Residues of organochlorine insecticides and polychlorinated biphenyls in fish from Lakes Huron and Superior, Canada--1968-76.

Five species of fish from Lake Superior and 12 species from Lake Huron were analyzed for organochlorine pesticides and polychlorinated biphenyls (PCBs) between 1968 and 1975. Mean residues of sigma DDT peaked at 1.72 ppm and 7.60 ppm in lake trout (Salvelinus namaycush) from Lakes Superior and Huron, respectively. By 1975, the mean level of sigma DDT had decreased in lake trout and was highest in bloaters (Coregonus hoi) from both lakes: 1.06 ppm and 1.87 ppm, respectively. Dieldrin levels in fish from Lake Superior changed little over the same period. However, in 1969-70, dieldrin levels in fish from Lake Huron exceeded the 0.3 ppm tolerance level set by Health and Welfare Canada or the Food and Drug Administration, U.S. Department of Health, Education, and Welfare in 5 percent of lake whitefish (Coregonus clupeaformis) and 10 percent of bloaters. By 1975, 50 percent of bloaters caught in Georgian Bay and North Channel had dieldrin levels above 0.3 ppm. PCB residues declined in lake trout and lake whitefish caught in Lake Superior between 1971 and 1975, but increased slightly in bloaters and white sucker (Catostomus commersoni). Mean PCB residues in bloaters caught in Lake Huron in 1969-71 and 1975-76, and splake (Salvelinus fontinalis and S. namaycush) and cisco (Coregonus artedii) caught in 1975 exceeded the 2 ppm tolerance level.     

Residues of organochlorine insecticides and polychlorinated biphenyls in fish from Lakes Saint Clair and Erie, Canada--1968-76.

Eighteen species of fish from Lake Saint Clair and 19 species from Lake Erie were analyzed for organochlorine pesticides and polychlorinated biphenyls (PCBs) between 1968 and 1976. Mean residues of sigma DDT peaked at 1.19 ppm in longnose gar (Lepisosteus osseus) caught in Lake Saint Clair in 1970-71, but had declined in all species by 1975-76. Dieldrin levels in fish tissues increased over the same period. White bass (Morone chrysops), caught in 1975 in Lake Erie, had the highest mean residue of dieldrin at 0.17 ppm. PCB residues increased in some species and decreased in others. PCB residues exceeding the tolerance level of Health and Welfare Canada were found in the following: from Lake Saint Clair, smallmouth bass (Micropterus dolomieui) in 1975 and channel catfish (Ictalurus punctatus) in 1971; from Lake Erie, coho salmon (Oncorhynchus kisutch) in 1970, smallmouth bass, alewife (Alosa pseudoharengus), freshwater drum (Aplodinotus grunniens), and gizzard shad (Dorosoma cepedianum) in 1971, and white bass in 1971 and 1976.     

Residues of the insecticides phorate and methomyl in mint hay and oil

Since mint oil is used as a flavouring agent for foods and cosmetics, pesticide residues in the oil are undesirable. The residual behaviour of two pesticides, phorate and methomyl, was studied as replacements for chlorinated hydrocarbon pesticides which leave residues in the oil. Phorate applications of 1.1 kg/ha resulted in oil residues of 0.24 mg/kg total phorate in Oregon samples and 1.69 mg/kg in Washington samples. Less than 1% of the residues in the hay distilled with the oil. Mint oil undergoes a 100- to 1000-fold dilution in commercial use with a corresponding reduction of residues in the final product. No residues of methomyl were found in the oil, even with hay residues as high as 5.34 mg/kg. Residues in hay decreased to half of initial levels in 2 to 4 days, independently of use conditions. It was concluded that the proposed use of phorate or methomyl for control of mint pests does not present a residue hazard. Details of the analytical methods used are also presented.     

Residues of synthetic pyrethroid insecticides on horticultural crops

Foliar applications of synthetic pyrethroids were made to several crops to determine residue levels at various intervals after application. On onions, residues of cypermethrin, permethrin and fenvalerate were negligible > 0.1 mg kg^?1, 7 days after application. On lettuce, residues of fenvalerate and permethrin were 0.8 mg kg^?1. On celery, residues of fenvalerate did not decline and ranged from 0.12 to 0.25 mg kg^?1 during the 14-day period. On green bush-beans, residues of permethrin and cypermethrin did not decline during the 14-day period and ranged from 0.1 to 0.6 mg kg^?1. By day 7, residues of cyfluthrin, cypermethrin, deltamethrin, fenvalerate and permethrin on strawberries were less than the acceptable maximum tolerance of 0.1 mg kg^?1 with the exception of cypermethrin, applied at the rate of 0.14 kg a.i. ha^?1 which gave a residue of 0.14 mg kg^?1.     

