Recovery of cholinesterase activity in five avian species exposed to dicrotophos,and organophosphorus pesticide

The responses of brain and plasma cholinesterase (ChE) activities were examined in mallard ducks, bobwhite quail, barn owls, starlings, and common grackles given oral doses of dicrotophos, an organophosphorus insecticide. Up to an eightfold difference in response of brain ChE activity to dicrotophos was found among these species. Brain ChE activity recovered to within 2 SD of normal within 26 days after being depressed 55 to 64%. Recovery of brain ChE activity was similar among species and followed the model Y = a + b (log₁₀X).     

嗜卷书虱和嗜虫书虱体内磷酸酯酶的生化与毒理学特性比较研究

采用药膜法对嗜卷书虱和嗜虫书虱进行生物测定,从5种杀虫剂对两种书虱的LC50可以看出,嗜卷书虱对两种拟除虫菊酯类药剂较嗜虫书虱敏感,嗜虫书虱对丁硫克百威较为敏感,而对有机磷类药剂的作用两种书虱的敏感性相似。两种书虱体内酸性磷酸酯酶（ACP）和碱性磷酸酯酶（ALP）的活力比较结果表明：嗜卷书虱和嗜虫书虱体内ACP的比活力为分别14 μmol/mg&#8226;30 min和2.2 μmol/mg&#8226;30 min,ALP的比活力分别为0.092 μmol/mg&#8226;30 min和0.046 μmol/mg&#8226;30 min。经方差分析,两种书虱ACP和ALP的比活力之间均存在显著性差异(p<0.05)。动力学参数比较结果显示,两种书虱ACP的V _max值之间的差异达到显著水平,而ALP的K _m值之间存在显著性差异。离体试验结果表明,5种药剂对磷酸酯酶的作用各不相同,个别药剂在低浓度下表现诱导作用,说明磷酸酯酶在不同外源毒物的解毒代谢过程中所起的作用有所不同。     

Oxidative stress, steroid hormone concentrations and acetylcholinesterase activity in Oreochromis niloticus exposed to chlorpyrifos

We investigated the endocrine disrupting effects of chlorpyrifos-ethyl which is suspected to be originated from oxidative stress. Initially, the 96 h LC₅₀ values of chlorpyrifos in juvenile and adult of Oreochromis niloticus were determined to be 98.67 μg/L and 154.01 μg/L, respectively. Sub-lethal concentrations of chlorpyrifos-ethyl (5 ppb, 10 ppb, 15 ppb) were administrated to adult fish for 15 and 30 days. Fish were then left to depurate for 15 days in pesticide-free water. Gonadal somatic indices, serum sex steroids as indicators of reproductive function and cortisol level as indicator of stress condition were measured to observe the endocrine disruption effects of chlorpyrifos-ethyl. Gonadal glutathione S-transferase and antioxidant enzyme activities and lipid peroxidation as indicators of oxidative stress were also measured. Acetylcholinesterase activity was measured as a marker of chlorpyrifos toxicity. Results showed that serum estradiol, testosteron and cortisol levels in fish exposed to chlorpyrifos were lower than those of the control fish while gonad somatic indices did not change during the experiments. After 30 days, chlorpyrifos exposure decreased GST activity, and increased SOD enzyme activity by up to 215-446% compared with the control, suggesting there was a oxidative stress. No statistically significant differences between GPx and CAT specific activities, protein contents and lipid peroxidation were determined between control and treatment groups in all exposure concentrations and periods. Acetylcholinesterase activity decreased (45.83-77.28%) in gonad tissues. After recovery serum estradiol and testosteron levels were similar to those of the control levels. An increase in the GST and SOD enzyme activities were determined. Cortisol level and AChE activity in all exposure groups decreased after the depuration period, and fish were unable to overcome the stress of chlorpyrifos. Thus, this study revealed that after chlorpyrifos treatments there exists a protective function of antioxidant enzymes against lipid peroxidation in gonad tissue of O. niloticus. There also exist lower testosteron and estradiol levels in exposed fish than those of the control fish without any alterations in oxidative stress, which is attributed to the capability of chlorpyrifos to impair steroid hormone levels.     

