几种楝科植物种核油对褐稻虱的拒食作用试验

某些楝科种核油对褐稻虱具有特殊的作用,它与常规的化学杀虫剂不同,并不直接杀死害虫,而是引起褐稻虱对使用种核油的水稻产生拒食或避忌,对褐稻虱重要天敌蜘蛛类并不伤害。     

青春双歧杆菌口嚼片生产中双歧杆菌存活因素初探

对生产双歧杆菌口嚼片过程中影响双歧杆菌存活的部分因素进行了研究,考察菌龄、干燥制剂的配料中辅应剂成分、水分含量等影响双歧杆菌稳定性的因素。结果表明,配料中一定比例的棕榈油、乙基纤维等疏水性填充剂具有保护与稳定双歧杆菌存活的作用,在双歧杆菌发酵液中,采用对数生长末期的细胞制备的干燥粉料中活菌数及其存活率都较高。产品水分含量以５％～６％、充氮包装、存放于低温环境更有利于提高存活率。     

FACTORS INVOLVED IN THE USE OF ORGANIC SOLVENTS AS PRECIPITATING AND DRYING AGENTS OF IMMUNE SERA

1. In concentrations of 70 to 75 per cent the organic solvents methyl, ethyl, and propyl alcohols, and acetone cause complete precipitation of serum proteins and produce maximum loss in solubility. We have referred to this concentration range as the critical concentration. 2. As the concentration of the solvents is increased from about 75 per cent precipitation continues complete but loss in solubility progressively decreases until at all concentrations above about 87 per cent the precipitates formed at room temperature are completely soluble. 3. The degree of resolubility of the precipitates formed even in these high concentrations of the organic solvent decreases as the temperature is raised and as the duration of exposure is increased. 4. At 5°C. the precipitates formed in all concentrations of these organic solvents are completely resoluble. Also these solvents exert maximum precipitating effect at lower temperature. 5. Maximum precipitating effect by these organic solvents occurs at about pH 6.0 precipitation becoming progressively less as the pH value is altered either way from this point. 6. The more concentrated the serum, the greater the proportion of protein present that will be precipitated by any given concentrations of organic solvent. 7. A method for preparing dry immune sera has been given. Such dried sera have been extracted with a number of organic compounds without loss in solubility or antibody activity.     

几种新杀虫剂的杀卵活性

就杀灭菊酯、三唑磷及喹硫磷三种新杀虫剂对粘虫、二化螟、玉米螟、菜粉蝶、棉铃虫、黑尾叶蝉、异色瓢虫及棉红蜘蛛8种节肢动物的卵,进行了室内杀卵活性试验。 三唑磷及喹硫磷对5种鳞翅目昆虫具有强大的杀卵活性,杀灭菊酯较差。三唑磷对水稻黑尾叶蝉及棉红蜘蛛的杀卵活性较喹硫磷强,杀灭菊酯几乎无效。杀灭菊酯对捕食性天敌——异色瓢虫的卵,显较三唑磷及喹硫磷安全,后二者则是毁灭性的。 杀灭菊酯对黑尾叶蝉的杀卵活性因卵的不同发育期而异,发育后期的卵对药剂的敏感性较强。 对粘虫卵的温度试验表明,杀灭菊酯不是一个负温度系数杀虫剂。     

杀虫剂混用方法——抗性治理的一种策略

本文根据种群遗传学的基本原理,采用计算机数值模拟的方法定量比较了合理混用、轮用、棋盘式使用等用药策略对害虫抗性增长的影响.结果表明,对半显性遗传,两性繁殖的害虫来说,在较有利的条件下合理混用与轮用效果基本一致,而优于棋盘式用药;在条件不利(抗性基因初始频率高,稀释作用小等)时,合理混用的方法明显优于其他两种方法.因此合理混用是一种有希望的抗性治理方法.     

ESSENTIAL OILS AS TAXONOMIC AIDS IN THE CLASSIFICATION OF DICHANTHIUM PARVIFLORUM

Essential oil components and gross morphological characters are closely correlated in Dichanthium parviflorum (R. Br.) de Wet et Harlan (Gramineae) and related species. Different species, varieties, and geographical races, as well as hybrids between them, can be identified on the basis of absence or presence and quantity of essential oil components. The morphologically variable D. parviflorum was subdivided into four varieties: var. parviflorum, var. capilliflorum (Steud.) de Wet et Harlan comb. nov., var. mutispiculum (Ohwi) de Wet et Harlan comb. nov., and var. spicigerum (S. T. Blake) de Wet et Harlan comb. nov. These varieties differ from each other morphologically in having respectively racemes with 1-4 and awned, 3-5 and awned, 1-2 and awnlass, and 4-10 and awned spikelet pairs per raceme.     

稀浓度化学药剂对马尾松毛虫越冬幼虫的毒效试验

1959—1960年作者等在江西、湖南等地区配合大面积防治森林害虫之际,开展了DDT等化学药剂对于不同越冬时期的马尾松毛虫幼虫的毒效试验。据野外观察结果,将马尾松毛虫越冬幼虫划分为5个时期。即越冬前活动期、越冬前期、越冬期、越冬后期、越冬后活动期。试验证明:不同化学药剂对越冬松毛虫幼虫的毒效随着不同时期和温度条件而变化。就一般论:DDT的效果,在比较低温(日均温10—20℃)时特别显著;666及敌百虫的效果,在比较高温时(20℃以上)为显著。其中尤以敌百虫为更甚。DDT对不同时期幼虫的毒效大小为:越冬后期>越冬前期>越冬期>越冬前活动期>越冬后活动期≥夏季(4-5龄)幼虫;其中以越冬后期幼虫抵抗力最弱。从原则上论这是施药的最适宜时期,从25% DDT乳剂4,000倍稀释液在越冬后期(2,3月间)施用,毒效可达92%以上,用6,000倍稀释液亦达82%以上。如用γ6%可湿性666,800倍稀释液在越冬前、后期使用,毒效可达70-80%以上。50%敌百虫乳剂在温度20℃以上时(越冬前、后活动期)毒效显著增高。此时如用5,000-6,000倍稀释液喷洒,毒效可达70-80%左右。由此,作者认为:在长江以北,每年发生2代以下的松毛虫地区,可用DDT和666稀释液在越冬前、后期进行防治。长江以南,每年发生2代以上的马尾松毛虫地区,不但可用DDT、666来防治越冬前、后期幼虫;而且在幼树林地内越冬期的幼虫亦可防治。在上述地区内,敌百虫乳剂仅适于在越冬前、后活动期或夏季幼虫期温度较高时使用。就一般论,在越冬前期施用药剂时,如能选定在寒流侵袭之前喷射,效果更为显著。