Dramatic discoveries in 2009
Throughout the world, honeybees are at risk. In recent years, beekeepers in Europe and Canada have lost up to 30 percent of their colonies, and in the winter of 2008, beekeepers in Japan reported unexplainable losses among their bee colonies. In the United States, researchers have monitored the state of the apiary industry for years, with extra effort in the last three years, as beekeepers reported annual colony losses of 30 percent.
Some suggest that the crisis among the world’s honeybees is indicative of a larger environmental crisis, with honeybees as the proverbial canary in the coal mine. Despite record losses in the United States, many researchers believe the industry as a whole is turning around.
With the low price of commodity honey, fee-based pollination is the new business model. Many commercial beekeepers remain in business because honeybees are the key, foundational pollinator of production agriculture. The U.S. apiary industry is comprised of three types of beekeepers: commercial, sideliner and hobbyists. The professional commercial industry controls a majority of the colonies, with individuals managing thousandss of colonies that they move throughout the country. Sideline beekeepers manage hundreds of colonies, and some move these throughout a small region. The majority of beekeepers are part-time hobby beekeepers, with one to 25 colonies in their backyard. Each group has different concerns, but across the board, beekeepers must address problems and challenges that are endemic to the honeybee.
Concerns for commercial beekeepers
Many insects pollinate crops, but the honeybee is the logical choice for a movable pollinator force. A mobile pollinator force is a tradition that dates back as far as ancient Egypt, when beekeepers moved bees up and down the Nile. However, Jerry Hayes, Florida’s state apiarist and a veteran in the industry, says the commercial industry is struggling with a new business model that by its nature creates large, consistent colony losses.
Dennis vanEngelsdorp, Pennsylvania’s acting state apiarist and senior extension associate at Penn State, disagrees. He says data from 2008 shows that beekeepers who moved hives lost fewer colonies than those who did not. Colony numbers have decreased steadily for the past 60 years. “We’re now getting to a critical level of colonies. If the large beekeepers that move their colonies throughout the country lose 50 percent or more of their colonies three years in a row, they’re going to go out of business.” VanEngelsdorp is starting to see this trend.
In the last four to five years, acreages of California almonds have increased dramatically. Because almonds rely nearly 100 percent on honeybees for pollination, the additional acreage has required half the colonies in the country. Now, commercial keepers are moving bees cross-country to those almond groves. However, beekeeping does not follow the laws of economics, where supply will rise to meet demand. As demand for movable pollinators grows, bees suffer stresses that may be contributing to overall colony losses. VanEngelsdorp emphasizes that beekeepers who suffer losses aren’t necessarily doing anything wrong. “I think a lot of it is chance.”
Researchers agree that by keeping bees well-nourished and by treating bees well, a beekeeper raises the chances of their colony being able to fight off infection. Why, then, are beekeepers who are doing things right still having trouble? VanEngelsdorp says scientific research is imperative in finding the answers to that question.
Growth in the small sector
The consolidation of large producers spurs interest in more traditional methods among purists. “Numbers tell the tale,” says Hayes. While commercial beekeepers individually decline, colony numbers are fairly stable and/or growing slightly. More part-time beekeepers and sideline beekeepers have entered the arena. Three years ago, Florida had fewer than 1,000 beekeepers. Today, the state boasts almost 1,500 beekeepers.
With net colony numbers fluctuating annually by 30 to 40 percent, apiarists must devote labor and expenses to restock many of their bees each spring. This affects both the beekeeper’s ability to provide adequate bees for pollination, and their bottom line for sustaining their businesses year after year. An increasing awareness of the vital roles bees play in food production helps the industry overall.
Developments in research
Since the 1990s, scientists have focused on unlocking the mysteries of colony collapse disorder (CCD). Hives suffering from CCD exhibit several unique symptoms: a strong colony with many individuals rapidly declines to a colony with few or no surviving bees; queens are found with a few young adult bees, lots of developing offspring and more-than-adequate food reserves. Finally, no dead adult bees remain in or near the colony; the corpses simply disappear.
In early studies, scientists suspected varroa mites and tracheal mites were key culprits in CCD. However, scientists are reaching new conclusions about the roles of these parasitic mites. Jay Evans, from the USDA-ARS Bee Research Lab in Beltsville, Md., points out that mites have been around the world for generations and in the U.S. for 20 years. “They are not likely to be the cause of CCD by themselves, though we do think they are guilty of both moving viruses among bees and increasing stress levels.”
These parasitic mites have developed resistance to some of the available chemical treatments. Despite the resulting mite population boom, Evans is encouraged by the success he and scientists at labs at the University of Illinois, University of Minnesota and Purdue are having in breeding for mite-resistant bees. Using genomics and other new biotechnologies can produce lines of bees that might survive long-term without miticidal treatments.
Although CCD is traumatic for colonies and beekeepers, incidences appear to be declining. In 2008, it hit only 5 percent of the operations responding to surveys conducted by the Apiary Inspectors of America in conjunction with the USDA.