Osmoregulatory function in ducks following ingestion of the organophosphorus insecticide fenthion

Salt gland function and osmoregulation in aquatic birds drinking hyperosmotic water has been suggested to be impaired by organophosphorus insecticides. To test this hypothesis, adult black ducks (Anas rubripes) were provided various regimens of fresh or salt (1.5% NaCl) water before, during, and after ingestion of mash containing 21 ppm fenthion. Ducks were bled by jugular venipuncture after 1, 7, and 12 days of treatment, and were then killed. Brain and salt gland acetylcholinesterase activities were substantially inhibited (44–61% and 14–36%) by fenthion. However, salt gland weight and Na⁺-K⁺-ATPase activity, and plasma Na⁺, Cl^?, and osmolality, were uniformly elevated in all groups receiving salt water including those ingesting fenthion. In a second study, salt gland Na⁺-K⁺-ATPase activity in mallards (A. platyrhynchos) was not affected after in vitro incubation with either fenthion oxon at concentrations ranging from 0.04 to 400 μM, but was reduced in the presence of 40 and 400 μM DDE (positive control). These findings suggest than environmentally realistic concentrations of organophosphorus insecticides do not markedly affect osmoregulatory function in adult black ducks.     

Effect of dichlorvos on cholinesterase activity of the European sea bass (Dicentrarchus labrax)

In this study, the acute toxicity of the organophosphorous pesticide (OP) dichlorvos and both in vitro and in vivo effects of dichlorvos on cholinesterase (ChE) activity of the European sea bass (Dicentrarchus labrax) were investigated. The characterisation of ChE and the “normal” range of activity in brain and muscle of non-exposed fish were determined in a first phase of the study. Acetylthiocholine was the substrate preferred of both brain and muscle ChE. Eserine sulphate and BW284C51 significantly inhibited the brain and muscle enzyme activity at low concentrations (μM range). Iso-OMPA had a significant effect in muscle, but not in brain tissue. These results suggest that acetylcholinesterase (AChE) is the predominant ChE form in brain tissue. In contrast, both acetylcholinesterase and butyrylcholinesterase seem to exist in muscle. Using acetylthiocholine as substrate, the “normal” range of fingerling head and muscle ChE were 58.05±2.11 and 118.03±8.67 U/mg protein, respectively. Corresponding values for juveniles were 43.32±4.42 and 19.44±2.44 U/mg protein for brain and muscle, respectively. Dichlorvos significantly inhibited the activity of ChE in the selected tissues, both in vitro and in vivo conditions. Differences in ChE sensitivity were found in relation to the age of the fish and the tissue analysed. The present study also showed that fingerlings of the European sea bass are relatively resistant to in vivo acute (96 h) dichlorvos exposure to concentrations between 0.125 and 1 mg/L, being able to tolerate high percentages of head ChE inhibition (37% and 76%) without lethal effects.     

Cell death localization in situ in laboratory reared honey bee (Apis mellifera L.) larvae treated with pesticides

