Data from: Surrounding pathogens shape maternal egg care but not egg production in the European earwig

Pathogens are ubiquitous in nature and typically entail major fitness costs in their hosts. These costs can be particularly important when individuals exhibit poor immune defenses, as it is often the case during early developmental stages. Hence, selection should favor parental strategies limiting the risks of pathogen exposure and infection in their offspring. In this study, we investigated 1) whether females of the European earwig Forficula auricularia avoid areas contaminated with spores of the entomopathogenic fungus Metarhizium brunneum prior to and at egg laying, as well as 2) whether spore presence entails an increase in females’ investment into both pre-hatching forms of care and clutch quantity and quality. Our results first show that females did not avoid contaminated areas prior to and at egg laying. However, females returned to their eggs faster in presence of living spores compared to UV-killed or no spores. They were also more likely to construct a nest when in presence of both living and UV-killed spores (but only in one studied population). Finally, we found that spore presence did not influence maternal investment into egg grooming, egg gathering and egg defense, as well as into clutch quantity and quality. Overall, our results demonstrate that earwig females do not avoid contaminated environments, but could mitigate the associated costs of pathogen exposure by adjusting their level of egg care. These findings emphasize the importance of pathogens in the evolution of pre-hatching parental care and, more generally, in the emergence and maintenance of family life in nature.病原体在自然界中无处不在，且通常会对宿主造成显著的适合度代价。当个体免疫防御能力较弱时，这在生物发育早期极为常见，这类代价的影响尤为突出。因此，自然选择应青睐能够降低后代暴露于病原体并引发感染风险的亲代策略。本研究探究了两个核心问题：其一，欧洲蠼螋（Forficula auricularia）雌虫是否会在产卵前及产卵期避开被昆虫病原真菌（entomopathogenic fungus）布氏绿僵菌（Metarhizium brunneum）孢子污染的区域；其二，孢子的存在是否会提升雌虫在孵化前亲代抚育行为以及卵块数量与质量方面的投入。研究结果首先显示，雌虫在产卵前及产卵期并未避开污染区域。但相较于紫外线灭活孢子组与无孢子组，存活孢子组的雌虫能够更快返回卵团。此外，当同时存在存活孢子与紫外线灭活孢子时，雌虫更倾向于构筑巢穴，但该现象仅在一个研究种群中被观测到。最后，本研究发现孢子的存在并不会影响雌虫的卵清洁、卵聚集与卵防御行为，以及卵块的数量与质量。总体而言，本研究结果表明，蠼螋雌虫并不会避开污染环境，但可通过调整卵抚育行为的强度来缓解病原体暴露带来的相关代价。这些发现凸显了病原体在孵化前亲代抚育行为演化中的重要性，更广泛地说，也揭示了其在自然界中家族生活的起源与维持过程中的关键作用。