Effect of dihydrodillapiole on pyrethroid resistance associated esterase inhibition in an Indian population of Spodoptera litura (Fabricius)

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.     

The toxicity and physiological effect of neem limonoids on Cnaphalocrocis medinalis (Guenée) the rice leaffolder

The effect of neem (Azadirachta indica) limonoids azadirachtin, salannin, deacetylgedunin, gedunin, 17-hydroxyazadiradione, and deaceytlnimbin on gut enzyme activity of the rice leaffolder larvae was investigated. When fed a diet of rice leaves treated with limonoids in bioassays, gut tissue enzymes—acid phosphatases (ACP), alkaline phosphatases (ALP), and adenosine triphosphatases (ATPase) activities of rice leaffolder (Cnaphalocrocis medinalis) larvae are affected. Azadirachtin was most potent in all experiments. Larvae that were chronically exposed to limonoids showed a reduction in weight (59-89%) and exhibited a significant reduction in ACP, ALP, and ATPase activities. These results indicate neem limonoids affects gut enzyme activities. These effects are most pronounced in early instars.     

Food consumption, utilization, and detoxification enzyme activity of the rice leaffolder larvae after treatment with Dysoxylum triterpenes

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.     

Evaluation of molluscicidal activities of Arisaema tubers extracts on the snail Oncomelania hupensis

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.     

The effects of Artemisia annua L. and Achillea millefolium L. crude leaf extracts on the toxicity, development, feeding efficiency and chemical activities of small cabbage Pieris rapae L. (Lepidoptera: Pieridae)

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.     

Binary combination of carbohydrates and amino acids as snail attractant in pellets containing molluscicides against the snail Lymnaea acuminata

Snail control is one of the important methods in the campaign to reduce the incidence of fascioliasis and schistosomiasis. In order to achieve this objective, the method of bait formulation containing an attractant and a molluscicide is an appropriate approach to lure the target snail population to the molluscicide. In the present study snail attractant pellets (SAP) were prepared from binary combination of carbohydrates (10 mM) and amino acids (20 mM) in 2% agar solution. These were tested on Lymnaea acuminata, an intermediate host of the digenean trematodes Fasciola hepatica and Fasciola gigantica. The behavioral responses of snails to these binary combination were examined. The fraction of snails that was in contact with the SAP at different times was used as a measure of attraction. Among all the binary combination of carbohydrates; (sucrose + starch)—72.9%, binary combination of amino acids; (proline + serine)—48.0% and binary combination of carbohydrates and amino acids; (sucrose + serine)—69.5%, emerged as the strongest attractant pellets. Toxicity of these SAP containing different concentrations of molluscicides were used as bait against the snail, L. acuminata. Thymol containing SAP emerged as the strongest bait formulation (96 h LC₅₀ 0.540%, 0.318% and 0.305%) against L. acuminata.     

The effect of single, binary, and tertiary combination of few plant derived molluscicides alone or in combination with synergist on different enzymes in the nervous tissues of the freshwater snail Lymnaea (Radix) acuminata (Lamark)

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.     

The effects of Saw palmetto on flumethrin-induced lipid peroxidation in rats

In the present study, 40 male Wistar albino rats were used and divided into 4 groups. The first group served as the control group; the second group was administered Saw palmetto extract at the dose of 20 mg/kg/bw; the third group was administered flumethrin at the dose of 15 mg/kg/bw; and the fourth group was administered a combination of 20 mg/kg/bw Saw palmetto extract and 15 mg/kg/bw flumethrin, for 21 days, orally. After the trial period, blood and tissue (liver, kidney and brain) samples were taken from the rats. Saw palmetto extract did not cause significant alterations in plasma and tissue malondialdehyde (MDA) levels, serum and tissue nitric oxide (NO) levels, erythrocyte and tissue superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities when compared to the controls (p > 0.05). Flumethrin led to increased plasma and tissue MDA levels, serum and tissue NO levels, tissue GSH-Px activities and decreased erythrocyte and tissue SOD and CAT activities, and erythrocyte GSH-Px activity, compared to the controls (p < 0.05). The flumethrin and Saw palmetto extract combination increased erythrocyte SOD activity and decreased brain GSH-Px activity as compared to flumethrin (p < 0.05). In conclusion, it was determined that Saw palmetto extract did not cause any negative effect on the prooxidant-antioxidant balance. While flumethrin stimulated lipid peroxidation; Saw palmetto extract at the dose of 20 mg/kg/bw did not exhibit enough antioxidant effect in rats.     

