And then, bang on cue, the bees arrived. A new brood had just chewed their way out of their pupal cells inside one of the laboratory’s hives. Wright’s team leapt into action, marshalling batches of bees into see-through boxes and spooning gloopy mixtures of pollen, fats and sugars into feeders. What these mini-colonies chose to eat over the coming weeks would feed a study of how honeybees balance their diet.
Across the lab, orderly rows of slim plastic tubes stood waiting. Each would soon be occupied by a single bee, held firm, snug and ready for tests on the ability to learn which flowers offer nutrients that the bee most needs. The tubes were lovingly hand-sculpted for comfort, with a bee-sized neck rest on one side and a plunging neckline on the other to allow room for the rise and fall of a bee’s breathing body. Each tube also flew a thin pennant of duct tape: part of a bee harness.
I’d never harnessed a bee, so I was keen to learn how it’s done. You take a sleepy bee and maneuver it gently until its head and first pair of legs emerge at the top of the tube. Flip the sticky strip over its “shoulders” and secure it, then wrap a second strip over the back to prevent escape. It sounded tricky, but these experts can get 60 done in no time.
Basic energy requirements are met by nectar (essentially sugar water), which provides the carbohydrate bees need for activities such as flight and keeping the colony warm. Pollen provides everything else a colony needs to thrive: proteins, fats and lipids plus an assortment of micronutrients including essential sterols, vitamins and minerals. “All these nutrients are important for different reasons at different times in the growth of the colony,” says Harmen Hendriksma, a Dutch entomologist currently working in the Toth Laboratory of Integrative Insect Sociobiology at Iowa State University.
To complicate matters, bees need carbs, proteins and fats in specific but shifting proportions according to season and what’s happening in the hive. As larvae, they require more protein and fat; as adults, their wants shift towards carbohydrates. Feeding experiments show that they try to achieve the right balance by controlling what foods they collect and eat. If caged nurse bees are offered a choice of two foods (one carb-heavy, say, and another overly rich in protein), they sample both in a proportion that helps them reach an optimal ratio.
Last year Hendriksma published work showing that when a colony is suffering a dietary deficiency, forager bees try to remedy it. He and Sharoni Shafir of the Benjamin Triwaks Bee Research Center in Rehovot, Israel, allowed free-flying honeybees to forage for a week on artificial diets that lacked one of the ten essential amino acids bees need. When the week was up, the researchers offered the bees a trio of foods: one exactly the same as before, one new but still missing the vital amino acid, and one containing the missing ingredient. They assumed bees would eat from all three, picking up at least some of the amino acid in the process. Instead, foragers more often made a beeline for the food with the missing ingredient, and collected measurably more of it. “Somehow, bees know when their food isn’t up to par and show a preference for food that counters the deficiency,” Hendriksma says.
A better strategy is to add more healthy options to the bees’ menu by providing greater diversity of natural forage. There are already many initiatives to do just that: sowing wildflowers in unused patches of farmland, around field boundaries, along hedgerows, in urban backyards and other green spaces; and cutting back on mowing in parks and along roadsides to give wildflowers the chance to bloom. Thanks to so much research into the nutritional value of different sorts of pollen, such schemes may soon be able to tailor seed mixes to best meet bees’ needs. “At Newcastle, we’ve analyzed the nectar and pollen of most of the UK’s wildflowers and will soon be able to recommend what to plant to provide the best forage,” says insect physiologist Dan Stabler, a member of the Newcastle bee team.
Providing more wildflowers makes instinctive sense. But how much of an impact can such measures have? Researchers in Iowa are beginning to get a good idea. The state was once covered by flower-filled prairie. Today 90 percent of it is farmland, mostly planted with corn and soybeans. Over the last decade, each winter has seen the death of around 60 percent of Iowa’s honeybee colonies.
Since 2007, a team from Iowa State University has been measuring the benefits of planting strips of prairie vegetation amid corn and soy crops. The recently published findings are hugely encouraging. By replacing 10 percent of the cropland with prairie strips, they bumped up the number of pollinators 350 percent, and the diversity of insects 260 percent.