In this study, cell death detected by DNA fragmentation labeling and phosphatidylserine (PS) localization was investigated in the honey bee (Apis mellifera L.) midgut, salivary glands and ovaries after treating larvae with different pesticides offered via an artificial diet. To do this, honey bee larvae reared in an incubator were exposed to one of nine pesticides: chlorpyrifos, imidacloprid, amitraz, fluvalinate, coumaphos, myclobutanil, chlorothalonil, glyphosate and simazine. Following this, larvae were fixed and prepared for immunohistologically detected cellular death using two TUNEL techniques for DNA fragmentation labeling and Annexin V to detect the localization of exposed PS specific in situ binding to apoptotic cells. Untreated larvae experienced ∼10% midgut apoptotic cell death under controlled conditions. All applied pesticides triggered an increase in apoptosis in treated compared to untreated larvae. The level of cell death in the midgut of simazine-treated larvae was highest at 77% mortality and statistically similar to the level of cell death for chlorpyrifos (65%), imidacloprid (61%), myclobutanil (69%), and glyphosate (69%) treated larvae. Larvae exposed to fluvalinate had the lowest midgut columnar apoptotic cell death (30%) of any pesticide-treated larvae. Indications of elevated apoptotic cell death in salivary glands and ovaries after pesticide application were detected. Annexin V localization, indicative of apoptotic cell deletion, had an extensive distribution in the midgut, salivary glands and ovaries of pesticide-treated larvae. The data suggest that the tested pesticides induced apoptosis in tissues of honey bee larvae at the tested concentrations. Cell death localization as a tool for a monitoring the subclinical and sub-lethal effects of external influences on honey bee larval tissues is discussed.     

Toxicity in the brain of organophosphate insecticides: Comparison of the toxicities of metabolites with parent compounds using an intracerebral injection method

The toxicity in the brain of several parathion, fenthion, and fensulfothion insecticides and their toxic metabolites was determined by a technique of directly injecting the compounds into the region of the third ventricle of conscious mice, an area rich in cholinesterase activity. The results were compared on a body weight basis to the toxicity of these compounds when given by ip and oral routes. The results show that there is a direct relationship between the relative inhibition of cholinesterase activity in the brain by the organophosphates (e.g., methyl paraoxon, Sumioxon, and some members of the fenthion series) and the toxicity of these compounds in the brain. Methyl paraoxon and Sumioxon were found to be very toxic in the brain, Sumioxon being three to four times less toxic than methyl paraoxon. This is of the same order of effect of these compounds in inhibiting cholinesterases. It is concluded that any selective effects of Sumithion compared with methyl parathion must be due to the greater rate of metabolism of Sumithion to less toxic metabolites as well as to the lower toxicity of the oxon metabolite and not due to the relative rates of penetration of the toxic oxygen metabolites as previously suggested [J. Miyamoto, Agr. Biol. Chem.28, 422 (1964)]. A gas-liquid chromatographic method was employed to assess the distribution in the brain following intracerebral injection of the parathion-type compounds. The results suggest that there may be intracerebral metabolism of thionophosphates in vivo.     

Chimeric mice with humanized liver as a model for testing organophosphate and carbamate pesticide exposure

BACKGROUND

Diagnosis of acute intoxication with organophosphate (OP) or carbamate (CM) pesticides in humans is achieved by measuring plasma butyrylcholinesterase (BuChE) activity. However, BuChE activity is not an ideal biomarker in experimental animal models. The aim of this study was to establish an experimental mouse model for evaluating exposure to OP and CM pesticides by monitoring BuChE activity using chimeric mice in which the liver was reconstituted with human hepatocytes.

RESULTS

A single oral administration of acephate (300 mg/kg), chlorpyrifos (10 mg/kg), fenobucarb (300 mg/kg) or molinate (250 mg/kg) in chimeric mice led to inhibition of >95%, > 95%, 28% and 60% of plasma BuChE activity after 7, 0.5, 0.5 and 7 h, respectively. Dose‐dependent decreases in plasma BuChE activity were also observed for acephate and chlorpyrifos. A 5‐day repeated‐dose study with 10 or 30 mg/kg acephate found a constitutive reduction in plasma BuChE activity to 80% and 70% of pre‐dose levels, respectively.

