Acute toxicity of diazinon on the common carp (Cyprinus carpio L.) embryos and larvae

In the present study, the toxic effects on the embryos and larvae of the common carp were used as a model to investigate the organophosphorus pesticide, diazinon, which contaminates aquatic ecosystems. Data obtained from the diazinon acute toxicity tests were evaluated using the Probit Analysis Statistical Method. The control and six test experiments were repeated five times. The number of dead embryos significantly increased in response to diazinon concentrations 0.25, 0.5, 1, 2, 4, and 8 mg L⁻¹ (p < 0.05 for each case). The 48 h LC₅₀ value (with 95% confidence limits) of diazinon for common carp embryos was estimated at 0.999 (0.698-1.427) mg L⁻¹. Dose-response decreases in hatching success were recorded as 84.60, 75.2, 54.1, 31.0, 6.0, and 0.0%, respectively (p < 0.05). The number of dead larvae significantly increased with increasing diazinon concentrations exposed for 24-96 h (p < 0.05). The 24, 48, 72, and 96 h LC₅₀ values (with 95% confidence limits) of diazinon for common carp larvae were estimated at 3.688 (2.464-8.495), 2.903 (2.019-5.433), 2.358 (1.672-4.005), and 1.530 (1.009-3.948) mg L⁻¹, respectively. There were significant differences in the LC₅₀ values obtained at different exposure times (p < 0.05). The results of the study suggest that low levels (0.25 mg L⁻¹) of diazinon in the aquatic environment may have a significant effect on the reproduction and development of carp.     

Persistent sub-lethal chlorine exposure elicits the temperature induced stress responses in Cyprinus carpio early fingerlings

Thermal effluents discharged through cooling systems of nuclear power plants often contain chlorine (used to control bio-fouling), which may affect the metabolic status of fishes. In order to evaluate the hypothesis, we tested the effect of high temperature and a persistent sub-lethal chlorine exposure on stress responses in Cyprinus carpio advanced fingerlings. Fishes were acclimated to four different temperatures (26, 31, 33, and 36 °C) and maintained for 30 days in two different groups. Subsequently, one of the groups was exposed to persistent chlorine (0.1 mg L₋₁) for another 28 days and was compared with their respective temperature controls (without chlorine exposure). Sub-lethal doses of pollutants and increasing temperatures with in the tolerance range may not always register any morphological changes Therefore, we studied organ specific biochemical pathways viz. aspartate amino transferase, alanine amino transferase (enzymes of protein metabolism) in liver and muscle; fructose 1,6 diphosphatase (gluconeogenic pathway), in liver; pyruvate kinase, malate dehydrogenase, and lactate dehydrogenase (glycolytic pathway) in muscle; glucose-6-phosphate dehydrogenase (pentose phosphate pathway) in liver; alkaline phosphatase (phosphorus metabolism) in intestine, liver, and muscle; acetylcholine esterase (neurotransmitting enzyme) in brain, and adenosine triphosphate (for membrane transport) in gills at two different acclimation periods (14 and 28 days). The results indicate that C. carpio fingerlings demonstrated metabolic readjustments with increasing temperatures, in order to cope with energy demand of the cell. However, exposure to chlorine at higher temperatures affected protein metabolism, gluconeogenic pathway and subsequently glycolytic pathway, leading to an energy-limited condition. In addition, alteration of membrane transport and neurotransmission might be an early indication of cellular damage. Overall results indicate that persistent sub-lethal chlorine exposure elicits temperature induced stress response in C. carpio early fingerlings.     

