Data from: Artificial light at night may decrease predation risk for terrestrial insects

Artificial light at night (ALAN) is thought to be detrimental for terrestrial insect populations. Whilst there exists evidence for lower abundance under ALAN, underlying mechanisms remain unclear. One mechanism by which ALAN may contribute to insect declines may be through facilitating increased predation. We investigated this by experimentally manipulating insect-substitute abundance under differential levels of light. We used insect-containing birdfeed placed at varying distances from streetlights as a proxy for terrestrial insects, inspecting the rate of predation before and after dusk (when streetlights are respectively off and on). We found that there was a significantly greater effect of increasing distance on predation after dusk, suggesting that predation was actually reduced by greater levels of artificial light. This may occur because ALAN also increases the vulnerability of insectivores to their own predators. Implications for foraging behaviour and alternative explanations are discussed.

夜间人工光照（Artificial Light at Night, ALAN）被认为会对陆生昆虫种群造成损害。尽管已有研究证实夜间人工光照下昆虫丰度有所降低，但其背后的潜在作用机制仍未明确。其中一种潜在机制为，夜间人工光照可通过提升捕食压力加剧昆虫种群衰退。本研究通过在不同光照强度下开展实验，调控昆虫替代物的丰度，对该机制进行了探究。我们采用放置在距离路灯不同距离处的含虫鸟食作为陆生昆虫的替代物，分别在黄昏前后（此时路灯分别处于关闭和开启状态）监测捕食发生速率。结果显示，黄昏后捕食速率随距离增加的影响效应显著更强，这提示较高强度的人工光照实际上会降低捕食发生概率。该现象的成因可能是，夜间人工光照同时会增加食虫动物自身被捕食的风险。本研究还讨论了该结果对觅食行为的启示以及其他可能的解释。