Parental care is a key component of an organism’s reproductive strategy that is thought to trade-off with allocation toward immunity. Yet, it is unclear how caring parents respond to pathogens: do infected parents reduce care as a sickness behavior or simply from being ill or do they prioritize their offspring by maintaining high levels of care? To address this issue, we investigated the consequences of infection by the pathogen Serratia marcescens on mortality, time spent providing care, reproductive output, and expression of immune genes of female parents in the burying beetle Nicrophorus vespilloides. We compared untreated control females with infected females that were inoculated with live bacteria, immune-challenged females that were inoculated with heat-killed bacteria, and injured females that were injected with buffer. We found that infected and immune-challenged females changed their immune gene expression and that infected females suffered increased mortality. Nevertheless, infected and immune-challenged females maintained their normal level of care and reproductive output. There was thus no evidence that infection led to either a decrease or an increase in parental care or reproductive output. Our results show that parental care, which is generally highly flexible, can remain remarkably robust and consistent despite the elevated mortality caused by infection by pathogens. Overall, these findings suggest that infected females maintain a high level of parental care, a strategy that may ensure that offspring receive the necessary amount of care but that might be detrimental to the parents’ own survival or that may even facilitate disease transmission to offspring.

中文翻译：

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继续照顾：尽管死亡率很高，受感染的女性仍继续照顾父母


亲代照顾是有机体繁殖策略的关键组成部分，人们认为它与免疫分配之间存在权衡。然而，尚不清楚有爱心的父母如何应对病原体：受感染的父母是否会因为生病而减少护理，或者只是因为生病而减少护理，还是他们会通过维持高水平的护理来优先考虑他们的后代？为了解决这个问题，我们研究了病原体粘质沙雷氏菌感染对埋葬甲虫 Nicrophorus vespilloides 的死亡率、提供护理时间、生殖产出以及母本免疫基因表达的影响。我们将未经治疗的对照雌性与接种活细菌的感染雌性、接种热灭活细菌的免疫缺陷雌性以及注射缓冲液的受伤雌性进行了比较。我们发现，受感染和免疫缺陷的雌性改变了其免疫基因表达，并且受感染的雌性死亡率增加。尽管如此，受感染和免疫功能低下的雌性仍保持着正常的护理水平和生殖能力。因此，没有证据表明感染会导致父母照顾或生殖产出的减少或增加。我们的研究结果表明，尽管病原体感染导致死亡率升高，但通常高度灵活的父母照顾仍然可以保持非常稳健和一致。总体而言，这些发现表明，受感染的雌性保持高水平的父母照顾，这种策略可以确保后代得到必要的照顾，但这可能不利于父母自身的生存，甚至可能促进疾病传播给后代。