四种稻田农药对克氏原螯虾的急性毒性研究

采用半静态方式水生生物急性毒性实验法,研究了在实验室常温条件下敌百虫、稻瘟灵、毒死蜱、阿维菌素四种稻田杀虫剂对克氏原螯虾（ Procambarus clarkii）的急性毒性。结果显示,敌百虫、稻瘟灵、毒死蜱、阿维菌素对体重为（34.43±7.04）g克氏原螯虾的24 h半致死浓度（24 h LC50）分别为65.07、42.16、0.71、1.23 mg/L,48 h半致死浓度（48 h LC50）分别为35.75、33.49、0.59、0.84 mg/L;96 h半致死浓度（96h LC50）分别为12.54、18.83、0.45、0.37 mg/L。其安全浓度分别为3.24、6.34、0.122、0.117 mg/L。根据国家标准和本实验数据可以看出,敌百虫和稻瘟灵对克氏原螯虾中毒,毒死蜱和阿维菌素对其高毒。     

Effect of high rates of zinc on several crops grown on an irrigated plainfield sand

Abstract

A field experiment was conducted to determine whether Zn applied for pathogen control could accumulate to a level which would be toxic to snapbeans, cucumbers, or corn. Zinc sulfate (ZnSO₄) was applied at rates varying from 0 to 363 kg Zn/ha on a Flainfield loamy sand to approximate 3, 9, 27 and 81 years of fungicidal treatment.

Even at the high rate of Zn, yields of snapbeans, cucumbers, or corn generally were not reduced. As rates of applied Zn increased, there was a corresponding increase in the level of Zn in the leaf tissue of all crops grown. At the high Zn rate, snapbean and cucumber leaf tissue accumulated over 350 ppm Zn. Available soil Zn was extracted with 0.1N HCl, EDTA, or DTPA. Highly significant correlations were observed between the Zn removed by each extractant and plant tissue Zn, thus, indicating that the various extractants were equally effective in predicting Zn uptake.

Very little downward movement of Zn was observed. Two and one‐half years after application, the Zn had leached to a depth of only 30 cm in the soil profile at the higher Zn rates.

These data indicate that application of Zn‐containing fungicides and bactericides should not cause a Zn toxicity problem on the Plainfield sand in the foreseeable future.     

Effects of Destruxin A on Hemocytes Morphology of Bombyx mori

Destruxin A (DA), a kind of cyclo-hexadepsipeptide isolated from entomopathogenic fungus, Metarhizium anisopliae, is an inhibitor of insect’s immunity. But its mechanism has not been clarified yet. In this study, the effects of DA on morphologic changes of in vivo and in vitro hemocytes of silkworm, Bombyx mori, were investigated by means of inverted phase contrast microscopy (IPCM), fluorescence microscopy (FCM) and environmental scanning electron microscopy (ESEM). The results indicated that DA was cytotoxic to granulohemocytes (GR) and plasmatocytes (PL). The LC 50 values of DA against in vitro GR and PL of silkworm were 68.77 and 84.11 μg mL-1, respectively. However, the hemocytes in vivo were more susceptible to DA, although at the extremely low dose of 10 μL of 12.5 μg mL-1 for each insect (i.e., 0.036 μg g-1 body weight, or approximately 0.25 μg mL-1 hemolymph), DA could induce obviously morphologic alterations of hemocytes in vivo. The results imply that there might be some factors in silkworm’s hemolymph, which influence the interaction of DA and hemocytes.     

