[Marxism] 2 Studies Point to Pesticide as a Culprit in Bees’ Decline

Louis Proyect lnp3 at panix.com
Thu Mar 29 13:06:43 MDT 2012


NY Times March 29, 2012
2 Studies Point to Pesticide as a Culprit in Bees’ Decline
By CARL ZIMMER

Scientists have been alarmed and puzzled by declines in bee 
populations in the United States and other parts of the world. 
They have suspected that pesticides played a part, but to date 
their experiments have yielded conflicting, ambiguous results.

In Thursday’s issue of the journal Science, two teams of 
researchers published studies suggesting that low levels of a 
common pesticide can have significant effects on bee colonies. One 
experiment, conducted by French researchers, indicates that the 
chemicals fog honeybee brains, making it harder for them to find 
their way home. The other study, by scientists in Britain, 
suggests that they keep bumblebees from supplying their hives with 
enough food to produce new queens.

The authors of both studies contend that their results raise 
serious questions about the use of the pesticides, known as 
neonicotinoids.

“I personally would like to see them not being used until more 
research has been done,” said David Goulson, an author of the 
bumblebee paper who teaches at the University of Stirling, in 
Scotland. “If it confirms what we’ve found, then they certainly 
shouldn’t be used when they’re going to be fed on by bees.”

But pesticides are only one of several likely factors that 
scientists have linked to declining bee populations. There are 
simply fewer flowers, for example, thanks to land development. 
Bees are increasingly succumbing to mites, viruses, fungi and 
other pathogens.

Outside experts were divided about the importance of the two new 
studies. Some favored the honeybee study over the bumblebee study, 
while others felt the opposite was true. Environmentalists say 
that both studies support their view that the insecticides should 
be banned. And a scientist for Bayer CropScience, the leading 
maker of neonicotinoids, cast doubt on both studies, for what 
other scientists said were legitimate reasons.

David Fischer, an ecotoxicologist at Bayer CropScience, said the 
new experiments had design flaws and conflicting results. In the 
French study, he said, the honeybees got far too much 
neonicotinoid. “I think they selected an improper dose level,” he 
said.

Dr. Goulson’s study on bumblebees might warrant a “closer look,” 
Dr. Fischer said, but he argued that the weight of evidence still 
points to mites and viruses as the most likely candidates for bee 
declines.

The research does not solve the mystery of the vanishing bees. 
Although bumblebees have been on the decline in the United States 
and elsewhere, they have not succumbed to a specific phenomenon 
known as colony collapse disorder, which affects only honeybees.

Yet the research is coming out at a time when opposition to 
neonicotinoids is gaining momentum. The insecticides, introduced 
in the early 1990s, have exploded in popularity; virtually all 
corn grown in the United States is treated with it. Neonicotinoids 
are taken up by plants and moved to all their tissues — including 
the nectar on which bees feed. The concentration of neonicotinoids 
in nectar is not lethal, but some scientists have wondered if it 
might still affect bees.

In the honeybee experiment, researchers at the National Institute 
for Agricultural Research in France fed the bees a dose of 
neonicotinoid-laced sugar water and then moved them more than half 
a mile from their hive. The bees carried miniature radio tags that 
allowed the scientists to keep track of how many returned to the hive.

In familiar territory, the scientists found, the bees exposed to 
the pesticide were 10 percent less likely than healthy bees to 
make it home. In unfamiliar places, that figure rose to 31 percent.

The French scientists used a computer model to estimate how the 
hive would be affected by the loss of these bees. Under different 
conditions, they concluded that the hive’s population might drop 
by two-thirds or more, depending on how many worker bees were exposed.

“I thought it was very well designed,” said May Berenbaum, an 
entomologist at the University of Illinois at Urbana-Champaign.

But James Cresswell, an ecotoxicologist at the University of 
Exeter in England, was less impressed, because the scientists had 
to rely on a computer model to determine changes in the hive. “I 
don’t think the paper is a trump card,” he said.

In the British study, Dr. Goulson and his colleagues fed sugar 
water laced with a neonicotinoid pesticide to 50 bumblebee 
colonies. The researchers then moved the bee colonies to a farm, 
alongside 25 colonies that had been fed ordinary sugar water.

At the end of each year, all the bumblebees in a hive die except 
for a few new queens, which will go on to found new hives. Dr. 
Goulson and his colleagues found that colonies exposed to 
neonicotinoids produced 85 percent fewer queens. This reduction 
would translate into 85 percent fewer hives.

Jeffery Pettis, a bee expert at the United States Department of 
Agriculture, called Dr. Goulson’s study “alarming.” He said he 
suspected that other types of wild bees would prove to suffer 
similar effects.

Dr. Pettis is also convinced that neonicotinoids in low doses make 
bees more vulnerable to disease. He and other researchers have 
recently published experiments showing that neonicotinoids make 
honeybees more vulnerable to infections from parasitic fungi.

“Three or four years ago, I was much more cautious about how much 
pesticides were contributing to the problem,” Dr. Pettis said. 
“Now more and more evidence points to pesticides being a 
consistent part of the problem.”




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