A new study published in the journal Biological Conservation, reports that insect populations are declining precipitously worldwide due to "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.
More than 40% of insect species could become extinct in the next few decades, according to the report, titled "Worldwide decline of the entomofauna: A review of its drivers".
Insect biomass is declining by a staggering 2.5% a year, a rate that indicates widespread extinctions within a century, the report found.
In addition to the 40% at risk of dying out, a third of species are endangered - numbers that could cause the collapse of the planet's ecosystems with a devastating impact on life on Earth.
The report, co-authored by scientists from the universities of Sydney and Queensland and the China Academy of Agricultural Sciences, looked at dozens of existing reports on insect decline published over the past three decades, and examined the reasons behind the falling numbers to produce the alarming global picture.
Its lead author, Francisco Sanchez-Bayo, of the School of Life and Environmental Sciences at the University of Sydney, called the study the first truly global examination of the issue.
The report also noted that while large numbers of specialist insects — which fill a specific ecological niche, and general insects were declining — a small group of adaptable insects were seeing their numbers rise, but nowhere near enough to arrest the decline.