Endocrine disruption and metabolic changes following exposure of Cyprinus carpio to diethyl phthalate

Diethyl phthalate (DEP) enter into aquatic environment from industries manufacturing cosmetics, plastic and many commercial products and can pose potential fish and human health hazard. This experiment evaluated effects of DEP in adult male (89 g) common carp (Cyprinus carpio) by exposing them to fractions of LC₅₀ (1/500-1/2.5) doses with every change of water for 28 days. Vitellogenin induction metabolic enzymes, somatic indices and bioaccumulation were studied on 7th, 14th, 21st and 28th day. The 96th hour LC₅₀ of DEP in fingerlings was found to be 48 mg/L. Compared to control, except increase (P < 0.01) in alkaline phosphatase activity (EC 3.1.3.1) and liver size, there was decrease (P < 0.01) in activity of acid phosphatase (EC 3.1.3.2), aspartate aminotransferase (EC 2.6.1.1), alanine aminotransferase (EC 2.6.1.2) and testiculosomatic index following exposure to 1, 5 and 20 ppm DEP. Significant (P < 0.01) dose dependant vitellogenin induction was observed with exposure of fish to 0.1, 1 and 5 ppm DEP. The bioaccumulation of DEP in testis, liver, brain, gills and more importantly in muscle tissues of fish increased significantly (P < 0.01) with increase of dose from 1 to 5 ppm. Significant interaction (P < 0.01) of dose and duration of exposure indicated that exposure period of a week to two was sufficient to bring about changes in quantifiable parameters studied. Fish exposed to 20 ppm DEP became lethargic and discolored during onset of the 4th week. This is the first report describing metabolic changes and vitellogenin induction following exposure of C. carpio to DEP dose that is as low as 1/500th fraction of LC₅₀.     

Ameliorative effect of lycopene on antioxidant status in Cyprinus carpio during pyrethroid deltamethrin exposure

The aim of the present study was to investigate the ameliorative properties of lycopene against the toxic effects of deltamethrin (DM) by examining oxidative damage markers such as lipid peroxidation and the antioxidant defense system components in carp (Cyprinus carpio). The fish were divided into seven groups of 15 fish each and received the following treatments: Group 1, no treatment; Group 2, orally administered corn oil; Group 3, oral lycopene (10 mg/kg body weight); Group 4, exposure to 0.018 μg/L DM; Group 5, exposure to 0.018 μg/L DM plus oral administration of 10 mg/kg lycopene; Group 6, exposure to 0.036 μg/L DM; and Group 7, exposure to 0.036 μg/L DM plus oral administration of 10 mg/kg lycopene. Treatment was continued for 14 days, and at the end of this period, blood and tissue (liver, kidney, and gill) samples were collected. Levels of malondialdehyde (MDA) and reduced glutathione (GSH) as well as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities were determined in blood and tissues for measurement of oxidant-antioxidant status. A significant elevation in the level of MDA, as an index of lipid peroxidation, and reductions in antioxidant enzyme activities (SOD, CAT, and GSH-Px) and low molecular weight antioxidant (GSH) levels were observed in DM-exposed fish. Treatment with lycopene attenuated the DM-induced oxidative stress by significantly decreasing the levels of MDA. In addition, lycopene significantly increased the SOD, CAT, and GSH-Px activities and the level of GSH. The present results suggest that administration of lycopene might alleviate DM-induced oxidative stress.     

One-tenth dose of LC50 of 4-tert-butylphenol causes endocrine disruption and metabolic changes in Cyprinus carpio

Of the huge annual worldwide production (500,000 MT in 1997) of alkylphenol polyethoxylates (APEs) that are widely used as nonionic surfactants and anti-oxidants in variety of products, 60% ends up in water bodies. They undergo biodegradation to form octyl-, butyl-, and nonyl-phenols. This experiment evaluated effects of 4-tert-butyl phenol (4-TBP) in Cyprinus carpio, a projected candidate species in sewage fed fisheries. The 96th h LC₅₀ of 4-TBP was found to be 6.9 mg/L. Fishes were treated with 1/10th (0.69 mg/L), 1/5th (1.38 mg/L), and 1/3rd (2.3 mg/L) dose of LC₅₀. Whereas there was significant (P < 0.01) decrease in alkaline phosphatase [EC 3.1.3.1] and aspartate aminotransferase [EC 2.6.1.1] activity; alanine aminotranferase [EC 2.6.1.2] and acid phosphatase [3.1.3.2] (except decrease at 1/10th dose of LC₅₀) activity, vitellogenin production in muscle and hepatic- and reno-somatic indices were increased compared to control. With all the dose levels tested, testicular-somatic index (testis size) was reduced (P < 0.01) and histo-architectural changes in testicular and liver tissue were found even in group given 1/3rd dose of LC₅₀.     

