylum triterpenes 3β,24,25-trihydroxycycloartane and beddomei lactone were evaluated on the rice leaffolder Cnaphalocrocis medinalis (Guenée). The LC50 [6.66 ppm (SD = 0.31), 5.79 ppm (SD = 0.33) for 3β,24,25-DHCL and BL, respectively] and LC 90 [14.63 ppm (SD = 0.36), 13.49 ppm (SD = 0.27) for 3β,24,25-DHCL and BL, respectively] were identified by probit analysis. Fourth instars were exposed to various concentrations (1.5, 3, 6, and 12 ppm) of Dysoxylum triterpenes. Results showed that treated larvae exhibited reduced food consumption and enzyme activity. Food consumption, digestion, relative consumption rate, efficiency of conversion of ingested food, efficiency of conversion of digested food, and relative growth rate values declined significantly but the approximate digestibility of treated larvae was significantly higher as a result of treatment (in particular 6 and 12 ppm). Likewise, the gut enzymes acid phosphatases, alkaline phosphatases, and adenosine triphosphatases were significantly inhibited by the Dysoxylum triterpenes. The high biological activity of these triterpenes from Dysoxylum sp. could be used as an active principle during the preparation of botanical insecticides for insect pest like rice leaffolder.  相似文献   

11.
In search for new local plant molluscicides for the control of the vectors of schistosomiasis, we compared the molluscicidal action of the extract of Ginkgo biloba sarcotesta by benzinum (EGSB) to that of arecoline (ARE) and niclosamide (NIC) against Oncomelania hupensis snails. NIC showed the highest toxicity on snails with 24 h LC50 vales of 0.12 mg/L and LC90 of 0.98 mg/L, while the LC50 and LC90 of EGSB were much lower than that of ARE. Sublethal in vivo 24 h exposure to 40% and 80% LC50 of NIC, EGSB and ARE altered the activities of different enzymes in different body tissues of snails. EGSB could significantly inhibit Choline esterase (ChE), Alanine aminotransferase (ALT), Alkaline phosphatase (ALP) and Malic dehydrogenase (MDH) activities both in the cephalopodium and liver. ARE could significantly cause a reduction in ChE, ALP activities in the cephalopodium and ChE, ALT, ALP, Succinodehydrogenase (SDH), MDH activities in the liver. NIC significantly altered activities of ChE, ALT, ALP, SDH, and MDH in the cephalopodium and ChE, ALT, ALP, SDH activities in the liver. All molluscicides could not affect Lactate dehydrogenase (LDH) activity in the cephalopodium and the liver. Maximum inhibition of ALT and MDH activities was found in the cephalopodium and liver of snails treated with 80% of 24 h LC50 of EGSB. However, NIC and ARE caused maximum reduction in ALP and SDH activities, respectively. The results indicated that molluscicidal action of EGSB was different to that of ARE and NIC in some extent.  相似文献   

12.
Molecular mechanisms of monocrotophos resistance in the two-spotted spider mite (TSSM), Tetranychus urticae Koch, were investigated. A monocrotophos-resistant strain (AD) showed ca. 3568- and 47.6-fold resistance compared to a susceptible strain (UD) and a moderately resistant strain (PyriF), respectively. No significant differences in detoxification enzyme activities, except for the cytochrome P450 monooxygenase activity, were found among the three strains. The sensitivity of acetylcholinesterase (AChE) to monocrotophos, however, was 90.6- and 41.9-fold less in AD strain compared to the UD and PyriF strains, respectively, indicating that AChE insensitivity mechanism plays a major role in monocrotophos resistance. When AChE gene (Tuace) sequences were compared, three point mutations (G228S, A391T and F439W) were identified in Tuace from the AD strain that likely contribute to the AChE insensitivity as predicted by structure analysis. Frequencies of the three mutations in field populations were predicted by quantitative sequencing (QS). Correlation analysis between the mutation frequency and actual resistance levels (LC50) of nine field populations suggested that the G228S mutation plays a more crucial role in resistance (r2 = 0.712) compared to the F439W mutation (r2 = 0.419). When correlated together, however, the correlation coefficient was substantially enhanced (r2 = 0.865), indicating that both the F439W and G228S mutations may work synergistically. The A391T mutation was homogeneously present in all field populations examined, suggesting that it may confer a basal level of resistance.  相似文献   

13.
The molluscicidal activity of cold water, boiled water, methanol, ethanol, acetone and chloroform extracts of Solanum siniacum and Artemisia judaica L. plants against Biomphalaria alexandrina snails was carried out. The tests revealed plant’s ethanol extract was more toxic to the snails than the other tested extracts. Therefore, it was tested against snails’ fecundity (Mx), reproduction rate (R0) and their infection with Schistosoma mansoni miracidia. In addition, biochemical parameters and the activities of some enzymes in tissues of snails treated with the two tested plants were determined. As well, glucose concentration in snails’ hemolymph was evaluated. Exposure of B. alexandrina snails to plant’s ethanol extract led to a significant reduction in their survival and snails’ fecundity, reproduction rate. In addition, it caused a considerable reduction in the infectivity of S. mansoni miracidia to the snails. Also, it caused a reduction in number of cercariae per snail during the patent period and in the period of cercarial shedding. The results revealed that the glucose concentration in hemolymph and Lactate level in soft tissues of treated snails were increased (P < 0.001) while glycogen, total protein, the lipid content and the pyruvate level in snail’s tissues decreased (P < 0.001). The activities of lactic dehydrogenase (LDH), pyruvatekinase (PK) and cytochrome oxidase (CY) enzymes in homogenate of snail’s tissues were reduced (P < 0.001) in response to treatment with the two tested plants while protease (PR) activity increased (P < 0.001). It is concluded that the application of LC25 of ethanol extract of S. siniacum and A. judaica L. may be helpful in snail control as it interferes with the snails’ biology and physiology.  相似文献   

