In recent years, scientists have been warning us about the disappearance of a type of creature we think we wouldn’t miss much – but the dramatic fall of insect numbers across the world has been driven into sharp focus by a new report which warns of a “catastrophic” collapse of natural ecosystems.
A newly published review of 73 reports on insect decline around the world has found that over 40 percent of insect species are threatened with extinction. For some comparison, that rate of local species extinction is eight times faster than we’re seeing in vertebrates such as mammals, birds, and reptiles.
Insects play a crucial role in the animal food chain, as well as pollinating plants and recycling nutrients in the environment. If they go, they take other animals with them, and that’s a major problem in maintaining a world we can all live in.
“Our work reveals dramatic rates of decline that may lead to the extinction of 40 percent of the world’s insect species over the next few decades,” write study authors Francisco Sánchez-Bayo from The University of Sydney and Kris Wyckhuys from the University of Queensland.
According to the researchers, the main driver of this massive decline is habitat loss due to our increasingly intensive agriculture practices, including heavy pesticide use.
Drawing data from 73 historical reports, mostly from Europe and North America, the pair found that the “biodiversity of insects is threatened worldwide.”
“Unless we change our ways of producing food, insects as a whole will go down the path of extinction in a few decades,” write the researchers. ”The repercussions this will have for the planet’s ecosystems are catastrophic to say the least.”
As land is farmed more aggressively, the researchers note, insect habitats have been obliterated – with bare fields replacing areas of vegetation. The team also points out increased urbanisation, climate change, pollution and a rise in invasive species that prey on insects as additional contributing factors.
When it comes to the contribution of climate change in particular, the authors note that warming temperatures in temperate regions might benefit some species, but in tropical regions insects have little tolerance for increased heat, and would thus be hit harder.
“Global warming has increased the populations of certain butterflies in northern Europe, expanded their geographical distribution and caused altitudinal shifts of certain species, yet populations of half of the world’s insects are declining counter to that trend,” they write.
The analysis revealed that specialist butterflies and moths are some of the most affected populations, with animals that feed on insects likely to be the first to be impacted – birds, reptiles, amphibians, and fish.
While there are gaps in the research in terms of figures for some kinds of insects, the study authors say there’s no reason to believe any insect species are bucking the overall trend. A small number of species may end up thriving though, as their insect enemies disappear, particularly bugs like cockroaches and houseflies.
“The evidence all points in the same direction,” biologist and conservationist Dave Goulson from the University of Sussex in the UK, who wasn’t involved in the research, told Damian Carrington at The Guardian.
“It should be of huge concern to all of us, for insects are at the heart of every food web, they pollinate the large majority of plant species, keep the soil healthy, recycle nutrients, control pests, and much more. Love them or loathe them, we humans cannot survive without insects.”
We’ve heard warnings about this before: a report published last year found insect numbers plummeting in several pockets of the world. Now it’s clear that the issue is a widespread one that needs addressing urgently.
In fact, this alarming development is part of what scientists are calling a modern mass extinction: a substantial drop in species numbers across all kinds of animals and plants, the size of which we’ve only seen five times in the last four billion years.
Whereas previous mass extinctions have been caused by ice ages and volcanic eruptions, this one is going to be largely down to human activity, scientists say – and we can include insects in that assessment.
Unless we start seriously limiting our impact on the planet, the future looks very bleak indeed. The researchers are calling for a massive change to our agricultural practices before it’s too late.
The research has been published Biological Conservation.