Index Page for Fipronil
Possible culprit identified in decline
The Star-Ledger (Newark, N.J.)
May 28, 2007
They are among the most sensitive and hardest-working creatures
in nature. Ancient navigators of the air, honeybees are guided
between hive and flower by the angle and direction of the sun.
Their internal clock signals the time of day a particular flower's
nectar is flowing. And daily changes in the earth's magnetic cycle
alert those in the darkened hive to sunrise and sunset.
A mysterious ailment, however, is causing the great pollinators
to lose their way home. The disorder, called "colony collapse,"
has resulted in the deaths of millions of honeybees worldwide
and up to half of the 2.5 million colonies in the United States.
The chief suspect, say many scientists, is the most commonly
used insecticide on the planet: imidacloprid.
"I grew up in the 1960s, and this reminds me of Rachel Carson's
"Silent Spring,"' says Douglas Fisher, a New Jersey
state legislator, referring to the 1962 book that warned the world
about the long-term effects of agricultural chemicals on the environment.
Last week Fisher escorted New Jersey's secretary of agriculture,
Charles M. Kuperus, to some hard-hit beekeeping operations in
the legislator's Salem County district.
Launched in 1994 by Bayer, the German health care and chemical
company, imidacloprid is used to combat insects such as aphids
that attack more than 140 crops, including fruits and vegetables,
cotton, alfalfa and hops. Sold under various brand names, such
as Admire, Advantage, Gaucho, Merit, Premise and Provado, imidacloprid
also is manufactured for use on flowers, lawns, trees, golf courses
and even pets in the form of flea collars. The list soon could
grow even longer. Last fall, Bayer announced findings indicating
imidacloprid's ability to promote plant health even in the absence
But while it is a successful insecticide, the chemical, in sublethal
doses, may be wreaking havoc on honeybees' nervous systems. In
the mid-1990s, imidacloprid was implicated in a massive bee die-off
in France, in which a third of the country's 1.5 million registered
hives were lost. After beekeepers protested, imidacloprid was
banned for several uses, including treatment of sunflowers and
corn seed. At the same time, beekeepers in Germany, Poland, Spain
and Switzerland were suffering similar losses.
"These things (imidacloprid insecticides) do a great job
on termites, fleas, ticks, but people forget honeybees are insects,
too," said Jerry Hayes, president of the Apirary Inspectors
of America and an entomologist with the Florida Department of
Agriculture. "It amazes me the disconnect that chemical companies
have - or are allowed to have - in terms of the effects (of pesticides)
on good insects."
Honeybees come into contact with pesticides because insects are
needed to pollinate scores of crops, such as apples, blueberries,
cantaloupes, cranberries, cucumbers, pumpkins and watermelons.
Imidcacloprid is one of the newer chemicals especially effective
against a wide range of pests. A member of a class of pesticides
called neonicotinoids, it is a synthetic derivative of nicotine
and works by impairing the central nervous system of insects,
causing their neurons to fire uncontrollably and eventually leading
to muscle paralysis and death.
The potent chemical can be sprayed on plants, or coated on seeds,
which then release the insecticide through the plants as they
In sublethal doses, however, research has
shown that imidacloprid and other neonicotinoids, such as fipronil,
can impair honeybees' memory and learning, as well as their motor
activity and navigation. When foraging for food and collecting
nectar, honeybees memorize the smells of flowers and create a
kind of olfactory map for subsequent trips.
However, in laboratory and field studies, honeybees exposed to
imidacloprid seem to wander off, which may explain, say scientists,
why hives all over the world are turning up empty.
Recent studies have reported on the "anomalous flying behavior"
of imidacloprid-treated bees where the workaholic insects simply
fall to the grass or appear unable to fly toward the hive.
In 2003, a French television documentary team filmed honeybee
activity after exposure to imidacloprid. Clumsy and uncoordinated,
their legs trembling, the bees looked like drunks unable to find
the key to the front door of their hive. Others had trouble leaving
the hive, seemed disoriented, and when they were eventually able
to make their way out, soon disappeared, never to return.
The possibility that neonicotinoids are
at the heart of the bee die-off implies a far more complex problem
because of the widespread use of pesticides. Every year
these chemicals are applied to hundreds of millions of acres of
agricultural lands, gardens, golf courses and public and private
lawns across the United States. Their use on major crops nearly
tripled between 1964 and 1982, from 233 million pounds to 612
million pounds of active ingredients. And since then, their use
has exploded. By 1999, the U.S. Environmental Protection Agency
reported 5 billion pounds of pesticides used on U.S. crops, forests,
lawns, flowers, homes and buildings.
Because of imidacloprid's emergence as a primary player in pest
management, a painful paradox has developed in relation to the
recent debate. Neonicotinoids are needed by farmers and growers
to maintain the health of crops, many of which also require pollination
"Neonicotinoids are now the best aphid insecticide we have,"
said Peter Shearer, a specialist in fruit tree entomology with
the Rutgers Agricultural and Extension Center in Bridgeton, N.J.
"It's very important to our pests that have shown resistance
to other chemicals. It's very important to eggplants, potatoes,
Shearer notes that apple farmers, for instance, don't use Provado,
which has imidacloprid as an active ingredient, until after the
bees, which are used for pollination, are removed from the orchards.
So it doesn't seem to be a logical route of bee die-off,"
he said. "It would have to last 11 months."
However, Shearer also acknowledges that some published studies
indicate that imidacloprid can persist on both vegetation and
in the soil for weeks, months and perhaps years.
In France, there have been inconsistent results since the bans
on imidacloprid went into effect. In 2005, for the first time
in a dozen years, the French honey harvest improved, but only
in certain regions, according to the countryÂ´s beekeeping
Some U.S. entomologists, who recently have been analyzing dead
bees, have found a remarkably high number of viruses and fungal
diseases in the carcasses, leading them to suspect there may be
other culprits besides neonicotinoids.
A 2004 University of North Carolina study, for instance, found
that some neonicotinoids, in combination with certain fungicides,
increased the toxicity of the "neonics" to honeybees
"I don't think there is one smoking gun," said Hayes.
"When neonicotinoids are used on termites, they can't remember
how to get home, they stop eating and then the fungus takes over
and kills them. That's one of the ways imidacloprid works on termites
- it makes them vulnerable to other natural organisms. So if you
look at what's happening to honeybees, that's pretty scary."
Last week the five-state Mid-Atlantic Apiculture Research and
Extension Consortium released a progress report on colony collapse
disorder. Its findings included "the high prevalence of fungi
in adult bees" which seemed "indicative of stress or
a compromised immune system; these symptoms have never been previously
Another entomologist at the Rutgers center, Gerald Ghidiu, knows
there is no simple answer to the problem.
They've been looking at this since the late 1990s," said
the vegetable specialist. "They've done quite a few studies
and they still can't find the direct link. Seventy-five percent
of the vegetable crops in Arizona gets imidacloprid, but they
have no problems with the honeybees right now. So why isn't it
straight across the board? Everyone is in the dark over this."