Mercury, arsenic, and cadmium in fish, water, and sediment of American Falls Reservoir, Idaho, 1974.

Mercury and cadmium were found in fish, water, and sediment of American Falls Reservoir (AFR), Idaho. Mercury and cadmium levels in some fish exceeded human health standards set by the Food and Drug Administration, U.S. Department of Health, Education and Welfare, and the World Health Organization. Analyses performed on the flesh of rainbow trout showed mercury residues of up to 1.20 mg/kg, which were higher than residues previously reported in trout collected in 1970 and 1971 from AFR. Cadmium residue levels were as high as 0.80 mg/kg. Although arsenic was found in reservoir sediment at levels of 1.36-2.40 mg/kg, it was not detected in fish.     

四种常用三唑类杀菌剂在香蕉上残留行为及使用评价研究

采用田间试验研究了戊唑醇、氟环唑、苯醚甲环唑、丙环唑等4种常用三唑类杀菌剂在香蕉上的残留行为, 并比较了戊唑醇在套袋与不套袋情况下的最终残留量。研究结果表明：香蕉上戊唑醇、氟环唑、苯醚甲环唑、丙环唑的降解半衰期分别为10.8~14.1、8.1~9.5、7.9~12.9、9.4~15.6 d。在试验剂量条件下, 末次施药后42 d时, 戊唑醇(不套袋)、戊唑醇(套袋)、氟环唑、苯醚甲环唑、丙环唑在蕉肉中的残留量分别为：0.01~0.04、<0.01、0.01~0.08、≤0.01 mg/kg和0.02~0.07 mg/kg; 在全蕉上的残留量分别为0.05~0.47、<0.01、0.10~0.36、0.03~0.19 mg/kg 和0.05~0.32 mg/kg。香蕉果肉占全果的比例约为55%~75 %, 全果的残留量约为果肉2~19倍, 表明香蕉中戊唑醇、氟环唑、苯醚甲环唑、丙环唑主要残存在果皮上。戊唑醇防治香蕉叶斑病, 在套袋情况下可以显著地减少其在收获期香蕉上的残留。     

Dieldrin residues in soybeans in Illinois, 1965, 1966, 1967, 1971, and 1974

The Illinois soybean crop was monitored in 1965, 1966, 1967, 1971, and 1974 for dieldrin residues resulting from aldrin applied to corn in the years before soybean cultivation. Residue levels of dieldrin in soybeans increased between 1965 and 1974. The percent of fields which had soybeans with a dieldrin level above 0.03 ppm increased between 1965 and 1974. Dieldrin residue levels in soybeans grown in Illinois are expected to decline now that the use of aldrin has diminished and will soon cease. No significant correlation was evident between the dieldrin levels in soybeans and the area of the State where they had grown, the date of planting, or the variety.     

Effects of temperature onPhytophthora porri in vitro,in planta,and in soil

Cardinal temperatures for mycelial growth ofPhytophthora porri on corn-meal agar were <5 (minimum), 15–20 (optimum) and just above 25 °C (maximum). The number of infections after zoospore inoculation of young leaf plants was relatively low at supra-optimal temperatures, but was not affected by sub-optimal temperatures. Even at 0 °C plants were infected. The incubation periods needed for symptom formation were 36–57 d at 0 °C, 13–18 d at 5 °C, and 4–11 d at > 11 °C, and were fitted to temperature between 0 and 24 °C with a hyperbolical model (1/p=0.00812^*T+0.0243). Oospore germination, reported for the first time forP. porri, was strongly reduced after 5 h at 45 °C, and totally absent after 5 h at 55 °C. Soil solarization for six weeks during an exceptionally warm period in May–June 1992 in The Netherlands raised the soil temperature at 5 cm depth for 17 h above 45 °C, but did not reduce the initial level of disease in August significantly.     

