Pesticide use is driving an “alarming” decline in the world’s insects that could have a “catastrophic” impact on nature’s ecosystems, researchers have warned.

More than 40 per cent of insect species are at risk of extinction with decades, with climate change and pollution also to blame, according to a global scientific review.

Their numbers are plummeting so precipitously that almost all insects could vanish within a century, the study found.

An overhaul of the agricultural industry is “urgently needed” to “allow the recovery of declining insect populations and safeguard the vital ecosystem services they provide,” wrote co-authors from Sydney and Queensland universities.

The biologists conducted a systematic review of 73 historic reports of insect declines across the world.

Insects at risk of extinction Show all 12 1 /12 Insects at risk of extinction Insects at risk of extinction Wasps Wasps are of the order Hymenoptera, one of the most at risk Getty Insects at risk of extinction Dragonflies Dragonflies are of the order Odonata, one of the most at risk Getty Insects at risk of extinction Bees Bees are of the order Hymenoptera, one of the most at risk Getty Insects at risk of extinction Butterflies Butterflies are of the order Lepidoptera, one of the most at risk Getty Insects at risk of extinction Ants Ants are of the order Hymenoptera, one of the most at risk Getty Insects at risk of extinction Dung Beetles Two dung beetles making an effort to roll a ball through gravel Getty Insects at risk of extinction Caddisflies Caddisflies make up the order Trichoptera, one of the most at risk Getty Insects at risk of extinction Stoneflies Stoneflies are of the order plecoptera, one of the most at risk Getty Insects at risk of extinction Saw-Flies Saw-Flies are of the order Hymenoptera, one of the most at risk Getty Insects at risk of extinction Moths Moths are of the order Lepidoptera, one of the most at risk Getty Insects at risk of extinction Damselfly Damselflies are of the order Odonata, one of the most at risk Getty Insects at risk of extinction Mayflies Mayflies are of the order Ephemeroptera, one of the most at risk Getty

Ten per cent of known insect species have already become extinct, compared to one per cent of vertebrates, they found. Of the insects that remain, 41 per cent are in decline.

Over the past 30 years, the total mass of all insects dropped an average of 2.5 per cent annually. The “dramatic” fall suggest none will be left in 100 years, warned Francisco Sanchez-Bayo, of the University of Sydney’s School of Life and Environmental Sciences.

“The rate of decline is really huge,” he told BBC Radio 4’s Today.

Butterflies and moths are among the worst affected, along with bees and dung beetles. Researchers said “a considerable proportion” of aquatic fly species had also been lost already.

The review highlighted four key drivers of extinction: habitat loss caused by agriculture, urbanisation and deforestation; pollution; biological factors such as invasive species and diseases; and climate change.

Agriculture was the “main culprit” in 40 per cent of the studies reviewed, with researchers highlighting “the way we apply pesticides” as a particular threat.

“We have been doing agriculture for thousands of years and we have never seen these declines,” said Dr Sanchez-Bayo. “The introduction of systemic insecticides has been in a big change in the way we do agriculture these days.”

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The review, published in the journal Biological Conservation, said: “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.”

Researchers added dwindling insect populations were further evidence of a sixth mass extinction underway among animal and plant species worldwide.