云南省江城县中老越三国交界地区叮人蚋种类鉴定

Identification of biting blackflies in the border area of China-Laos-Vietnam of Jiangcheng county,Yunnan province

目的对中老越三国交界边境地区白天叮咬人,并引起严重皮炎的吸血蚋进行系统分类鉴定,明确其准确种类,为该地区防控相关疾病提供科学依据。方法 2019年5月6日下午17∶00在云南省江城县中老越三国交界边境地区河边采用人诱法采集吸血昆虫样本,采用无损伤昆虫形态的方法消化昆虫体表细胞,提取基因组DNA,PCR扩增昆虫COI基因,测序;分别采用Clustal X2.1、DNAStar(MegAlign)和Mega-X等生物信息学软件进行序列分析;同时对昆虫进行透明、脱水等处理,在显微镜下观察昆虫形态学特征。结果在云南省江城县中老越三国交界边境地区小河边采集到9只吸血蚋,它们叮咬人后都能引起严重皮炎症状。9只吸血蚋形态学鉴定结果显示,它们都具有:体色较黑,头额部较宽,两复眼分离,触角11节,口器短厚;翅宽阔,翅膜透明,翅上无鳞,翅脉发达,径分脉不分叉,无基室,翅径脉基段光裸;中胸盾片黑色,无纵条,中胸侧膜、下侧片光裸;腹部有一个球形受精囊,表面无饰纹等相似的形态学特征。但在生殖叉突,有8只蚋生殖叉突两臂末端膨大,有外突和内突,形成三叉头状;而另1只蚋生殖叉突两臂末端不膨大,具有外突,并骨化。分子鉴定结果显示,9只蚋位于两个进化分支内,其中8只蚋与S. nodosum(节蚋)处于相同进化分支,核苷酸同源性最高(97.3%~100%);而另一只与S. siripoomense处于相同进化分支,核苷酸同源性最高(96.8%~98.5%)。结论江城县存在S. nodosum和S. siripoomense两种白天叮咬人并引起严重皮炎的吸血蚋,其中S. nodosum为优势种群,S. siripoomense为国内首次报道。

Objective To systematic identify the blood-sucking blackflies causing severe dermatitis by biting people during daytime in the border area between China,Laos and Vietnam,and to provide scientific basis for the prevention and control of related diseases in this area. Methods On May 6,2019,blood-sucking insects were collected at 5∶00 p.m. at the riverside of the border area between China,Laos and Vietnam in Jiangcheng county,Yunnan province.A small number of insect surface cells were digested by non-invasive insect morphology. Genomic DNA of the in-sect was extracted,and COI gene was amplified by PCR and sequenced. Sequence analysis was performed by bioinformatics software such as Clustal X2.1,DNAStar(MegAlign) and Mega-X. Simultaneously,the insects were treated with transparency and dehydration,and the morphological characteristics of insects were observed under the stereo microscope. Results The 9 blood-sucking blackflies collected along the riverside at the border area between China,Laos and Vietnam of Jiangcheng county caused severe dermatitis symptoms in humans. The morphological identifica-tion of 9 blood-sucking blackflies showed that they all had morphological characteristics :body color was black,head and forehead were wider,double eyes were separated,antennae were 11,mouth organs were short and thick,wings were broad,wing membranes were transparent,scaleless on wings,wing veins were developed,diameter veins were not bifurcated,no basal chamber,basal segment of wing veins were bare,middle thoracic shield was black,without longitudinal strips,middle pleura and lower side were bare,abdomen was bare. The abdomen had a spherical fertilization sac with no ornamentation on the surface. Among them,8 had enlarged ends of the genital fork process arms,and the outer and inner processes formed a tridentate head,while the other one blackfly had no enlarged ends of the genital fork process arms,with external processes and ossification. Sequence analysis showed that 9 blackfly were lo-cated in two independent evolutionary branches,of which 8 were in the same evolutionary branch with S. nodosum,with the highest nucleotide homology(97.3%-100%),while BS9 and S. siripoomense were in the same evolutionary branch,the nucleotide homology was 96.8%-98.5%. Conclusion In Jiangcheng county,there were two species of blood-sucking blackflies,S. nodosum and S. siripoomense,which bite people during the day and cause severe dermatitis,which S. nodosum was the dominant population and S. siripoomense was the first report in China.