Population dynamics of Rhizoctonia,Oculimacula, and Microdochium species in soil,roots, and stems of English wheat crops

This study aimed to elucidate the population dynamics of Rhizoctonia, Oculimacula, and Microdochium species, causing the stem base disease complex of sharp eyespot, eyespot, and brown foot rot in cereals. Pathogen DNA in soil, roots, and stem fractions, and disease expression were quantified in 102 English wheat fields in two seasons. Weather data for each site was collected to determine patterns that correlate with assessed diseases. Oculimacula spp. (66%) and R. solani AG 2-1 (63%) were most frequently detected in soil, followed by R. cerealis (54%) and Microdochium spp. (33%). Oculimacula spp. (89%) and R. cerealis (56%) predominated on roots and soil but were not associated with root rot symptoms, suggesting that these species used soil and roots for survival and as inoculum source. M. nivale was more frequently detected than M. majus on stems up to GS 21–30 and co-occurred on plant samples with O. acuformis. O. yallundae had higher DNA concentration than O. acuformis at the lower 5 cm basal region at GS 37–45. R. cerealis predominated in the upper 15 cm above the base beyond stem extension. Brown foot rot by Microdochium spp. was favoured by cool and wet autumns/winters and dominated in English wheat. Eyespot and sharp eyespot disease index by Oculimacula spp. and R. cerealis, respectively, correlated with wet/humid springs and summers. Results suggested that stem base pathogens generally coexisted; however, their abundance in time and space was influenced by favourable weather patterns and host development, with niche differentiation after stem extension.     

Multiple forms of esterases in mouse,rat, and rabbit liver,and their role in hydrolysis of organophosphorus and pyrethroid insecticides

Six to seven esterases from mouse, rat, and rabbit liver microsomes were resolved by chromatofocusing in the pH range 7–4. Each esterase peak showed a different substrate specificity pattern with the substrates evaluated. Malathion and paraoxon hydrolysis always corresponded with p-nitrophenyl acetate and methylthiobutyrate hydrolysis, whereas the pattern of fenvalerate hydrolysis was more complicated. Phosphorotriester hydrolase activity was isolated, and was found to be more specific toward paraoxon than toward the other insecticides. Time-course studies of paraoxon hydrolysis indicated that the hydrolysis of paraoxon by carboxylesterase was an inhibitory reaction. This reaction and phosphorotriester hydrolase activity can serve as a detoxication reaction toward organophosphate insecticides.     

DDT and BHC residues in some body tissues of goats, buffalo, and chickens, Lucknow, India

Muscle, liver, brain, and abdominal body fat samples of goats, buffalo, and chickens, all common meat sources in India, were analyzed by gas-liquid chromatography (GLC) for residues of DDT and benzene hexachloride (BHC). A few samples of goat and buffalo bone marrow were also included. Relatively high residue levels were found in body fat and bone marrow compared with other tissues. DDT and BHC residue levels were highest in chicken body fat, averaging 4.157 ppm sigma DDT and 3.879 ppm BHC. DDT content was much higher in goat and buffalo bone marrow than in the corresponding body fat. DDT levels in brain samples were highest (0.138 ppm) in buffalo. p,p'-TDE levels were higher than p,p'-DDE levels in buffalo; overall DDT levels were lowest in goats. BHC residues were generally low in buffalo; alpha-BHC accounted for most BHC residues in brain tissues. Greater accumulations of DDT and BHC were found in leg muscles than in breast muscles of chickens.     

毒死蜱、吡虫啉、螺虫乙酯及其代谢物和苯醚甲环唑在梨中的残留消解动态

利用仪器分析方法和田间试验法，研究了毒死蜱、吡虫啉、螺虫乙酯及其代谢物和苯醚甲环唑在梨中的残留消解动态。样品经乙腈提取，氯化钠盐析净化，毒死蜱采用气相色谱-质谱联用仪检测，其他3种农药采用液相色谱-质谱联用仪检测，外标法定量。结果表明:毒死蜱、吡虫啉、螺虫乙酯及其代谢物和苯醚甲环唑4种农药在梨中的消解动态均满足一级反应动力学方程，半衰期分别为4.4、12.2、13.1和10.3 d。施药后7 d至收获期，4种农药在梨中的最终残留量均未超出中国国家标准中规定的最大残留限量值，按照推荐剂量及其操作规范在梨上施用是安全的。     