Effect of atrazine and chlorpyrifos exposure on heat shock protein response in the brain of common carp (Cyprinus carpio L.)

Atrazine (ATR) and chlorpyrifos (CPF) are the most common pesticides found in freshwater ecosystems throughout the world. In the present study, the common carps were exposed to ATR, CPF and their mixture as describe in Table 1. Then we investigated the HSPs (HSP60, HSP70 and HSP90) expression in the brain of common carp by western blot and real-time PCR. Results indicated that HSP60 and HSP70 were significantly increased as compared to corresponding controls after 40 d exposure (P < 0.05). While the increased expression levels of HSP90 in exposure groups was only observed at 4.28 μg/L ATR group and 1.16 μg/L CPF group, and after 40 d recovery, the expression levels of HSP90 were higher than most of exposure groups (P < 0.05). It was suggested that the increased gene expression of HSPs was possible to protect injured cell mass caused by ATR, CPF and their mixture exposure. The present results provided new insights into the mechanisms used by fish to adapt to stressful environments.     

The effects of metribuzin on early life stages of common carp (Cyprinus carpio)

Metribuzin belongs to the triazine group of herbicides, which are frequently used in agriculture. The aim of this study was to assess the impact of metribuzin on growth and development of early life stages of fish. Subchronic toxic effects of metribuzin at concentrations of 0.9, 4, 14, and 32 mg/L on embryos and larvae of common carp (Cyprinus carpio) were investigated during a 30 day toxicity test under experimental conditions. Exposure to metribuzin at 32 mg/L was associated with increased mortality. Negative effects on total body length, weight, and inhibition of specific growth rate were induced by all experimental concentrations. Length and weight parameters were the most sensitive. The negative impact of metribuzin was observed in the highest tested concentration beginning on day 6 of exposure. Retardation of early ontogeny was associated with concentrations ?4 mg/L. Histological examination revealed changes in liver and caudal kidney after 30 days exposure to 32 mg/L. Based on growth parameters, development, and histological examination, the Lowest Observed Effect Concentration (LOEC) value was 0.9 mg/L.     

Effect of terbutryn at environmental concentrations on early life stages of common carp (Cyprinus carpio L.)

The aim of this study was to assess the toxicity of terbutryn to early developmental stages of common carp (Cyprinus carpio). Based on accumulated mortality in the experimental groups, lethal concentrations of terbutryn were estimated at 36 day LC50 = 3.06 mg l⁻¹ terbutryn. Based on inhibition of growth in the experimental groups, lowest observed-effect concentration (LOEC) = 0.005 mg l⁻¹ terbutryn; and no observed-effect concentration (NOEC) = 0.0007 mg l⁻¹ terbutryn. Fulton’s condition factors were significantly lower in fish exposed to 2 mg l⁻¹ compared with controls. By day 30, fish exposed to 0.00002 mg l⁻¹ - real environmental concentration in Czech rivers - 0.02, 0.2, and 2 mg l⁻¹ terbutryn showed significantly lower mass and total length compared with controls. No significant negative effects on hatching or embryo viability were demonstrated at the concentrations tested, but significant differences in early ontogeny among groups were noted. Fish from the two highest tested concentrations (0.2 and 2 mg l⁻¹) showed a dose-related delay in development compared with the controls. At concentrations of 0.02, 0.2, and 2 mg l⁻¹ damage to caudal kidney tubules when compared to control fish was found.     

