Data from: Night warming on hot days produces novel impacts on development, survival and reproduction in a small arthropod

1. An asymmetric increase of nighttime temperatures on hot days is one of the main features of global climate change. But the biological effects of an increased nighttime temperature combined with high daytime temperature are unclear. 2. We used six thermal regimens to simulate nighttime temperatures on hot days and investigated the effects of night warming on life history traits of the English grain aphid Sitobion avenae. Experimental temperatures fluctuated in continuous diurnal cycles, increasing from 27 °C to a maximum 35 °C and then declining to 27 °C gradually before further dropping to different minima (13, 16, 19, 21, 23 or 25 °C) representing nighttime temperatures. 3. When compared to expectations based on constant temperatures, night warming raised the optimum temperature for development by 3 °C, in contrast to results from experiments where temperature variability was altered symmetrically or in a parallel manner. Night warming also reduced aphid survival under heat from 75% to 37%, and depressed adult performance by up to 50%. Overall, night warming exacerbated the detrimental effects of hot days on the intrinsic rate of population increase, which was predicted to drop by 30% when nighttime minimum temperatures exceeded 20 °C. 4. Our novel findings on development challenge the ‘Kaufmann effect’, suggesting this is inapplicable to night warming likely to be encountered in nature. Although many average temperature models predict increasing pest outbreaks, our results suggest that outbreaks of some species might decrease due to the effects of night warming on population dynamics.

1. 高温日夜间温度的非对称性升高是全球气候变化的主要特征之一。但夜间升温与日间高温共同作用所产生的生物学效应仍不明确。
2. 本研究设置6种温度处理方案以模拟高温天的夜间温度条件，探究夜间升温对麦长管蚜（English grain aphid, Sitobion avenae）生活史性状的影响。实验温度以连续昼夜周期波动：从27 ℃升至峰值35 ℃，随后逐渐回落至27 ℃，再进一步下降至13、16、19、21、23或25 ℃等不同最低温度，以此代表夜间环境温度。
3. 与基于恒温条件的预期结果相比，夜间升温使昆虫发育的最适温度升高了3 ℃，这与温度波动呈对称或平行变化的实验结果形成鲜明对比。夜间升温还将蚜虫的耐热存活率从75%降至37%，并使成虫的综合性能降低多达50%。总体而言，夜间升温加剧了高温日对种群内禀增长率的不利影响：当夜间最低温度超过20 ℃时，种群内禀增长率预计将下降30%。
4. 我们关于发育的全新发现对“考夫曼效应（Kaufmann effect）”提出了质疑，表明该效应或许并不适用于自然界中可能出现的夜间升温情境。尽管多数基于平均温度的模型预测害虫种群暴发频次会增加，但本研究结果显示，部分物种的种群暴发可能因夜间升温对种群动态的影响而减少。