超级稻病虫发生特点及其药剂防治技术

超级稻从孕穗末至齐穗期如遇上连续阴雨天,稻曲病大发生,纹枯病发生较普遍;二化螟、稻飞虱发生量大,危害较重。在超级稻大田生长期,抓住施药适期,选用高效、内吸、广谱、环保型农药,进行3～4次防治,可有效防控病虫危害,达到节本增效、减少农药污染的目的。     

重庆地区柑桔衰退病毒多态性研究

柑桔衰退病毒(CTV)存在着复杂的株系分化现象.在使用弱毒株交叉保护防治柑桔衰退病时需要对田间病毒株系组成进行分析,并对选用的株系进行单蚜分离纯化.作者运用限制性片段长度多态性和单链构象多态性对田间获得的168个CTV样品和2个蚜传毒株的外壳蛋白基因进行分析,了解重庆市田间CTV组群构成情况,发现田间CTV以多株系混合发生为主,其中主要是CP/HinfⅠRFLP第1、3和6组群,约占总数的90%,并以强毒株混合感染为主.甜橙中CP/HinfⅠRFLP的组群构成最为复杂.单头褐色桔蚜从柚类至甜橙传播CTV的效率低(不足1%),该蚜的取食可改变CTV的株系组成.     

Evaluation of cinnamamide as an avian repellent: Determination of a dose—response curve

The dose-response curve was quantified for the avian repellency of cinnamamide, a derivative of the plant secondary compound cinnamic acid, using a three-day, ‘short-term no-choice’ test. This test was designed to resemble more closely the availability of alternative food in the birds' natural environment than in previous no-choice studies. Cinnamamide reduced food consumption by feral pigeons (Columba livia Gmelin) at concentrations as low as 6.17 μmole g^?1 food (0.09% w/w) and this reduction increased with concentration. An R₅₀ index, the concentration at which food consumption was reduced by 50% was interpolated from the dose-response curve as 18.4 (±0.38) μmole g^?1 food 10.26% w/w). This index can now be matched with those of related compounds in future structure-activity studies. The birds' response to cinnamamide changed over the three-day trial with respect to concentration. Repellency declined at concentrations < R₅₀ and increased at concentrations > R₅₀. This suggests that pigeons become habituated to cinnamamide at low concentrations but at high concentrations they may develop a conditioned aversion. This study provides quantitative confirmation of previous laboratory and field demonstrations of cinnamamide's effectiveness as a non-lethal chemical repellent suitable for reducing avian pest damage.     

武昌郊区蔬菜害虫(鳞翅目)寄生六索线虫的生物学特性

武昌郊区蔬菜种植地的六索线虫其含胚卵和Ⅱ期幼虫在土壤中全年均可存在,故在害虫发生季节,就有自然感染现象发生的可能;由于受降水量和气温的影响,一年中只出现春、秋两个感染高峰期,在最适条件下,六索线虫一年可完成两个世代;六索线虫的Ⅳ期幼虫、成虫、含胚卵和Ⅲ期幼虫均可越冬,且越冬的含胚卵和Ⅱ期幼虫是春季感染的主要线虫虫源.不合理地使用农药和不适时地更换茬口是影响六索线虫资源保护和利用的主要人为因子;伏秋干旱季节,采用畦间沟灌法抗旱,可提高自然感染率并使六索线虫资源得以充分利用.     

甘蓝型低芥酸油菜单株产量基因效应的研究

用5×5半双列杂交研究甘蓝型低芥酸油菜单株产量的遗传,结果表明:供试的甘蓝型低芥酸油菜品系中,单株产量的遗传符合加性显性模型,显性性质为超显性,平均显性度为1.404。显性基因约为隐性基因的3倍多,并且多数增效基因表现显性,但也有显性的减效基因存在。单株产量的广义遗传力h_B~2=71.4％,狭义遗传力h_N~2=33.18％。供试亲本显性效应的强弱依次为81007>81006>81018>81004>81033,增效基因的多少依次为81018>81006>81007>81004>81033。一般配合力的大小依次为81018>81006>81004>81033>81007。     

杂交肉牛不同年龄,营养水平的肥育效果研究

利用利木赞与本地牛杂交一代7～8月龄公犊12头，10～11月龄公牛12头，供给日增重0．9千克，1．2千克和1．5千克营养水平的日粮，经120天肥育，结果表明：7～8月龄和10～11月龄高营养水平组平均日增重分别为1．274±0．06千克和1．340±0．15千克；7～8月龄组对不同营养水平敏感，各组间差异极显著（P＜0．01）；产肉性能以高营养水平组最好，屠宰率62．4％，净肉率52．98％，眼肌面积91平方厘米。     

Rabies Antibodies in Vaccinated Dogs

Forty-seven healthy, owned dogs were vaccinated with Madivak and 85 with Rabisin. Geometric mean titres of 17.40 and 1.03 IU/ml were measured by the rapid immunofluorescent focus inhibition test 30–40 and 350–370 days, respectively, after a single injection. Four out of 130 (3.1%) and 18 out of 106 (17% ) dogs had a titre of less than 0.5 IU/ml in serum 30–40 and 350–370 days after vaccination. Twenty-one dogs (19.8%) had a titre of 0.5 IU/ml 350–370 days after vaccinaton. There was no significant difference in antibody levels between animals vaccinated with Rabisin or Madivak. Our results indicate that a booster is always necessary after a single injection to ensure that all dogs have a lasting antibody titre.     

