天敌对烟粉虱捕食作用的SCAR标记检测

Detection of Predation on Bemisia tabaci by Using SCAR Markers

以烟粉虱和捕食性天敌为研究对象,采用特征序列扩增区域(SCAR)标记法,通过对目的片段的克隆与测序设计烟粉虱特征片段扩增引物,检验该引物的种、虫态及性别特异性,并利用该引物检测捕食性天敌对棉田烟粉虱的捕食作用。研究结果表明,利用SCAR标记法获得了长度为347bp的烟粉虱特异性片段(GenBank登录号为AY841800),根据此片段的碱基序列设计烟粉虱特异引物1对TB-F/TB-R94585,其扩增片段约为240bp;种特异性检验结果表明,该引物只对烟粉虱具有扩增能力,对温室粉虱及其它相关种类不具有扩增效果;同时该引物对不同虫态、不同性别的烟粉虱具有同样的扩增效应。田间检测结果表明,同种天敌昆虫幼体捕食作用检出率高于成虫;在所检测的4类群9种捕食性天敌中,龟纹瓢虫幼虫、异色瓢虫幼虫、草蛉幼虫及东亚小花蝽成虫和蜘蛛对烟粉虱捕食作用的检出率高于50%。

DNA markers of Bemisia tabaci (Gennadius) were developed to detect the remains of whitefly in the gut of Propylaea japonica (Thunberg) reared in lab and various predators collected in cotton fields. An approximately 350 bp DNA fragment of B. tabaci, absent in other closely related prey species, cotton and in the predators banding pattern, was identified by random amplified polymorphic DNA (RAPD) analysis. After cloning and sequencing the target fragment (347 bp, AY841800 in GenBank), one pair of sequence-characterized amplified region (SCAR) primers was developed, amplified single band of ca. 240 bp. Specificity tests performed with this pair of primers showed the presence of the band for B. tabaci in all stages and in both sexes. The target DNA fragment of B. tabaci was equally detected in P. japonica adult fed with 10 red-eyed nymphs of B. tabaci and in all predator species collected in cotton fields. The detection rate of B. tabaci DNA in predators, such as the larvae of P. japonica, Harmonia axyridis, Chrysopa spp., adult Orius sauteri and spiders, was over 50%.