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.     

狗牙根种质对冷害的生理反应

对采自佛山市的3个狗牙根材料(狗牙根1号,3号和5号)及杂交狗牙根品种天堂419的抗寒性进行了比较研究,发现田间种植的狗牙根材料在受到2004年12月的寒潮袭击后,相对电导率升高,其中天堂419的升高幅度最大,而狗牙根1号和5号的升高幅度较小;天堂419的光合速率降低最多,而狗牙根5号的光合速率仅轻微降低;叶片的可溶性糖含量均提高,狗牙根5号的根系可溶性糖含量升高,但其他材料的可溶性糖含量降低。在韶光地区霜冻条件下的试验结果表明,狗牙根5号的草坪质量评分最高,绿期最长,表明狗牙根5号的抗寒性较强。     

青藏高原江河源区退化草地人工改良措施对高原鼠兔种群动态影响

通过对江河源区退化草地采取建植人工和半人工草地的措施进行改良,以影响害鼠(高原鼠兔)种群,达到防治鼠害的目的。     

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。     

椰心叶甲在国内的危害与防治研究概况

本文介绍了椰心叶甲在国内的发生、危害、生物学及发生规律,并对椰心叶甲的防治技术作了简要综述。     

甜玉米田玉米螟发生危害及防治措施

甜玉米在我国大面积种植历史较短,对甜玉米田亚洲玉米螟发生危害和防治技术研究较少。本文对国内外甜玉米上玉米螟成虫产卵习性、幼虫危害和防治技术研究和应用现状进行了综述,为我国甜玉米田亚洲玉米螟的研究和防治提供参考。     

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。     

稻田中华稻蝗发生动态、危害损失及防治指标

系统地研究了中华稻蝗发生动态与危害损失。结果表明,中华稻蝗在浙江年发生1代,主要危害早稻和早播单季晚稻。水稻分蘖期接入虫量10～50头/m2,叶被害率为52.61%～78.81%,叶被害指数为14.51～25.00,产量损失率为2.31%～27.42%,孕穗至破口期接入虫量1～17头/m2,叶被害率为56.63%～88.00%,叶被害指数为14.69～31.32,产量损失率为1.28%～32.74%,随着虫口密度增加,危害程度上升,产量损失率加大,两者具有密切相关性,建立了危害损失关系式。水稻叶片受害、光合能力减弱、幼穗分化不良、实粒减少、秕谷增加和粒重下降是导致水稻减产的主要原因。模拟测试表明,随着水稻受害生育期推迟损失增大,且分蘖期危害具有一定的补偿能力。在现有生产条件下,经济允许损失水平为2.5%～3.0%;2～3龄蝗蝻为防治适期,氟虫腈、三唑磷等有较好防治效果。提出水稻分蘖期和孕穗至破口期防治指标分别为10头/m2和5头/m2。     

黄胸蓟马对香蕉的危害及其防治

１９９６～１９９７年在香蕉花期调查结果表明,黄胸蓟马在广州地区香蕉园中普遍存在,香蕉花感虫率达１００％,平均每花苞感虫８２．８头。感虫数与花苞着生高度有关,以高度１２０～１４０ｃｍ的花苞感虫数最高,以后随高度的增加剧减。黄胸蓟马只危害稍开和已开的第１至第４苞片内花段,且虫口数由外向里递减。园中杂草有助于蓟马对香蕉花的危害,平均每花苞虫口数多杂草蕉园比管理精细的无杂草园多３．６倍。室内药效试验结果表明,毒死蜱、乐果、丁基克百威和灭多威对黄胸蓟马有很好的毒杀效果,氯氰菊酯和顺式氯氰菊酯效果不理想。     

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。