Nature Studies by Michael McCarthy: Small species: spare parts that matter

An American botanist once suggested to me that I should think of the living plant and animal species of the earth as the parts of a dismantled Boeing 747, laid out on the ground. If 10 per cent of those parts were removed, he said, would you still be happy to fly in the Jumbo Jet, if the plane were put back together without them? Hardly, I said. So by analogy, he said, would you think you were safe on planet Earth with 10 per cent of its parts missing?

I was taken aback; it was one of those moments when somebody offers you an insight, and you find an avenue of new understanding stretching away behind it. He was talking about extinctions, of course, living things disappearing, and how their disappearances might matter; how a single missing part might bring the plane down – or cause terrible trouble for the Earth.

But it's not a widely shared view. Celebrity-obsessed as we are, we care about the big beasts vanishing, the icons – we don't want to lose our whales, our tigers and our polar bears – yet on the whole we are supremely indifferent to the disappearance of much of the rest of the world's wildlife, especially the small things, the amphibians, the smaller plants, the insects, even though many of them are now heading for the exit door so fast that biologists believe we are embarking upon the Sixth Great Extinction. (There appear to have been five great extinctions in the geological record, when much of the Earth's life was wiped out, the last one being 65 million years ago when the asteroid did for the dinosaurs; this sixth one, likely to happen in the 21st century, is being caused by us.)

The indifference I have noticed most keenly has been to insect decline. Over the past few years it has become clear that there has been an immense reduction in insect numbers in Britain, probably because of the pesticides in which our farmland has been drenched, and not to put too fine a point on it, nobody gives a tinker's cuss. Well, why should they? We are mostly stuck in the cultural matrix we grew up with, and people are happier with fewer flies around. Insects are unsympathetic creepy-crawlies in the popular mind, creatures you get rid of with spray cans.

Yet it has long struck me that this decline is so great that it cannot be looked upon complacently, that it is signalling loudly that all's not right with the world. At first, the evidence for it was anecdotal; for example, people began to remark upon the absence of "moth snowstorms", those great clouds of moths which until about 30 years ago you would encounter on a car drive on a warm summer's night, and which would blanket your windscreen by the end of it. They've gone. But then the anecdotal became statistical: in 2004 the agricultural research station at Rothamsted in Hertfordshire analysed 35 years of moth trap records and found that, out of the 337 species of larger moths they examined, more than 200 had declined over the period, nearly 70 of them by more than 50 per cent.

In fact, decline seems to be evident wherever insect population trend data is available, in butterflies, in mayflies (the upwing flies of rivers), in beetles, in bumblebees.

I was so preoccupied with this that a few years ago, over a boozy dinner, I dreamed up with a chum from the RSPB a device called the splatometer, which could be attached to the fronts of cars to register the countless moth and other insect collisions of a summer's night, so you might observe them change over time. (It was trialled, but never got off the ground.)Yet the fact that our insects seemed to be vanishing faster than snowflakes in the desert seemed to bother no one in officialdom, no one in the scientific community – or at least, no one in the policy community – the slightest bit. Until this week.

On Monday, a major set of research projects was launched in London: the insect pollinators initiative. With a budget of £10m, this will explore the reasons for the declines and disappearances of insects with a particularly pivotal role: those which pollinate our plants, our crops, our fruit trees.

Honeybees, declining alarmingly, are the main concern, but the research will also seek to highlight the reasons behind the loss of bumblebees and other pollinators such as solitary bees and hoverflies.

Buzzing from flower to flower in search of nectar, and taking pollen, the plant's male sex cells, with them as they go, insects pollinate at least a third of the range of agricultural crops grown globally, and it has been estimated that the loss of insect pollinators could cost the UK alone £440m per year. Hey! Suddenly insects are not creepy-crawlies any more! They're a vital economic resource! Here are some of the parts of the Jumbo Jet which were left out when it was reassembled, even though most of us continue blithely unconcerned, and are perfectly happy to board the plane.

Could this be a mystery solved?

It is possible that insect decline is behind the loss of several of our bird species, including the two which have gone extinct in the past half-century, an enchanting mini-predator, the red-backed shrike (which fed on big beetles) and the small brown woodpecker, the wryneck (which fed on ants).

It may also be at the root of the disappearance of the house sparrow from our towns and cities (young sparrow chicks are fed on aphids) and of the cuckoo from the countryside (cuckoos feed on big moth caterpillars). Get rid of the small things, and the ramifications never end.

m.mccarthy@independent.co.uk

For further reading

'A World Without Bees', by Alison Benjamin and Brian McCallum (Guardian Books, 2008)