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Insects Are In 'Catastrophic' Decline Worldwide, Scientists Warn

More than 40 percent of insects are at risk of extinction within 100 years.

by Becky Ferreira
Feb 11 2019, 5:49pm

Monarch butterfly. Image: Simon Koopman

Insect populations are collapsing worldwide and may vanish within a century, according to new research.

More than 40 percent of insects are at risk of extinction within the 21st century as a result of human pressures such as habitat loss, invasive species, pesticide pollution, and climate change, says the analysis published in Biological Conservation.

“Unless we change our ways of producing food, insects as a whole will go down the path of extinction in a few decades,” warned Francisco Sánchez-Bayo, an entomologist at the University of Sydney, and Kris Wyckhuys, an insect ecologist at the China Academy of Agricultural Sciences, who authored the new study. “The repercussions this will have for the planet’s ecosystems are catastrophic to say the least.”

As key species in global food webs, insects play a major role in natural ecosystems and agriculture, both of which humans rely on for food and survival. Without pollinators such as bees, ants, and butterflies, major cash crops will not be able to grow.

Insects are also crucial to the diets of many birds, fish, and mammals that humans eat. Losing them could reduce the world’s food supply, and cause other ecological ripple effects.

Scientists have been raising red flags about the downward spiral of insect populations for decades. Sánchez-Bayo and Wyckhuys synthesized information from 73 of these previous reports about insect declines to estimate the rate at which insects are disappearing as a whole.

The team found that the world’s total insect biomass is decreasing at a rate of 2.5 percent per year—eight times the pace of decline for mammal, bird, and reptile populations. This trend suggests bugs could be virtually wiped out in 100 years, which should be “alarming,” the team said.

“We wanted to really wake people up,” Sánchez-Bayo told the Guardian. “It is a big concern.”

Insect populations started declining in the 20th century, and have been rapidly falling since the 1950s. The families suffering the biggest drops on land are Lepidoptera (butterflies and moths), Hymenoptera (including bees and ants), and Coleoptera (dung beetles). Aquatic species such as stoneflies, mayflies, and dragonflies are also experiencing serious losses.

The study lays the bulk of the blame on industrial agriculture, which has caused widespread habitat loss and has saturated wild and farmed environments with insect-killing pesticides.

“The main cause of the decline is agricultural intensification,” Sánchez-Bayo said. “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 fertilisers and pesticides.”

Read More: Colony Collapse Disorder Is Spreading to Wild Bees

Invasive species and disease are also factors, as is climate change. Warming temperatures have caused devastating insect collapses in Puerto Rico, for instance, which lost 98 percent of its ground rainforest bugs in just 35 years.

Insects have been on Earth for more than 400 million years, and are a core food source for countless animals and even some plants—not to mention their central role in crop reproduction.

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