湘黄猪杂交配合力测定

为了给湘黄猪的深化选育及开发推广提供依据,采用非完全双列杂交配合力测定模型,对湘黄、大约克、长白和湘白等4个猪种进行配合力测定.结果表明,繁殖性状以湘白猪为优,其一般配合力:产仔数0.53头,产活仔数0.84头,21日龄育成仔数0.85头,窝重2.74kg;生长肥育和胴体肉质性状以湘黄猪为优,其一般配合力:日增重49.44g,料重比-0.07,后腿率0.60%,均膘厚-0.05cm,眼肌面积0.89cm2,瘦肉率1.50%,失水率-0.31%.在组合效应上,繁殖性状以黄×长为强,其特殊配合力:产活仔数0.25头,21日龄育成数0.32头,21日龄窝重0.61kg;生长肥育性状以黄×湘为强,其特殊配合力:日增重25.69g;胴体性状以黄×大为强,其特殊配合力:膘厚-0.03cm,瘦肉率0.22%.这既反映了湘黄猪、湘白猪分别作为瘦肉型猪父系、母系猪种较强优势的一般配合力,也体现出湘黄猪与长白、大约克和湘白等猪种在多项重要经济性状上所具有的较强的特殊配合力.     

Comparison of antibody values in sera of pigs vaccinated with a subunit or an attenuated vaccine against classical swine fever

Ten pigs, aged 85 days, were vaccinated with a subunit vaccine containing 32 g of classical swine fever virus glycoprotein E2 (gp E2) (group 1), and a further 10 pigs were vaccinated with a C strain vaccine (10^4±0.15 TCID₅₀/ml), produced by amplification in minipig kidney (MPK) cell culture (group 2). Nine non-vaccinated pigs served as a control group (group 3). Serum samples were collected before (day 0) and at 4, 10, 21 and 28 days after vaccination and were analysed by two commercially available enzyme immunoassays and by a neutralizing peroxidase-linked assay (NPLA). At the same times, peripheral blood was taken for determining the total leukocyte count and the body temperature was taken daily. Antibodies were not detected in serum samples collected before vaccination (day 0), and no side-effects that could be connected with vaccination were observed during the trial. Ten days after vaccination 6/10 pigs vaccinated with the subunit vaccine were seropositive. On days 21 and 28, the ratios of serologically positive to vaccinated pigs were 9/10 and 10/10, respectively. Four of the ten pigs that were vaccinated with the C strain vaccine were positive on day 21 and 9/10 on day 28. However, the results of the NPLA showed that only 4/10 pigs had an antibody titre >1:32 at the end of the trial in both the vaccinated groups, even though the subunit vaccine initiated an earlier and higher level of neutralizing antibodies than the vaccine produced from the C strain. Challenge was performed 28 days after vaccination on four randomly selected pigs from both vaccinated groups. The pigs survived the challenge without showing any clinical signs of classical swine fever (CSF), while two nonvaccinated control pigs died on the 10th and 12th days after infection.     

Protective Effects Against Erwinia amylovora Induced by hrp Mutants in the Whole Plant are Only Partially Mimicked in Cultivated Cells

A virulent strain of Erwinia amylovora, the causal agent of fire blight of Maloideae, and two of its non-virulent hrp mutants (a secretory and a regulatory mutant) were inoculated into apple cell suspensions either alone or in mixed inoculations. In single inoculations, death of 4- to 5-day-old apple cells occurred only when the concentration of the virulent strain of E. amylovora reached a threshold inoculum concentration of 10⁴CFUml^–1, while high concentrations of the hrp mutants were unable to kill apple cells. When mixed inoculated with the virulent parental strain, both hrp mutants protected apple cells from death caused by the virulent strain. The protective effect was associated with a decrease in the population level of the virulent strain and it was dependent on the non-virulent to virulent inoculum concentration suggesting a competition between the non-virulent mutant and the virulent strain. However, no differential protective ability between the two types of mutants could be noticed, contrary to previous results obtained with apple seedlings or apple flowers in which the regulatory mutant was significantly more effective than the secretory mutant. In conclusion, inoculation of apple cell cultures with E. amylovora does not seem to be a model suitable for investigating mechanisms leading to protection.