猕猴桃根结线虫病的初步研究

猕猴桃根结线虫病是危害猕猴桃的主要病害,株发病率达60％～70％,病情指数为18.12～21.50.1986～1988年期间笔者对此病作了初步的研究。根据病原线虫雌虫的会阴花纹特征,雄虫头部、口针的形态,2龄幼虫的长度,确定病原线虫为下列3个种:南方根结线虫(Meloidogyne incognita)爪哇根结线虫(M. jaranica),花生根结线虫(M. arenaria),其中以南方根结线虫为优势种,它1年发生6代。防治此病的药剂以力满库效果最佳。     

日本松干蚧口针及其危害枝条切片观察

日本松干蚧(Matsucoccus matsumurae Kuwana)发生数十年以来,各地均进行了研究和防治,取得了成果和效益。而研究日本松干蚧口针和吸食部位以及损害松树的原因尚未见有报导。笔者自1985年起开展这一研究,现将初步结果整理如下。     

Early intracellular punctures by two aphid species on near-isogenic melon lines with and without the virus aphid transmission (Vat) resistance gene

The Vat resistance gene (in Cucumis melo L.) inhibits the transmission of non-persistent viruses by Aphis gossypii Glover, but does not affect transmission by Myzus persicae (Sulz.). To see whether this difference was behaviourally determined, we investigated the stylet penetration behaviour of these two aphid species by recording EPGs (Electrical Penetration Graphs) of 8 and 20 min on two sets of susceptible and resistant isogenic melon lines. During the 20 min EPG study, inoculation with CMV (Cucumber Mosaic Virus) was also investigated. For both sets of isogenic lines, the two aphid species were able to detect the presence of Vat. The mean duration of individual intracellular punctures on the resistant genotypes was significantly reduced for both M. persicae and A. gossypii (-10% and -8% respectively for duration of pattern ‘pd’ in the 20 min experiment); this reaction appeared faster for M. persicae, a species for which melon was not a suitable host-plant. Therefore, in contrast to Vat's anti-transmission effect, this behavioural effect was not aphid species-specific. Also, the frequency of intracellular punctures on the resistant genotypes was significantly reduced in A. gossypii (but not in M. persicae): on average, this frequency dropped from ≈0.65 pd.min^-1 on the susceptible genotypes to ≈0.5 pd.min^-1 on the resistant ones. It was concluded that (intracellular?) chemical cues were detected very early by aphids probing on the resistant genotypes carrying the Vat gene. However, a comprehensive analysis of the behavioural traits of both aphids on the two genotypes could not alone account for the complete inhibition of transmission which was found only to occur for A. gossypii on resistant genotypes. None of the differences detected (between aphid species or between plant genotypes) could account for the Vat phenotype, although they may explain quantitative differences in transmission efficiencies between aphid species. It was thus concluded that Vat effect was primarily chemically mediated. Finally, some intracellular punctures bearing typical subphases have been identified in both aphid species and were designated as ‘long potential drops’ (pd-L). For A. gossypii, these were observed early after plant contact and their mean duration was twice that of standard intracellular punctures (≈8.5 s vs ≈4.2 s). Although not necessary for CMV inoculation, the duration of such phases was positively correlated with a high transmission efficiency by A. gossypii on the susceptible genotype. The nature of this pattern and a putative mechanism of action of the Vat gene are discussed.     

不同地区褐飞虱的形态变异及其与迁飞关系的研究

根据我国不同地区和南京灯下的褐飞虱长翅型雌虫形态特征的测定,表明在前翅、后足腿节、上颚口针、第Ⅰ、Ⅱ、Ⅲ产卵瓣的长度方面存在不同程度的差异。经统计分析,证明南京地区7月25日前灯下虫峰的虫源系来于南方,7月下旬至8月上、中旬灯下的虫峰为本地双季早稻迁出世代所构成。 通过不同地区种群的杂交试验和蛋白电泳谱带比较研究,初步认为环境因素是影响褐飞虱种群形态变异的重要原因。