http://www.capitalpress.info/main.asp?
SectionID=67&SubSectionID=616&ArticleID=44085&TM=54280.73
Beekeepers suspect pesticide in hive deaths
Bayer says evidence anecdotal, as watermelon growers agree to curb neonicotinoid use
Cecilia Parsons
Capital Press
Los Banos beekeeper Gene Brandi made a decision last year that cut into his bottom line, but he
thinks it may ensure the survival of his bees.
He will no longer allow his bees to pollinate watermelon crops - no matter how badly the growers
need him.
"Hives I've placed in watermelons over the last several years have had low winter survival rates,
less than 50 percent, so for me the risk was too high to continue," Brandi said.
Brandi suspects his bees were affected by a systemic pesticide melon growers use to kill aphids.
He said the bees are picking up minute doses of neonicotinoid pesticides from crops they
pollinate, and the pesticide is affecting their nervous systems. It doesn't kill them outright, Brandi
said, but it seems to cause them to lose their appetites and become disorientated.
The issue of neonicotinoid pesticides has potentially widespread consequences: Bee hives are
collapsing at alarming rates and should this pesticide prove to be a factor in that collapse,
farmers of all kinds of crops may have to change the way they treat their fields.
Neonicotinoid pesticides are manufactured by Bayer CropScience and have been registered for use
on a multitude of crops since 1994. They were much welcomed by growers who found they were
especially effective against sucking insects such as aphids. They've also been hailed as "softer
pesticides," in contrast with contact-killing organo-phosphates.
Imidacloprid was the first commercially successful neonicotinoid insecticide. As of 2006, there
were 115 active registered products containing imidacloprid, which is registered in California
under a number of trade names, including Admire, Gaucho, and Provado.
Products include seed coatings, soil applications and foliar sprays. According to Bayer, they work
by interfering with the transmission of impulses in the nervous system of insects.
Use of imidacloprid in California agriculture is widespread, with grape and lettuce crops using the
most at 20,000 to 23,000 pounds annually. Broccoli crops used 6,500 pounds in 2006 and citrus
used about 6,000 pounds. It is also used to kill termites.
Beth Grafton-Cardwell, integrated pest management specialist and director of the UC Lindcove
Research Station said there is great potential for use of imidacloprid in the citrus industry to help
eradicate exotic pests such as the Asian citrus psyllid and brown citrus aphid. In citrus, the
pesticide is applied through the irrigation water and, if label instructions are followed, bees
should not come in contact with it, she said.
Glenn Brank, spokesman for the state Department of Pesticide Regulation, said imidacloprid has
been studied as a potential hazard to bees for some time. The department is in the process of
putting together data from a number of different studies to see if the state needs to changes its
regulations.
UC honeybee specialist Eric Mussen said there is no doubt that imidacloprid does damage to the
nervous systems of bees - and that significant amounts of the pesticide would kill bees on the
spot. There are questions about sub-lethal doses of the pesticide over a period of time, he said.
Like Brank, Mussen said there's no shortage of studies on the effects of neonicotinoids on
honeybees. What it does to them may be different depending on whether they encounter the
pesticide in pollen rather than nectar, he said. Also, different plants treated with the pesticide may
have different amounts of the chemical in their pollen.
"It is extremely difficult to say if it affects bees in the way they say it does. I have not seen where a
specific amount causes this (effect) to happen," Mussen said.
Beekeeper Dave Mendes, vice president of the American Beekeepers Federation, acknowledges
that much of the evidence against neonicotinoids is anecdotal.
"We're seeing these losses, but there is no data to back it up," Mendes said. His bees live in
Florida, but Mendes brought thousands of hives to California last winter to keep them out of citrus
in his home state, where growers use imidacloprid to fight the Asian citrus psyllid.
Mendes thinks concentrations of the pesticide in pollen is causing developmental problems in bee
broods. He participated in a study last year that found levels of imidacloprid in his hives at 15-17
parts per billion.
"What does that mean? I want to know the long-term effects of that in my hives," he said. Mendes
said he plans to push for research funding to find some answers.
"If you don't know what the cause is (for losing bees), it creates a lot of anxiety. From what we
read, this could be a problem, but we have no data."
Documents supplied by Bayer say the maximum concentration of the pesticide in pollen and
nectar is five parts per billion, far less than what is expected to kill bees. In addition, Bayer reports
that long-term exposure doesn't hurt bees because they metabolize the neonicotinoids.
"Controlled field studies have demonstrated over and over again that use of neonicotinoid
insecticides use per label instructions do not harm bee colonies," Bayer spokesman Greg Coffey
said.
Coffey also noted that colony collapse disorder is a recent occurrence, whereas neonicotinoid use
has been widespread for many years.
All this leaves Fresno-area watermelon grower Parry Klassen in a difficult situation.
His beekeeper also told him he wouldn't place bees in the field if imidacloprid were used. Klassen
obliged, but aphids killed part of his crop.
Klassen said other materials aren't as effective against aphids and other sucking insects, such as
whiteflies.
"It hasn't been proven to be the cause of the bee deaths. They're looking at all kinds of things,"
Klassen said. "If I can't use that product, I might as well stop growing watermelons."
****************************************************
* General Information About BEE-L is available at: *
* http://www.honeybeeworld.com/bee-l/default.htm *
****************************************************
|