CONCLUSION

Changes in plasma BuChE activity in chimeric mice with humanized liver clearly reflected the exposure levels of OP and CM pesticides. These results suggest that the humanized‐liver mouse model may be suitable for estimating levels of exposure to these pesticides in humans. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

嗜卷书虱和嗜虫书虱体内磷酸酯酶的生化与毒理学特性比较

采用药膜法对嗜卷书虱和嗜虫书虱进行生物测定,从5种杀虫剂对两种书虱的LC50可以看出,嗜卷书虱对两种拟除虫菊酯类药剂较嗜虫书虱敏感,嗜虫书虱对丁硫克百威较为敏感,而对有机磷类药剂的作用两种书虱的敏感性相似.两种书虱体内酸性磷酸酯酶(ACP)和碱性磷酸酯酶(ALP)的活力比较结果表明:嗜卷书虱和嗜虫书虱体内ACP的比活力为分别14μmol/mg·30 min和2.2 μmol/mg·30 min,ALP的比活力分别为0.092μmol/mg·30 min和0.046μmol/mg·30 min.经方差分析,两种书虱ACP和ALP的比活力之间均存在显著性差异(p<0.05).动力学参数比较结果显示,两种书虱ACP的Vmax值之间的差异达到显著水平,而ALP的Km值之间存在显著性差异.离体试验结果表明,5种药剂对磷酸酯酶的作用各不相同,个别药剂在低浓度下表现诱导作用,说明磷酸酯酶在不同外源毒物的解毒代谢过程中所起的作用有所不同.     

Risk assessment of pesticides and fungicides for acid-base regulation and salt transport in rainbow trout tissues

Carbonic anhydrase enzymes have been shown to play an important role in ion transport and pH regulation in several organisms including fish. Despite this information and the wealth of knowledge regarding the significance of CA enzymes in fish, few studies have reported the hazardous effects of chemicals on fish CA. Using rainbow trout (Oncorhynchus mykiss) as a model, this study aimed to determine the risk of pesticides and fungicides on fish carbonic anhydrase enzymes. For this purpose, screening of rainbow trout carbonic anhydrase activities was carried out in the presence of some pesticides and fungicides. Carbonic anhydrase enzymes were initially purified from rainbow trout liver, muscle, kidney and brain, and exposed to pesticides and fungicides, including mancozeb, cypermethrin, deltamethrin and dinocap. Pesticides and fungicides dose-dependently decreased in vitro CA activity at micromolar concentrations. Since deltamethrin was the most powerful inhibitor for all tissues in in vitro experiments, it was chosen for in vivo analysis as well. rtCAs were significantly inhibited by the three concentrations of deltamethrin (0.25, 1.0 and 2.5 μg/L) at 24th and 48th hours. Our findings indicate that deltamethrin, dinocap, mancozeb and cypermethrin are potent inhibitors for fish CA enzymes, and might cause undesirable results by disrupting acid-base regulation as well as salt transport in freshwater or seawater adapted fish.     

Activity changes of glyoxalase system enzymes and glutathione-S-transferase in the bivalve mollusc Scapharca inaequivalvis exposed to the organophosphate chlorpyrifos

The present report was aimed to study possible changes in the activity of glutathione-dependent enzymes glyoxalase I (G I) and glyoxalase II (G II), forming the glyoxalase system, and glutathione-S-transferase in tissues (gills, foot, and digestive gland) of the mediterranean bivalve mollusc Scapharca inaequivalvis, after a 4- or 15-day exposure to a sublethal concentration (0.1 ppm) of the organophosphate pesticide chlorpyrifos (CPF). Control experiments were also performed on untreated animals. G I activity decreased in gills and foot, and increased in the digestive gland after 4 days of CPF exposure. Glyoxalase II activity in the gills decreased after a 15 days exposure to CPF, was unchanged in the foot and increased after 15 days in the digestive gland. Glutathione-S-transferase activity, which is involved in the detoxification of xenobiotics, increased significantly in all tissues after CPF exposure. The results suggest that sublethal CPF exposure of S. inaequivalvis does not compromise the cellular redox balance in these tissues.     