Identification of resistance-responsive proteins in larvae of Bactrocera dorsalis (Hendel), for pyrethroid toxicity by a proteomic approach

Insect resistance to the pyrethroid toxins has been examined previously using a number of traditional biochemical and molecular techniques. In this study, a proteomic approach involving two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and tandem mass spectrometry (MS/MS) were applied to examine changes in resistant stains larvae of Bactracera dorsalis Hendel induced by pyrethroid treatment over a 3 h, 6 h and 12 h time period, and a number of proteins changes were observed to change in the level of regulation. Out of total 15 proteins, 9 proteins were observed only after pyrethroid treatment; 6 proteins showed different expression. After MALDI-TOF analyses and peptide mapping method, the data was compared with those of the known proteins available in public databases. Sequence analyses revealed that resistance response correlates with up-regulation (glycerol-3-phosphate dehydrogenase) and down-regulation (ATP-ADP antiporter) of energy-related proteins. It indicated that increased metabolism and energy-indeed as a resistance response to pyrethroid toxins. The regulation of cytoskeleton proteins were possibly a B. dorsalis tissue repair response or in cell division. Up-regulation of protein synthesis would results in substantial bioenergetic enhancement, suggesting a trade-off insect resistance to pyrethroid. Down regulation of neural protein indicated that neural system was physically injured after pyrethroid stress. Some remaining proteins were not identifiable, suggesting these may be novel proteins. Oriental fruit fly proteomes of pesticide induced provide an integrative basis for consolidating our knowledge of insect resistance. The results pave the way for future investigation of the alteration of the insect resistance to chemical pesticides.     

Effects of the herbicide LASSO MTX (alachlor 42% W/V) on biometric parameters and liver biomarkers in the common carp (Cyprinus carpio)

The aim of the study was to evaluate the effect of subchronic exposure to the herbicide LASSO MTX (alachlor 42% W/V) on biometric parameters and important liver biomarkers in the common carp (Cyprinus carpio). One year old fish were exposed for 28 days to LASSO MTX added to the tank water at concentrations of 240 and 2400 μg L⁻¹. The exposure did not affect fish biometric parameters. Glutathione-S-tranferase (GST) activity in liver (hepatopancreas) remained unchanged in exposed fish when compared to controls. However, significant induction of total cytochrome P 450 (CYP 450), ethoxyresorufin-O-deethylase (EROD) activity and elevated glutathione (GSH) in liver of exposed fish were detected.     

长枝木霉对禾谷胞囊线虫卵的寄生和毒杀作用及其机制

为了明确长枝木霉Trichoderma longibrachiatum对小麦禾谷胞囊线虫Heterodera avenae卵的防治潜力和作用机制,在室内测定了长枝木霉分生孢子悬浮液对小麦禾谷胞囊线虫卵的寄生和毒杀作用,并通过温室盆栽试验测定了长枝木霉分生孢子悬浮液对小麦禾谷胞囊线虫卵的防治效果.室内试验中1.5×107 CFU/mL的长枝木霉分生孢子悬浮液处理12 d对小麦禾谷胞囊线虫卵的寄生率和卵孵化的相对抑制率分别为91.33％和88.35％.温室盆栽试验中1.5×107 CFU/mL处理对土壤中胞囊、线虫和根系中线虫的相对防治效果分别为89.84％、92.67％和88.30％;接种卵悬浮液和长枝木霉分生孢子悬浮液后,小麦幼苗株高、根系长度、地上部鲜重和根系鲜重的增长率分别为66.72％、159.31％、169.09％和170.19％;叶绿素总量和根系活力显著高于对照,分别为17.52 mg/g和356.25 μg·g-1·h-1.研究表明长枝木霉可作为小麦禾谷胞囊线虫的生防制剂.     

