Aphid Facultative Symbionts Aid Recovery of Their Obligate Symbiont and Their Host After Heat Stress
Aphid Facultative Symbionts Aid Recovery of Their Obligate Symbiont and Their Host After Heat Stress
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DOI：
10.3389/fevo.2020.00056
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发表时间：
2020-03-19
影响因子：
3
通讯作者：
Ferrari, Julia
中科院分区：
文献类型：
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作者：
Heyworth, Eleanor R.;Smee, Melanie R.;Ferrari, Julia
环境条件影响昆虫的适应性，许多物种受到特定温度范围的限制。蚜虫仅限于温带气候，据推测，这部分是由于它们的耐热专性营养共生体Buchnera。蚜虫通常携带额外的兼性共生体，这些共生体可以在热胁迫后增加宿主的适应性。在这里，我们使用豌豆蚜虫（Acyrthosiphon pisum）和三个兼性内共生体（Escheridatus Regiella insecticola，Escheridatus Fukatsuia symbiotica（X型; PAXS），和Escheridatus Hamiltonella defensa），以调查这些物种如何应对热应激，以及它们的存在是否会影响宿主或专性共生体的适应性。我们暴露于一个单一的高温事件和测量一生的专性和兼性共生体的繁殖力和人口密度的蚜虫线。热休克减少蚜虫的繁殖力，但对于蚜虫感染的两个兼性共生体（Regiella或Fukatsuia），这种减少是小于未感染的蚜虫。热激处理后，蚜虫种群密度也有所下降，仅在感染Regiella和Fukatsuia的蚜虫中恢复，而在未感染的蚜虫或感染Hamiltonella的蚜虫中则没有恢复。虽然热休克最初减少了两个兼性共生体（Hamiltonella和Fukatsuia）的密度，所有兼性共生体密度恢复成年。因此，两个兼性共生体测试援助的专性共生体和主机的恢复，我们讨论了可能的潜在机制。我们的工作突出了保护性共生体对热应激后专性共生体恢复的有益影响，以及兼性共生体如何影响更广泛的生态群落。
Environmental conditions affect insect fitness, with many species constrained by specific temperature ranges. Aphids are limited to temperate climates and it is hypothesized that this is partly due to their heat-susceptible obligate nutritional symbiont Buchnera. Aphids often carry additional facultative symbionts which can increase the host's fitness after heat stress. Here we used the pea aphid (Acyrthosiphon pisum) and three of its facultative endosymbionts (Candidatus Regiella insecticola, Candidatus Fukatsuia symbiotica (X-type; PAXS), and Candidatus Hamiltonella defensa) to investigate how these species respond to heat stress and whether their presence affects the fitness of the host or the obligate symbiont. We exposed aphid lines to a single high temperature event and measured lifetime fecundity and population densities of both obligate and facultative symbionts. Heat shock reduced aphid fecundity, but for aphids infected with two of the facultative symbionts (Regiella or Fukatsuia), this reduction was less than in uninfected aphids. The population density of Buchnera was also reduced after heat shock, and only recovered in aphids infected with Regiella or Fukatsuia but not in uninfected aphids or those with Hamiltonella. Although heat shock initially reduced the densities of two of the facultative symbionts (Hamiltonella and Fukatsuia), all facultative symbiont densities recovered by adulthood. Two of the facultative symbionts tested therefore aided the recovery of the obligate symbiont and the host, and we discuss possible underlying mechanisms. Our work highlights the beneficial effects of protective symbionts on obligate symbiont recovery after heat stress and how facultative symbionts may affect the wider ecological community.