汞毒性对草木樨（Melilotus officinalis）幼苗基因型的差异性抑制研究

采用水平淀粉凝胶电泳技术对草木樨（Melilotus officinalis）的磷酸葡萄糖异构酶（Pgi）和苹果酸酶（Me）进行了基因频率分析。所研究的草木樨种群具有较高的多态性（A=3.0,Ho=0.346～0.401）,将草木樨种子暴露于HgCl2溶液（30mg·L-1）,萌发后测量各幼苗的上、下胚轴长度以及测定其基因型,判定各基因型与上、下胚轴长度的关系。ANOVA分析表明,对照组中Me-AA基因型幼苗具有下胚轴生长优势,Me-AA基因型个体的下胚轴长度（35.20mm±4.63mm）显著大于以下各基因型个体的下胚轴长度：Me-AB（22.84mm±1.34mm）,Me-BB（22.82mm±0.68mm）和Me-BC（20.00mm±1.21mm）。HgCl2急性暴露对Me各基因型下胚轴的抑制作用呈现均一性。在Pgi基因座,草木樨对照组中各基因型的生长不存在差异,但在HgCl2急性暴露下,Pgi-AC基因型幼苗的下胚轴长度（19.75mm±0.73mm）显著大于Pgi-BB基因型的下胚轴长度（14.67mm±1.04mm）,表明Pgi-AC基因型个体对HgCl2的耐受性更强。等位酶分析技术可用来确定植物的种群遗传结构对生长或重金属的耐受性关系，这种关系的确立对遗传育种、生态修复具有潜在的应用价值。     

15种杀虫杀螨剂对皮氏叶螨的毒力测定

采用玻片浸渍法，对15种杀虫杀螨剂对香蕉皮氏叶螨的室内毒力进行了测定。结果表明：供试药剂中以阿维菌素对皮氏叶螨的雌成螨的毒力为最高，LC50为0.005 5 mg/L，其次为鱼藤酮，LC50为0.017 3 mg/L，毒力最低的为吡虫啉，LC50为113.101 4 mg/L；15种供试药剂对皮氏叶螨的毒力大小顺序依次为：阿维菌素＞鱼藤酮＞唑螨酯＞哒螨灵＞毒死蜱＞辛硫磷＞高氯苯＞联苯菊酯＞功夫＞螺螨酯＞甲氰菊酯＞丙溴磷＞敌敌畏＞炔螨特＞吡虫啉。     

几种杀螨剂对3种叶螨的毒力比较

作者于 1 996年对二斑叶螨 (TetranychusurticaeKoch)、朱砂叶螨 [T .cinnabarinus(Boisdural) ]和山楂叶螨 (T .viennensisZacher)进行了三氯杀螨醇、甲氰菊酯、哒螨酮、霸螨灵等 4种杀螨剂的毒力测定 ,并对 3种叶螨在LC50 和LC95水平上 ,比较了相互之间的毒力差别。结果表明 ,二斑叶螨的毒力最高 ,朱砂叶螨次之 ,山楂叶螨毒力最低。     

七星瓢虫不同虫态对杀虫剂反应的研究初报

室内条件下对七星瓢虫(Coccinella septempunctata)卵、幼虫、蛹和成虫的触杀毒力测定结果表明,不同发育阶段的七星瓢虫对抗蚜威、伏杀磷和久效磷的反应一致;与对照药剂久效磷相比:①抗蚜威、伏杀磷处理七星瓢虫卵120小时的相对毒力指数分别为0.0483和0.3187;②抗蚜威和伏杀磷对七星瓢虫四龄幼虫24小时的相对毒力指数分别为0.1088和0.4056;③抗蚜威和伏杀磷处理蛹216小时的相对毒力指教分别为0.0540和0.5990;④抗蚜威和伏杀磷对瓢虫成虫24小时的相对毒力指数分别为0.1406和0.0623。可见,与常规使用的杀虫剂久效磷相比,抗蚜威和伏杀磷对七星瓢虫的各种虫态均具有高度选择性。     

苏云金杆菌D—1(血清型H3ab)新菌株的研究

D—1菌株系从自然死亡的灯蛾虫尸分离的一株苏云金杆菌新菌株。经菌种鉴定与Bt.var.kurstaki相同,属血清Ⅲ型。其培养特性表现为:对培养基成分和培养温度适应范围较小,在温度28-30℃,培养基含固量为4.1-6.7％,C/N为5.7-6.2时发酵正常。32℃以上和浓培养基则影响其正常繁殖。这与HD-1菌株相吻合。对菜青虫、棉铃虫、玉米螟和松毛虫等4种昆虫毒力测定结果表明,D—1菌兼有H_5型青虫菌81—6和H_3型HD-1的杀虫特性。它对菜青虫和松毛虫的毒力与81—6相接近而高出HD—12.7—5.1倍。对棉铃虫和玉米螟的毒力则明显高于81—6也比HD—1强。     

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.