Effects of N-acetylcysteine on oxidative responses in the liver of fenthion exposed Cyprinus carpio

The aim of this study was to evaluate the effects of different N-acetylcysteine doses on the tolerance to fenthion-induced oxidative stress, alterations in glutathione metabolism and cholinesterase specific activities in the liver by using freshwater fish Cyprinus carpio (Cyprinidae) as a model organism. An acute toxicity study was carried out to determine 96-h median lethal concentration of fenthion for this species (2.16 mg/L) and 80% of this concentration was applied in toxicity studies. Four groups, each containing eight fish were constituted as follows: Control group, fenthion treated group, 0.5 or 400 mg/kg NAC-injected + fenthion-treated groups. Biochemical analyses were carried out spectrophotometrically. Fenthion treatment significantly decreased total glutathione and glutathione levels, glutathione/glutathione disulfide ratio together with glutathione reductase and γ-glutamylcysteine synthetase specific enzyme activities. The higher dose of N-acetylcysteine increased the toxic effects of fenthion and γ-glutamyl transpeptidase specific activity while decreasing glutathione S-transferase specific activity. However, injection of the lower dose provided a limited protection against fenthion toxicity. In all exposure groups, lipid peroxidation increased and total protein levels decreased, while protein depletion was prevented by low dose of N-acetylcysteine application. Acetylcholinesterase and butyrylcholinesterase activities were at similar levels in the liver of C. carpio. A dose-dependent inhibition was observed in butyrylcholinesterase activity by N-acetylcysteine application. The results showed that fenthion had a significant oxidative stress inducing potential through the reduction of glutathione redox capacity. The critical point for overcoming oxidative stress by N-acetylcysteine in fenthion toxicity was the selection of the dose; N-acetylcysteine exerted its toxic effects by means of oxidative stress in fish liver at the higher dose.     

Physiological effect of chitinase purified from Bacillus subtilis against the tobacco cutworm Spodoptera litura Fab.

An extracellular chitinase was purified from Bacillus subtilis. The lethal concentration (LC₅₀) was determined by using chitinase in first, second, and third instars of Spodoptera litura Fab. Chitinase showed the highest insecticidal activity at 6 μM concentration within 48 h. The nutritional indices were also significantly affected by the 6 μM concentration (P < 0.05). Food consumption, efficiency of conversion of ingested and digested food, relative growth rate, and consumption values declined significantly while approximate digestibility was increased. Our study indicates that treatment of host plant leaves with the chitinase can regulate (reduce) larval growth and weight, and enhance the mortality. This may serve as an effective biocide and alternative to Bt toxin.     

Biological and biochemical parameters of Biomphalaria alexandrina snails exposed to the plants Datura stramonium and Sesbania sesban as water suspensions of their dry powder

Four plant species, as a dry powder of their leaves, were tested against Biomphalaria alexandrina snails, the intermediate host of Schistosoma mansoni. The bioassay tests revealed the plants Datura stramonium and Sesbania sesban to be more toxic to the snails than the other two ones. Therefore, they were tested against snails’ fecundity (M_x), reproduction rate (R_o) and their infection with S. mansoni miracidia. In addition, total protein concentration and the activities of the transaminases (AsT and AlT) and phosphatases (AcP and AkP) enzymes in hemolymph and tissues of snails treated with these plants were determined. As well, glucose concentration in snails’ hemolymph was evaluated.Exposure of snails for 4 weeks to LC₁₀ and LC₂₅ of the plants D. stramonium and S. sesban dry powder markly suppressed their M_x and R_o. The reduction rates of R_o for snails exposed to LC₂₅ of these plants were 62.1% and 76.4%, respectively. As well, a considerable reduction in the infection rates of snails exposed to these plants either during, pre- or post-miracidial exposure was recorded. Thus, infection rates of snails treated during miracidial exposure with LC₁₀ of D. stramonium and S. sesban were 41.7% and 52.2%, respectively, compared to 92.6% for control group (P < 0.01). These plants, also, reduced the duration of cercarial shedding and cercarial production/snail. So, snails exposed to LC₂₅ of these plants shed 372.8 and 223.2 cercariae/snail, respectively, compared to 766.3 cercariae/infected control snail (P < 0.01).The results, also, revealed that glucose and total protein concentrations in hemolymph of snails treated with LC₁₀ and LC₂₅ of these plants were decreased, meanwhile, the activities of the enzymes AsT, AlT, AcP and AkP were elevated (P < 0.01). However, the activity of AcP in tissues of treated snails was decreased compared to that of control ones. It is concluded that LC₂₅ of the plants D. stramonium and S. sesban negatively interferes with biological and physiological activities of B. alexandrina snails, consequently it could be effective in interrupting and minimizing the transmission of S. mansoni.     

