Tolerance to the Nephrotoxic Component of Narthecium ossifragum in Sheep: The Effects of Repeated Oral Doses of Plant Extracts

Young adult sheep were dosed with extracts of Narthecium ossifragum plants by the oral or parenteral routes and the resulting nephrotoxicity was assessed from the increases in the concentrations of creatinine and urea in the serum. Following single intraruminal or intraperitoneal doses of extracts derived from 30 g N. ossifragum (wet weight) per kg live weight (kg lw), serum creatinine concentrations increased from about 100 mol/L to between 260 and 510 mol/L. The serum urea concentrations increased from about 5–8 mmol/L to between 11 and 66 mmol/L in individual sheep. Daily intraruminal administration of 5–30 g/kg lw to three sheep over a 10- or 15-day period increased creatinine concentrations from 100 mol/L to 300–760 mol/L, and urea concentrations from 5–8 mmol/L to 35 mmol/L. A single intraperitoneal challenge dose of 30 g/kg lw, delivered 7 or 12 days after the final intraruminal dose, did not lead to increased serum creatinine or urea concentrations, indicating that oral treatment had apparently resulted in an increased tolerance to the nephrotoxic principle(s) in N. ossifragum.     

The effect of the herbicide diuron on soil microbial activity

The inhibitory effect of the herbicide diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] on microbial activity in red Latosol soil was followed using microcalorimetry. The activity of the micro-organisms in 1.50 g of soil sample was stimulated by addition of 6.0 mg of glucose and 6.0 mg of ammonium sulfate under 35% controlled humidity at 298.15 (+/- 0.02) K. This activity was determined by power-time curves that were recorded for increasing amounts of diuron, varying from zero to 333.33 micrograms g-1 soil. An increase in the amount of diuron in soil caused a decrease of the original thermal effect, to reach a null value above 333.33 micrograms g-1 of herbicide. The power-time curve showed that the lag-phase period and peak time increased with added herbicide. The decrease of the thermal effect evolved by micro-organisms and the increase of the lag-phase period are associated with the death of microbial populations caused by diuron, which strongly affects soil microbial communities.     

新兽药喹烯酮亚慢性经口毒性研究

研究了新兽药喹烯酮对大鼠的亚慢性毒性作用.SD大鼠连续6个月经口染毒,剂量分别为32.8、164、820 mg/(kg bw·d),观察染毒期间大鼠一般情况、体重和进食量,于染毒第3和第6个月进行血常规和生化指标检测,取染毒第6个月大鼠的尿分析尿常规指标;染毒结束时处死全部实验动物,计算脏器系数,进行组织病理检查并分析喹烯酮对脏器的损害情况.研究结果表明,820 mg/(kg bw·d)剂量组雄、雌性动物分别有2、3只死亡,且动物的体重明显低于对照组,脑、肺、肝、脾等主要脏器的脏器系数及雄性动物总蛋白、白蛋白含量均显著高于对照组,病理组织学检查发现肝胆管增生;164 mg/(kg bw·d)剂量组雄性大鼠肝、脾、睾丸和雌性大鼠脑、心、肝脏的脏器系数显著高于对照组.因此,新兽药喹烯酮对大鼠的最大无作用剂量为32.8 mg/(kg bw·d).     

杀虫药剂对茄二十八星瓢虫及瓢虫柄腹姬小蜂的选择毒性

在室内测定了8种杀虫剂对茄二十八星瓢虫幼虫及其主要天敌瓢虫柄腹姬小蜂的毒力。结果 表明，阿维菌素对茄二十八星瓢虫和瓢虫柄腹姬小蜂具有较高的选择性，氰戊菊酯次之，而氟虫腈等则无选择性，建议在天敌较丰富的季节，优先选用阿维菌素防治茄二十八星瓢虫，氰戊菊酯可与阿维菌素交替使用。     

特谱唑防治小麦锈病毒理与应用技术的初步研究

据室内测定结果,特谱唑具有很强的内吸传导性能,用灌土法施药的效果可与叶面喷雾法相比拟,但基本上是向上传导。此药具有很强的治疗和铲除作用,在病菌潜育期施药,可控制到不发病,最多只显退绿斑;在退绿期施药,可使病菌夏孢子堆变成褐色小点,孢子粉极少,但对夏孢子的萌发影响则弱。此药剂比三唑酮毒力强,其毒力指数(三唑酮为100)都在900以上,即达到 EC_(50)和 EC_(95)所需的剂量,前者只需后者的11%以下,特别是保护作用突出。据田间试验结果,此药剂的用药量比三唑酮少,如控制条锈病为害所需的剂量只要三唑酮的三分之一。防治条锈病的用药量一般以45—47g/ha(有效成分)为合适;用药期以病叶率5%—10%、小麦处于旗叶伸长期为宜;施药次数以上述的合适剂量和适期喷施1次即可控制整个成株期条锈病为害,收到最佳的经济效益。     

