Loss of wild pollinators serious threat to crop yields, study
Wild bees and other insects twice as effective as honeybees in
producing seeds and fruit on crops
* The Guardian, Thursday 28 February[masked] EST
A bee collects pollen from a sunflower. Photograph: Michael
The decline of wild bees and other pollinators may be an even more
alarming threat to crop yields than the loss of honeybees, a
worldwide study suggests, revealing the irreplaceable contribution
of wild insects to global food production.
Scientists studied the pollination of more than 40 crops in 600
fields across every populated continent and found wild pollinators
were twice as effective as honeybees in producing seeds and fruit on
crops including oilseed rape, coffee, onions, almonds, tomatoes and
strawberries. Furthermore, trucking in managed honeybee hives did
not replace wild pollination when that was lost, but only added to
the pollination that took place.
"It was astonishing; the result was so consistent and clear," said
Lucas Garibaldi, at the National University in Río Negro, Argentina,
who led the 46-strong scientific team. "We know wild insects are
declining so we need to start focusing on them. Without such
changes, the ongoing loss is destined to compromise agricultural
Pollination is needed for about three-quarters of global food crops.
The decline of honeybee colonies due to disease and pesticides has
prompted serious concern. Jason Tylianakis, at the University of
Canterbury, New Zealand, described them as "the species charged with
protecting global food security".
The new research shows for the first time the huge contribution of
wild insects and shows honeybees cannot replace the wild insects
lost as their habitat is destroyed. Garibaldi said relying on
honeybees was a "highly risky strategy" because disease can sweep
through single species, as has been seen with the varroa mite, and
single species cannot adapt to environmental changes nearly as well
as a group of wild pollinators.
"The studies show conclusively that biodiversity has a direct
measurable value for food production and that a few managed species
cannot compensate for the biodiversity on which we depend," said
Tylianakis, who was not part of the research team.
Garibaldi's team, whose work was published in the journal Science on
Thursday, warn: "Global degradation of natural services can
undermine the ability of agriculture to meet the demands of the
growing, increasingly affluent, human population."
Garibaldi said: "Without wild pollination, you will not get the best
yields and the best agricultural land already farmed, so it is very
important to get the maximum yield." He added that, across the
world, the yields of crops that needed pollination were rising
significantly more slowly than crops that did not.
Wild pollinators perform better than honeybees because they deploy a
wider range of pollinating techniques, such as "buzz" pollination.
They also visit more plants, meaning much more effective
cross-pollination than honeybees, which tend to carry pollen from
one flower to another on the same plant.
A second new study published in Science on Thursday showed more than
half the wild bee species were lost in the 20th century in the US.
It made use of a remarkable record made of plants and pollinators at
Carlinville, Illinois between 1888 and 1891 by entomologist Charles
Robertson. Scientists combined that with data from[masked] and new
data from[masked] to discover the changes in pollination seen over
the century as widespread forest was reduced to the fragments that
They found that half of the 109 bee species recorded by Robertson
had been lost and there had been a serious degradation of the
pollination provided by the remaining wild insects, with their
ability to pollinate specific plants falling by more than half.
There was an increasing mismatch between when plants flowered and
when bees were active, a finding consistent with climate change,
according to the researchers.
Laura Burkle, at Washington University in Montana, who led the work,
said: "There are two sides to this coin. These pollination systems
are incredibly robust to environmental change, it is almost
miraculous that they continue to pollinate given the land use
changes. But the system is also incredibly compromised and further
degradation will have serious impacts."
*** NOTICE: In accordance with Title 17 U.S.C. Section 107, this
material is distributed, without profit, for research and
educational purposes only. ***