Effects of insecticides on plant-growth-promoting activities of phosphate solubilizing rhizobacterium Klebsiella sp. strain PS19

In this study, four technical grade insecticides, fipronil, pyriproxyfen, imidacloprid and thiamethoxam were applied at the recommended and the higher doses to investigate their effects on plant growth-promoting activities of phosphate-solubilizing Klebsiella sp. strain PS19, isolated from mustard rhizosphere. All tested insecticides displayed a concentration-dependent inhibition in plant growth promoting traits, like, inorganic phosphate solubilization, biosynthesis of phytohormones and siderophores, of rhizobacterial strain PS19. For example, the phosphate-solubilizing activity of Klebsiella sp. PS 19 was reduced maximally by 95%, at 3900 μg l⁻¹ pyriproxyfen over control. At the recommended rate, the magnitude of toxicity of insecticides to plant growth promoting traits was less severe compared to the higher doses. The sequence of insecticide-toxicity expressed as percent decrease, determined at highest dose rate of each insecticide, over control was: pyriproxyfen (95) = imidacloprid (95) > thiamethoxam (94) > fipronil (85), for phosphate-solubilizing activity while for salicylic acid (SA) it was: thiamethoxam > pyriproxyfen = imidacloprid > fipronil. The impact of the highest dose rate of insecticides on 2,3-dihydroxybenzoic acid (DHBA) was almost equal to those observed for SA. Thiamethoxam decreased the indole acetic acid (IAA) synthesis maximally by 86% whereas fipronil had least toxicity and reduced it by 67% relative to the control. Among the experimental insecticides, pyriproxyfen at 3900 μg l⁻¹ in general, had the greatest toxic effects for plant growth promoting activities of the test strain. The study inferred that insecticides affect the plant beneficial activities of rhizobacteria adversely. These findings are likely to add a new insight into the pest management practices.     

Inactivating hemocyanin from Oncomelania hupensis with 4-(chloroacetyl)catechol and its application in snail control

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.     

Protein metabolism in Spodoptera litura (F.) is influenced by the botanical insecticide azadirachtin

Azadirachtin, as a botanical insecticide, affects a wide variety of biological processes, including reduction of feeding, suspension of molting, death of larvae and pupae, and sterility of emerged adults in a dose-dependent manner. However, the mode of action of this toxin remains obscure. By using proteomic techniques, we analyzed changes in protein metabolism of Spodoptera litura (F.) induced by azadirachtin. Following feeding 4th instar larvae of Spodoptera litura (F.) with an artificial diet containing 1 ppm azadirachtin until pupation, 48 h old pupae were collected and protein samples prepared. Total soluble protein content was measured and the results showed that azadirachtin significantly influenced protein level. Moreover, the proteins were separated by 2-DE (two-dimensional polyacrylamide gel electrophoresis) and 10 proteins were significantly affected by azadirachtin treatment when compared to an untreated control. Six of these proteins were identified with peptide mass fingerprinting using MALDI-TOF-MS after in-gel trypsin digestion. These proteins are involved in various cellular functions. One identified protein may function as an ecdysone receptor, which regulates insect development, and reproduction. It is suggested that the botanical insecticide azadirachtin affects protein expression and the azadirachtin-related proteins would be essential for a better understanding of the mechanisms by which neem toxins exert their effects on insects.     

