Zahra Akkerhuys reports on a crisis in the insect world . . .

It's a fact that without insects humankind would not exist. They may individually appear insignificant but en masse their role in eco-systems across the globe must not be underestimated.

But a crisis is looming in the insect world as some of Britain's smallest creatures, which for generations have been so common in the countryside, head towards extinction because their habitat is under threat.

Chris O'Toole, based at the Hope Entomological Collections at Oxford's University Museum, warns that entire eco-systems are in danger of collapsing if the number of insects continues to decline at its current rate.

A recent survey by English Nature has found that overall, seven per cent of Britain's native insect population has become extinct over the past century.

And some studies show that the insect population has dwindled by up to 20 per cent in recent years in some parts of the country.

Mr O'Toole says a change in modern farming methods and a decline in the number of wild flowers scattered across the country are largely to blame for the critical situation. The increased use of pesticides in agriculture is thought to play only a negligible role.

Bumblebees and butterflies in particular are prime examples of groups in decline. Until 20 years ago, all five species of bumblebees were relatively common in this country. However, the past two decades have seen such a sharp decline in the number of Bombus subterraneus bees that they are now extinct.

Mr O'Toole says that particular species of bee became extinct because the species could not find an adequate source of the pollen they needed.

The large garden bumblebee, Bombus ruderatus, is also in danger for the same reason.

Mr O'Toole, who is currently researching the diversity of bees in the Middle East, says: "Britain's insect population is one of the best recorded in the world and it has become apparent that some groups have gone into severe decline.

"Bees have an obligate relationship with flowers. They require a diversity of flowers but modern agriculture methods have brought about a large decline of the country's flora.

"The Bombus subterraneus, a long-tongued species which gathered pollen from yields in particular from red clover.

"Farmers nowadays are concentrating more on growing silage."

Many different species are finding their natural habitat under constant attack. For centuries they have been able to live and breed in hedgerows and pockets of rural England.

However, a total of 160,000 miles of hedgerows have been lost since the end of the Second World War. And the efficiency of modern farming equipment means that farmers are now able to cultivate practically every inch of their land, no longer leaving pockets of uncultivated land where the plough is unable to reach.

The Government has stepped in to halt further decline and protect the wildlife that is left. It is no longer legal to destroy hedgerows and grants are being awarded to those farmers who replant those that are lost.

Mr O'Toole explains: "The amount of hedgerow that has been lost has major ramifications for the eco-system.

"There always used to be areas of land where the plough could not reach and they used to be breeding sites for a range of insects. However, all that has changed through the development of modern machinery which can go into corners. A number of schemes aimed at encouraging farmers to be more aware of the impact of their methods on the ecological system are being introduced.

"It is vital that the decline is halted now, because in a few years it will be too late.

"We rely on insects for a range of services. If it weren't for them we could end up being knee-deep in corpses and dung which have to be prepared by insects before the process of decomposition, helped along by bacteria and fungi, can start."