两个入侵烟粉虱隐种MEAM1与MED对番茄黄曲叶病毒水平传播能力的比较

【目的】烟粉虱 Bemisia tabaci 是番茄黄曲叶病毒（Tomato yellow leaf curl virus, TYLCV）在自然界的唯一传播媒介，除了可以直接取食获取TYLCV，烟粉虱还可以通过交配获取此植物病毒。虽然前人研究证明了烟粉虱Middle East-Asia Minor 1 （MEAM1）和Mediterranean （MED）隐种都可以通过交配在两性个体之间水平传播TYLCV，但有关MEAM1与MED隐种水平传播TYLCV的能力是否存在差异，不同研究的结果却并不一致。另外，目前尚无关于烟粉虱的水平传播行为是否有助于TYLCV在田间扩散的相关研究。【方法】从浙江、广东、云南和河南4个省份的田间采集MEAM1和MED隐种烟粉虱种群，在室内应用分子标记对各种群所属隐种鉴定后分别建立7个供试种群，然后观察每个种群内带毒成虫与不带毒成虫通过交配在不同性别个体之间水平传播TYLCV的能力，并选用采自广东的MEAM1隐种烟粉虱模拟群体交配实验探究通过交配获毒的烟粉虱个体是否具有传播TYLCV致健康番茄植株发病的能力。【结果】4个省内的MEAM1和MED隐种烟粉虱都可通过交配对TYLCV进行水平传播，但传播频率一般在10%以下。不同省份的MEAM1隐种种群之间在水平传播TYLCV的能力上无显著差异，不同省份的MED隐种种群之间也不存在显著差异。另外，同一省份的MEAM1隐种与MED隐种之间在水平传播TYLCV的能力上也不存在显著差异，而且在两个隐种中，带毒雄虫将病毒水平传播给不带毒雌虫与带毒雌虫将病毒水平传播给不带毒雄虫的频率没有显著差异。研究还表明，采自广东的MEAM1隐种烟粉虱个体通过交配水平获毒后不能致健康番茄植株发病。【结论】综合以上结果，我们推测TYLCV在中国境内两个入侵烟粉虱隐种MEAM1和MED各自种群内个体之间的水平传播概率较低，对该病毒在田间的扩散可能没有作用或作用不大。

Comparison of horizontal transmission efficiency of Tomato yellow leaf curl virus between two invasive cryptic species MEAM1 and MED of the whitefly Bemisia tabaci complex (Hemiptera: Aleyrodidae)

【Aim】 The whitefly Bemisia tabaci is the only vector of Tomato yellow leaf curl virus (TYLCV) in the field. In addition to direct acquisition of the virus through feeding, the whitefly can acquire the virus via mating. Although previous studies have shown that both cryptic species Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED) of the whitefly complex can achieve horizontal transmission of TYLCV via mating, the results on the efficiency of virus transmission via this means by the two species were not consistent. Moreover, experimental evidence is yet lacking to show whether this type of horizontal transmission of TYLCV may facilitate the spread of the virus in the field. 【Methods】 We first collected the field populations of cryptic species MEAM1 and MED of B. tabaci from four provinces in China, including Zhejiang, Guangdong, Yunnan and Henan, and following molecular identification ofthe species status of each of the populations we established seven pure cultures for experiments. Then, we observed the capacity of TYLCV transmission between viruliferous and non-viruliferous adults in each of the populations. And finally, we used the MEAM1 culture from Guangdong Province to simulate a scenario of group mating and examined the capacity of the adults, which acquired TYLCV via mating, in transmitting the virus to tomato plants. 【Results】 Both MEAM1 and MED populations of B. tabaci collected from the four provinces were able to achieve horizontal transmission of TYLCV via mating, although the efficiency of transmission was in general low, mostly below 10%. No significant differences were detected in the efficiency of transmission between the MED populations from the four provinces, between MEAM1 populations from three of the four provinces, and between the two cryptic species within each of the provinces. In each of the two cryptic species, both viruliferous male and female adults were able to transmit viral DNA to individuals of the opposite sex, and no significant differences in the efficiency of virus transmission between the two sexes were found. The data of the group mating test indicated that the originally non viruliferous individuals were unable to transmit TYLCV to tomato plants following their acquisition of the virus via mating. 【Conclusion】 These results demonstrate that for the virus TYLCV and whiteflies of the cryptic species MEAM1 and MED of B. tabaci tested here low efficiency of horizontal transmission of TYLCV can be expected. However, the data obtained with the Guangdong MEAM1 population suggest that the low horizontal transmission does not increase the number of individuals capable of transmitting the virus to infect new tomato plants. Consequently, the horizontal mode of transmission is unlikely to have much epidemiological relevance in the field.