The pesticide module of the Root Zone Water Quality Model (RZWQM): testing and sensitivity analysis of selected algorithms for pesticide fate and surface runoff

The Root Zone Water Quality Model (RZWQM) is a one-dimensional, numerical model for simulating water movement and chemical transport under a variety of management and weather scenarios at the field scale. The pesticide module of RZWQM includes detailed algorithms that describe the complex interactions between pesticides and the environment. We have simulated a range of situations with RZWQM, including foliar interception and washoff of a multiply applied insecticide (chlorpyrifos) to growing corn, and herbicides (alachlor, atrazine, flumetsulam) with pH-dependent soil sorption, to examine whether the model appears to generate reasonable results. The model was also tested using chlorpyrifos and flumetsulam for the sensitivity of its predictions of chemical fate and water and pesticide runoff to various input parameters. The model appears to generate reasonable representations of the fate and partitioning of surface- and foliar-applied chemicals, and the sorption of weakly acidic or basic pesticides, processes that are becoming increasingly important for describing adequately the environmental behavior of newer pesticides. However, the kinetic sorption algorithms for charged pesticides appear to be faulty. Of the 29 parameters and variables analyzed, chlorpyrifos half-life, the Freundlich adsorption exponent, the fraction of kinetic sorption sites, air temperature, soil bulk density, soil-water content at 33 kPa suction head and rainfall were most sensitive for predictions of chlorpyrifos residues in soil. The latter three inputs and the saturated hydraulic conductivity of the soil and surface crusts were most sensitive for predictions of surface water runoff and water-phase loss of chlorpyrifos. In addition, predictions of flumetsulam (a weak acid) runoff and dynamics in soil were sensitive to the Freundlich equilibrium adsorption constant, soil pH and its dissociation coefficient.     

Effect of pesticides on phosphate solubilization by Bacillus sphaericus and Pseudomonas cepacia

Intensive screening of phosphate solubilizing bacteria with genetic potential for increased tolerance to high salt, high pH and high temperature could enhance production of food and forage in semi-arid regions. Emphasizing particularly on this hypothesis 165 phosphate solubilizing bacteria was isolated. Among these, two cultures Bacillus sphaericus and Pseudomonas cepacia were selected on the basis of salt tolerance property and PS activity with different forms of phosphates. In the present investigation both these culture were assessed for the effect of six different pesticides, to confirm its successful realistic application as microbial inoculants in actual farm conditions. Both cultures showed better phosphate solubilizing activity with phosphate containing pesticides. Among these two isolates P. cepacia was a better performer in terms of phosphate solubilizing activity with different pesticides. It may be due to its well documented extra ordinary, versatile metabolic activity. The present study may prove them to be potential candidates to be used as microbial inoculants.     

Effect of pesticides on spiders occurring on apple and citrus in Israel

Field experiments in an apple orchard and in a citrus grove were carried out to evaluate the effect of four commercial pesticides in common use in Israel against apple and citrus pests, on the spider populations inhabiting the trees. The spider populations on apple were markedly suppressed by the pesticides, the order of toxicity being Talstar (biphenate) >Mavrik (fluvalinate) > Smash (fenpropathrin) > Dursban (chlorpyrifos). When grapefruit trees were treated with carbaryl + formothion, 232 spiders were sampled in the unsprayed plot, 55 days after treatment, as compared with only 11 spiders in the treated plot. Two and 7 days after treatment with chlorobenzilate, the sample from the treated plot numbered 68 and 55 spiders, respectively, as compared with 50 spiders collected 24 h before treatment. In addition, laboratory tests were carried out to determine the susceptibility of the spiderChiracanthium mildei L. Koch to 17 pesticides. When the spiders were exposed to grapefruit leaves which had been dipped 1 h previously for 5 sec in the aqueous emulsions of the pesticides, chlorpyrifos, fenpropathrin, fenvalerate, phosphamidon and biphenate caused 100%, and cypermethrin and fluvalinate 60% mortality, whereas all the other pesticides tested - acaricides, fungicides and herbicides - caused about 10-40% mortality.     