Effects of trichlorfon and sodium dodecyl sulphate on antioxidant defense system and acetylcholinesterase of Tilapia nilotica in vitro

The effects of organophosphorus insecticide trichlorfon, surfactant sodium dodecyl sulphate (SDS), and the mixture of trichlorfon and SDS on the antioxidant defense system and acetylcholinesterase (AChE) in Tilapia nilotica were assessed in vitro. Various concentrations of trichlorfon (0, 0.0001, 0.001, 0.01, 0.1 and 1 g/L) and SDS (0, 0.0625, 0.125, 0.25, 0.5, 1 g/L) were incubated with homogenate of liver and muscle, respectively, at 25 °C for 0, 30, 60 and 90 min. Two concentrations of mixture of trichlorfon and SDS (0.0001 g/L trichlorfon + 0.5 g/L SDS, 0.1 g/L trichlorfon + 0.5 g/L SDS) and 0.0001 g/L trichlorfon, 0.1 g/L trichlorfon, 0.5 g/L SDS and control, were incubated simultaneously with homogenate of liver and muscle, respectively, at 25 °C for 60 min. After incubation, the content of reduced-glutathione (GSH) and the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) in homogenate of liver were determined, and the activities of AChE in homogenate of muscle were also measured.Treatment with trichlorfon caused a significant concentration-dependent and time-related inhibition of AChE activity at all treatment concentrations and times since trichlorfon is a cholinesterase inhibitor. For the same trichlorfon treatment, an apparent decrease in GSH content was found in concentration of 0.01, 0.1, 1 g/L, whereas no significant alteration in antioxidant enzyme activity were found at all experiment concentrations and times, which might indicate that antioxidant enzymes have not involved in the metabolism of trichlorfon. The depletion of GSH might indicate that ROS could be involved in the toxic effects of trichlorfon. Exposure of SDS can inhibit activities of AChE, GST and CAT at concentrations of 0.5 and/or 1 g/L, which could be due to the denaturing process of SDS to the enzymes. For the mixture exposure of trichlorfon and SDS, the effect of the mixture of 0.0001 g/L trichlorfon and 0.5 g/L SDS on inhibition of AChE shows synergistic other than simple additive of trichlorfon and SDS. The combined effects of chemicals and detergents deserve to be particularly noted. It should be noted that the toxicity experiments were made in tissue homogenates instead of whole organisms. The responses against the toxic compounds will not be the same in both systems.     

Effects of diazinon at different doses on rat liver and pancreas tissues

Diazinon is one of the most widely used organophosphates in agriculture. Toxic effects of diazinon are due to the inhibition of acetylcholinesterase, an enzyme needed for proper nervous system function. This study was designed to investigate the effects of diazinon at different doses on pancreas and liver tissues and in which dose level diazinon shows its effects. Sixty male Wistar albino rats were included in this study. Animals were initially divided into control and diazinon given groups. There were 10 animals in the control group and 50 animals in diazinon administered group. The latter was divided into five equal subgroups: 25, 50, 100, 200 and 300 mg/kg of diazinon administered groups. Control group was given only saline. All animals in 300 mg/kg diazinon group died. After 24 h, rats were sacrificed under ether anesthesia. Tissue and blood samples were taken for biochemical and histopathological analysis. Sample tissues were examined under light microscope. In biochemical analysis, AST, ALT, LDH, amylase and lipase enzyme activities were measured. One-way ANOVA test was used to compare the groups. In 200 mg/kg diazinon given group, it has been observed some histopathological changes in pancreas and liver tissues. Cholinesterase activities were significantly decreased and alkaline phosphatase levels were increased in all diazinon given groups, when compared with the controls. There was statistically significant difference between the control and diazinon given groups by means of serum amylase, lipase, ALT and AST activities (p < 0.05). LDH activities were significantly increased in 100 and 200 mg diazinon given groups, when compared with the controls (p < 0.05). Histopathological changes were observed only in 200 mg diazinon given group. This evidence suggest that diazinon effect is dose dependent and this is possibly 10-15% of the LD₅₀ dose (200 mg/kg), which cause acute pancreatitis and histopathological changes in liver.     

Sublethal effects of larval exposure to indoxacarb on reproductive activities of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae)

Sublethal effects of larval exposure to indoxacarb on reproductive activities of the diamondback moth, Plutella xylostella (L.) were studied. The third instar male and female larvae of the diamondback moth were fed with collard leaves dipped with a lethal dose of 20% mortality of indoxacarb in order to determine its impact on reproductive activities of adult survivors. Females from indoxacarb treatment had similar peak calling percentage (100%) and mean calling hours (5.83 ± 0.47 h) compared to control females (92% of peak calling, 5.05 ± 0.55 h of mean calling hours) at the first scotophase, but had slightly lower peak calling percentages and shorter calling hours at the subsequent scotophases. The sex pheromone blend or single component from the blend for P. xylostella elicited similar electroantennography responses compared with those from control males and indoxacarb-treated male survivors. Indoxacarb did not alter the number of eggs produced per female and female longevity. However, larval treatment of males with indoxacarb showed a decreased copulation success rate, and this effect was not observed in identically treated female survivors.     