The pyrethroid resistance status and mechanisms in Aedes aegypti from the Guerrero state,Mexico

Dengue is one of the most important vector-borne diseases worldwide and is a public health problem in Mexico. Most programs in dengue endemic countries rely on insecticides for Aedes control. In Mexico, pyrethroid insecticides (mainly permethrin and deltamethrin) have been extensively used over a decade as adulticides and represented a strong selection for insecticide resistance for dengue vectors in several parts of the country. We studied the type, frequency and distribution of insecticide resistance mechanisms in Aedes aegypti from six municipalities in the state of Guerrero selected on the basis of historically intense chemical control and a high risk for dengue transmission. Ae. aegypti eggs were collected from October 2009 to January 2010 using ovitraps. F₁ adults, emerged from these collections, were exposed to permethrin, deltamethrin and DDT in WHO diagnostic tests and showed high resistance levels to both pyrethroids and DDT. This was consistent with the presence of increased metabolic enzyme activities and target site insensitivity due to kdr mutations. Biochemical assays showed elevated esterase and glutathione S-transferase activities in the six municipalities. The V1016I kdr mutation on the IIS6 domain of the sodium channel gene was present in an overall frequency of 0.80. A second mutation, F1534C on the IIIS6 domain of the same gene was also detected, being the first report of this mutation in Guerrero. The multiple resistance mechanisms present in Ae. aegypti from Guerrero state represent a warning for the efficacy of the pyrethroid usage and consequently for the success of the dengue control program.     

In vitro and in vivo effects of some pesticides on carbonic anhydrase enzyme from rainbow trout (Oncorhynchus mykiss) gills

Here we investigated the in vitro and in vivo effects of the pesticides, deltamethrin, diazinon, propoxur and cypermethrin, on the activity of rainbow trout (rt) gill carbonic anhydrase (CA). The enzyme was purified from rainbow trout gills using Sepharose 4B-aniline-sulfanilamide affinity chromatography method. The overall purification was approx. 214-fold. SDS-polyacrylamide gel electrophoresis showed a single band corresponding to a molecular weight of approx. 29 kDa. The four pesticides dose-dependently inhibited in vitro CA activity. IC₅₀ values for deltamethrin, diazinon, propoxur and cypermethrin were 0.137, 0.267, 0.420 and 0.460 μM, respectively. In vitro results showed that pesticides inhibit rtCA activity with rank order of deltamethrin > diazinon > propoxur > cypermethrin. Besides, in vivo studies of deltamethrin were performed on CA activity of rainbow trout gill. rtCA was significantly inhibited at three concentrations (0.25, 1.0 and 2.5 μg/L) at 24 and 48 h.     

Effects of deltamethrin on hematological parameters and enzymatic activity in Ancistrus multispinis (Pisces, Teleostei)

Deltamethrin (DM) is a pyrethroid insecticide widely used in Brazilian crops and in pest-control programs because of its low environmental persistence and toxicity. It has been shown to exert a wide range of effects on non-targeted organisms including fishes. The aim of this study to evaluate the effects of deltamethrin through the hematological and biochemical parameters using Ancistrus multispinis as animal model. First, blood of A. multispinis was collected by cardiac puncture in order to evaluate the basal values of the total cell counts, hemoglobin and hematocrit rates. A. multispinis showed low number leukocytes, red blood cells and hemoglobin compared to other species. The intoxication with DM (0.1 or 0.3 mg kg⁻¹) induced leukocytosis and increases the number of erythrocytes and hemoglobin levels 96 h after the injection when compared to vehicle-injected animals. The injection of lipopolysaccharide (LPS) also induced a significant leukocytosis and increased the erythrocytes number 4 h after the injection. The combination of the higher dose of DM with LPS showed an additional effect in the number of leukocytes and erythrocytes. The GST and EROD activities were also evaluated in the gills and liver, respectively, 96 h after intoxication with both doses of DM. The GST activity decreased after DM intoxication in both doses while EROD activity was not significantly different. These results suggest that A. multispinis is a valuable model for ecotoxicological studies. Also, DM can affect the metabolizing system (GST) and immunologic system of A. multispinis, a condition that can be worsened in the presence of inflammation or infection.     