新烟碱类杀虫剂在苹果果实不同部位中的残留

为了明确噻虫嗪、烯啶虫胺、吡虫啉、啶虫脒、噻虫胺和呋虫胺6种新烟碱类杀虫剂在苹果果实不同部位中的迁移转化规律,以10年生红富士苹果树为试材,分别于蚜虫发生期 (7月10日) 和果实采收前1 d (9月25日) 通过整株喷雾施药,随机取样,采用高效液相色谱仪测定,外标法定量,分析各杀虫剂在生长期套袋果实和不套袋果实及储藏期果实不同部位中的残留量及迁移规律。结果表明:在果实套袋情况下,施药后72 h内果实不同部位各新烟碱类杀虫剂的含量均呈现先逐渐上升而后下降的趋势,且在果皮中的残留量最低 (均低于0.08 mg/kg),其中烯啶虫胺和吡虫啉在果皮中的残留量低于最低检测浓度,而在果柄和果肉中的残留量明显高于果皮中的,表明套袋果实中药剂主要来源于枝叶运输,经果柄进入果实后易向果肉累积;在果实未套袋情况下,施药后72 h 6种杀虫剂在果肉中的含量均高于套袋果实果肉中的,分别是套袋果实果肉中含量的7.75、3.52、3.36、6.57、2.92和3.06倍,表明套袋可有效降低果实中该类药剂的残留量。储藏试验结果表明:直接向果面喷施6种新烟碱类杀虫剂后,药剂主要存在于果皮中,施药后14和21 d在果肉中的含量均低于最低检测浓度,表明储藏期果皮为该类药剂的主要残留部位,且不易向果肉中转移。     

拟除虫菊酯类杀虫剂在烟叶烘烤过程中的消解动态与最终残留

采用气相色谱-质谱联用技术,测定了良好农业规范(GAP)条件下3种常用拟除虫菊酯类杀虫剂高效氯氟氰菊酯、高效氯氰菊酯及溴氰菊酯在山东、四川、云南、辽宁和江西5地烟叶中的消解动态及最终残留。样品经乙腈提取,SPE-PSA柱净化,气-质联用、选择离子监测模式(GC-MS/SIM)下测定,外标法定量。结果表明:在0.01 ~1 mg/kg添加水平下,3种农药在鲜烟叶和干烟叶中的平均回收率分别在82.9% ~ 110.9%和85.2%~108.3%之间,相对标准偏差(RSD)分别为1.7% ~4.4%和2.3% ~5.7%;3种农药在鲜烟叶和干烟叶中的定量限(LOQ)均为0.01mg/kg;方法的准确度和精密度均符合农药残留检测要求。烘烤过程中残留农药消解明显,高效氯氟氰菊酯、高效氯氰菊酯和溴氰菊酯的消解率分别高达78%、89%和91%。高效氯氟氰菊酯、高效氯氰菊酯和溴氰菊酯乳油分别按有效成分450~675 g/hm2、600~900 g/hm2及450~675 g/hm2于烟叶采 烤初期喷雾施药2次,距末次施药后14d,干烟叶中3种农药的残留量分别为0.022~ 0.50、0.14~0.82和0.046~0.21 mg/kg,均低于国际烟草合作研究中心(CORESTA)提出的指导性农药残留限量标准(GRL)值(0.5、1和1mg/kg),因此建议其安全间隔期可定为14d。     

Membrane partitioning of organophosphorus and organochlorine insecticides and its implications for mechanisms of toxicity

