Light pollution may not be the leading cause of insect declines – but we must still take action

It has been hard to escape media reports of plummeting insect populations over recent years (so-called ‘insect Armageddon’). Of course, the picture is far more uncertain and nuanced than newspaper headlines suggest (shocker!). Nonetheless, there is solid evidence of worrying long-term declines in insect numbers for some parts of the world. This is extremely concerning, not least because insects are the glue that holds the natural world together.

Given we often lack even the most basic data on insect populations, it will come as no surprise that our understanding of the factors that are causing declines is far from complete. But they are likely to be numerous and complex.

For biodiversity loss globally, conservation groups have traditionally recognised five key threats: habitat change (ranging from its complete removal through to more subtle degradation effects), species overexploitation (fishing, hunting), invasive species and diseases, climate change, and pollution (which usually refers to chemicals, including pesticides and fertiliser).

But as often turns out to be the case, reality can be more complicated (or even quite different) to long-held conventional wisdom. Some potential causes of wildlife declines appear to have been overlooked historically, or at least, their impacts have gone largely unstudied.

One of these neglected areas is undoubtedly the consequences of the surge in artificial lighting.

A pervasive human influence: satellites images highlight the extent of artificial lighting. Image: Tim Peake/ESA/NASA (continental Europe and UK shown, 2016).

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