PA Farm News - Colonies in collapse: What's causing massive honeybee die-offs? Part 1

Colonies in Collapse: What's Causing Massive Honeybee Die-Offs? Part 2
This article is part two of a three-part in-depth series
By Melissa Beattie-Moss, Research Penn State Magazine
UNIVERSITY PARK — Whodunit? To solve a murder mystery with millions of victims and no smoking gun requires CSI-style teamwork, or as Pennsylvania state apiarist Dennis vanEngelsdorp likes to say, “a coordinated effort that takes a page from the beehive, where all the individuals play a role to make the hive successful.”

Penn State’s entomology department, long recognized for its strengths in disease research and chemical analysis, has emerged as a leader in honey bee and CCD research nationwide. "We are one of the major contributors in understanding bee health," notes Diana Cox-Foster, professor of entomology and co-chair of the Colony Collapse Disorder Working Group. She adds that currently 19 faculty and graduate students on the University Park campus are doing research projects related to bee health.

Notes Cox-Foster, “We’ve got Maryann Frazier, Chris Mullins and Jim Frazier working together, asking questions about the impact on the bees of pesticides, including insecticides, fungicides and herbicides — and they’ve been making a lot of discoveries there.”

Jim Tumlinson, a National Academy of Sciences member and director of the Penn State Center for Chemical Ecology, “is working with his grad students on a honeybee pest called the small hive beetle and looking into developing traps to keep them from moving around.”

In the Department of Crop and Soil Sciences, Dave Mortensen is interested in fencerows — plantings on the edges of fields — that will encourage pollinators to move into the crops for natural pollination.

In fact, adds Cox-Foster, “There are several people working on different aspects of pollination. Rob Berghage in Horticulture is collaborating with the Master Gardeners association to develop guidelines for pollinator-friendly gardens. He also directs the University’s Center for Green Roof Research.”

We’re also looking at what role mites could be playing, she continues. “Nancy Ostiguy and I are investigating the relationship between varroa mites and bee diseases — particularly endemic viruses — in honeybee colonies.”

Adds Frazier, “Penn State is the No. 1 land-grant university working on this problem. Others are definitely contributing significantly, but Penn State has maintained a commitment to apiculture research and extension programs while many universities have given that up.”

Cautious optimism, then frustration
As news of the crisis spread, the public began weighing in with theories (a “mind-boggling” number, admits Cox-Foster) about CCD’s cause. Proposed culprits include everything from viruses, pesticides and genetically modified crops, to cell phone radiation, erratic weather, conspiracy theories and even a “Bee Rapture.”

To create a way for CCD investigators to exchange information and collaborate on the most promising research avenues, Cox-Foster and colleagues pulled together a coalition called the Colony Collapse Disorder Working Group (CCDWG) in the early months of 2007. The group — which she co-directs with entomologist Jeff Pettis, of the USDA’s Agricultural Research Service — is a network of scientists, regulatory officials, extension educators and industry representatives, including members from the University of Montana, the University of Illinois, North Carolina State, the Florida and Pennsylvania Departments of Agriculture, and Columbia University.

Three fundamental questions emerged as they began formulating hypotheses: Are new or re-emerging pathogens responsible for CCD? Are environmental chemicals causing the immunosuppression of bees and triggering CCD? Or is a combination of factors, such as varroa mites, diseases and nutritional stress, interacting to weaken bee colonies and allowing stress-related pathogens such as fungi to cause a hive’s final collapse?

The group started conducting autopsies on bees from hives suspected of undergoing collapse — and what they found surprised them.

Van Engelsdorp recalls staring through the microscope in his Harrisburg lab, expecting to see the usual perpetrators, namely mites or amoebae. Instead, he was confronted with the sight of swollen and blackened internal organs, scarred intestinal tracts and discolored sting glands — all signs of weakened immune systems and infection. “The more we looked, the more we found,” he says. “There were multiple infections within each bee, including mites, fungi and a parasitic disease called Nosema ceranae."