啶酰菌胺在南瓜、芦笋、山楂、芒果和木瓜上的膳食摄入风险评估

为明确啶酰菌胺在南瓜、芦笋、山楂、芒果和木瓜上使用可能产生的膳食摄入风险，通过进行规范田间残留试验，检测了南瓜、芦笋、山楂、芒果和木瓜中啶酰菌胺的最终残留量，结合国内和国际两种膳食消费量数据，评估了啶酰菌胺的长期膳食摄入风险，并就两种方法的评估结果进行了比较分析。样品采用QuEChERS方法前处理，液相色谱-串联质谱 (LC-MS/MS) 定量分析。结果表明:南瓜在0.01、0.1和3 mg/kg，芦笋在0.01、0.1和20 mg/kg，山楂在0.01、0.1和60 mg/kg，芒果在0.01、0.1和4 mg/kg，木瓜在0.01、0.1和10 mg/kg添加水平下，啶酰菌胺在空白样品中的平均回收率为79%~101%，相对标准偏差为2%~14%。采用 “中国居民营养与健康状况调查报告” 的膳食消费数据，计算得啶酰菌胺针对普通人群的国家估算每日摄入量 (NEDI) 为0.707 5 mg/(kg bw)，风险商 (RQ) 为28.1%；采用世界卫生组织 (WHO) 提供的每种农产品的单独膳食量进行计算，啶酰菌胺的每日摄入量为0.128 2 mg/(kg bw)，风险商 (RQ) 为5.1%。两种方法的评估结果均表明啶酰菌胺对一般人群的健康不会产生不可接受的风险，然而，采用不同膳食消费数据进行计算会导致风险评估结果存在较大差异，其原因主要是由于中国所采用的膳食消费数据是作物分类基础上的数据，而不是具体某种农产品的单独消费量，因而易导致中国的膳食摄入风险评估结果过于保守。因此建议相关部门进一步完善居民的营养与健康状况调查监测工作，提供具体到每一种农产品的膳食消费数据，以便于科学评价农药对人体健康的风险。     

Induction, Regulation, and Role in Pathogenesis of Appressoria in Monilinia fructicola

ABSTRACT Monilinia fructicola, which causes brown rot in stone fruit, forms appressoria on plant and artificial surfaces. On nectarine, the frequency of appressoria produced by conidial germlings depends to a large degree on the stage of fruit development, with numerous appressoria formed on immature (stage II) nectarine fruit, and no appressoria observed on fully mature fruit (late stage III). On polystyrene surfaces, appressorium formation was increased from <10% of germinated conidia to >95% of germinated conidia when the conidia were washed to remove residual nutrients and self-inhibitors. M. fructicola appressorium formation also appears to be regulated by the topography of the plant surface. On fruit, appressoria formed on stomatal guard cell lips, on the grooves of lateral cells adjacent to stomata or between two epidermal cells, and on the convex surfaces of epidermal cells. Pharmacological effectors indicate that cyclic AMP-, MAP kinase-, and calcium/calmodulin-dependent signaling pathways are involved in the induction and development of appressoria. KN-93, an inhibitor of calmodulin-dependent protein kinase II, did not inhibit conidial germination but did inhibit appressorium formation and brown rot development on flower petals, suggesting that appressoria are required for full symptom development on Prunus spp. petals.     

Movement and persistence of imazaquin, oxyfluorfen, flurochloridone and terbacil in soil

