* Farm pests move more than 25 kms per decade towards poles
* Faster than movement of wildlife
By Environment Correspondent Alister Doyle
OSLO, Sept 1 Crop-damaging pests are moving
towards the poles at a rate of more than 25 km (16 miles) a
decade, aided by global warming and human transport, posing a
potential threat to world food security, a study showed on
The spread of beetles, moths, bacteria, worms, funghi and
other pests in a warming world may be quicker than for many
types of wild animals and plants, perhaps because people are
accidentally moving them with harvests, it said.
Scientists based in Britain studied more than 600 types of
pests around the world and found that their ranges shifted on
average towards the poles by 26.6 kms per decade since the
1960s, occupying vast new areas.
"We believe the spread is driven to a large degree by global
warming," lead author Daniel Bebber of Exeter University told
Reuters of the findings in the journal Nature Climate Change.
They wrote it was the first study to estimate how pests are
moving because of a changing climate.
The spread of pests is "a growing threat to global food
security", the study said. Between 10 and 16 percent of crop
production is lost to pests, with similar losses after harvest,
The rate of spread, away from the equator and towards the
north and south poles, is slightly faster than 17.6 kms found in
a study in 2011 for wild animals and plants that was in turn
quicker than 6.1 kms for wildlife estimated in a 2003 study.
The rate, however, is virtually identical to a theoretical
prediction in 2011 that rising temperatures would allow a
poleward shift of wildlife of 27.3 kms a decade, the experts
wrote. Many crops are growing nearer the poles due to warming.
Researchers say crop pests are moving into new areas at a
quicker rate than their predators, meaning they can do more
damage to crops.
Wild species may find it harder to move because their
habitats are getting fragmented by deforestation, farms, roads
or cities. "Pest species are constantly being shifted around the
world by trade...We are giving them a helping hand," Bebber
"I'm not surprised," by the faster rate than for wild
animals and plants, said Gary Yohe, a professor at Wesleyan
University in the United States who was co-author of the 2003
study that put the average pole wards shift at 6.1 kms.
A tiny pest is more likely than the average animal or plant
to be carried inadvertently be taken on an train, truck or
airplane to a new area, he noted. And he said the 2003 study was
Another possibility is that the rate of movement by wildlife
"has really speeded up" in recent decades, said Michael Singer,
a professor who works at both Plymouth University in England and
the University of Texas.
And some insects pests may be getting more mobile since they
are often forced to move by humans. "They have to be mobile
because humans are constantly ploughing or otherwise modifying
their habitats," Singer said.
Sunday's study said that there were many problems in
determining how far climate was driving the pests' movements.
"New crop varieties and agricultural technologies have
extended the agricultural margin northward in the United States
and deforestation has increased production in the tropics, thus
providing new opportunities for pest invasions at high and low
latitudes," it said.
The scientists urged governments to think more about where
to plant crops and monitor trade more closely to limit losses.
For the study, click here:
(Editing by Keiron Henderson)