By Tom Avril
The honeybees looked perfectly healthy, buzzing about their boxy wooden hive on a warm autumn day in central Pennsylvania.
Honeybees have been in decline for decades, causing headaches and higher costs for farmers who depend on the insects to pollinate their apples, almonds and 130 other fruit, nut and vegetable crops. The issue made headlines in 2006 with the emergence of a mysterious new phenomenon called colony collapse disorder, but the broader downturn in bee health was underway well before that, and it continues to this day.
The causes include climate change, pesticides, and disease, said Capaldi, who studies insect behavior and neuroscience at the liberal arts university in Lewisburg. In bad years, the combination of insults can wipe out more than half of a beekeeper's colonies.
"Honeybees are suffering," she said. "All of these factors have united together to create a stressful environment for honeybee colonies across the country."
She and Rovnyak, a chemistry professor at Bucknell, realized five or six years ago that the problem might lend itself to an interdisciplinary solution. The pair joined forces with colleague Marie Pizzorno, an expert in viruses—as one factor in the insects' decline is a virus that deforms their wings.
They want to to identify chemical stress indicators that become elevated in a bee's brain months before the insect displays any outward signs of decline.
The cylindrical device Rovnyak uses to detect these substances, called a spectrometer, would be impractical for any beekeeper or farmer. But once the researchers determine which chemicals are the best predictors of bee health, they want to develop a low-cost test that could be deployed in the real world.
Finding the culprits
The first sign of trouble for the insects came in the 1980s with the introduction of a parasitic mite from overseas, said Pizzorno, the Bucknell virologist.
Relative to the size of the honeybee, these parasites, called Varroa destructor, are enormous.
"It'd be like having a tick on your body that's the size of a dinner plate," she said.
Scientists later would discover that in addition to inflicting harm directly, the parasites also transmitted a virus to the honeybees that deforms their wings.
Researchers also have established that climate change affects the bees in a variety of ways, Capaldi said. Early warm spells or unusual rain patterns can cause flowers to bloom too early and disappear by the time the insects are looking for nectar.
"When the colony is growing, the flowers may not be available," she said.
Certain pesticides and other practices of large-scale industrial agriculture also can add to the stress, she said. That includes the way the bees are deployed, trucked from farm to farm where they subsist on one crop for days at a time.
Telltale chemicals
The stout silver spectrometer at Bucknell contains a magnet more powerful than the ones used in MRI machines, said Rovnyak, the chemistry professor. To identify telltale metabolic chemicals in a bee brain, he places the tiny clump of material in a small receptacle at the center of the device, then hits it with radio waves, causing the various substances to resonate in such a way that their relative amounts can be measured.
"Each molecule rings with a distinct set of patterns, like a chord," he said.
In one study, he and the others found that an amino acid called proline was elevated in the brains of honeybees that were infected with the deformed-wing virus—well before they showed outward signs of disease.
The scientists have since identified other protein fragments that may be signs of stress—possibly because the insects are changing their eating habits in response to infection—but more work is needed.
Once the Bucknell researchers narrow down the best chemical predictors of a bee's decline, they hope to develop a low-cost rapid test that beekeepers could use.
"If we could come up with something for a few bucks, that might be appealing," Rovnyak said.
He likened the approach to certain blood tests for humans, such as those that can identify metabolic signs of Type 2 diabetes years before the onset of disease. Much like humans with pre-diabetes can ward off disease by changing their diet, beekeepers could do the same for the insects. Feeding them sugar, for instance, but starting earlier than Capaldi did last year with Bucknell's colonies. Or deploying other tactics that have shown promise in limiting colony collapse disorder, such as treating for mites, relocating hives, or swapping in a different queen bee.
Click here to see more...