勒克瑙根结线虫居群对我国亚热带丝瓜的危害

通过田间对感根结虫病的丝瓜植株取样调查发现 ,勒克瑙根结线虫居群对中国亚热带地区丝瓜生产危害较大 ,受害面积占调查面积的30% ,减产25%以上。研究发现勒克瑙根结线虫居群危害丝瓜的原因是丝瓜属于勒克瑙根结线虫的寄生植物 ;防治勒克瑙根结线虫居群危害最有效、最经济的方法是利用勒克瑙根结线虫属专性植物寄生线虫的生物学特性 ,实行蔬菜品种轮作。     

水稻病虫为害损失试验初报

本文探讨了测算水稻病虫为害总损失、虫害损失、病害损失、挽回损失和实际损失等五组数据的田间试验设计和方法，并以此来评估水稻病虫为害损失情况，同时分析造成为害损失的病虫主次。     

模拟螟害对水稻产量影响的研究

设置了模拟螟害、氮肥和基本苗三因索随机区组试验。结果表明各因素对产量及其构成因素的影响都极显著。水稻9—15叶期,分别损失分蘖8%、20%、20%、4%、4%、1%、1%以上亩穗才显著减少,分别损失分蘖8%、20%、20%、12%、8%、4%、1%以上才显著减产。随着损失叶期和损失度增大,亩穗渐减,着粒数、实粒数和千粒重不同程度增加。12—14叶期,1%—2%的损失产量反而略提高。讨论了氮肥和基本苗对产量及其构成因素的影响,认为每亩(666.7m~2)施5kg 纯氮的氮肥、移栽3.428万棵苗/亩有利于高产。     

应用模糊聚类评价布氏田鼠为害等级

由于各地环境条件和布氏田鼠密度与种群分布格局的差异,其为害程度很难用统一的数量化指标加以评价,造成了准确测报该鼠为害水平的困难。本文试采用模糊聚类的方法,结合该鼠数量、分布格局以及多项环境因子的定性、定量指标加以综合分析,依其聚类结果可进行该鼠为害等级的全面评价,根据作者收集的20组数据的微机处理,表明这种方法可进行大区域不同环境条件下的为害等级评价,具有良好的应用前景。     

小地老虎为害棉苗缺株产量损失及棉株群体补偿力模拟试验

研究结果明确了模拟棉苗受小地老虎为害造成断苗缺株后，周围棉株有不同程度的补偿作用，主要表现在有效铃的增加和产量的提高，缺１株苗成铃能获得１０１．８５％的补偿，籽棉平均补偿率达８７．２４％，损失率为１２．７６％。但自连续缺２株以上，则补偿率下降为５０．６２％－３５．７５％，损失率上升为４９．３７％－６４．２４％。补偿量和损失量（率）是随缺株数的增加而增长，而补偿率则随缺株数增加而下降，在不同缺株数间     

Cardiac troponins in canine babesiosis

This study compared the sensitivity of ECG and cardiac troponins to predict cardiac histopathological changes, clinical severity, and survival in canine babesiosis. One control group (n = 9) and 4 groups of dogs with mild uncomplicated babesiosis (n = 8), severe uncomplicated babesiosis (n = 9), complicated babesiosis (n = 8), and babesiosis and concurrent immune-mediated hemolytic anemia (IMHA) (n = 9) were studied. A 1-minute lead II ECG was recorded, and cardiac troponin I (cTnI) and T (cTnT) concentrations in plasma were measured. cTnI concentrations were significantly higher in the complicated (mean, 9.9; SE, +/-5.76) and concurrent IMHA (mean, 6.53; SE, +/-4.32) groups and in the 3 dogs that died of the disease (mean, 22.17; SE, +/-12.85) than in the control dogs (concentration below detection limit of test, -0.3 ng/mL). The 3 nonsurvivors had the most severe cardiac histopathological changes, but no arrhythmia and minimal other ECG changes. Dogs with babesiosis developed a variety of ECG abnormalities, but the abnormalities were not associated with disease severity, outcome, or plasma cardiac troponin concentrations. The exception was the presence of ventricular premature complexes (VPCs), which were associated with high cardiac troponin concentrations. This study showed an association between cTnI concentration and histological changes, clinical severity, and survival and no correlation between ECG abnormalities and histological changes or biochemical evidence of myocardial damage as reflected by cTnI concentrations. From this study, it was concluded that the analysis of plasma cTnI is a feasible and sensitive test and is superior to cTnT in diagnosing cardiac involvement in dogs with babesiosis.     

