甘蓝夜蛾高毒力Bt菌株的筛选

东北农业大学昆虫教研室从黑龙江地区病死鳞翅目昆虫体内分离出苏云金杆菌（Bacillusthuringiensis,Bt）菌株74株,随后以甘蓝夜蛾为供试昆虫对这些菌株的毒力进行了测定,结果表明,很多菌株对甘蓝夜蛾的初孵幼虫均具有一定的毒力,经过初筛、复筛,试验选出了毒力相对较高的5个菌株,当菌液浓度在8×10~7个芽孢·mL(－1)时,甘蓝夜饿死亡率分别达到80％～95％,Lc50分别为43,63,68,710,1778倍液。     

芸薹根肿菌SSR标记的开发及遗传多样性研究

芸薹根肿菌（Plasmodiophora brassicae）专性寄生于十字花科作物根部引起根肿病,且变异迅速。本研究利用Williams鉴别寄主系统鉴定出32株根肿菌,根据根肿菌基因组序列分析了根肿菌基因组中的简单重复序列（Simple sequence repeats,SSR）的分布特性,并结合SSR标记的开发研究了根肿菌遗传多样性。主要结果如下：从收集自8个省市31个地区的32株根肿菌中,鉴定出2、4、7和11号生理小种;根肿菌基因组存在3 164个SSR,即每7.6 kb存在1个SSR。核苷酸重复类型以2和3为主,分布频率分别为45.92％和53.04％。从62对SSR引物中,筛选出31个多态性标记,多态率50％,平均PIC值为0.407;聚类分析表明,同一地区的根肿菌大多聚类到一起,但同时存在变异。     

十字花科根肿病菌(Plasmodiophora brassicae)致病力分化研究方法

目前国际上已有Williams、ECD、Somé和Kuginuki 4套鉴别系统用于十字花科作物根肿病菌(Plasmo-diophora brassicae Woron)生理小种和致病型的鉴定。其中Williams和ECD鉴别系统被广泛应用,但还存在一些不足。Somé和Kuginuki分别根据法国和日本的病原菌致病力分化特点,在Williams和ECD鉴别系统的基础上,建立Somé和Kuginuki两个鉴别系统。根肿病菌的单孢子分离是生理小种或致病型鉴定中的研究难点,目前主要采用琼脂法和液滴法。不同研究人员使用的病害鉴定方法及分级标准不同,目前主要采用蘸根法、点滴法和菌土法。     

油菜根肿病对油菜光合作用及酶活性的影响

选取在大田中种植的苗期健康油菜和不同发病等级的油菜作为对象,通过测定它们的光合作用参数及根和叶中SOD、POD、CAT3种酶活性,探索油菜根肿病对油菜光合作用及酶活性的影响。结果表明：随着油菜发病等级的不断增大,净光合作用速率（Pn）不断降低,健康油菜的Pn最高、为53.08μmol/m2·s,发病等级为7级时油菜的Pn最低、为23.73μmol/m2·s;根和叶中SOD活性先降低后又升高,POD活性则先降低后升高再降低;发病油菜根中CAT活性都比健康油菜高。     

稻曲病气象风险评估及适宜度等级预测技术

为了弄清适宜稻曲病发生发展的气象条件以及对应的气象适宜度等级,提高水稻气象型病害防控能力,本文利用江苏省稻曲病大田调查资料,结合历史气象资料,通过评估发病敏感时段和致病风险,以及分析江苏省稻曲病最大成灾风险度出现日期以及空间分布情况,指出8月下旬为稻曲病高发期,对于发病风险高且程度重的沿淮、沿江以及江淮之间地区需要加强病害防御。在此基础上,综合考虑不同连续致病天数对稻曲病流行的影响,利用最优化技术,构建了综合稻曲病指数,并划分气象条件适宜度等级。通过单站和多站检验发现该指数对"中等、大流行"发病实况的判定准确率极高,但容易高估"轻度流行"的程度。     

Plasmodiophora brassicae resting spore dynamics in clubroot resistant canola (Brassica napus) cropping systems