Biochemical and histological hepatic changes of Nile tilapia Oreochromis niloticus exposed to carbaryl

The purpose of this study was to evaluate biochemical and morphological responses induced by carbaryl in the liver of Nile tilapia (Oreochromis niloticus) exposed during 21 days to sublethal concentrations (0.25 and 0.5 mg L⁻¹), testing also recover for 14 days in clean water, after 14 days exposure. The activities of the following enzymes were measured: superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), glutathione reductase (GR), and reduced (GSH) and oxidized glutathione (GSSG). Globally, our data showed that exposure to carbaryl decreased the SOD, CAT, GR, and GST activities, except for the SOD and GST activities after 14 days exposure to 0.25 mg L⁻¹. In contrast, after 14 days exposure the GR activity of the hepatic tissue from carbaryl-treated fish showed significant elevation in relation to the control. When fish were left to recover, a positive response was seen in the GSH and GSSG contents. The results of the recovery group suggest that the toxicity produced by carbaryl is reversible to some extent within 15 days. The liver histological analysis showed differences between fish concerning the cellular vacuolization degree (VD) of the hepatocytes. In fish exposed to carbaryl it was observed an increasing hepatocellular basophilia. No other histological alterations were observed when fish was exposed to carbaryl, except a few necrotic foci at day 7. The sections stained with PAS reaction showed that the vacuolization was always not due to glycogen deposits, thus suggesting lipid accumulation. The combined increased basophilia and glycogen depletion is a common, although non-specific, liver response to many toxicants. In short, this work shows a relation between histological and biochemical changes in liver and carbaryl exposure. The effects of carbaryl were observed at different concentrations.     

Ameliorative effects of Mesorhizobium sp. MRC4 on chickpea yield and yield components under different doses of herbicide stress

The present study was conducted to assess the plant growth promoting activities of Mesorhizobium sp. in the presence of technical grade herbicides and its ameliorating effects on herbicide toxicity to chickpea grown in herbicide treated soils. The quizalafop-p-ethyl and clodinafop-tolerant Mesorhizobium isolate MRC4 recovered from the nodules of chickpea plants significantly produced IAA, siderophores, hydrogen cyanide and ammonia in medium amended with or without technical grade quizalafop-p-ethyl and clodinafop. Quizalafop-p-ethyl at 40, 80 and 120 μg kg⁻¹ soil and clodinafop at 400, 800 and 1200 μg kg⁻¹ soil in general, decreased the growth attributes of chickpea plants inoculated with Mesorhizobium MRC4 and un-inoculated chickpeas. The three concentrations of quizalafop-p-ethyl were comparatively more toxic and substantially decreased biomass, nodulation and leghaemoglobin content, nutrient uptake, seed yield and grain protein over the un-inoculated chickpea. Interestingly, Mesorhizobium isolate MRC4 with any concentration of the two herbicides significantly increased the measured parameters when compared to the plants grown in soils treated solely (without inoculant) with similar concentration of each herbicide. Conclusively, Mesorhizobium isolate MRC4 could be exploited as bio-inoculant for facilitating chickpea growth under herbicide stress.     

Subacute chlorpyrifos-induced oxidative stress in rat erythrocytes and the protective effects of catechin and quercetin

This study examined the effects of chlorpyrifos in the rat erythrocyte antioxidant system and evaluated the ameliorating effects of catechin and quercetin on the oxidative damage induced by chlorpyrifos. Sexually mature male Wistar rats were given chlorpyrifos (5.4 mg/kg, 1/25 of the oral LD₅₀), catechin (20 mg/kg), quercetin (20 mg/kg), catechin plus chlorpyrifos, and quercetin plus chlorpyrifos daily via gavage for four weeks. No statistical differences were found in the catechin-only and quercetin-only groups compared with the control group. By the end of the fourth week, chlorpyrifos alone increased the levels of malondialdehyde (MDA) and decreased superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities compared with the control group in rat erythrocytes. In the catechin-plus-chlorpyrifos and quercetin-plus-chlorpyrifos groups, there were statistically significantly decreased MDA levels and increased SOD, CAT, and GPx activities compared with the chlorpyrifos-only group. Thus, it appears that catechin and quercetin ameliorate chlorpyrifos-induced oxidative stress in rat erythrocytes in vivo.