Global Insect Numbers in Catastrophic Decline Warns New Study

Urgent action is needed to avoid mass extinction.
Jessica Miley

A new study tells the catastrophic story of the world's massive decline in insect numbers. Two Australian scientists have looked into the drivers behind the devastating losses with their results published in the April edition of Biological Conservation.


The study warns that more than 40% of insect species could become extinct in the next few decades if behaviors aren’t quickly changed. World insect biomass is disappearing a rate of 2.5% a year.

Mass extinctions loom 

If these devastating numbers continue, there is likely to be widespread extinctions with a century. Insects are a key part of the earth's ecosystems, and any insect extinctions can have massive knock-on effects for fragile food chains.

The report is a collaboration between two Australian universities and the Chinese Academy of Agricultural Sciences. It reviewed dozens of existing reports on insect decline published over the past three decades and looked for patterns in the reasons behind the decrease in insect population numbers.

Importance of insects can't be overlooked

Lead author of the study, Francisco Sanchez-Bayo, of the School of Life and Environmental Sciences at the University of Sydney, said it is the first truly global examination of the issue. This study exclusively looked at the populations of insects to draw attention to the critical role they play in interconnected ecosystems and the food chain.


While small and at times annoying the importance of insects can't be overlooked, especially as bugs make up around 70% of all animal species. 

The loss of so many insects can be attributed to multiple reasons including "habitat loss and conversion to intensive agriculture and urbanization," pollution, particularly from pesticides and fertilizers, as well as biological factors, such as "pathogens and introduced species" and climate change.

Insects play an essential role across foodchain

The report describes insects as "the structural and functional base of many of the world's ecosystems since their rise ... almost 400 million years ago." The loss of insects affects the ecosystem in several ways.

First, if one species of insects decline, more dominant species may colonize their place, this might have an impact on agricultural areas as well as other plant populations. 80% of wild plants rely on insects for pollination.

Insects are also an important food source; their diminishing numbers affects not only those that eat them as a primary source such as birds but the animals further up the food chain that rely on those below. The report calls for urgent and radical action to stop the decline.

Urgent action needed

"Because insects constitute the world's most abundant and (species-diverse) animal group and provide critical services within ecosystems, such events cannot be ignored and should prompt decisive action to avert a catastrophic collapse of nature's ecosystems," they wrote

The report's authors suggest agricultural methods need an immediate review with a particular emphasis on reducing the number of pesticides.