14.
The susceptibility to phosalone and biochemical characteristics of acetylcholinesterase (AChE) were compared between susceptible (SS) strain and four field populations of Colorado potato beetle (CPB) collected from commercial potato fields of Hamedan Province in west of Iran. Bioassays involving topical application of phosalone to fourth instars revealed up to 252 fold resistance in field populations compared with the SS strain. Synergism studies showed that although esterase and/or glutathione S-transferase metabolic pathways were present and active against phosalone, they were not selected for and did not have a major role in resistance. It is likely that piperonyl butoxide (PBO) reduced phosalone toxicity by inhibiting bio-activation of phosalone. The affinity (Km) and hydrolyzing efficiency (Vmax) of AChE to selected substrates, namely, acetylthiocholine iodide (ATC), propionylthiocholine iodide (PTC), and butyrylthiocholine iodide (BTC) were examined. AChE inhibition by higher substrate concentration was evident only in the SS strain. In resistant field populations, Aliabad (Aa), Bahar (B) and Dehpiaz (Dp), substrate inhibition at higher concentrations was not seen. There was no definite optimal concentration found for any of the substrates examined. When ATC, PTC, and BTC were used as substrate, the reaction rates of AChE from Yengijeh (Yg) population increased as the concentration of all three substrates were increased, but were almost constant at concentration of ATC ? 3.98, PTC ? 2.8, and BTC ? 5 mM. The susceptible form of AChE had the most efficient ATC hydrolysis but very low BTC hydrolysis activity. In contrast, AChEs from field populations elicited relatively reduced ATC hydrolysis, but relatively increased BTC hydrolysis. The in vitro inhibition potency of some organophosphates (OPs), on AChEs of the field populations and SS strain was determined. The rank order from the most potent inhibitor to the least as determined by their bimolecular reaction constants (Ki) was ethyl paraoxon > diazoxon > methyl paraoxon for AChE from Aa, B, Dp, and Yg populations, respectively, whereas the rank order for the susceptible strain was methyl paraoxon > ethyl paraoxon > diazoxon.  相似文献   

15.
Glutathione transferase (GST) was purified from the hindgut of grasshopper (Zonocerus variegatus) a polyphagous insect. The purified enzyme had a native molecular weight of 40 kDa and a subunit molecular weight of 19 kDa. The purified enzyme could conjugate glutathione (GSH) with 1-chloro-2,4-dinitrobenzene (CDNB), paranitrobenzylchloride, paranitrophenylacetate, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBDCl), and 1,2-dichloro-4-nitrobenzene (DCNB) with specific activities of 3.3 ± 0.3, 0.49 ± 0.10, 0.10 ± 0.002, 1.2 ± 0.2, and 1.7 ± 0.4 μmol/min/mg protein, respectively. CDNB appears to be the best substrate with a specificity constant, kcat/Km, of 1.8 ± 0.1 × 10−4 M−1 S−1. The kinetic mechanism of Z. variegatus GST (zvGST) in the conjugation of GSH with some electrophilic substrates appears complex. Conjugation of GSH with DCNB was inhibited by high DCNB concentration, while with NBDCl, as the electrophilic substrates, different values of Km were obtained at high and low concentrations of the substrates. Cibacron blue, hematin, S-hexylglutathione, and oxidized glutathione inhibited the enzyme with I50 values of 0.057 ± 0.004, 0.80 ± 0.2, 33 ± 2 μM, and 5.2 ± 0.3 mM, respectively. The nature of inhibition by each of these inhibitors is either competitive or non-competitive at varying GSH or CDNB as substrates. NADH and NAD+ inhibited the enzyme with an I50 value of 0.4 ± 0.01 and 11 ± 1 mM, respectively. NADH at a concentration of 0.54 mM completely abolished the activity. As part of its adaptation, the flexible kinetic pathway of detoxication by zvGST may assist the organism in coping with various xenobiotics encountered in its preferred food plants.  相似文献   