Oxidation of chlorpyrifos, azinphos-methyl and phorate by myeloperoxidase

The present paper deals with the investigations of optimal conditions for the myeloperoxidase (MPO) mediated oxidation of chlorpyrifos, azinphos-methyl and phorate, organophosphorous pesticides (OPs) containing phosphorothionate group, from thio- to oxo-forms, in the presence of hydrogen peroxide. The aim of the work was to apply this oxidation method in the AChE based bioanalytical tests for OPs determination. The maximum concentration of oxo-forms for all tested pesticides was achieved after 10 min incubation of OPs in 50 mM phosphate buffer (pH 6.0) with 100 nM MPO in the presence of 50 μM H₂O₂. Optimal temperature for obtaining maximal concentration of oxo-forms was 37 °C. Only the parent compounds and their oxo-forms were identified chromatographically in the OPs samples after their exposure to MPO. Moreover, no hydrolysis products were detected in the time interval of 1 h after the MPO catalyzed reaction was stopped by catalase. The efficiency of OPs transformation from thio- to oxo-forms was measured using acethylcholinesterase (AChE) test, by comparison of percent of AChE inhibition before and after exposure to the oxidized sample.     

三种有机磷农药胚胎期暴露对新生鼠脑组织结构的影响

探讨了3种常用的有机磷农药胚胎期暴露对新生鼠脑组织结构的影响。在母鼠妊娠期7.5～11.5 d时,连续5 d每天分别经皮下注射2 mg/kg bw的二嗪磷(diazinon)、2 mg/kg bw的毒死蜱(chlorpyrifos)及50 mg/kg bw乙酰甲胺磷(acephate),显微镜下观察并计数大脑皮层S1区胶质细胞和神经元数量及比率,以及海马CA1、CA3区锥体细胞的数量及体积密度。结果表明,二嗪磷与毒死蜱处理分别使得大脑皮层S1区胶质细胞数减少了14.29%和21.43%;毒死蜱处理导致胶质细胞与神经元比率下降了24.19%;二嗪磷与毒死蜱处理后海马CA1区锥体细胞数量分别下降了9.30％与20.93％,毒死蜱处理后锥体细胞体积密度下降了27.05％;二嗪磷与毒死蜱处理后海马CA3区锥体细胞数量分别下降了22.22％和19.44％,锥体细胞体积密度分别下降了23.54％和18.98％;而乙酰甲胺磷对新生鼠大脑皮层与海马细胞均无明显影响。     

Cholinesterase (ChE) inhibition in pumpkinseed (Lepomis gibbosus) as environmental biomarker: ChE characterization and potential neurotoxic effects of xenobiotics

Inhibition of cholinesterases (ChEs) has been widely used as an environmental biomarker of exposure to organophosphates (OP) and carbamate (CB) pesticides. More recently, this biomarker has been suggested as a putative biomarker for exposure to detergents. The use of cholinesterase inhibition as effect criterion in Ecotoxicology requires the previous characterization of the specific enzymatic forms that may be present in different tissues or organs. Different ChEs isoforms may be present in the same tissue and may exhibit distinct sensitivities towards environmental contaminants. This work intended to characterize the soluble ChEs present in pumpkinseed sunfish (Lepomis gibbosus) total head and dorsal muscle homogenates, through the use of different substrates and selective inhibitors of cholinesterasic activity. Also, the in vitro effects of sodium dodecylsulphate (SDS - anionic detergent) and chlorfenvinphos (organophosphate pesticide) on the enzymatic activity of the mentioned species were investigated. In general terms, the predominant cholinesterasic form present in both tissues was acetylcholinesterase. Chlorfenvinphos was responsible for inhibitory effects on AChE activity, while SDS did not cause any significant effect. These results suggest that in environmental monitoring programs, L. gibbosus head and dorsal muscle AChE can be an adequate diagnostic tool for exposure to OP pesticides; this conclusion however is not applicable to detergent residues. We also discuss the usefulness of L. gibbosus as an alternative model system and valuable option for freshwater ecotoxicological monitoring programs.     

