Diapause is an adaptation that insects have evolved to synchronize their life cycle with that of seasonal climatic changes and resources availability. However, cues for its induction are not always clear and, in some cases, a maternal effect may be involved. At the population level, just a part of the individuals may exhibit diapause with important consequences in terms of winter survival. Moreover, clear indicators of diapause state are difficult to identify. Diapause induction was thus investigated in the aphid parasitoid species Aphidius ervi Haliday (Hymenoptera: Braconidae) developing in the aphid Sitobion avenae (Hemiptera: Aphididae) at four crossed photo-thermal regimes (16°C and 8°C, 16: 8 h L: D and 8: 16 h L: D), and during 2 successive generations. We analyzed the reliability of changes in mummy color to assess for the diapausing state compared to dissections, and we measured parasitoid morphological and physiological traits. We observed that the proportion of dark brown mummies increased after one generation under low photothermal regime compared to other regimes. No diapause was recorded at 16°C, 16: 8 h L: D, while we observed 16.2% and 67.5% diapause incidence at 8°C, 8: 16 h L: D, at 1st and 2nd generation, respectively. Diapause induction is thus increased by short day-length conditions and low temperatures as well as by maternal effects. All parasitoid life-history traits (weight, size, fat content, water content, egg-load and longevity) were affected by the photo-thermal regime and/or the generation. These results raise new questions on the environmental thresholds needed to induce diapause and on survival and adaptation potential of commercially available parasitoid strains in different environments. This article is protected by copyright. All rights reserved.

中文翻译：

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寄生蜂 Aphidius ervi Haliday 商业品系滞育诱导的跨代表型可塑性和相关的适应性成本

滞育是昆虫进化以使其生命周期与季节性气候变化和资源可用性同步的一种适应。然而，其诱导的线索并不总是很清楚，在某些情况下，可能涉及母体效应。在种群水平上，只有一部分个体可能表现出滞育，对冬季生存产生重要影响。此外，滞育状态的明确指标难以确定。因此，在四种交叉光热状态（16°C 和 8°C，16:8 小时 L : D 和 8: 16 h L: D)，并且在连续 2 代期间。我们分析了木乃伊颜色变化的可靠性，以评估与解剖相比的滞育状态，并测量了寄生蜂的形态和生理特征。我们观察到，与其他模式相比，在低光热模式下，深棕色木乃伊的比例在一代后增加。在 16°C、16:8 小时 L:D 下未记录到滞育，而我们在 8°C、8:16 小时 L:D 下分别观察到 16.2% 和 67.5% 的滞育发生率，第一代和第二代。因此，短日照条件和低温以及母体效应会增加滞育诱导。所有寄生蜂生活史特征（重量、大小、脂肪含量、含水量、产卵量和寿命）都受到光热机制和/或世代的影响。这些结果对诱导滞育所需的环境阈值以及不同环境中市售拟寄生物品系的生存和适应潜力提出了新的问题。本文受版权保护。版权所有。