Tim Newbold, UCL and Charlie Outhwaite, UCL

Speed read

• The world may be facing a devastating “hidden” collapse in insect species due to the twin threats of climate change and habitat loss.
• UCL’s Centre for Biodiversity & Environment Research has carried out one of the largest-ever assessments of insect declines around the world – assessing three-quarters of a million samples from around 6,000 sites.
• The new study, published in Nature, finds that climate-stressed farmland possesses only half the number of insects, on average, and 25% fewer insect species than areas of natural habitat.
• Insect declines are greatest in high-intensity farmland areas within tropical countries – where the combined effects of climate change and habitat loss are experienced most profoundly.
• The majority of the world’s estimated 5.5 million species are thought to live in these regions – meaning the planet’s greatest abundances of insect life may be suffering collapses without us even realising.
• Lowering the intensity of farming by using fewer chemicals, having a greater diversity of crops and preserving some natural habitat can mitigate the negative effects of habitat loss and climate change on insects.
• Considering the choices we make as consumers – such as buying shade-grown coffee or cocoa – could also help protect insects and other creatures in the world’s most climate-vulnerable regions.

Long read

Insects are critical to the future of our planet. They help to keep pest species under control and break down dead material to release nutrients into the soil. Flying insects are also key pollinators of many major food crops, including fruits, spices and – importantly for chocolate lovers – cocoa.

The growing number of reports suggesting insect numbers are in steep decline is therefore of urgent concern. Loss of insect biodiversity could put these vital ecological functions at risk, threatening human livelihoods and food security in the process. Yet across large swathes of the world, there are gaps in our knowledge about the true scale and nature of insect declines.

Most of what we do know comes from data collected in the planet’s more temperate regions, especially Europe and North America. For example, widespread losses of pollinators have been identified in Great Britain, butterflies have experienced declines in numbers of between 30 and 50% across Europe, and a 76% reduction in the biomass of flying insects has been reported in Germany.

Information on insect species numbers and their abundance in the tropics (the regions either side of the Equator including the Amazon rainforest, all of Brazil, and much of Africa, India and Southeast Asia) is far more scarce. Yet the majority of the world’s estimated 5.5 million insect species are thought to live in these tropical regions – meaning the planet’s greatest abundances of insect life may be suffering calamitous collapses without us even realising.

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