The reproductive success of many insects is considered to be limited by two main factors: the availability of mature eggs to lay (termed egg limitation) and the time to locate suitable hosts (termed time limitation). High host density in the environment is likely to enhance oviposition opportunities, thereby selecting for higher investment in egg supply. In contrast, a shortage of food (e.g. sugar sources) is likely to increase the risk of time limitation, thereby selecting for higher allocation to initial energy reserves. To our knowledge, the combined effect of host and food availability on these optimal life‐history allocations has never been investigated. We thus modelled their simultaneous effects on a three‐dimensional trade‐off between initial investment in energy reserves, egg number and egg size, while focusing on insect parasitoids. The model was based on Monte Carlo simulations coupled with genetic algorithms, in order to identify the optimal life‐history traits of a single simulated parasitoid female in an environment in which both hosts and food are present in varying densities. Our results reproduced the simple predictions described above. However, some novel predictions were also obtained, especially when specific interactions between the different factors were examined and their effects on the three‐dimensional life‐history surface were considered. The work sheds light on long‐lasting debates regarding the relative importance of time versus egg limitation in determining insect life‐history traits and highlights the complexity of life‐history evolution, where several environmental factors act simultaneously on multiple traits.

中文翻译：

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基于三维权衡面的寄主和食物供应对优化寄生蜂生活史性状的综合影响

许多昆虫的繁殖成功被认为受到两个主要因素的限制：成熟卵的可产性（称为卵限制）和找到合适宿主的时间（称为时间限制）。环境中的高宿主密度可能会增加产卵机会，从而选择对鸡蛋供应进行更高的投资。相比之下，食物（例如糖源）的短缺可能会增加时间限制的风险，从而选择更高的初始能量储备分配。据我们所知，从未研究过宿主和食物供应对这些最佳生活史分配的综合影响。因此，我们模拟了它们对能量储备初始投资、卵数和卵大小之间的三维权衡的同时影响，同时专注于昆虫寄生。该模型基于蒙特卡罗模拟与遗传算法相结合，以在宿主和食物以不同密度存在的环境中识别单个模拟寄生雌性的最佳生活史特征。我们的结果再现了上述简单的预测。然而，也获得了一些新的预测，特别是当检查不同因素之间的特定相互作用并考虑它们对三维生活史表面的影响时。这项工作揭示了关于时间与卵子限制在确定昆虫生活史特征方面的相对重要性的长期争论，并突出了生活史进化的复杂性，其中几个环境因素同时作用于多个特征。