Trade‐offs in the time and energy allocated to different functions, such as reproductive activities, can be driven by alterations in condition which reduce resources, often in response to extrinsic factors such as pathogens or parasites. When individuals are challenged by a pathogen, they may either reduce reproduction as a cost of increasing defence mechanisms or, alternatively, modify reproductive activities so as to increase fecundity thereby minimizing the fitness costs of earlier death, a behaviour consistent with the terminal investment hypothesis (TIH). The TIH predicts that individuals with decreased likelihood of future reproduction will maximize current reproductive effort, which may include shifts in reproductive timing. We examined how wild, adult female click beetles (Agriotes obscurus) responded after exposure to the fungal pathogen Metarhizium brunneum. Field‐collected beetles exposed to a high concentration of M. brunneum died earlier and in greater numbers than those exposed to a low concentration. Using a multivariate approach, we examined the impact of pathogen challenge on lifespan and a suite of reproductive traits. Stepdown regression analysis showed that only female lifespan differed among the fungal treatments. Fungal‐induced reductions in lifespan drove changes in the reproductive schedule, characterized by a decrease in preoviposition period. Moving the start of egg laying forward allowed the females to offset the costs of a shortened lifespan. These changes suggest that there is a threshold for terminal investment, which is dependent on strength of the survival threat. From an applied perspective, our findings imply that exposing adult click beetles to M. brunneum to reduce their population density might not succeed and is an approach that needs further investigation.

中文翻译：

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响应野生昆虫病原体暴露的繁殖计划的修改：支持终端投资假设

分配给不同功能（例如生殖活动）的时间和能量的权衡可以由减少资源的条件改变驱动，通常是对病原体或寄生虫等外在因素做出反应。当个体受到病原体的挑战时，他们可能会减少繁殖作为增加防御机制的成本，或者改变繁殖活动以增加繁殖力从而最小化早期死亡的适应成本，这种行为与终端投资假设一致。 TIH)。TIH 预测，未来生殖可能性降低的个体将最大限度地提高当前的生殖努力，这可能包括生殖时间的变化。我们研究了多么狂野，成年雌性点击甲虫（Agriotes obscurus）在接触真菌病原体绿僵菌后有反应。田间采集的暴露于高浓度 M. brunneum 的甲虫比暴露于低浓度的甲虫死得更早，数量也更多。我们使用多变量方法研究了病原体挑战对寿命和一系列生殖特征的影响。递减回归分析表明，真菌治疗中只有女性的寿命不同。真菌引起的寿命缩短推动了生殖时间表的变化，其特征是产卵前期的减少。提前开始产卵使雌性能够抵消寿命缩短的成本。这些变化表明终端投资存在门槛，这取决于生存威胁的强度。