Hive Collapse and Pesticides

‘Highly Likely’ Insecticides Trigger Bee Colony Collapse: Harvard Study

Activist Post

Two widely used neonicotinoids—a class of insecticide—appear to significantly harm honey bee colonies over the winter, particularly during colder winters, according to a new study from Harvard School of Public Health (HSPH). The study replicated a 2012 finding from the same research group that found a link between low doses of imidacloprid and Colony Collapse Disorder (CCD), in which bees abandon their hives over the winter and eventually die. The new study also found that low doses of a second neonicotinoid, clothianidin, had the same negative effect.

Further, although other studies have suggested that CCD-related mortality in honey bee colonies may come from bees’ reduced resistance to mites or parasites as a result of exposure to pesticides, the new study found that bees in the hives exhibiting CCD had almost identical levels of pathogen infestation as a group of control hives, most of which survived the winter. This finding suggests that the neonicotinoids are causing some other kind of biological mechanism in bees that in turn leads to CCD.

The study appears online May 9, 2014 in the Bulletin of Insectology (link at bottom).

“We demonstrated again in this study that neonicotinoids are highly likely to be responsible for triggering CCD in honey bee hives that were healthy prior to the arrival of winter,” said lead author Chensheng (Alex) Lu, associate professor of environmental exposure biology at HSPH.

Since 2006, there have been significant losses of honey bees from CCD. Pinpointing the cause is crucial to mitigating this problem since bees are prime pollinators of roughly one-third of all crops worldwide. Experts have considered a number of possible causes, including pathogen infestation, beekeeping practices, and pesticide exposure. Recent findings, including a 2012 study by Lu and colleagues, suggest that CCD is related specifically to neonicotinoids, which may impair bees’ neurological functions. Imidacloprid and clothianidin both belong to this group.Lu and his co-authors from the Worcester County Beekeepers Association studied the health of 18 bee colonies in three locations in central Massachusetts from October 2012 through April 2013. At each location, the researchers separated six colonies into three groups—one treated with imidacloprid, one with clothianidin, and one untreated.

There was a steady decline in the size of all the bee colonies through the beginning of winter—typical among hives during the colder months in New England. Beginning in January 2013, bee populations in the control colonies began to increase as expected, but populations in the neonicotinoid-treated hives continued to decline. By April 2013, 6 out of 12 of the neonicotinoid-treated colonies were lost, with abandoned hives that are typical of CCD. Only one of the control colonies was lost—thousands of dead bees were found inside the hive—with what appeared to be symptoms of a common intestinal parasite called Nosema ceranae.

While the 12 pesticide-treated hives in the current study experienced a 50% CCD mortality rate, the authors noted that, in their 2012 study, bees in pesticide-treated hives had a much higher CCD mortality rate—94%. That earlier bee die-off occurred during the particularly cold and prolonged winter of 2010-2011 in central Massachusetts, leading the authors to speculate that colder temperatures, in combination with neonicotinoids, may play a role in the severity of CCD.

“Although we have demonstrated the validity of the association between neonicotinoids and CCD in this study, future research could help elucidate the biological mechanism that is responsible for linking sub-lethal neonicotinoid exposures to CCD,” said Lu. “Hopefully we can reverse the continuing trend of honey bee loss.”
Sub-lethal exposure to neonicotinoids impaired honey bees winterization before proceeding to colony collapse disorder,” Chensheng Lu, Kenneth M. Warchol, Richard A. Callahan, Bulletin of Insectology, online Friday, May 9, 2014. Press release source.


Oregon Bumblebee Deaths

AS if the bee population were not already threatened enough, this happens:

Pesticide blamed in death of 25,000 bumblebees in Oregon

Conservationists in Oregon are trying to figure out why 25,000 bees died in a parking lot.

By Devin KellyJune 21, 2013, 1:08 p.m.

A pesticide used to control aphids has been singled out as the cause in this week’s deaths of tens of thousands of bumblebees in a retail parking lot in Oregon, state officials said Friday.

At least 25,000 bees were found dead and more were dying in a Target parking lot in Wilsonville, about 18 miles southwest of Portland, in what experts have described as the largest known die-off of  bees in the United States.

Witnesses reported bees falling from trees and littering the ground.

Crews worked Friday morning to wrap protective netting, purchased by the city, around the 55 European linden trees in the area. Workers stood on cherry-pickers to place the bee-proof shade material around the large trees, which are in full bloom.

On Monday, concerned calls from shoppers prompted the Xerces Society for Invertebrate Conservation — a Portland-area conservation group — to sound an alarm. The Oregon State Department of Agriculture responded by sending staff to collect samples of insects and foliage from the linden trees.

State officials were able to directly link the deaths to the pesticide Safari, which was sprayed on the trees Saturday to control aphids, the department said Friday in a statement. Officials have not yet identified the property management agency or the crews that applied the pesticide.

“It was a mistake to put it on linden trees in bloom,” said Dan Hilburn, director of plant programs with the Oregon State Department of Agriculture. Linden flowers contain nectar highly attractive to bees.

The pesticide, in a class called neonicotinoids, is lethal to bees and other pollinators. Honeybees, ladybird beetles (ladybugs) and syrphid flies were also found dead in the lot, said Scott Hoffman Black, executive director of the Xerces Society.

In terms of assessing penalties, investigators are focusing on whether the pesticide was applied incosistently with its labeling, and whether the activity was conducted in a faulty, careless or negligent manner, said Dale Mitchell, the pesticide compliance program manager with the Oregon Department of Agriculture.

Violations can carry fines ranging from $1,000 to $10,000, Mitchell said.

In fact, the product label reads:

“This product is highly toxic to bees exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops or weeds if bees are visiting the treatment area.”

The environmental impact of neonicotinoids has come under increasing scrutiny worldwide. In April, the European Union banned the use of three types of neonicotinoid pesticides in crops that attract bees.

In the United States, one group, the Center for Food Safety, has sued the Environmental Protection Agency, saying that neonicotinoids are not regulated properly.

In a statement, the U.S. Environmental Protection Agency said it was aware of the Wilsonville bee deaths. “The EPA is tracking the incident closely but at this time we cannot comment on ongoing investigations,” the agency said.

The Wilsonville incident marked an ominous start to National Pollinator Week, an event designed to bring attention to the disappearance of bees. An estimated 10 billion hives have been lost since colony collapse disorder first emerged in 2006.

Bumblebee hives are much smaller than honeybee hives, and an estimated 150 colonies were destroyed in Wilsonville, Black said.