Data from: Dynamics of short- and long-term association between a bacterial plant pathogen and its arthropod vector

The dynamics of association between pathogens and vectors can strongly influence epidemiology. It has been proposed that wilt disease epidemics in cucurbit populations are sustained by persistent colonization of beetle vectors (Acalymma vittatum) by the bacterial phytopathogen Erwinia tracheiphila. We developed a qPCR method to quantify E. tracheiphila in whole beetles and frass and used it to assess pathogen acquisition and retention following variable exposure to infected plants. We found that (i) E. tracheiphila is present in frass in as little as three hours after feeding on infected plants and can be transmitted with no incubation period by vectors given brief exposure to infected plants, but also by persistently colonized vectors several weeks following exposure; (ii) duration of exposure influences rates of long-term colonization; (iii) frass infectivity (assessed via inoculation experiments) reflects bacterial levels in frass samples across time; and (iv) vectors rarely clear E. tracheiphila infections, but suffer no apparent loss of fitness. These results describe a pattern conducive to the effective maintenance of E. tracheiphila within cucurbit populations.

病原体与媒介的互作动态可对流行病学进程产生显著影响。已有研究提出，葫芦科种群中的萎蔫病流行，是由植物病原细菌嗜管欧文氏菌（Erwinia tracheiphila）在甲虫媒介——黄瓜条跳甲（Acalymma vittatum）体内持续定殖所维持的。本研究开发了一种实时荧光定量PCR（qPCR）方法，可在整只甲虫及其虫粪中定量嗜管欧文氏菌，并利用该方法评估了甲虫在不同时长暴露于染病植株后的病原获得与留存情况。研究结果显示：（1）甲虫取食染病植株后仅需3小时即可在其虫粪中检测到嗜管欧文氏菌；短暂暴露于染病植株的媒介可直接传播该病原（无潜伏期），而暴露数周后仍持续定殖该菌的媒介同样具备传播能力；（2）暴露时长会影响媒介的长期定殖率；（3）虫粪侵染性（通过接种实验评估）可反映不同时间点虫粪样本中的细菌载量；（4）媒介几乎无法清除体内的嗜管欧文氏菌感染，但未表现出明显的适合度损失。上述结果揭示了一种有利于嗜管欧文氏菌在葫芦科种群中有效维持的传播格局。