陆良莴苣类蔬菜斑萎病的侵染循环及其发生流行特点

Infection Cycle and Epidemic Characteristics of Spotted Wilt Diseases on Genera Lactuca Vegetables in Luliang County, Yunnan Province

【目的】探明陆良莴苣类蔬菜斑萎病的侵染循环及其发生流行特征,为绿色防控提供指导。【方法】调查和采集不同发病时期的莴苣类蔬菜斑萎病样品、田间可能的中间寄主杂草与作物、苗棚种苗,应用ELISA检测、电子显微镜负染色与超薄切片观察,确定陆良莴苣类蔬菜斑萎病伴随的病毒种类、侵染循环及其发生流行特征。【结果】陆良莴苣类蔬菜斑萎病的发病率在15%~36%,伴随的病毒仅有番茄斑萎病毒(Tomato spotted wilt Orthotospovirus,TSWV),细胞病理观察表明生菜斑萎病样品的细胞中仅分布TSWV粒体。TSWV的中间寄主有鬼针草,以及辣椒、马铃薯、烟草等作物。苗棚生菜种苗中TSWV的检出率100%。【结论】陆良莴苣类蔬菜主要病害是由TSWV侵染引起的斑萎病,TSWV在周年分布的鬼针草中形成初侵染源,通过传毒介体蓟马传播到莴苣类蔬菜种苗以及中间寄主作物辣椒、马铃薯、烟草等作物,并在夏秋蔬菜生产季节在这些作物及杂草之间相互传播,形成侵染循环。种苗带毒是陆良莴苣类蔬菜发病率高的主要原因,中间寄主植物的分布、蓟马传播与农事操作进一步加剧斑萎病的发生流行。

【Objective】In order to investigate the infection cycle and epidemic characteristics of spotted wilt diseases on genera Lactuca vegetables in Luliang county, Yunnan province, and provide guidance for green prevention and control of these diseases. 【Methods】We investigated and collected different samples including of genera Lactuca vegetables with spotted wilt symptoms, the intermediate hosts on the field like weeds, crops and the seedlings on greenhouses. Using varieties of detection methods, including ELISA, electron microscope observation of negative staining samples and ultrathin sectioning samples, the viral species were confirmed,and infection cycles and epidemic characteristics of spotted wilt disease on genera Lactuca vegetables in Luliang county was studied.【Results】The incidence rate of genera Lactuca spotted wilt was 15 %-36 %, and the only isolate was Tomato spotted wilt Orthotospovirus(TSWV). Cytopathological result showed that only TSWV particles were observed in the cells of the genera Lactuca vegetables samples with spotted wilt symptom. The intermediate host of the TSWV included weeds, as well as pepper, potato, tobacco and other crops. TSWV detection rate of seedlings on greenhouses was 100 %.【Conclusion】The disease on genera Lactuca vegetables with spotted wilt symptom was mainly caused by TSWV. The Bidens pilosa, as a annual distribution weeds, was the primary infection source of TSWV. TSWV was spread from Bidens pilosa to lettuce vegetables seedlings and intermediate host crops like chili pepper, potato, tobacco by thrips, forming a cycle of infection. Seedlings that carried the virus was the main factor for the high incidence of TSWV disease on genera Lactuca vegetables in Luliang county, and the intermediate host plants, thrips transmission and farming practices further aggravated the occurrence and prevalence of TSWV.