Story URL: http://news.medill.northwestern.edu/chicago/news.aspx?id=206601
Story Retrieval Date: 4/17/2015 11:33:54 AM CST
Courtesy of Peter Griffin
Household and farm pesticides called neonicotinoids may be linked to the deaths of millions of bees, European scientists report.
Experts explain why this pesticide may be jeopardizing bee populations and the pollination of crops and flowers. But they call for more research.
While the scents and sounds of summer surround us, you may have noticed that the volume is down on the humming of the bees. Now, a common household pesticide may be linked to millions of dying bees.
But scientists here also suggest that a particular pest, the Varroa mite, are taking a toll on bee populations. They are working to develop breeds of bees that are resistant to the mites. All of the efforts are racing against the potentially disastrous impact of colony collapse.
Since 2006, scientists, farmers, and beekeepers have confronted a baffling mystery of the sudden disappearance of the bees through colony collapse.
Millions of bees are dying off and experts have been frantically searching for an explanation, critical since 35 percent of the world crop production depends on pollinators such as the honey bees.
Earlier this year, studies reported by French and British researchers on colony collapse – the phenomenon of the whole colonies of bees dying off – looked at the correlation with neonicotinoid pesticides.
“This is the most recent development in the long-running mystery of colony collapse disorder,” said Karen Wilson, living invertebrate specialist at the Peggy Notebaert Nature Museum in Chicago. “If I am understanding it all correctly, pesticides with this active ingredient are readily available to homeowners over the counter.”
This pesticide is a favorite among farmers worldwide because of its effective pest prevention over long periods of time. This same pesticide can also be found in root drench or seed treatment products.
The studies exposed numerous colonies of honey bees to neonicotinoids. A French study found that the bees had a harder time finding their way back to their hives and a British study found that exposure made it harder for bees to supply the hive with enough food to help the colony survive. The journal Science published both studies.
A review of neonicotinoids in the journal Ecotoxicology suggests that the pesticide acts as a toxic agent, impacting the mobility of bees and causing uncoordinated movements that include falling down, trembling and dizziness.
The French study exposed bees to the pesticides and followed them with radio-frequency identification technology. The study references the abnormal foraging activity that the pesticide induces in bees and also discusses the impacts on their memory (their ability to get back to the hive) and learning abilities.
“Yet, the consequences of such behavioral difficulties on the fate of free-ranging foragers and on colony dynamics are extremely difficult to assess in the field" and require more investigation, the researchers reported.
The British study exposed bumble bees to neonicotinoids and allowed them to pollinate under natural conditions. "Treated colonies had a significantly reduced growth rate and suffered an 85 percent reduction in production of new queens compared with control colonies," the study reported.
“The studies are very disconnected,” said May Berenbaum, an entomologist at the University of Illinois at Urbana-Champaign. The studies don't address factors relating to the bees’ health, she said. "And neither of the studies were conducted in the U.S., where the biggest drop in honey bee populations have occurred.”
Berenbaum said the research does demonstrate the neurological impacts of the pesticides on bees.
Beekeeper from Long Lane Honey Bee Farms in Fairmount, David Burns, said he is also not entirely convinced that this is the answer regarding the disappearance of the honey bees.
“I am not excited about neonicotinoids being the answer to all our problems,” Burns said. “Varroa mites continue to vector viruses which keep colonies in trouble more than pesticides and seed coating in my opinion.”
According to the University of Kentucky, Varroa mites are external parasites that attack and feed off of adult bees and larvae. Infestations of these mites destroy honey bee colonies and the collapse of the colonies are often confused with winter mortality or “queenlessness.”
But intervention is giving bees a better chance at survival.
“The newest numbers suggest that bee populations have been improving in the U.S.,” Berenbaum said. “The last five years of the careful attentiveness to the health of the bees has been a factor. People are no longer taking honey bees for granted.”
Efforts to develop bees resistant to the mites are underway at the University of Minnesota, she said.