Jan 31, 2011

Challenges pile up for honeybees, other pollinators

How has pollination changed during the last 50 years? In many ways – most of them bad.

Let’s start with rental fees. If you don’t have native bees to pollinate your crops, you can rent honeybee colonies. Over the last five decades, however, rental rates have gone up.

Michigan surveys have shown an average rental fee increase of 30 percent for honeybee communities, according to Rufas Isaacs, small fruit entomologist for Michigan State University (MSU). The rates vary by grower, region and year across the nation. One cost factor is which crop is to be pollinated. Some provide a healthier food source for the bees, Isaacs said.

“Probably the largest change is the number of miles that are put on colonies for crop pollination,” said Eric Mussen, an entomologist with University of California-Davis (UCD). “Pollination used to be a somewhat local endeavor. Now it is common to have colonies trucked from the East Coast to the West Coast, through the northern tier of states down into the southern states and back to the East Coast in a year.”

Isaacs pointed to the almond crop in California as a source for the increase, an idea Mussen shared.

“During the last 50 years, and continuing at this moment, is the increase in the acres of almonds that require cross-pollination in order to produce a crop,” Mussen said. “We have exceeded 750,000 acres, and planting is continuing.”

Not only does that generate a need for nearly 1.5 million colonies of honeybees, but the colonies have to meet a certain minimum strength requirement, Mussen said. Growers now expect to rent colonies with eight frames, or more, of bees. In many parts of the country, the colonies would naturally winter at sizes significantly smaller than that. So, the bees must be fed pollen, pollen substitutes or supplements and sugar syrup most of the late summer, fall and early winter to maintain colony populations. All of which adds to the costs.

Part of that cost comes from how bees are loaded and moved, said James Tew, an entomologist with Ohio State University.

“It used to be that bees were moved entirely by hand,” he said. “You’d hammer the boxes shut, pounding away on a box filled with bees that were already angry to begin with. Now the big operations are almost completely mechanized with special loaders and skid-steers.”

But there is a reward for the grower. Isaacs said he has a pretty good estimate of the value of pollination to the agricultural economy.

“Roughly, we’re talking $15 billion for honeybees and an additional $3 billion for native bees in the U.S.,” he said. “Across the globe, I think it comes in at around $200 billion.”

Colony Collapse Disorder

Colony Collapse Disorder (CCD) has been a huge issue in the last few years, causing a decline in the number of honeybee colonies and a decrease in native bee numbers. Reports have yet to link CCD with one cause, but instead focus on several combined elements including parasites, disease and other factors.

“Globalization has led to the introduction of many previously unknown parasites and diseases of honeybees into the U.S.,” Mussen said. “Perhaps the most serious, to date, is Varroa destructor. Originally a parasite of the Asian honeybee, Apis cerana, it switched hosts onto Apis mellifera, our honeybee from Europe. Not only does the mite harm the bees by depleting nutrients from the hemolymph (blood) of infested bees, but it vectors many of the viruses that we now find associated with CCD.”

One of the most destructive viruses, Israeli acute paralysis virus, is presumed to have originated in the Asian honeybee – but so has the recently discovered Nosema ceranae, common to all colonies succumbing to CCD. Another microbe common to CCD bees is a yet-to-be-named and sequenced iridescent virus, Mussen said. It is too soon to determine where that originated or how long it has been in U.S. bees.

Penn State researchers found that native pollinators, such as wild bees and wasps, are infected by the same viral diseases as honeybees, and that these viruses are transmitted via pollen. This study provided new insights into viral infections in native pollinators, suggesting that viral diseases may be key factors impacting pollinator populations.

Pollinator populations have declined for various reasons, including ribonucleic acid (RNA) viruses, which are emerging as a serious threat, said Diana Cox-Foster, a professor of entomology at Penn State,
“RNA viruses are suspected as major contributors to CCD, where honeybee colonies die with few or no bees left in the hives. Recent detection of these viral species in bumble bees and other native pollinators indicates a possible wider environmental spread of these viruses, with potential broader impact,” Cox-Foster said.

The researchers have studied viral distributions from pollen pellets of honeybees and other pollinators collected from flowering plants in Pennsylvania, New York and Illinois.

“For the first time, RNA viruses such as deformed wing virus, sacbrood virus and black queen cell virus were detected in pollen pellets collected directly from forager bees,” Cox-Foster said. “Pollen pellets from several uninfected forager bees were detected with virus, indicating that pollen itself may harbor viruses. The viruses in the pollen and honey stored in the hive were demonstrated to be infective, with the queen becoming infected and laying infected eggs after these virus-contaminated foods were given to virus-free colonies.”

The detection of RNA viruses in other pollinators, including bumble bees, solitary bees and wasps, suggests that viruses might have a deeper impact on ecosystem health, given that these pollinators are essential.
“The bees have been weakened by the viruses and the mites,” Tew said. “Bees require a lot more babysitting now than they used to. It used to be that a beekeeper would see maybe 10 percent die-off during the winter. Now, it is up to 30 to 35 percent. It is harder to build a larger, healthier hive.”

Iasacs was excited about genetic developments related to bees. In 2006, scientists from the University of Illinois and Baylor University sequenced the honeybee genome. The sequencing and mapping of the genome has opened up a whole new world of discovery, he said.
Pesticides have also evolved during the last 50 years. Chlorinated hydrocarbon, organophosphate and carbamate insecticides have given way to pyrethroids and neonicotinoids. Bees can be damaged in different ways by the newer chemistries.

“More effective chemistries in fungicides and herbicides have changed the way we view the interactions between honeybees and those materials, which we used to consider of little concern for the bees,” Mussen said.

Alternatives

With the strains on honeybees, alternative pollinators have become available commercially. Bumblebee colonies can be purchased, most importantly in the greenhouse industry, but are being used in some open-field operations as well, Isaacs said. Blue orchard bees have shown to be very effective in cherry orchards.
Isaacs said his focus has turned to native bees and the role they play in crops.

“A farm in Michigan that we tested had over 100 species of native bees that were visiting a blueberry field that was in bloom,” he said. “That leads us to look at what the farmer could do around that farm to help the native bee populations.”

A recent review of native bee declines showed that loss of habitat was a major problem, Isaacs said. Natural Resources Conservation Service programs that work to preserve native habitats can play a massive role in helping native bee populations.

What does it mean?

It means pollination is a bigger part of the puzzle, one each grower needs to deal with on an everyday basis. Beekeeping is no longer a low-input endeavor. Many more hours, much more food and medications and significantly higher costs are associated with keeping colonies healthy and transporting them to pollination and honey locations.

“The long hours, high colony losses and meager income are attracting very few new beekeepers into the profession,” Mussen said.

Tew has seen a gradual erosion of the sideline-income beekeeper.

“In the last 25 years or so, you don’t see as much of the guy who worked with 300 to 400 hives on the weekend,” he said. “You tend to have the large operations or the small, local guys who don’t move their hives much.”

– By Derrek Sigler