Changes in farming methods are urgently needed to avert a 'catastrophic' loss of insects which could see 40pc of species become extinct in a few decades, a scientific study has warned.
The global review of insect decline warned that the world was witnessing the 'largest extinction event on Earth' for millions of years, in the face of habitat loss, pesticides, disease and invasive species and climate change.
Because of the importance of insects to natural systems and other wildlife, 'such events cannot be ignored and should prompt decisive action to avert a catastrophic collapse of nature's ecosystems', the scientists warned.
The researchers said the intensification of agriculture over the past six decades was 'the root cause of the problem' and that the widespread use of pesticides was having a major impact.
The researchers Francisco Sanchez-Bayo and Kris Wyckhuys said: 'The conclusion is clear: unless we change our ways of producing food, insects as a whole will go down the path of extinction in a few decades.'
They called for habitat restoration, a dramatic reduction in pesticides and changes to agriculture to help insects, such as flower-rich strips planted along the margins of fields, or rotating crops with clover to benefit bumblebees.
A leading Norfolk farming conservationist said farmers were already at the forefront of finding ways to reverse the decline of insects and wildlife – but all parts of society needed to work together to find solutions rather than 'naming and shaming' individual sectors.
Jake Fiennes, conservation general manager at the Holkham Estate and a member of the National Farmers' Union's environment forum, said: 'We can all accept that there has been a decline in insects, whether we gain our information as a result of scientific data or anecdotes,' he said. 'The intensification of agriculture to feed rapidly-growing populations and their demands for low-cost and readily-available food, has a part to play in this.
'Farmers and land managers understand the importance of insects in natural cycles and that diversity and abundance is crucial to the health of the natural environment and food production.
'The balancing of high food production and the conservation of ecosystems is imperative. The British agricultural sector is at the forefront of addressing these issues; constantly looking at ways to improve productivity in harmony with nature.
'We must all work together to find solutions rather than naming and shaming individual sectors. All of us as individuals are responsible and therefore we should unite in finding alternative methods in the production of food that sits harmoniously alongside nature.'
MORE: Pesticide ban could threaten viability of East Anglia's sugar beet industry, farmers toldThe review, published in the journal Biological Conservation, looked at 73 historical reports on insects from around the world, including studies in the UK, and found insects ranging from butterflies and bees to dung beetles were among the most affected.
The study says the biggest driver in insect declines is the loss of habitat and conversion of land to intensive farming and urban areas, followed by pollution, mainly by chemical pesticides and fertilisers.
Insects are also being hit by biological factors, such as pathogens and introduced species, and by climate change, where rising temperatures could affect the range of places where they can live, it says.
Insects are key to functioning natural systems, from providing a food source for other wildlife such as birds, mammals and amphibians, to pollinating plants and recycling nutrients.
Matt Shardlow, chief executive of wildlife charity Buglife, added: 'It is gravely sobering to see this collation of evidence that demonstrates the pitiful state of the world's insect populations.
'There is not a single cause, but the evidence is clear, to halt this crisis we must urgently reverse habitat fragmentation, prevent and mitigate climate change, clean up polluted waters and replace pesticide dependency with more sustainable, ecologically-sensitive farming.'
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