Partition coefficients of organophosphorus and organochlorine insecticides were determined in several types of membrane. Insecticide partitioning varied among the membranes under study, depending on temperature, cholesterol content and on the physico-chemical profiles of membrane components and the insecticides themselves. The maximal partitions for DDT, lindane, parathion and malathion in egg phosphatidylcholine bilayers over the temperature range from 10 to 37°C (at which the lipid is in the liquid-crystalline state) were about 260000, 2000, 1000 and 120, respectively. Incorporation of 50 mol% cholesterol in egg phosphatidylcholine bilayers dramatically decreased the partition and almost abolished the temperature effect. First-order phase transitions of dimyristoyl-, dipalmitoyl- and distearoylphosphatidylcholines (DMPC, DPPC and DSPC) were accompanied by a sharp increase in insecticide partition. Furthermore, the insecticides under study were more easily accommodated in bilayers of short-aliphatic-chain lipids, since higher values of partition were obtained in DMPC bilayers. Partition values in native membranes depended considerably on the membrane type and composition and were higher in sarcoplasmic reticulum (SR) and mitochondria than in brain microsomes, myelin and erythrocytes. Identical results were obtained in related liposomes of total extracted lipids, although the absolute partitions showed decreased values. In general, the incorporation of insecticides correlated reasonably with the cholesterol content of the membranes. The order of partitioning of the above insecticides did not run parallel with their toxicity to mammals and, both in model and in native membranes, followed the sequence: DDT ? lindane > parathion > malathion.     

Persistence of some organophosphorus insecticides in hen-house litter

Thin-layer chromatography was used to assess semi-quantitively the persistence of six organophosphorus insecticides in hen-house litter. Malathion disappeared within 4 h of application. Carbofenthion was the most persistent. Four weeks after treatment the proportions of the applied doses extracted from the litter were: carbofenthion 46%, phorate 21%, diazinon 13%, coumaphos 7% and fenitrothion 3%.     

Interactions of carotenoids with some organophosphorus insecticides

The interactions of some organophosphorus insecticides (OPI) with carotenoids from oranges were studied in vitro. In the initial step, 5,6-epoxy (di-epoxy) xanthophylls are isomerised to 5,8-furano (di-furano) xanthophylls. This reaction can also be brought about by hydrogen ions. Degradation products of OPI or impurities present in commercial samples may be acidic. Subsequent reactions lead to complete loss of the long wavelength chromophore.     

高效液相色谱法测定糙米和土壤中6种杀虫剂的残留

建立了糙米和土壤中氟啶虫酰胺、氯虫苯甲酰胺、甲氧虫酰肼、氟虫双酰胺、虫螨腈和虱螨脲6种杀虫剂残留的高效液相色谱检测方法。样品用乙腈浸泡过夜后振荡提取,其中糙米过氨基小柱净化,土壤无需净化;采用高效液相色谱仪,以甲醇-乙腈-水为流动相,利用C18柱和二极管阵列检测器(检测波长:265、254、230 nm)对待测组分进行分离和测定。结果表明,在0.05~5 mg/L范围内,标准品质量浓度与峰面积之间呈良好的线性关系(R2=0.999 4~1)。在0.1、0.5和1 mg/kg 3个添加水平下,糙米和土壤中氟啶虫酰胺、氯虫苯甲酰胺、甲氧虫酰肼、氟虫双酰胺、虫螨腈和虱螨脲的平均回收率在84.5%~113.2%之间,相对标准偏差(RSD)≤9.3%;供试6种农药在样品中的检出限(LOD)为0.010~0.016 mg/kg,定量限(LOQ)为0.03~0.05 mg/kg。所建 立的方法具有准确、快速、简便、重复性好等特点,其准确度和精密度均能满足农药残留分析的要求。     

斑蝥素与几种杀虫剂混配的增效作用

在前期工作中,初步发现斑蝥素具有杀虫活性,同时发现其具有增效作用。为进一步探索斑蝥素与杀虫剂的混配增效效果,筛选具有增效作用的组合物,采用浸叶法在室内条件下测定了1．0%斑蝥素乳油与5种杀虫剂单剂及其混配制剂对小菜蛾Plutella xylostella(L．)的毒力,筛选出了药剂间的较佳配比,评价了各配方的增效作用。研究结果表明,斑蝥素与阿维菌素混配,协同毒力指数测定值为-1．75,表现为相加作用;斑蝥素与硫丹、氟啶脲、杀虫双和灭多威等4种杀虫剂分别以LC_(50)剂量比为1:1、2:3、3:7和4:1比例混配,其共毒系数分别为408．11、718．97、216．39和414．64,CTC测定值均显著大于100,表明斑蝥素与这4种供试药剂混配均具有不同的增效作用,其中与氟啶脲混配增效比值最大,增效效果最为显著。     

