Meet the Natives: Wild Bees

Before I met Claudio Gratton, an entomologist at the University of Wisconsin-Madison, my idea of a “bee” was a little striped insect that lives in a hive and makes honey, pollinating the flowers whose nectar it collects.

But according to Gratton, the honeybee that I’m imagining is only one of a huge, diverse -- and largely unknown -- set of bee species on the planet. Despite their ubiquity in North America, honeybees are a European import.

“There’s a lot of other pollinators out there,” explains Gratton. The 500 or 600 wild bee species that live in Wisconsin are only a fraction of the 4,000 native to the United States. But because they tend to be solitary, aren’t easily managed, and don’t produce honey, they’ve mostly flown under the radar.

I saw some of these native bees neatly pinned in glass cases in Gratton’s lab. They range from big, fluffy bumblebees to tiny creatures barely larger than the head of the pin skewering them. Some are iridescent -- almost otherworldly.

Much more than just eye-catching novelties, native bees could be the key to avoiding an impending agricultural crisis.

We rely on honeybees to pollinate about three-quarters of the world’s food. Crops like almonds, apples, onions, and blueberries all need animals like insects and bats to ferry pollen from anther to stigma. Most commercial farmers rent honeybee hives each year to provide pollination services. But over the last decade the honeybee population has been devastated by an onslaught of agricultural chemicals, diseases, parasites, and climate-change-induced shifts in plant behavior. In combination, these forces cause Colony Collapse Disorder, which has claimed a third of the nation’s honeybees every year for the last seven years.

Could wild, native bees step into the breach and offer the same agricultural support long provided by honeybees?

“Using native pollinators as a substitute for honeybees is something we’re looking at,” Gratton says. After all, before European settlers arrived with their straw beehives in the 17th century, wild bees and other native pollinators turned America’s flowers into food. Based on Gratton’s studies of cranberry farms in Wisconsin (the country’s largest cranberry producer), they may be doing it again. Some cranberry farmers can get a good yield without bringing in any honeybees at all. A study in New Jersey found similar results for watermelons. In fact, some recent data suggest that wild bees may be even more efficient pollinators than honeybees.

So how can farmers encourage wild bees to pollinate crops? Studies suggest that strategies like planting small patches of other flowering plants among crops, avoiding pesticides and herbicides, and planning crop rotations to ensure blossoms throughout the season can all encourage native-pollinator activity. But perhaps most critical, says Gratton, is keeping agricultural landscapes diverse. Because wild bees depend on natural landscapes for habitat and food, interspersing fields with uncultivated areas like grasslands and forests can actually increase crop yield.

As Gratton points out, “We often think of these areas as wastelands, as unproductive environments, when in fact they’re very productive.”

But even if farmers are able to attract native bees, one of the key questions is whether or not these bees will be able to sidestep the challenges facing honeybees.

The answer is “maybe.” In honeybee colonies, tens of thousands of bees pick up an array of pesticides and herbicides as the hives are trucked around the country chasing blooming crops. These chemicals get commingled and concentrated in the food fed to the queen bee and her young. This can create a toxic cocktail that wipes out generations of larvae. But most native bees tend to be loners. A single bee feeding only her own offspring might be able to avoid the disastrous effects of concentrating and combining agricultural chemicals.

But these are new questions, and the answers won’t reveal themselves without much more data, which can be difficult for researchers to collect. Wild bees’ solitary habits make them especially challenging to study.

“One of the things I would love to do,” says Gratton, “is to have eyes everywhere in the landscape.” But even if you can find them, bee species are tricky to tell apart -- even for experts -- so Gratton is working with colleagues in the engineering department to develop a computer program that can identify a bee’s species just by looking at the veins on its wings. He’s hoping that one day this technology will become a mobile app, so anyone anywhere could snap a cell phone picture and help entomologists like Gratton make sure that native pollinators keep on pollinating.

For now, Gratton and his students troop into the landscape with low-tech equipment, trapping bees with insect nets, bowls of soapy water, and simulated nests made out of bamboo. They painstakingly catalog the insects they catch. And they hope that the data they collect will shed light on the promise that native pollinators can help build sustainable agricultural systems -- with or without honeybees.