Pesticides-induced depression of photosynthesis was alleviated by 24-epibrassinolide pretreatment in Cucumis sativus L

The phytotoxicities of nine pesticides (paraquat, fluazifop-p-butyl, haloxyfop, flusilazole, cuproxat, cyazofamid, imidacloprid, chlorpyrifos, and abamectin) at practical dosages on photosynthesis were investigated in cucumber (Cucumis sativus L. cv. Jinyan No. 4) by gas exchange and chlorophyll fluorescent measurements. Plants treated with paraquat showed the severest phytotoxic symptom with the highest reduction in net photosynthetic rate (Pn), while other pesticides except flusilazole inhibited Pn to various degrees. The inhibition of Pn by cuproxat was accompanied by declines both in stomatal conductance (Gs) and intercellular CO₂ concentration (Ci), whereas decreased Pn for the cyazofamid was associated with increased Ci. For other 6 pesticides, however, inhibition of Pn was accompanied by decrease in Gs, while Ci was increased or unaffected. Paraquat almost completely inhibited the maximal quantum efficiency of PSII (F_v/F_m), while other pesticides had no significant effect on F_v/F_m. Quantum efficiency of PSII (Φ_PSII) was significantly reduced by paraquat, fluazifop-p-butyl, and chlorpyrifos and the reduction was mostly attributed to decrease in photochemical quenching coefficient (qP). In comparison, Φ_PSII was not significantly affected by haloxyfop, flusilazole, cyazofamid, imidacloprid, and abamectin. Non-photochemical quenching (NPQ) was suppressed by paraquat and haloxyfop, while apparent upregulation was evident after exposure to other pesticides. Interestedly, inhibitions of Pn were alleviated by 24-epibrassinolide (EBR) pretreatment, as for the pesticides examined in this study except paraquat and flusilazole. EBR pretreatment also increased Φ_PSII and qP. It is likely that EBR enhanced the resistance of cucumber seedlings to pesticides by increasing CO₂ assimilation capacity and activities of antioxidant enzymes.     

毒死蜱和甲氰菊酯对蚯蚓毒性与安全评价研究

按照“化学农药环境安全评价试验准则”的规定,测定了2种常用农药毒死蜱和甲氰菊酯对蚯蚓的毒性。结果表明：对蚯蚓的LC50(7d)毒死蜱为89．25mg／kg,甲氰菊酯为142．4mg／kg;LC50(14d)毒死蜱为83．63mg／kg,甲氰菊酯为36．41mg／kg。供试2种农药对蚯蚓的毒性均为低毒。     

防治桃小食心虫越冬幼虫的有效药剂及其降解动态

研究树下土表施药防治桃小食心虫越冬幼虫的取代药剂。用毒土法测定了分属4类的13种药剂对桃小食心虫越冬幼虫的触杀毒力,其结果以毒死蜱、三唑磷、高效氯氟氰菊酯、甲基对硫磷和辛硫磷毒力较高,LC_(90)值依次为18．38、22．48、35．95、47．63及49．57 mg·kg~(-1),甲氰菊酯、丙溴磷、阿维菌素、甲胺基阿维菌素、氰戊菊酯、马拉硫磷、丙硫克百威和丁硫克百威LC_(90)值处于77．11～205．86mg·kg~(-1)之间。用高效液相色谱法测定了毒力较高的毒死蜱、三唑磷、高效氯氟氰菊酯以及阿维菌素在土壤中的降解动态,半衰期分别为8．28、11．37、10．17及19．70天。欲达30天的有效控制期,按LC_(90)值计算,这4种药剂在土壤中的初施浓度应分别为226．36、139．90、278．03及346．81mg·kg~(-1)。从药剂毒力、降解速率、相同控制期所需剂量及应用成本综合评价,毒死蜱、三唑磷具有较高的应用价值。