Scanning the sky with his binoculars, he searches carefully for any sign of movement: the steady beat of a blackbird's wings, the fluttering of a flock of starlings. It has been a week now since he saw the starlings: just four of them flitting from tree to tree, feasting on the autumn berries.
Birds are a real rarity these days. In his boyhood, he recalls, he would watch
the acrobatics of entire flocks as they ducked and dived after insects. But
now the skies are silent, barring the hum of the odd airplane. Turning back
to his fruit and vegetable patch, he continues the laborious task of
pollinating the raspberry plants by hand, gently brushing pollen onto the
slender stigmas inside the flowers. In the past, bees, wasps, butterflies
and flies would have done this job for him; nowadays such insects are
likewise a rarity. Farmers instead resort to robot bees to pollinate their
crops: tiny motors, encased in fuzzy fabric, which hover from flower to
Will this bleak outlook be a reality for future generations? It is nearly 50
years since Rachel Carson wrote Silent Spring, the book that warned of
environmental damage the pesticide DDT was causing. Today, DDT use is banned
except in exceptional circumstances, yet we still don't seem to have taken
on board Carson's fundamental message.
According to Henk Tennekes, a researcher at the Experimental Toxicology
Services in Zutphen, the Netherlands, the threat of DDT has been superseded
by a relatively new class of insecticide, known as the neonicotinoids. In
his book The Systemic Insecticides: A Disaster in the Making, published this
month, Tennekes draws all the evidence together, to make the case that
neonicotinoids are causing a catastrophe in the insect world, which is
having a knock-on effect for many of our birds.
Already, in many areas, the skies are much quieter than they used to be. All
over Europe, many species of bird have suffered a population crash. Spotting
a house sparrow, common swift or a flock of starlings used to be
unremarkable, but today they are a more of an unusual sight. Since 1977,
Britain's house-sparrow population has shrunk by 68 per cent.
The common swift has suffered a 41 per cent fall in numbers since 1994, and
the starling 26 per cent. The story is similar for woodland birds (such as
the spotted flycatcher, willow tit and wood warbler), and farmland birds
(including the northern lapwing, snipe, curlew, redshank and song thrush).
Ornithologists have been trying desperately to work out what is behind these
rapid declines. Urban development, hermetically sealed houses and barns,
designer gardens and changing farming practices have all been blamed, but
exactly why these birds have fallen from the skies is still largely
However, Tennekes thinks there may be a simple reason. "The evidence
shows that the bird species suffering massive decline since the 1990s rely
on insects for their diet," he says. He believes that the insect world
is no longer thriving, and that birds that feed on insects are short on
So what has happened to all the insects? In the Nineties, a new class of
insecticide – the neonicotinoids – was introduced. Beekeepers were the first
people to notice a problem, as their bees began to desert their hives and
die, a phenomenon known as Colony Collapse Disorder (CCD).
The first cases were in France in 1994, but the epidemic quickly fanned out
across Europe, and by 2006 CCD reached the US too. Between 2006 and 2009 one
third of American beekeepers reported cases of colony collapse. Aside from
the loss of revenue in honey sales, this is worrying news because honey bees
are one of the world's most important pollinators, and 35 per cent of
agricultural crops rely on pollinators.
As a service, pollination is worth an estimated £440m a year to the UK economy
and a staggering $15bn (£9.3bn) to US farmers. And it isn't just the Western
world that is affected: in China the lack of bees has become so serious that
farmers in some regions are already resorting to pollinating their crops by
Controversy has swirled around the issue, with everything from mobile phones
to GM crops being held to blame. The key contenders include parasites, viral
and fungal infections, and insecticides.
Last month the problem appeared to have been cracked, when a group of US
scientists published a paper in the online journal PLoS One which indicated
that CCD was caused by the interaction between a virus, the invertebrate
iridescent virus, and a fungus known as Nosema apis (http://ind.pn/9NKzPD).
But since then it has emerged that the study's lead author, Jerry Bromenshenk,
has in recent years received a research grant from Bayer Crop Science (a
leading manufacturer of neonicotinoid insecticides) to study bee
pollination. Bromenshenk has, however, said that no Bayer funds were used in
the earlier study. Jeroen van der Sluijs, of the Netherlands' Utrecht
University, doesn't doubt Bromenshenk's findings, but says they don't
address the key issue: "Previous research has shown that exposure to
neonicotinoids makes colonies more prone to the Nosema fungus and virus
If that is so, then neonicotinoid insecticides could be the root cause of the
problem. But why are they so much worse than other insecticides?
"Neonicotinoids are revolutionary because they are put inside seeds and
permeate the whole plant because they are water-soluble (which is why they
are called systemic insecticides). Any insect that feeds on the crop dies,"
Even small doses can kill. Recent research, carried out on honey bees in the
lab, showed that these insecticides build up in the central nervous system
of the insect, so that very small doses over a long time period can have a
fatal effect. The reason that neonicotinoids can have such a powerful
long-term effect is down to the way they work – binding irreversibly to
receptors in the central nervous systems of insects.
"An insect has a limited amount of such receptors. The damage is
cumulative: with every exposure, more receptors are blocked, until the
damage is so big that the insect cannot function any more and dies,"
explains van der Sluijs.
And unfortunately the robust nature of neonicotinoids means that they can
travel far beyond the crops they were used to treat. "Neonicotinoids
are water-soluble and mobile in soil. They can be washed out of soils and
into surface and groundwater – as we've seen in the Netherlands since 2004.
As a result, neonicotinoids are probably readily taken up by wild plants as
well, and in this way spread throughout nature, causing irreversible damage
to non-target insects," says Tennekes.
Many scientists now agree that there is strong evidence to suggest that
neonicotinoid insecticides are damaging to bees. But what about the other
insects? Are they being poisoned in the same way? "It is very difficult
to prove, but I believe that most insects will have declined since the
introduction of neonicotinoids in the 1990s. The problem is that we are not
really interested in insects, apart from bees (because we need them) and
butterflies (because they are pretty). However, the few insect species that
we monitor closely indicate massive decline," says Tennekes.
A new PhD thesis goes some way to backing up Tennekes's claim. This year,
Tessa van Dijk at Utrecht University demonstrated a strong link between
increased pollution levels and a reduced presence of insects, and especially
flying insects, in regions of the Netherlands where residues of
neonicotinoids are high.
Others agree that Tennekes may be onto something. "It is a plausible
theory that birds that feed on insects, or that feed their chicks on insects
only, will suffer from insect decline. But much more data are needed to
understand how big the role of neonicotinoids is," says van der Sluijs.
Nigel Raine, a bee expert from Royal Holloway, University of London, concurs. "There
is not yet enough evidence to show that neonicotinoid insecticides are
environmentally safe in the longer term. But if it can be proved that they
are causing a decline in insects, it is reasonable to assume a link to a
decline in the bird species that eat insects."
Some argue, however, that the story is unlikely to be so simple. "Bird
decline started before neonicotinoids hit the scene. Like so many things,
the decline of bird populations is almost certainly multifactorial,
involving pesticides, habitat loss and many other variables," says Gard
Otis, an entomologist at the University of Guelph in Ontario, Canada.
Nonetheless, some countries have already begun to take action. In 2008 the
German, Italian and Slovenian authorities imposed a ban on the use of two
types of neonicotinoid insecticides on maize. Meanwhile France has had a ban
in place since 1999, on a neonicotinoid insecticide used to dress sunflower
But for Tennekes the only solution is a global ban. "Neonicotinoids act
like chemical carcinogens, for which there are no safe levels of exposure.
The message is that we must act quickly and ban these compounds, to avoid a
catastrophe," he says.