[Pollinator] Wired Science - Backyard Pesticide Use May Fuel Bee Die-Offs

[Matthew Shepherd]

http://www.wired.com/wiredscience/2012/04/neonicotinoids-gardens/

 

 


Backyard Pesticide Use May Fuel Bee Die-Offs


By Brandon Keim


April 13, 2012 


 

The controversy over possible links between massive bee die-offs and
agricultural pesticides has overshadowed another threat: the use of those
same pesticides in backyards and gardens.

Neonicotinoid pesticides <https://en.wikipedia.org/wiki/Neonicotinoid>  are
ubiquitous in everday consumer plant treatments, and may expose bees to far
higher doses than those found on farms, where neonicotinoids used in seed
coatings are already considered a major problem by many scientists
<http://www.wired.com/wiredscience/2012/03/neonicotinoids-bee-collapse> .

"It's amazing how much research is out there on seed treatments, and in a
way that's distracted everyone from what may be a bigger problem," said Mace
Vaughan, pollinator program director at the Xerces society, an invertebrate
conservation group.

The vast majority of attention paid to neonicotinoids, the world's most
popular class of pesticides, has focused on their agricultural uses and
possible effects. A growing body of research suggests that, even at
non-lethal doses, the pesticides can disrupt bee navigation
<http://www.wired.com/wiredscience/2012/03/neonicotinoids-bee-collapse/?utm_
source=Contextly&utm_medium=RelatedLinks&utm_campaign=Previous>  and make
them vulnerable to disease and stress.

Neonicotinoids are now a leading suspect in colony collapse disorder
<https://en.wikipedia.org/wiki/Colony_collapse_disorder> , a mysterious
condition that's decimating domestic and wild bee colonies across much of
North America and Europe. The emergence of colony collapse disorder
coincided with a dramatic increase in agricultural neonicotinoid use.

Several European countries, including France, Germany and Italy, have banned
agricultural neonicotinoids, though some researchers and
pesticide-manufacturing companies say evidence of low-dose harm is still
incomplete and methodologically unsound.

 <http://www.wired.com/images_blogs/wiredscience/2012/04/store_neonics.jpg>
http://www.wired.com/images_blogs/wiredscience/2012/04/store_neonics.jpg

A garden center shelf. To determine if a pesticide contains a neonicotinoid,
look at the ingredients: Imidacloprid, acetamiprid, dinotedfuran,
clothianidin, thiacloprid and thiamethoxam are all neonicotinoids. Photo:
Matthew Shepherd/The Xerces Society

Few researchers, however, doubt that high doses of neonicotinoids are
harmful to bees - and though research on neonicotinoid use by gardeners,
nurseries and urban landscapers has proceeded slowly, a troubling picture
has emerged of products found on the shelves of most any garden center.

"For homeowner use products, for backyard plants, the amount of
neonicotinoids used is like 40 times greater than anything allowable in
agricultural systems," said entomologist James Frazier of Penn State
University.

The Environmental Protection Agency sets its LD50 - the dose at which 50
percent of exposed honeybees will die - for imidacloprid, a common
neonicotinoid, at a range of 40 to 400 parts per billion. In a recent study
on the effects of imidacloprid
<http://www.wired.com/wiredscience/2012/04/neonicotinoids-colony-collapse/?u
tm_source=Contextly&utm_medium=RelatedLinks&utm_campaign=Previous> , a food
dose of just 20 ppb destroyed honeybee colonies. Critics said that bees in
the wild wouldn't be exposed to such a high dose.

Even higher doses, however, have been measured in neonicotinoid-treated
gardens. According to toxicologist Vera Krischik of the University of
Minnesota, using a standard Bayer plant care product produced imidacloprid
levels of 501 ppb in milkweed nectar and 682 ppb in the nectar of agastache,
a bee foraging favorite.

In an official company statement from Bayer CropScience, the company said
that its "neonicotinoid-based insecticides - both for lawn and garden and
crop applications - are safe for honey bees and other pollinators when used
according to label directions."

