Outhwaite said their findings “may only represent the tip of the iceberg”, due to the limited amount of evidence in some areas.
Tom Oliver, professor of applied ecology at the University of Reading, said in a statement that scientists do not yet know when insect populations might reach a tipping point, where their losses would be too great to be sustained. overcome.
“When it comes to a potential tipping point where the loss of insects causes entire ecosystems to collapse, the honest answer is that we just don’t know when the point of no return is,” Oliver said. , who did not participate in the study. “We know you can’t continue to lose cash without ultimately causing a catastrophic outcome.”
He likened the gradual loss to pulling rivets out of an airplane, which you can’t keep doing “without it eventually falling out of the sky.”
The researchers defined high-intensity agriculture as the type characterized by the use of chemical pesticides or fertilizers, low crop diversity, large field sizes, or high livestock density, among others – all of which are relatively common features of modern agriculture.
And, scientists say, extreme land use is having a combined effect with the climate crisis. The destruction of natural habitats for agriculture can significantly change the local climate of the region and trigger extreme temperatures. The researchers found substantial declines in insect populations in regions of the world that are much warmer, particularly in the tropics, where Outhwaite noted alarming reductions in insect biodiversity.
The researchers analyzed data from a 20-year period for more than 6,000 sites and studied nearly 18,000 species of insects, including butterflies, moths, dragonflies, grasshoppers and bees.
They concluded that in areas with low-intensity agriculture, less global warming and nearby natural habitat, insects declined by only 7%, compared to 63% in areas with less natural habitat cover. . Many insects depend on plants for shade on sweltering days – the loss of nearby natural habitats could make them more exposed and vulnerable to warming temperatures. And as climate change progresses, scientists say these natural buffers may become less effective.
“Whether these remaining insects can continue to support ecosystem functioning or eventually go extinct on their own remains an open question,” Oliver said. “Under the precautionary principle, however, it would be best to act now so that we never discover ecosystem collapse by experiencing it.”