There have been warning signs for years about plummeting insect populations worldwide, but the extent of the potentially “catastrophic” crisis had not been well-understood — until now.
The first global scientific review of insect population decline was published this week in the journal Biological Conservation and the findings are “shocking,” its authors said.
More than 40 percent of insect species are dwindling globally and a third of species are endangered, concluded the peer-reviewed study, which analyzed 73 historical reports on insect population declines.
Chillingly, the total mass of insects is falling by 2.5 percent annually, the review’s authors said. If the decline continues at this rate, insects could be wiped off the face of the Earth within a century.
“It is very rapid. In 10 years you will have a quarter less, in 50 years only half left and in 100 years you will have none,” study co-author Francisco Sánchez-Bayo, an environmental biologist at the University of Sydney, Australia, told The Guardian.
“If insect species losses cannot be halted, this will have catastrophic consequences for both the planet’s ecosystems and for the survival of mankind,” Sánchez-Bayo added.
Scientists have warned that a human-caused sixth mass extinction is now underway on Earth. Vertebrate species, both on land and under the sea, are threatened at a global scale because of human activities.
But according to the new review, the proportion of insects in decline is currently twice as high as that of vertebrates and the insect extinction rate is eight times faster than that of mammals, birds and reptiles.
Insects play a profoundly important role in Earth’s ecosystems. They are a food source for many animals, are critical pollinators and recycle nutrients back into the soil.
In a November New York Times report about a possible “insect apocalypse,” scientists were asked to imagine a world with no insects.
They found “words like chaos, collapse, Armageddon,” the Times wrote. ”[One entomologist] describes a flowerless world with silent forests, a world of dung and old leaves and rotting carcasses accumulating in cities and roadsides, a world of ‘collapse or decay and erosion and loss that would spread through ecosystems.’”
According to the new scientific review, habitat loss because of intensive agriculture is the top driver of insect population declines. The heavy use of pesticides, climate change and invasive species were also pinpointed as significant causes.
“Unless we change our ways of producing food, insects as a whole will go down the path of extinction in a few decades,” the review’s co-authors wrote. “The repercussions this will have for the planet’s ecosystems are catastrophic to say the least.”