Data from: Survival relative to new and ancestral host plants, phytoplasma infection and genetic constitution in host races of a polyphagous insect disease vector

Dissemination of vectorborne diseases depends strongly on the vector's host range and the pathogen's reservoir range. Because vectors interact with pathogens, the direction and strength of a vector's host shift is vital for understanding epidemiology and is embedded in the framework of ecological specialization. This study investigates survival in host-race evolution of a polyphagous insect disease vector, Hyalesthes obsoletus, whether survival is related to the direction of the host shift (from field bindweed to stinging nettle), the interaction with plant-specific strains of obligate vectored pathogens/symbionts (stolbur phytoplasma), and whether survival is related to genetic differentiation between the host races. We used a twice repeated, identical nested experimental design to study survival of the vector on alternative hosts and relative to infection status. Survival was tested with Kaplan–Meier analyses, while genetic differentiation between vector populations was quantified with microsatellite allele frequencies. We found significant direct effects of host plant (reduced survival on wrong hosts) and sex (males survive longer than females) in both host races and relative effects of host (nettle animals more affected than bindweed animals) and sex (males more affected than females). Survival of bindweed animals was significantly higher on symptomatic than nonsymptomatic field bindweed, but in the second experiment only. Infection potentially had a positive effect on survival in nettle animals but due to low infection rates the results remain suggestive. Genetic differentiation was not related to survival. Greater negative plant-transfer effect but no negative effect of stolbur in the derived host race suggests preadaptation to the new pathogen/symbiont strain before strong diversifying selection during the specialization process. Physiological maladaptation or failure to accept the ancestral plant will have similar consequences, namely positive assortative mating within host races and a reduction in the likelihood of oviposition on the alternative plant and thus the acquisition of alternative stolbur strains.

虫媒传染病（vectorborne diseases）的传播在很大程度上取决于媒介生物（vector）的宿主谱与病原体（pathogen）的储存宿主谱。由于媒介生物与病原体存在相互作用，媒介生物的宿主转移方向与强度对于流行病学研究至关重要，且这一过程隶属于生态特化（ecological specialization）的研究框架。本研究针对多食性昆虫病媒——淡翅菱飞虱（Hyalesthes obsoletus）的宿主宗演化过程中的存活情况展开探究，具体分析存活情况是否与宿主转移方向（从田旋花至荨麻）相关、是否与专性媒介病原体/共生体（stolbur phytoplasma，即植原体stolbur）的植物特异性菌株互作相关，以及是否与宿主宗之间的遗传分化（genetic differentiation）有关。本研究采用两次重复的相同嵌套实验设计，探究媒介生物在替代宿主上的存活情况及其与感染状态的关联。存活情况通过Kaplan-Meier生存分析（Kaplan–Meier analyses）进行检验，而媒介种群间的遗传分化则通过微卫星等位基因频率（microsatellite allele frequencies）进行量化。研究结果显示，两种宿主宗中均存在宿主植物（错误宿主上的存活率显著降低）与性别（雄性存活时长显著长于雌性）的显著直接效应，同时宿主（荨麻种群受影响程度大于田旋花种群）与性别（雄性受影响程度大于雌性）亦存在相对效应。仅在第二次实验中，田旋花种群在显症田旋花上的存活率显著高于无症状田旋花。感染可能对荨麻种群的存活具有正向影响，但由于感染率较低，该结果仅具有参考意义。遗传分化与存活率无显著关联。在衍生宿主宗中，植物转移的负效应更为显著，但stolbur植原体未表现出负效应，这表明在特化过程中的强定向选择发生之前，该种群已对新型病原体/共生体菌株产生了预适应（preadaptation）。生理适应不良或无法接受祖先宿主植物将带来类似后果，即宿主宗内部出现正选型交配，且在替代植物上产卵的概率降低，进而减少了获取替代stolbur植原体菌株的可能性。