Professor Diana Cox-Foster, of Penn State University’s entomology department, has spent over 10 years looking at diseases in honeybees and the effect of varroa mites on honeybees. She says despite challenges and an annual average colony loss of 30 percent and greater, the industry is improving. “The concern is that overall losses within honeybees are still at unsustainable levels.”
Work at Penn State indicates Israeli acute paralysis virus (IAPV) produces symptoms that are similar to CCD, with adult bees leaving the colony and dying outside the colony. In greenhouse studies where Cox-Foster’s team infected colonies with IAPV, virally infected bees died away from the colony, along the walls of the greenhouse. In contrast, in the colonies in identical greenhouse conditions that didn’t receive the virus, dying bees frequently remained right in front of the colony. The control bees did not die in high numbers along the edges of the greenhouse. Like the bees in CCD colonies, the virus-infected bees seem to remove themselves from the colony as much as possible before dying.
Incidences of IAPV have been increasing across the U.S. Related viruses are also part of the problem. “For viral diseases to cause CCD, there must be triggers in place, like environmental toxins or nutritional stress,” says Cox-Foster. “We do think chemical exposures might be affecting the bee immune system.”
Cox-Foster and Penn State collaborators—Professors Jim Frazer and Chris Mullin and Senior Extension Associate Maryann Frazier—are investigating possible triggers of CCD by collecting bees and randomly assigning them to different treatments of chemical exposure, then challenging them with diseases and measuring the impacts. Over 14 researchers at Penn State are examining different aspects of pollinator biology, including sampling colonies both from organic orchards and from orchards treated with reduced pesticide loads.
For larger surveys, a team of collaborators from USDA, Penn State and Florida collect samples from beekeepers throughout the U.S. and quantify as many different factors as possible, like the history of the bees, where they’ve been and the status of the colony. Collecting hive products from beekeepers enables the scientists to collect additional data. Researchers take remaining survivors from colonies on the verge of completely dying. Unfortunately, the dead bees are missing from the CCD hives.
“These colonies are in areas where vegetation may hide the dead, but we also know that in some situations, animals like ants see these corpses as a good food source and remove them quickly,” explains Cox-Foster.
New findings released in August suggest a connection between CCD and the concurrent presence of the pathogens Nosema apis and Nosema ceranae. Many entomologists now feel that there is not one single cause of CCD, but several factors that contribute to suppressing the immune system of the honeybee. Effectively, the honeybee population is facing its own AIDS-like crisis.
VanEngelsdorp says colonies are falling prey to a variety of deadly viruses. “That implies it’s an immune deficiency allowing all these [pathogens] to establish,” he explains. Researchers are currently exploring anti-viral drugs that beekeepers might be able to use to protect their colonies.
The scientists at USDA-ARS Bee Research Lab in Beltsville, Md., are collaborating with researchers across the nation to understand and prevent sudden losses of adult bees from CCD and to decrease the devastating winter losses exceeding 30 percent of managed colonies. “Our role has been to focus on genetic markers for ailing bees and for the parasites and pathogens that they pick up, in hopes we can both regulate pests and determine which management and breeding practices reduce the impacts of pests and other stresses,” says Evans.
CCD brought the crisis in the bee colonies to national attention, but bees have been dying from several other things. From 2008 to 2009, vanEngelsdorp, in partnership with the USDA, observed 280 commercial, migratory colonies along the East Coast. Sixty percent died in 11 months. The astronomical mortality rate was mostly the result of queen failure.
The honeybee queen is solely responsible for the reproduction of the colony. Her single task is laying eggs; during peak periods in spring and fall she may lay as many as 1,500 to 2,000 a day. It is essential for the queen to maintain a high rate of egg-laying if the colony is to replace all the workers that die during the normal development of the colony. (Workers typically live only six weeks in the summer months.) The egg-laying ability of the queen is key to success of the colony, and ultimately to the beekeeper, since a large population of worker bees is needed to optimize honey yields and pollinate crops. Unlike worker bees, a queen may live for five or six years. When a queen dies without leaving a replacement queen, the colony experiences queen failure and is in danger.
VanEngelsdorp is surprised by the number of queen failures, and inspired to search harder for answers to this complex problem. “Pathogens can be involved, pesticides can be involved, queen-rearing conditions can be involved.”
Hayes suggests recent colony losses are the result of an overload of stressors building up in the bee’s system. “Lots of really smart people with expensive equipment are looking at all aspects of honeybee biology, physiology and epidemiology, so we have [discovered] a tremendous amount of information on viruses, chemicals, diseases, etc., but that doesn’t mean that they were not there before. Nobody in the past had the resources or reason to look.”
Scientists know that honeybees have been exposed and stressed by some levels of environmental toxins, parasites and pathogens for years and have previously dealt with these stressors successfully. Hayes says this should serve as a warning to us all. “Honeybees are environmental samplers and bring all sorts of things back to the nest,” he explains. “Are they trying to tell us something about our environment that we should be listening to?”
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The author is a freelance writer based in Massachusetts and a monthly contributor to Growing.