16.
In order to gain insight into the development of insecticides with novel modes of action, the effects of salicylidene aniline (a), salicylidene-4-chloroaniline (b), salicylidene-4-bromoaniline (c), and salicylidene-4-nitroaniline (d) on partially purified phenoloxidase (PO) from Pieris rapae L. were investigated. The results showed that the 4 compounds could inhibit PO activity, and the inhibitor concentrations leading to a loss of 50% activity (IC50) were estimated to be 0.025 mmol L−1, 0.732 mmol L−1, 0.471 mmol L−1, and 0.675 mmol L−1, respectively. Meanwhile, all the inhibitors showed reversible competitive inhibition, except (d), which showed reversible mixed inhibition. The KI values were determined as 0.106 mmol L−1, 10.059 mmol L−1, 8.390 mmol L−1, and 20.198 mmol L−1 for the four compounds, respectively. The UV-vis spectra of (a) and (d) in the presence of copper ions and the enzyme showed that (a) could directly chelate the copper ions of PO; however, (d) could neither chelate the additional copper ions nor the copper ions of PO.  相似文献   

17.
The hemocyanin of Oncomelania hupensis (OhH) is essential for the survival of O. hupensis and may be an effective target for the development of new molluscicide. 4-(Chloroacetyl)catechol is a substrate analogue of OhH. In this study, we evaluated the toxicity of 4-(chloroacetyl)catechol to O. hupensis and Kunming mice. 4-(Chloroacetyl)catechol had strong molluscicidal activities and the molluscicidal activities was time and dose-dependent. With the increase of exposure time, the LC50 values of the 4-(chloroacetyl)catechol decreased from 6.5 mg/L (24 h) to 3.1 mg/L (72 h). The LC90 values decreased from 16.4 mg/L (24 h) to 4.9 mg/L (72 h). In the acute toxicity test of mice, no evident poisoning symptoms and no animal death were detected after 14 days’ continuous observation, which indicated that 4-(chloroacetyl)catechol was a low toxic substance for Kunming mice. These results indicated that 4-(chloroacetyl)catechol is potent molluscicides.  相似文献   

18.
The effect of single, binary, and tertiary combination of few plant derived molluscicides alone or in combination with synergist on different enzymes (acetylcholinesterase—AChE, lactic dehydrogenase—LDH, and acid/alkaline phosphatase—ACP/ALP in the nervous tissue of the freshwater snail Lymnaea acuminata were studied. Sublethal in vivo 24 h exposure to 40 and 80% of LC50 of Azadirachta indica oil (AI), oleoresin of Zingiber officinale (OL), Cedrus deodara oil (CD), Allium sativum (AS), and Polianthes tuberosa (PT) bulb powder singly, their binary combination of AI + OL, AS + CD, AS + PT, CD + OL, CD + PT, OL + PT, and tertiary combination of these binary combinations with the synergist piperonyl butoxide (PB) or MGK-264 significantly altered the activity of these enzymes. Tertiary combination with PB or MGK was very effective. Combination of CD + PT + MGK was more effective against AChE whereas, the combination of CD + OL + PB, CD + AS + PB, and CD + PT + PB were more effective against LDH, ACP, and ALP, respectively.  相似文献   

19.
Rice (Oryza sativa), a relatively tolerant species, and early watergrass (Echinochloa oryzoides; EWG), a relatively susceptible species, were exposed to 14C-labeled clomazone to determine accumulation, biotransformation, and mass balance. On a total mass basis, rice absorbed more clomazone than EWG (p < 0.05), but on a nmol/g basis, there was no significant difference between the two species (p > 0.05). Rice contained more extractable 14C residues (7.7 ± 0.5 vs. 4.8 ± 0.5 nmol in rice vs. EWG, respectively; p < 0.5), but the concentration in EWG was significantly higher (4.2 ± 0.5 vs. 1.8 ± 0.1 nmol/g in EWG vs. rice, respectively; p < 0.01). More metabolized residue was measured in EWG compared to rice (84.1% vs. 67.9%; p < 0.01). Both species produced hydroxylated forms, β-d-glucoside conjugates, and several other unidentified polar metabolites, but EWG generally produced higher metabolite concentrations. The concentration of the suspected active metabolite, 5-ketoclomazone, was significantly higher in EWG vs. rice (21 ± 2 vs. 5.7 ± 0.5 pmol/g, respectively; p < 0.01). Differences in sensitivity to clomazone between rice and EWG appear to be due to differential metabolism, but in this case the more susceptible EWG qualitatively and quantitatively metabolized more clomazone than the more tolerant rice. This is consistent with the action of a metabolically activated herbicide. This metabolic difference could be exploited to develop herbicide safeners for use with clomazone.  相似文献   

20.
The effects of azadirachtin (AZA) and nucleopolyhedrovirus (NPV) on midgut enzyme activity in Spodoptera litura Fabricius (Lepidoptera: Noctuidae) (Tobacco cutworm) were evaluated. Gut enzyme activities were decreased by AZA and NPV individually and in combination. When S. litura larvae were fed a diet of castor leaves treated with AZA and NPV in bioassays, gut enzyme—acid phosphatases, alkaline phosphatases, adenosine triphosphatases, and lactate dehydrogenase—activities were decreased. There were statistically significant differences (P ? 0.05) in enzyme activities between combined and individual treatment. A synergistic effect of botanical insecticides and virus was found when combined in low doses. These effects are most pronounced in early instars. Maximum weight loss (59-72%) occurred, when AZA and NPV were combined.  相似文献   

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