Bees are normally pretty resilient creatures, Cox-Foster notes. When dissected bees show traces of nearly every known bee disease that has been observed over the last century, it’s clear that their immune systems have been compromised. “It’s like bee AIDS,” observes Hackenberg. “Their bodies are broken down and every little thing that comes into their system causes them problems.”

Still hoping to identify a singular — or, at least, dominant — cause for CCD, Cox-Foster organized a research team including scientists from Penn State (including Edward Holmes of the Center for Infectious Disease Dynamics), the Columbia University Mailman School of Public Health, and the University of Arizona — to investigate one of their strongest hunches, namely that a particularly destructive virus might be responsible for the disorder. Using genetic technologies such as high-throughput DNA sequencing, and new analytic methods developed at Columbia, the team surveyed the microflora in numerous samples of CCD hives, normal hives and imported royal jelly.

Their findings were dramatic: Genetic tests revealed that in 96 percent of the hives stricken with CCD, a little-known virus called Israeli acute paralysis disease (IAPV) was present. All of the bee samples for the study came from operations that had imported bees from Australia — a country that, since 2005, has sold large stocks of bees to American beekeepers trying to keep up with the growing demand for almond pollination in California.

Results from the group’s study were published in Science in September of 2007, in an article titled "A Metagenomic Survey of Microbes in Honey Bee Colony Collapse Disorder." In the article, the researchers declared that IAPV was “strongly correlated with CCD,” and, with those hopeful words, news spread rapidly that researchers had made the first big break in the case and were closing in on a definitive answer. (The finding that abandoned hives could be sterilized with gamma radiation and successfully repopulated with healthy bees strengthened the belief that an infectious agent — most likely, IAPV — was the prime suspect in CCD.)

Despite the researchers’ efforts to qualify their results as preliminary (“I hope no one goes away with the idea that we’ve actually solved the problem,” the USDA’s Pettis told The New York Times) their study was hailed in the media as a major breakthrough — and subsequently found itself the target of criticism and controversy. Two prominent Australian entomologists, Denis Anderson and Iaian J. East, issued a rebuttal in Science, calling any links between IAPV and CCD “tenuous” and pointing to the facts that non-Australian bees with IAPV had been identified in the U.S. since 2002 — three years prior to the surge in importation of Australian bees — and that IAPV is not proving to be lethal among Australia’s bee colonies. “It would now be appropriate for the authors of the Science report to issue a retraction of the claims linking CCD to importation of Australian bees,” they wrote, adding that future collaborations between the U.S. and Australia would “result in more secure trade for package honeybees to meet the growing demands of the United States pollination industry.”

In her response, Diana Cox-Foster and colleagues defended their study, and concluded that although “research on products important to international trade may lead into politically and economically sensitive territory,” they hold to the belief that “trade issues should not color research.” Cox-Foster has since published another paper examining the different strains of IAPV, which supports the belief that imported Australian bees are one source of the virus in the U.S.

A complex moving target
To further investigate the potential link, Cox-Foster and her graduate students are exposing healthy hives to IAPV to see if CCD develops. To date, these greenhouse studies suggest that IAPV is a particularly pathogenic virus. Yet while Penn State researchers still believe that IAPV is one marker for CCD, they agree that it is not necessarily the cause.

“We were very hopeful early on that we would find something wrong and we could fix it,” says Maryann Frazier. “Unfortunately, I don’t think there’s going to be one pivotal ‘A-ha!’ moment that solves the problem.”

Dennis vanEngelsdorp reluctantly agrees. “I was really hoping we would discover a distinct cause, but we haven’t found that yet. So the next logical thing is to move towards a multifactorial analysis, with the assumption that a combination of factors — some of which don’t cause colony mortality on their own — are operating together to tip the balance.”

Click HERE for Part 1

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POSTED 081116_1200 ET