Severe Global Insect Decline Threatens Ecosystem Collapse

The world is at the cusp of sixth mass extinction, scientists warn, with insects declining at an alarming rate according to a global scientific review.

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More than 40 percent of insect species are declining in numbers, and a third are endangered, the report, "Worldwide decline of the entomofauna: A review of its drivers," which was published this week in the Biological Conservation journal.

The rate of extinction is eight times faster than that of mammals, birds, and reptiles. The total mass of insects is falling by 2.5 percent each year, which suggests a complete annihilation in 100 years.

“The main cause of the decline is agricultural intensification,” said Francisco Sanchez-Bayo from the University of Sydney, Australia, who co-authored the paper on insect extinction with Kris Wyckhuys at the China Academy of Agricultural Sciences in Beijing.

“That means the elimination of all trees and shrubs that normally surround the fields, so there are plain, bare fields that are treated with synthetic fertilizers and pesticides” he said, adding that the decline of insects seems to have kicked off at the beginning of the 1900s, then accelerated during the 1950s and 1960s when farming intensification became a phenomenon post-World War II, and has since reached “alarming proportions” in the past 20 years.

Sanchez-Bayo has said that he believes new classes of insecticides introduced in the last 20 years, including neonicotinoids and fipronil, have been particularly damaging. 

Bugs are essential species for natural habitats as they serve as pollinators for plants, food for other animals and creatures, and they recycle nutrients. Without them, whole ecosystems can collapse. 

"If this food source is taken away, all these animals starve to death,"  Sanchez-Bayo said. “The [insect] trends confirm that the sixth major extinction event is profoundly impacting [on] life forms on our planet. Unless we change our ways of producing food, insects as a whole will go down the path of extinction in a few decades.”

“The repercussions this will have for the planet’s ecosystems are catastrophic, to say the least.”