The movement and persistence of imazaquin, oxyfluorfen, flurochloridone and terbacil residues were studied using a bioassay based on the shoot growth of Raphanus sativus L. var, radicula DC (radish) in a sandy loam soil under field conditions in 1992 and 1993. Imazaquin (0.3 kg a.i. ha^-1) was more mobile in the soil than the other three compounds. In 1992, under heavy rainfall conditions, the herbicide was distributed down to 60 cm in amounts of about 0.01 mg kg^-1. Conversely, in the dry year of 1993, the maximum depth of penetration was 20 cm and persistence in the surface soil layer (0-5 cm) was greater. After the first month in 1992, residues of terbacil were distributed in the 0-20 cm layer, and after 2, 3 and 5 months the herbicide had penetrated to a depth of 40 cm. In 1993, terbacil residues were distributed in the 0-10 cm layer only. In both years, residues of flurochloridone (1.0 kg a.i. ha^-1) were located mainly in the 0-5 cm layer, but there was some penetration to 10 cm. Oxy-fluorfen (1.2 kg a.i, ha^-1) showed least mobility in the soil profile. It was retained in the 0-5 cm layer throughout the experimental period in both. years.     

Absorption,translocation, and metabolism of ethalfluralin and trifluralin in Solanum spp

Seedlings of Solanum scabrum Mill. and Solanum ptycanthum Dun. were treated with [¹⁴C]ethalfluralin (N-ethyl-α,α,α-trifluoro-N-(methylallyl)-2,6-dinitro-p-toluidine) and [¹⁴C]trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) supplied in nutrient solution to determine the basis for differences in response by these two species to these two herbicides. Plants of S. scabrum absorbed more [¹⁴C]ethalfluralin and [¹⁴C]trifluralin than plants of S. ptycanthum. During the first 24 h, S. scabrum seedlings, but not S. ptycanthum seedlings absorbed more [¹⁴C]ethalfluralin than did plants treated with [¹⁴C]trifluralin. More [¹⁴C]ethalfluralin than [¹⁴C]trifluralin was found in the shoots of plants of both species. Seventy-two hours after treatment with [¹⁴C]herbicides, the conversion to water-soluble metabolites was greater for [¹⁴C]ethalfluralin than for [¹⁴C]trifluralin. In the shoots of plants from both species an average of nearly 55% of the ¹⁴C recovered was found in the water-soluble fraction following [¹⁴C]ethalfluralin treatment whereas an average of only 40% was found in the water-soluble fraction following [¹⁴C]trifluralin treatment.     

Prevalence and pathogenicity of spinach root pathogens of the genera Aphanomyces, Phytophthora, Fusarium, Cylindrocarpon, and Rhizoctonia in Sweden

In a 4-year disease survey in commercial spinach fields, pathogens were isolated from spinach root pieces placed on selective agar media. Aphanomyces cladogamus was the most abundant pathogen, followed by Phytophthora. cryptogea and Fusarium oxysporum. Rhizoctonia solani was found only occasionally. Other pathogens isolated were F. redolens, F. sambucinum and Cylindrocarpon destructans. P. cryptogea was the most severe pathogen, causing death of most plants, but A. cladogamus also caused severe root damage. Isolates of F. oxysporum ranged from highly pathogenic, i.e. P. oxysporum f.sp. spinaciae race 1. to moderately pathogenic and non-pathogenic, Rhizoctonia solani isolates also varied widely in their pathogenicity. Only a small number of the F. redotens and F. sambucinum isolates were pathogenic and most C. destructans isolates were weakly pathogenic. Isolation frequencies were relatively stable from year to year, but P. cryptogea was isolated more frequently in autumn than in spring. No clear relationships were found between pathogen prevalence and disease severity index of surveyed field plants, between pathogen prevalence and plant developmental stage, or between prevalence of the different pathogens isolated.     

Metabolism of the methoxychlor isostere,dianisylneopentane, in mouse,insects, and a model ecosystem

Dianisylneopentane or 1,1-bis(p-methoxyphenyl)-2,2-dimethylpropane was metabolized largely by O-demethylation to form mono- and diphenol derivatives. Only a small percentage was degraded by α-hydroxylation and rearrangement. In the model ecosystem, dianisylneopentane reacted very similarly to methoxychlor, accumulating in fish to about the same extent and yielding a slightly higher ratio of polar to nonpolar metabolites. The neopentyl group proved to be approximately as stable in biological systems as the isosterically equivalent trichloromethyl group.     

