Protecting our Pollinators

People and bees have a long shared history. Honeybees, natives of Europe, were carried to the United States by early settlers to provide honey and wax for candles. As agriculture spread, bees became increasingly important to farmers as pollinators, inadvertently fertilizing plants by moving pollen from male to female plant parts as they collected nectar and pollen for food. Today, more than two-thirds of the world’s crop plants—including many nuts, fruits and vegetables—depend on animal pollination, with bees carrying the bulk of that load.

It’s no surprise that beekeeping has become a big business in the farm-rich Midwest. Wisconsin is one of the top honey-producing states in the country, with more than 60,000 commercial hives. The 2012 state honey crop was valued at $8.87 million, a 31 percent increase over the previous year, likely due in part to the mild winter of 2011–2012.

But other numbers are more troubling. Nationwide, honeybee populations have dropped precipitously in the past decade even as demand for pollination-dependent crops has risen. The unexplained deaths have been attributed to colony collapse disorder (CCD), a mysterious condition in which bees abandon their hives and simply disappear, leaving behind queens, broods and untouched stores of honey and pollen. Annual overwintering losses now average around 30 percent of managed colonies, hitting 31.1 percent this past winter; a decade ago losses were around 15 percent. Native bee species are more challenging to document, but there is some evidence that they are declining as well.

Despite extensive research, CCD has not been linked to any specific trigger. Parasitic mites, fungal infections and other diseases, poor nutrition, pesticide exposure and even climate change all have been implicated, but attempts to elucidate the roles of individual factors have failed to yield conclusive or satisfying answers. Even less is known about native bees and the factors that influence their health.

Poised at the interface of ecology and economy, bees highlight the complexity of human interactions with natural systems. As reports of disappearing pollinators fill the news, researchers at CALS are investigating the many factors at play—biological, environmental, social—to figure out what is happening to our bees, the impacts of our choices as farmers and consumers, and where we can go from here.

The Inner Lives of Cows

What do biofuels look like on the Wisconsin landscape? Some might think of corn or switchgrass. But what about that herd of cows?

What you can’t see might fool you. Cows are walking natural biodigesters, says CALS bacteriology professor Garret Suen. Their rumens are filled with rich bacterial communities that break down the cellulose found in feed into nutrients usable by the animal.

“The cow is arguably one of the most efficient cellulose degraders around, and the main reason why is that we’ve domesticated them to be that way through selection,” Suen explains. “What I argue is that we didn’t just domesticate the cow, we domesticated their microbes.”

Efficiently breaking down cellulose into simpler usable materials—a key challenge in biofuel production—is a feat naturally performed primarily by microbes. “A cow couldn’t exist without its bacteria, because it has no way on its own to break down the plants that it eats,” he says.

Suen, a researcher with the Wisconsin Bioenergy Initiative, is exploring the workings of the ruminant system in the hope of harnessing its power for industrial applications. He’s focusing on three strains of bacteria in the rumen that use different strategies to degrade cellulose. Drawing upon his background in both computational biology and genomics, Suen is using next-generation sequencing to hone in on the individual genes, enzymes and other proteins used by each and how they work together.

“Understanding the different ways that nature has come up with to degrade recalcitrant plant material will be very useful,” he says.

To date, Suen’s research group has identified some sets of genes they believe are involved, including some interesting surprises that he isn’t quite ready to share. He recently received a five-year, $750,000 early career award from the U.S. Department of Energy to advance the project. Suen hopes the work could ultimately extend even beyond bioenergy.

“Understanding how the microbes are breaking down these plant biomasses doesn’t only impact biofuels. It also has implications for areas like improving digestibility of feed and nutrient yield for the cow—which could directly affect everything from milk production to feed costs to beef quality,” he says.

Marching to the Music

Future queen or tireless toiler? A paper wasp’s destiny may be set by the rhythmic vibrations of its colony caretakers.

Like many social insects, paper wasps have distinct castes. Workers build the nest and care for the young, while “gynes,” which hatch late in the season, can become queens. Both hatch from eggs laid by the colony’s queen and tend to look alike, but the similarities end there. Gynes, unlike workers, develop large stores of body fat and other nutrients to help them survive the winter, start a new nest and produce eggs.

“The puzzle has been how the same egg and the same genome can give rise to two such divergent phenotypes,” says Sainath Suryanarayanan, a researcher in the department of community and environmental sociology.

The answer might lie in the music. While feeding a colony’s larvae, the paper wasp queen and other dominant females periodically beat their antennae in a rhythmic pattern against the nest chambers. This antennal drumming is in some instances clearly audible even to humans and was thought to be a type of communication, says Robert Jeanne, a CALS professor emeritus of entomology. But its purpose was unknown.

Now Suryanarayanan and Jeanne have shown that antennal drumming may drive developing larvae toward a lifetime of labor.

In the lab, they simulated the vibrations of antennal drumming using piezoelectric devices designed by John Hermanson, an engineer at the USDA Forest Products Laboratory in Madison. Vibrating the late-season nests—which normally would hatch gynes—instead produced wasps resembling workers, with much lower fat stores.

“We think it initiates a biochemical signaling cascade of events,” says Suryanarayanan. “Larvae who receive this drumming may express a set of genes that is different from larvae who don’t—genes for proteins that relate to caste.” These could be hormones, neurotransmitters or other small biologically active molecules.

The researchers’ conclusions mesh well with field observations that antennal drumming is common early in the season when colonies are pumping out workers but drops to nearly zero by late summer, when the reproductive wasps—males and future queens—are being reared.

Studies in other species also have shown that vibrations can have profound effects on animal development and physiology, Jeanne notes. In one study, young mice exposed to low-frequency vibrations developed less fat and more bone mass than other mice.