Persistence and performance of esfenvalerate residues on broccoli

The efficacy of esfenvalerate (84 g litre-1 EC; Asana XL) at 7.0 g AI ha-1 on broccoli was tested against the flea beetle, Phyllotreta cruciferae Goeze (Chrysomelidae: Coleoptera) and the imported cabbage worm, Pieris rapae L (Pieridae: Lepidoptera) under field conditions. Insect populations were monitored before and after treatment. Periodic sweep-net collections and examination of the leaves in treated and untreated broccoli plots revealed mean reductions of P cruciferae levels of nearly 98% 1 week post-application compared with untreated plots. The residual toxicity of esfenvalerate was also effective for 2 weeks in reducing population density of P rapae by 69% on broccoli leaves. The impact of esfenvalerate on feeding damage to broccoli leaves was established by counting the number of feeding holes made by P cruciferae on spring broccoli and P rapae on fall broccoli. As the leaf area ingested increased, a linear relationship was seen between the number of holes and number of insects. Results indicated that forage destruction by the two pests was significantly reduced by esfenvalerate application. Esfenvalerate was extracted from broccoli at 1 h and 1, 3, 7, 10, and 14 days post-application for residue analysis. Residues on spring broccoli were 12.2, 5.2 and 2.9 micrograms cm-2 on the leaves and 0.13, 0.05 and 0.02 microgram g-1 on the heads at 1 h, 1 and 3 days, respectively. Only trace levels (0.001 microgram g-1) were detected in/on the heads 14 days after spraying. On the basis of half-life (T1/2) values, persistence of esfenvalerate on spring broccoli leaves (T1/2 = 1 day) was shorter than on fall broccoli (T1/2 = 1.6 days). T1/2 values were 2.1 and 3.6 days on spring and fall broccoli heads, respectively. The implications of these residue levels on re-entry times into treated fields are discussed.     

丁酸梭菌对肠道上皮细胞黏附及对鳗弧菌抑制的研究

本试验以鱼肠道上皮细胞为模型,以肠道的致病鳗弧菌为对照,研究了丁酸梭菌对鱼肠道上皮细胞的黏附作用及黏附对细胞的损伤和成活率的影响。结果表明∶丁酸梭菌对鱼的肠道上皮的黏附率为7.39±1.85,低于鳗弧菌的黏附率(P<0.05);对细胞的损伤率为1.02±0.35,显著低于鳗弧菌对细胞的损伤率(P<0.05);黏附后丁酸梭菌组对细胞的成活率的影响与正常对照组比较,差异不显著;当酪酸菌、鳗弧菌与肠道上皮细胞共同培养时,使鳗弧菌的黏附率下降7.03%(P<0.05)。因此,该株丁酸梭菌可以安全地黏附鱼肠道上皮细胞,并能有效抑制鳗弧菌的黏附。     

F-2毒素致体外培养大鼠睾丸支持细胞DNA损伤

为探讨F-2毒素对雄性生殖机能的影响,取大鼠睾丸支持细胞进行体外培养,运用单细胞凝胶电泳技术检测51、0、20和40 mg/L的F-2毒素攻毒后24 h支持细胞DNA的损伤情况。结果显示,F-2毒素在一定浓度范围内对体外培养的支持细胞DNA产生损伤作用,且受损程度随着F-2毒素攻毒剂量而升高,具有明显量效关系。除5 mg/L剂量组外,其余各组的细胞受损率、彗星尾长和DNA损伤程度与阴性对照组相比差异极显著（P〈0.01）,表明F-2毒素对体外培养的大鼠睾丸支持细胞有毒性作用,能够损伤细胞DNA。     

西北地区沙尘暴的危害及对策

该文以大量的例证,详实的数据介绍了西北地区沙尘暴的危害,并综合分析了沙尘暴产生形成原因、危害方式,为保护生态环境提出了治沙防沙的基本对策。