The soilborne pathogen Plasmodiophora brassicae, causal agent of clubroot of canola (Brassica napus), is difficult to manage due to the longevity of its resting spores, ability to produce large amounts of inoculum, and the lack of effective fungicides. The cropping of clubroot resistant (CR) canola cultivars is one of the few effective strategies for clubroot management. This study evaluated the impact of the cultivation of CR canola on P. brassicae resting spore concentrations in commercial cropping systems in Alberta, Canada. Soil was sampled pre-seeding and post-harvest at multiple georeferenced locations within 17 P. brassicae-infested fields over periods of up to 4 years in length. Resting spore concentrations were measured by quantitative PCR analysis, with a subset of samples also evaluated in greenhouse bioassays with a susceptible host. The cultivation of CR canola in soil with quantifiable levels of P. brassicae DNA resulted in increased inoculum loads. There was a notable lag in the release of inoculum after harvest, and quantifiable P. brassicae inoculum peaked in the year following cultivation of CR canola. Rotations that included a ≥2-year break from P. brassicae hosts resulted in significant declines in soil resting spore concentrations. A strong positive relationship was found between the bioassays and qPCR-based estimates of soil infestation. Results suggest that CR canola should not be used to reduce soil inoculum loads, and crop rotations in P. brassicae infested fields should include breaks of at least 2 years away from B. napus, otherwise the risk of selecting for virulent pathotypes may increase.     

长春地区大菜粉蝶生物学特性观察

大菜粉蝶Pieris brassicae是十字花科蔬菜上的重要害虫之一。本文通过田间观察结合室内饲养,系统描述了该虫各发育阶段的形态特征,记录了发育历期、生活史及其生活习性。大菜粉蝶在长春地区1年发生3代,以蛹越冬。成虫多产卵于叶背面,每块卵10～207粒。幼虫5个龄期,群集为害,随着幼虫龄期的增长,头壳宽度与体长逐渐增加,各龄期头壳宽度和体长生长模型为：y_W=1.727e^0.557x(R²=0.998)和y_L=0.031x²+0.339x-0.013(R²=0.994)。取食白菜、油菜、甘蓝和萝卜4种寄主的幼虫发育历期存在显著差异,取食白菜发育最快,取食油菜的蛹最重,白菜和油菜更适宜其生长发育。本研究描述了大菜粉蝶各发育阶段的形态特征,明确了其主要生物学特性,为该害虫的识别监测和综合防控提供了理论基础。     

中间寄主对甘蓝夜蛾赤眼蜂寄生行为的影响

麦蛾卵和米蛾卵作繁蜂寄主对甘蓝夜蛾赤眼蜂G和F两个品系的寄生行为是有影响的。尽管两种卵均可作为甘蓝夜蛾赤眼蜂繁蜂寄主 ,但用米蛾卵繁殖甘蓝夜蛾赤眼蜂比用麦蛾卵繁蜂更好。甘蓝夜蛾赤眼蜂G和F品系在米蛾卵上的总寄生卵量分别为 75.90粒和 67.00粒 ,明显高于在麦蛾卵上的总寄生卵量。用麦蛾卵和米蛾卵作繁蜂寄主 ,将甘蓝夜蛾赤眼蜂G和F品系各 20头进行5d的逐日寄生试验 ,结果表明 :每日平均的寄生卵量、子代羽化率、子代发育历期以及子代性比均随寄生日期的推延而降低。     

Effects of cyazofamid against Plasmodiophora brassicae Woronin on Chinese cabbage

Cyazofamid (4-chloro-2-cyano-N,N-dimethyl-5-p-tolylimidazole-1-sulfonamide) is a novel fungicide with high levels of activity against Oomycetes fungi and Plasmodiophora brassicae Woronin. The effects of cyazofamid were investigated against P. brassicae, the causal agent of clubroot disease in Chinese cabbage. Cyazofamid at 0.3 mg litre(-1) inhibited resting spore germination of this pathogen by about 80%. Cyazofamid at 3-10 mg litre(-1) exhibited fungicidal activity to resting spores of P. brassicae 1-10 days after treatment. When cyazofamid was applied to infested soil, both root-hair infections and club formation caused by P. brassicae were strongly inhibited at 1-3 mg kg(-1) dry soil. These results suggest that cyazofamid directly inhibits resting spore germination, thereby leading to the inhibition of root-hair infection and club formation. Cyazofamid at 3 mg kg(-1) dry soil also exhibited complete control of clubroot disease. The effect of broadcast soil application using a dust formulation at 2 kg AI ha(-1) (equivalent to 1.3 mg AI kg(-1) dry soil), and plug seedling tray application by a suspension concentrate formulation at 200 and 400 mg AI tray(-1) (30 x 60 x 4 cm3) against P. brassicae was also evaluated. Cyazofamid exhibited good efficacy against the pathogen. The sequential treatment including plug seedling tray application with cyazofamid and pre-plant broadcast soil application with the fungicide fluazinam also exhibited excellent levels of control. These results indicate that cyazofamid has a high potential to be an effective fungicide for the control of clubroot disease.