Yet Krischik's results came from by-the-label use. "It's not an artificially
high dose," said Krischik, who doesn't consider agricultural neonicotinoids
to be a threat to bees. "It's a much higher rate in landscapes than in
agriculture. It's 4 milligrams per square foot in agriculture, but you can
put up to 250 milligrams in a three-gallon pot."

Not everyone may follow instructions, either. "Gardeners have no training in
their use, and will often overdose," said bee biologist Dave Goulson of
Scotland's University of Stirling, co-author of a recent paper on
neonicotinoids and hive health
<http://www.wired.com/wiredscience/2012/03/neonicotinoids-bee-collapse/> .
Goulson said in an e-mail that "gardens and fruit-growing areas are
potentially interesting/bad."

A review of neonicotinoids published by the Xerces Society
<http://www.xerces.org/neonicotinoids-and-bees/>  cited several other
findings of extremely high non-agricultural imidacloprid levels: up to 850
ppb in rhododendron blossoms measured nearly six months after being treated,
and roughly 2,000 ppb in cherry trees tested more than one year after
dosing.

'I don't think anybody should be using these things in their backyards.'

According to Krischik, several other studies have found extremely high
neonicotinoid levels in eucalyptus, maple and linden trees. "Linden trees
are the best bee plants out there," she said. The Xerces Society also
calculated that non-commercial apple trees receive neonicotinoid doses an
order of magnitude higher than their commercial counterparts.

An open research question is whether neonicotinoids, which spread through a
plant's vascular system and remain active for extended periods of time,
accumulate from year to year, especially in perennial plants. "Maybe if we
treat once, it stays below lethal levels. But if you treat it two or three
or four times, we have no idea," said Vaughan.

Vaughan said that neonicotinoids are also commonly used in nurseries. People
may purchase plants with the intent of providing habitat for bees, but end
up poisoning them.

However, Vaughan stressed that an outright ban on neonicotinoids would be a
mistake. They're popular in large part because they're far less toxic to
people than earlier pesticides. In certain situations, such as in-home
termite control, they may be appropriate. The key, he said, is determining
what those situations are.

More than 1.25 million people have petitioned
<http://www.msnbc.msn.com/id/46815289/ns/technology_and_science-science/t/be
ekeepers-ask-epa-ban-pesticide-toxic-bees/#.T4iOp443T8Y>  the Environmental
Protection Agency to review its stance on neonicotinoids, which were
approved on the basis of limited, largely industry-run safety studies
<http://www.wired.com/wiredscience/2010/12/epa-clothianidin-controversy/> .

"The EPA didn't ask for the data. They didn't realize systemic insecticides
last a long time in pollen and nectar. They didn't give money to researchers
to look at this. It was an oversight," said Krischik. "It's not anybody's
fault. Things happen. And we need to fix it before we lose the bees."

"I don't think anybody should be using these things in their backyards. I
think they don't understand that they're having such a negative impact,"
said Vaughan, who wants all neonicotinoid-containing consumer pesticides to
be labeled. "Maybe a big butterfly with an X over it and a sign that says,
'May Kill Pollinators.'"

 

 

________

 

Matthew Shepherd

Senior Conservation Associate

 

The Xerces Society for Invertebrate Conservation

1971 - 2011: Forty Years of Conservation!

 

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628 NE Broadway, Ste 200, Portland, OR 97232-1324, USA

 <mailto:mdshepherd at xerces.org> mdshepherd at xerces.org 

Tel: (503) 232-6639 ext. 110

Toll free: 1-855-232 6639 ext. 110

Cell: (503) 807-1577

Fax: (503) 233-6794

 

The Xerces Society for Invertebrate Conservation is an international
nonprofit organization that protects wildlife through the conservation of
invertebrates and their habitat.

 

To join the Society, make a donation, or read about our work, please visit
<http://www.xerces.org/> www.xerces.org.

 

NEW BOOK NOW AVAILABLE:

 
<http://www.xerces.org/announcing-the-publication-of-attracting-native-polli
nators/> Attracting Native Pollinators. Protecting North America's Bees and
Butterflies

 

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