"From our compilation of published scientific reports, we estimate the current proportion of insect species in decline (41 per cent) to be twice as high as that of vertebrates, and the pace of local species extinction (10 per cent) eight times higher, confirming previous findings," they wrote.
The report highlights the ongoing loss of biodiversity as environmental degradation, pollution, over hunting, habitat loss and climate change deplete animal populations to worrying levels.
Humans have wiped out about 60 per cent of the planet's animal life since 1970, according to the latest Living Planet Index.
Due to the high level off species loss, Earth is considered to have entered into its sixth mass extinction event in half-a-billion years as conservationists warn that more needs to be done to protect our environmental systems.
The review of declining insect populations was conducted by Dr Francisco Sánchez-Bayo from the University of Sydney and Kris Wyckhuys from the University of Queensland, and published online this month in the journal Biological Conservation.
Sánchez-Bayo told the Guardian the stakes were seriously high.
"If insect species losses cannot be halted, this will have catastrophic consequences for both the planet's ecosystems and for the survival of mankind," he said.
Insects are considered vital to many of nature's ecosystems for the productive role they play, particularly in controlling populations of other organisms.
They maintain soil structure and fertility, pollinate plants and control insect and plant pests. Many insects feed on dead animals and fallen trees, thereby recycling nutrients back into the soil.
Various insects are also a common food source for larger animals. "If this food source is taken away, all these animals starve to death," Sánchez-Bayo said.
The pair of researchers set out to "systematically assess the underlying drivers" of the drop in insect populations.
The main driver behind the decline, they found, was habitat loss due to intensive agriculture and urbanisation.
They also pointed to the growing use of pollutants, mainly synthetic pesticides and fertilisers, as well as the impact of invasive species and climate change.
"Unless we change our ways of producing food, insects as a whole will go down the path of extinction in a few decades," the report said. "The repercussions this will have for the planet's ecosystems are catastrophic to say the least."
Conservation and biodiversity groups have called on the more careful use of chemical pesticides and fertilisers in agriculture to address the problem.
"A rethinking of current agricultural practices, in particular a serious reduction in pesticide usage and its substitution with more sustainable, ecologically-based practices, is urgently needed to slow or reverse current trends, allow the recovery of declining insect populations and safeguard the vital ecosystem services they provide," the report said.
