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，葫芦科植物种群中的萎蔫病流行，是由植物病原细菌气管欧文氏菌（Erwinia tracheiphila）在甲虫媒介条纹黄瓜甲虫（Acalymma vittatum）体内持续定殖所维持的。本研究开发了一种可定量检测整只甲虫及其虫粪中气管欧文氏菌的定量聚合酶链反应（qPCR）方法，并利用该方法评估了媒介昆虫在不同时长暴露于染病植株后对病原菌的获取与留存情况。研究结果显示：(i) 甲虫取食染病植株后仅3小时即可在其虫粪中检测到气管欧文氏菌；短时间暴露于染病植株的媒介昆虫可在无潜伏期的情况下传播病原菌，且暴露数周后仍处于持续定殖状态的媒介昆虫也可传播该菌；(ii) 暴露时长会影响病原菌的长期定殖率；(iii) 虫粪的侵染活性（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；(iv) 媒介昆虫极少能清除体内的气管欧文氏菌感染，但未表现出明显的适合度损失。上述结果揭示了一种可有效维持葫芦科植物种群内气管欧文氏菌存续的传播模式。