Sublethal effects of larval treatment with deltamethrin on moth sex pheromone communication system of the Asian corn borer, Ostrinia furnacalis

The first, third, and fifth instar larvae of Asian corn borer, Ostrinia furnacalis (Guenée) (Lepidoptera: Pyralidae), were treated with a lethal dose 30% of deltamethrin to determine its sublethal effects on chemical communication of the adult survivors. The capability of all males surviving deltamethrin to contact the pheromone source in a wind tunnel was significantly reduced, but those treated as the first and third instars also exhibited lower percentages of `orientation,' `up-wind flight,' and `approaching' behaviors than the control males. Female moths from the deltamethrin treatment exhibited similar calling periodicity and percentages to the control moths during 10-h scotophase. However, approximately 20% of the females that survived the pyrethroid in the first and third instars contained significantly higher amounts of sex pheromone and wider coefficients of variation of the ratio of E12-tetradecenyl acetate to its Z isomer in those female survivors. There was no significant difference in the pheromone titers and coefficients of variation in control females and the females treated in the fifth instars. The present study indicates that the Asian corn borer may possess a compensation system by which the males that survived treatment at larval stage present a lower response to the pheromone, while the female survivors produce and release more pheromone.     

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.     

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.     

The role of cytochrome P450 monooxygenase in the different responses to fenoxaprop-P-ethyl in annual bluegrass (Poa annua L.) and short awned foxtail (Alopecurus aequalis Sobol.)

Herbicide resistance or tolerance in weeds mediated by cytochrome P450 monooxygenase is a considerable problem. However, cytochrome P450 mediated resistance or tolerance in weeds was less studied. Thus, in this work, the role of the cytochrome P450 monooxygenase in the different responses of Poa annua and Alopecurus aequalis to fenoxaprop-P-ethyl was studied. We found that the effect of fenoxaprop-P-ethyl could be synergized by piperonyl butoxide (PBO) in P. annua, but not by malathion. After being treated with fenoxaprop-P-ethyl (containing mefenpyr-diethyl), the contents of cytochrome P450 and cytochrome b₅ in P. annua increased significantly compared to plants treated with mefenpyr-diethyl only or untreated plants. However, the increase was less in A. aequalis, which was susceptible to fenoxaprop-P-ethyl. The activities of ρ-nitroanisole O-demethylase (PNOD), ethoxyresorufin O-deethylase (EROD), ethoxycoumarin oxidase (ECOD) and NADPH-dependent cytochrome P450 reductase mediated by cytochrome P450 monooxygenase increased in P. annua after treatment with fenoxaprop-P-ethyl, especially the activities of ECOD and cytochrome P450 reductase. Besides this, cytochrome P450 monooxygenase activity toward fenoxaprop-P-ethyl in P. annua increased significantly compared to untreated or treated with mefenpyr-diethyl plants and treated or untreated A. aequalis. Cytochrome P450 monooxygenase may play an important role in the different responses to fenoxaprop-P-ethyl in P. annua and A. aequalis.     

小菜蛾感染玫烟色棒束孢后的病征及组织病理变化

为了明确玫烟色棒束孢对小菜蛾的致病作用,分别以1×10⁵孢子/mL和1×10⁸孢子/mL浓度的玫烟色棒束孢菌株EBCL03011孢子悬浮液感染小菜蛾幼虫,观察了感病幼虫体表和体内器官组织的病变情况。结果显示,感病虫体颜色由局部浅褐色逐渐变为大面积深褐色,病虫出现缩短、强直等外部形态的变化。组织切片观察显示,接种后4 h,附着于体壁的分生孢子开始萌发入侵;16 h后,小菜蛾内表皮被分解,菌丝段进入血腔。与此同时,被幼虫取食进入消化道的分生孢子也增殖产生菌丝段,以菌丝段突破肠壁细胞,向附近的脂肪体入侵;随着玫烟色棒束孢继续在虫体内增殖,24 h后各组织器官遭到不同程度破坏;48 h后,感病幼虫死亡,虫尸体内的菌丝突破体表,在虫体外形成菌丝层。表明玫烟色棒束孢入侵小菜蛾有两条途径,第1条为体表途径,第2条为消化道途径。