中国鼠害防控需求的差异、矛盾、挑战与对策

绝大多数啮齿动物种类为植食性的小型哺乳动物，其生物学特性导致了鼠类危害的复杂性。当前，面对日益提高的生态安全需求，粮食安全、人民健康和生物安全以及生态安全对鼠害控制需求的差异造成了中国鼠害防控策略制定及实施的困扰。尤其在草原地区，如何在应急性灭杀和长效缓控之间找到一个平衡点是目前鼠害防控面临的一个巨大挑战。针对这些矛盾和挑战，该文分析了我国鼠害监测防控的现状、主要瓶颈与短板，并从技术层面提出“精准监测指导精准防控”可能会是解决这些矛盾的有效途径，是在有效控制鼠害暴发对粮食生产和人民健康安全威胁的前提下，推进生态保护和修复的有效途径。     

Adsorption-desorption studies of alachlor, metolachlor, EPTC, chlorothalonil and pirimiphos-methyl in contrasting soils

Five soils with different organic matter contents ranging from 0.48 to 10.4% were used to study the adsorption and desorption of alachlor, metolachor, EPTC, chlorothalonil and pirimiphos-methyl in batch experiments. The isotherm shapes according to Giles classification were S-type for alachlor, metolachlor and chlorothalonil, changing to L-type for the latter as the level of soil organic matter increased, and L-type for EPTC and pirimiphos-methyl. The adsorption isotherms fitted the Freundlich equation x/m = KfCe1/n. The Kf values increased with the increase of organic matter content. The amounts of pesticides adsorbed over a range of concentrations of 0.1-20 mg litre-1 reached 63.1% for alachlor, 69.2% for metolachlor, 89.3% for EPTC, 98.4% for chlorothalonil and 96.3% for pirimiphos-methyl. The increase of the amounts desorbed with acetone indicated that the sorption of organic compounds onto organic matter occurred principally via weak London-type induction forces, or dispersion forces which are characteristics of the physical adsorption process.     

我国茶树叶部主要真菌病害及绿色防控现状、挑战及展望

茶树是我国重要的经济作物, 而真菌病害是造成茶叶品质下降和经济损失的主要因素之一。因缺乏安全、有效、经济的绿色防控措施, 限制了我国茶产业的高质量发展。为破解我国茶树病害绿色防控的难题, 推动茶产业高质量发展, 本文概述了茶树叶部主要真菌病害的发生流行、病害病原的鉴定和致病机制的研究工作, 系统梳理了茶树健康栽培、病害免疫诱抗、生物防治和化学防治等技术的现状, 重点探讨了我国茶树真菌病害治理所面临的挑战, 并展望了我国茶树真菌病害绿色防控的对策和实现路径。     

氟唑磺隆、甲基二磺隆、炔草酯和炔草酸在小麦中的残留分析

以QuEChERS前处理方法为基础，采用高效液相色谱-串联质谱(HPLC-MS/MS)检测技术，建立了除草剂氟唑磺隆、甲基二磺隆、炔草酯及其代谢物炔草酸4种化合物在小麦中残留的分析方法。麦粒样品中加入5 mL体积分数为0.1%的甲酸水溶液后，以10 mL乙腈提取，用50 mg C₁₈与100 mg 无水硫酸镁净化；麦秆样品中加入10 mL体积分数为2%的甲酸水溶液后，以10 mL乙腈提取，用100 mg C₁₈与200 mg无水硫酸镁净化。结果表明:氟唑磺隆在0.005、0.01和0.1 mg/kg，甲基二磺隆在0.01、0.02和0.1 mg/kg，炔草酯和炔草酸在0.05、0.1和0.5 mg/kg添加水平下，4种化合物在麦粒中的回收率在76%~97%之间，在麦秆中的回收率在83%~102%之间，相对标准偏差均小于10%，r > 0.99。4种化合物在麦粒和麦秆中的定量限分别为:氟唑磺隆0.005 mg/kg，甲基二磺隆0.01 mg/kg，炔草酯和炔草酸均为0.05 mg/kg。该方法可满足小麦样品中4种化合物的残留分析要求。