Animal senses and signals are amazingly diverse, and the major modalities by which animals acquire sensory input from their environments are sound, light, vibration, and chemical signals. Insects mainly rely on visual, nociceptive, and olfactory cues to discriminate between rewards and risks. It has been shown that the visual and olfactory cues of predators substantially affect the adult phenotype in Drosophila melanogaster (Krams et al. 2016), a prominent animal model for biological research. A recent study has found that fruit flies can rely solely on vision in predator detection (de la Flor et al. 2017). However, the olfactory system of D. melanogaster is also highly developed and can be efficiently used in parasitoid (Ebrahim et al. 2015) and predator detection. Relying on olfaction as an additional sensory modality is adaptive because fruit flies may be active under conditions of low light when vision is limited as an antipredator tool (Izutsu et al. 2016). In this study, we investigated whether the larvae of D. melanogaster respond to chemical cues of spiders by changing adult body mass and stoichiometry of body nitrogen (N) and carbon (C) in a similar way as it occurs in the presence of a real spider (Krams et al. 2016). The general stress paradigm (GSP) states that predator exposure generally increases the production of glucocorticosteroids in prey. Predator-induced stress generally causes oxidative stress and induces glucogenesis, which in turn increases metabolic rate, raising the overall demand for carbohydrate-based fuel and shifting the metabolic balance away from the anabolism that produces the nitrogen-rich (N) proteins necessary for growth (Hawlena and Schmitz 2010; Trakimas et al. 2019). These complex processes generally increase the C/N ratio (Hawlena and Schmitz 2010). However, D. melanogaster fruit flies reared together with spiders have a high concentration of body N and lower body mass, while their body C remains the same as fruit flies in the control group. Based on the results of Krams et al. (2016), we predicted higher N in flies reared with spiders and in flies grown in the presence of olfactory cues from spiders (but in absence of actual spiders), relative to flies in the control group. Methodological details can be found in the Supplementary materialsSupplementary materials.

中文翻译：

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蜘蛛气味引起果蝇果蝇的化学计量变化

动物的感觉和信号异常丰富，动物从环境中获取感官输入的主要方式是声音，光，振动和化学信号。昆虫主要依靠视觉，伤害和嗅觉来区分奖励和风险。研究表明，捕食者的视觉和嗅觉提示会严重影响果蝇（Drosophila melanogaster）的成年表型（Krams et al.2016），这是生物学研究的重要动物模型。最近的一项研究发现果蝇在捕食者检测中可以完全依靠视觉（de la Flor et al.2017）。然而，嗅觉系统的果蝇它也是高度发达的，可以有效地用于拟寄生物（Ebrahim et al。2015）和捕食者检测。依靠嗅觉作为一种额外的感觉方式是适应性的，因为当视力受到限制时，果蝇可能会在光线不足的情况下活跃（Izutsu等人，2016）。在这项研究中，我们调查了D. melanogaster的幼虫是否通过改变成年人的体重以及人体氮（N）和碳（C）的化学计量来响应蜘蛛的化学线索，其方式与在真实蜘蛛存在下发生的方式类似（Krams等人2016）。一般应激范式（GSP）指出，捕食者接触通常会增加猎物中糖皮质激素的产生。捕食者引起的应激通常会引起氧化应激并引起糖异生，进而增加代谢率，提高了对以碳水化合物为基础的燃料的总体需求，并使代谢平衡从合成代谢转变为产生生长所需的富氮（N）蛋白（Hawlena and Schmitz 2010; Trakimas et al.2019）。这些复杂的过程通常会提高C / N比（Hawlena和Schmitz，2010年）。但是，D。melanogaster与蜘蛛一起饲养的果蝇体内N含量较高，体重较低，而其C体与对照组的果蝇相同。根据Krams等的结果。（2016），我们预测与对照组相比，在蜘蛛饲养的果蝇以及存在来自蜘蛛的嗅觉提示下生长的果蝇（但没有实际的蜘蛛）中的氮含量更高。方法学细节可在补充材料补充材料中找到。