对小菜蛾高毒的苏云金杆菌菌株筛选试验初报

从田间自然死亡的小菜蛾虫尸中分离到Ｂ．ｔ．９４１９茵株，经复壮选育及摇瓶考核，在自选培养基上生长良好，２４ｈ孢子开始脱落形成晶体，３６ｈ全部形成晶体。晶体大、宽棱形、角尖。４８ｈ发酵液含菌量为３５亿／ｍＬ。经发酵液对小菜蛾毒力测定，４８ｈＬＣ_５０：对照ＨＤ－１含菌量为２７４ｍＬ／Ｌ，而９４１９仅１２４ｍＬ／Ｌ。     

我国稻区稗草对丁草胺抗药性现状

１９９１－１９９３年，对我国三大栽培类型稻区内９个监测网点的稗草抗药水平发展动态进行了系统的追踪监测。结果显示：我国稗草对丁草胺已产生了明显的抗药性。以ＬＣ５０和ＬＣ９０作为标准，最高抗性系数分别由１９９１年的２．９０和２．７９，上升至１９９３年的５．４２和１１．０４。在丁草胺连续使用８年以上地区，抗性水平呈急剧上升之势。稗草对丁草胺的抗性水平与连续使用时间呈正相关，而与ａ－淀粉酶活性抑制率呈反相     

Metal chelate molluscicides: The redistribution of iron diazaalkanolates from the gut lumen of the slug,Deroceras reticulatum (Müller) (Pulmonata: Limacidae)

Two related iron chelates, one toxic to slugs by ingestion, the other not, were introduced into the foregut of D. reticulatum. The subsequent movement and redistribution of the metal within the slug tissues was studied by labelling the chelates with the radioactive isotope ⁵⁵Fe. In slugs which survived treatment approximately half of the ⁵⁵Fe was voided in faeces. The iron retained became unevenly distributed, the highest concentration occurring in the digestive gland, irrespective of the chelate used. At high doses, slugs treated with tris(1-oxo-1,2-diazabutan-2-oxido)Fe(III) were fatally poisoned while those treated with the homologue, tris(1-oxo-1,2-diazaoctan-2-oxido)Fe(III) were not. Slugs killed by the toxic chelate consistently contained proportionally less iron in the digestive gland and proportionally more in the body wall and reproductive system. Dosing slugs already killed by carbon dioxide asphyxiation gave a similar pattern, suggesting that the greater mobility of the iron from the toxic chelate was not a function of the slugs' metabolism.     

清塘净对鱼类等水生生物急性致毒的研究

清塘净对鱼类等水生生物毒性强，毒力降解速度较快，是好的清塘药物。对黄鳝等水生生物９６ｈ的ＬＣ５０及安全质量浓度分别为：黄鳝２．４１ｍｇ／Ｌ和０．２４１ｍｇ／Ｌ；鲤鱼苗０．３８ｍｇ／Ｌ和０．０３８ｍｇ／Ｌ；草鱼苗０．４１ｍｇ／Ｌ和０．０４１ｍｇ／Ｌ；大型蚤０．５２ｍｇ／Ｌ和０．０５２ｍｇ／Ｌ；湖螺２．３３ｍｇ／Ｌ和０．２３３ｍｇ／Ｌ；泥鳅３．０４ｍｇ／Ｌ和０．３０４ｍｇ／Ｌ。     

Contribution of contact toxicity and wheat condition to mortality of stored-product insects exposed to spinosad

Spinosad, a reduced-risk commercial insecticide derived from a bacterial fermentation product, possesses both contact and oral toxicities against insects. Contact toxicity of spinosad to adults of Rhyzopertha dominica (F), Sitophilus oryzae (L), and Tribolium castaneum (Herbst) was evaluated by exposure for 24 or 48 h to treated glass Petri dishes. Adults were exposed to different deposits (0.001-0.79 mg cm(-2)) of spinosad in 24-h tests and to deposits of 0, 0.0016 and 0.016mg cm(-2) in 48-h tests. Rhyzopertha dominica was most susceptible to spinosad in 24- and 48-h tests, followed by S. oryzae, and T. castaneum. The 24-h LD50 values were 0.0004, 0.077 and 0.189mg cm(-2) for R. dominica, S. oryzae, and T. castaneum, respectively. All R. dominica adults were dead following 48 h exposure to both spinosad deposits, whereas mortality of S. oryzae and T. castaneum ranged from 10 to 85% and 12 to 48%, respectively. Rhyzopertha dominica, T. castaneum, and O. surinamensis adults were exposed for 14 days to whole wheat, cracked wheat and wheat flour treated with 0, 0.1 and 1.0 mg kg(-1) of spinosad. Rhyzopertha dominica adults were highly susceptible to spinosad, followed by O. surinamensis and T. castaneum. Immatures (eggs and larvae) of T. castaneum and O. surinamensis exposed for 14 days were more susceptible on spinosad-treated whole wheat than on treated cracked wheat and wheat flour. This is the first report documenting contact activity of spinosad, and the effect of grain condition on spinosad toxicity, to stored-product insects.