Low Levels of Artificial Light at Night Strengthen Top-Down Control in Insect Food Web
Low Levels of Artificial Light at Night Strengthen Top-Down Control in Insect Food Web
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DOI：
10.1016/j.cub.2018.05.078
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发表时间：
2018-08-06
期刊：
影响因子：
9.2
通讯作者：
Gaston, Kevin J.
中科院分区：
文献类型：
--
作者：
Sanders, Dirk;Kehoe, Rachel;Gaston, Kevin J.
人造光改变了地球大片地区的夜间环境，88%的欧洲和近50%的美国经历了光污染的夜空[1]。对生态系统的影响从暴露在直接光源附近的高光强，到更远的非常广泛但较低的光照水平[2]。虽然已知物种对人工夜间照明表现出一系列的生理和行为反应[例如，3-5]，但有必要从机制上了解整个生态群落的影响[6，7]，特别是对不同光照强度的影响。利用昆虫群落的中观野外实验，我们确定了从0.1到100勒克斯的人工光强度对不同营养水平和物种之间相互作用的影响。引人注目的是，我们发现在低水平的人工照明(0.1到5勒克斯)下影响最大，这导致总体上蚜虫密度减少了1.8倍。从机理上讲，夜间人工光照提高了寄生蜂攻击蚜虫的效率，在弱光下的寄生率是未光照对照的两倍。然而，在较高的光照水平下，寄生蜂离开蚜虫寄主植物的时间更长，从而削弱了这种提高的效率。因此，与较低的光照水平相比，在较高的光照强度下，蚜虫的密度达到较高的水平，而较高的寄生效率限制了它们的密度。我们的研究强调了不同强度的人造光在推动物种相互作用和生态系统功能方面的重要性。
Artificial light has transformed the nighttime environment of large areas of the earth, with 88% of Europe and almost 50% of the United States experiencing light-polluted night skies [1]. The consequences for ecosystems range from exposure to high light intensities in the vicinity of direct light sources to the very widespread but lower lighting levels further away [2]. While it is known that species exhibit a range of physiological and behavioral responses to artificial nighttime lighting [e.g., 3-5], there is a need to gain a mechanistic understanding of whole ecological community impacts [6, 7], especially to different light intensities. Using a mesocosm field experiment with insect communities, we determined the impact of intensities of artificial light ranging from 0.1 to 100 lux on different trophic levels and interactions between species. Strikingly, we found the strongest impact at low levels of artificial lighting (0.1 to 5 lux), which led to a 1.8 times overall reduction in aphid densities. Mechanistically, artificial light at night increased the efficiency of parasitoid wasps in attacking aphids, with twice the parasitism rate under low light levels compared to unlit controls. However, at higher light levels, parasitoid wasps spent longer away from the aphid host plants, diminishing this increased efficiency. Therefore, aphids reached higher densities under increased light intensity as compared to low levels of lighting, where they were limited by higher parasitoid efficiency. Our study highlights the importance of different intensities of artificial light in driving the strength of species interactions and ecosystem functions.