玉米象的形态和分子特征鉴定

Morphology Observation and Molecular Characteristics of the Sitophilus zeamais

[目的]通过形态和分子特征鉴定玉米象。[方法]从采集到的大米样本中分离出玉米象,分别在高速度数码显微系统和扫描电镜下观察其外部形态和细微形态并进行拍照鉴定。同时提取DNA对cox1和ITS基因进行测序和分析。[结果]玉米象的体躯由头、胸、腹3部分组成,胸部由3个胸节组成,有胸足3对,体表散布密集的刻点。明显的鉴别特征有头部的额和颊延伸成象鼻状的喙,触角呈膝状弯曲,共见8个小节,口器位于细长喙的端部,上唇基本退化,代之为口上片,下颚须和下唇须退化而僵直,外咽片消失。雄虫外生殖器隐藏于腹部,来源于第9腹节,阳茎背面扁平,有2条平行的纵凹沟,雌虫Y形骨片尖。经克隆PCR扩增得到cox1、ITS基因片段大小分别为441、1 445 bp,与已报道的玉米象cox1基因同源性分别为99.7%~100%,ITS基因为99.0%~99.3%。[结论]根据高速度数码显微系统和电镜下玉米象的形态特征,结合cox1和ITS基因序列分析,可为玉米象的鉴定和生物学分类提供依据,也可为防治玉米象对储粮的危害奠定基础。

[Objective]To identify Sitophilus zeamais according to morphology and molecular characteristics.[Method]Sitophilus zeamais were collected from the rice, then observed under an high speed digital microscope system and scanning electron microscope.PCR and walking sequencing were used to obtain cox1 and ITS sequences of the DNA samples extracted from Sitophilus zeamais.[Result]The body of Sitophilus zeamais was composed of three parts: head, chest and abdomen.The chest was composed of three thoracic ganglia, which had three pairs of feet.The distinguishing features were as follows: the forehead and cheek of the head extend into an elephant nose-like beak, the antennae bend knee-like, a total of 8 sections can be seen, the mouth organ is located at the end of the slender beak, the upper lip was basically degenerated, replaced by the upper lip, the mandibular and lower lip whiskers were degenerated and rigid, and the external pharynx slice disappears.The male genitalia was hidden in the abdomen and originates from the 9 th abdominal ganglion.The dorsal surface of the male was flat with two parallel longitudinal grooves.The length of ITS and cox1 from the Sitophilus zeamais were 1 445 bp and 441 bp, respectively.Compared with reported Sitophilus zeamais,the homology of cox1 and ITS gene were 99.7%-100% and 99.0%-99.3%,respectively.[Conclusion]The Sitophilus zeamais was identified according to the morphological characteristics under high speed digital microscope system and scanning electron microscope, and the molecular characteristics based on cox1 and ITS genes.It provides a basis for identification and biological classification of Sitophilus zeamais,and also lays a foundation for controlling the harm of Sitophilus zeamais to grain storage.