Over 40 per cent of insect species could go extinct in the next few decades, with butterflies, bees and dung beetles most affected. The main cause is habitat loss. That鈥檚 the alarming conclusion of a review of all long-term surveys of insects published in the past 40 years.
鈥淭he repercussions this will have for the planet鈥檚 ecosystems are catastrophic to say the least, as insects are at the base of many of the world鈥檚 ecosystems,鈥� says the paper, by Francisco Sanchez-Bayo at the University of Sydney, Australia, and Kris Wyckhuys at the China Academy of Agricultural Sciences in Beijing.
The study is a major step forward, says ecologist Georgina Mace of University College London. But there are still huge gaps in our knowledge, she says. 鈥淚 don鈥檛 think it gives us the detailed information we need to really assess the consequences.鈥�
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What鈥檚 more, while it has been presented as a global study, almost all of the 73 studies reviewed were done in Europe and the US. For the entire continents of South America and Africa, for instance, the reviewers could find just one relevant study from Brazil and one from South Africa.
鈥淭he information presented here refers mostly to developed countries of Europe and North America since those regions have the most comprehensive historical records,鈥� says the paper. So for huge parts of the planet, we simply do not know how insects are faring.
This is probably聽unlikely to be good news, though. 鈥淎ctually the situation for tropical invertebrates is worse now than for temperate ones,鈥� says Mace. 鈥淭he review could be underestimating the situation in the tropics.鈥�
According to the studies reviewed, the single largest cause of the decline in insects is habitat loss. Next up is pollution, from the pesticides and fertilisers used on farms to聽emissions from factories and cities.
Parasites and diseases are also playing a role. For instance, the spread of the varroa mite is contributing to the decline of honeybees, though honeybees themselves are an introduced species in many parts of the world.
Finally, climate change also appears to be playing a part. Insects in tropical regions may have a narrow tolerance for temperatures, and may already suffering declines as a result of global heating.
Biological Conservation