Residues of organochlorine pesticides in broilers from feed fortified with known levels of these compounds

p, p'-DDT, HEOD, endrin, heptachlor epoxide, hexachlorobenzene and lindane were fed in combination to day-old broiler chickens at levels of 0.05, 0.15 and 0.30 part/million in the feed, for a period of about 7 weeks. Birds were killed at regular intervals and samples of abdominal fat and other tissues examined for residues of the chlorinated pesticides by gas-liquid chromatography. The lipid content of each sample was determined and the residue levels calculated for the whole tissue and also for the fat contained in the sample. At the end of the 7 weeks (when in practice broilers are slaughtered) residues were highest for heptachlor epoxide, followed by hexachlorobenzene, HEOD, DDT (total), endrin, and lindane. Heptachlor epoxide residue levels in fat were 13 times the levels in the feed, for lindane the ratio was 3.3. Fat residues of each pesticide reached a plateau level relatively quickly, and these levels were proportional to the fortification rates in the feed. HEOD and p, p'-DDT alone were fed to separate groups of birds. No differences in residue build-up of these compounds were found between these groups and the groups that had received these compounds in combination with the other pesticides. The total amounts of each pesticide in the tissues were reduced when the meat was fried, probably by loss of fat during preparation and frying. For p, p'-DDT and heptachlor epoxide also smaller residue were observed in the remaining fat after frying.     

The mobility of some organophosphorus sheep dip insecticides in soil

The technique of soil thin-layer chromatography has been adapted to permit the use of repeated or prolonged irrigation procedures so that the mobility characteristics of relatively non-mobile insecticides may be studied. The procedure has been used to study the relative movement of organophosphorus insecticides such as chlorfenvinphos, trithion, delnav and dichlofenthion which are widely used as sheep dips.     

Transfer of insecticide residues to food stored on or near plywood impregnated with organochlorine insecticides

Formulations of aldrin and dieldrin have been used for a number of years to treat exposed timber components used in the construction of freight containers. The extent to which these insecticides migrate to foodstuffs stored on or near treated plywood has been examined under laboratory conditions and is reported here. A limited survey of organochlorine insecticide residues in samples of foodstuffs, taken from commercial loads carried in freight containers, indicated that residue levels are unlikely to present a health hazard.     

Observations on some nematodes parasitic in freshwater fishes in Laos

In 1989, samples of some freshwater fishes collected in Vientiane Province (R. Mekong basin) in Laos were examined for helminths. This material comprised 11 species of parasitic nematodes (7 adults and 4 larvae), including 3 species new to science: Camallanus (Camallanus) hampalae sp. n. from Hampala macrolepidota, Procamallanus (Punctocamallanus) punctatus sp. n. from Mystus rhegma and Mystus sp., and Rhabdochona (Globochona) equispiculata sp. n. from Hampala macrolepidota and H. dispar. Zeylanema Yeh, 1960 is considered a subgenus of the genus Camallanus, Dentocamallanus subgen. n. (type species C. (D.) sweeti (Moorthy, 1937)) is proposed for the species of Paracamallanus with teeth in the buccal capsule, and Punctocamallanus subgen. n. (type species P. (P.) punctatus sp. n.) for the species of Procamallanus with the buccal capsule ornamented with punctations. The name Rhabdochona wangi nom. nov. is proposed for R. bagarii Wang et Guo, 1983 (a homonym to R. bagarii Gupta et Srivastava, 1982) and Camallanus gomtii Gupta et Verma, 1978 is newly synonymized with Neocamallanus ophiocephali (Pearse, 1933). All the nematodes are recorded from Laos for the first time. The parasites are briefly described and illustrated and some problems concerning their taxonomy and geographical distribution are discussed.     

Effect of some biorational insecticides on Spodoptera eridania in organic cabbage

BACKGROUND: To reduce pest attack, several biorational products are allowed for use on organic vegetables in Brazil. This study investigated eight biorational products applied singly or in combination against Spodoptera eridania Cramer in field plots of cabbage intercropped with coriander. The treatments were applied once a week over a 5 week period, beginning 34 days after transplanting. The evaluations consisted of counting the larvae of S. eridania on the day before and 7 and 21 days after spraying. The damage to leaves and cabbage head, the commercial weight of head and the percentage of head losses were evaluated.RESULTS: Leaf injury in plots treated with Beauveria bassiana and neem oil (Dalneem) yielded scores of 1.3 and 2.5 (scale ranging from 0 to 4) respectively, in comparison with a score of 3.6 from untreated plots. Head weight losses were 6.1, 5.3 and 4.9% with an aqueous extract of neem leaves, neem oil and B. bassiana respectively, compared with 24.6% lost from untreated plots.CONCLUSION: Dalneem, B. bassiana and the extract of neem leaves at 20% exhibited the best performance for control of S. eridania.