...From the pages of Agricultural Research magazine
New Cuisine Wins Rave Reviews
Honey bees devour a new,
nutrient-rich food. This
artificial diet resulted
from 5 months of research.
Honey bee hives from Maine to California are abuzz with news about
a new food that originated from a chance conversation between two ARS
scientists. At an Entomological Society of America meeting in the summer
of 2001, entomologists Gloria DeGrandi-Hoffman, who specializes in honey
bee research, and Allen C. Cohen, who is internationally recognized
for his pioneering work with foods for insects, met and discussed a
problem that has plagued California's almond growers for years.
These orchardists, producers of the nation's $1 billion almond crop, need bustling colonies of honey beesalive with strong workers and healthy young, known as broodto pollinate their vast orchards during the winter months. That's the time of year these trees begin to flower. But it's also when bees are in a near-hibernating state and not being very industrious.
Entomologists Gloria DeGrandi-Hoffman
(right) and Gordon Wardell
observe comparison feeding
trials in which different
diets are offered and bee
preference is monitored.
Cohen and DeGrandi-Hoffman, now research leader at the ARS Carl Hayden Bee Research Center, Tuscon, Arizona, decided to collaborate in developing a recipe for an artificial diet that would give honey bees the whole package of nutrients they need in an easily digestible liquid. This would keep the bees rearing brood and ready to work once the almond blossoms appear.
Presently, beekeepers use soy patties to feed bees during winter, before
almond blossomsfloral treasure troves of pollen and nectarare
readily available. The major problem with these patties is that they
are costly and labor-intensive. Beekeepers must either go from hive
to hive and manually insert the patties or place large tubs of the dry
patty mix near their beehives.
The pattiestypically made of corn syrup, soy flour, and brewer's yeastcreate another problem. For reasons not yet understood, bees that eat soy patties eventually lose their ability to produce a food, called worker jelly, that's vital for the brood.
Gordon Wardell prepares a
variation of Allen Cohen's
classic recipe, a scrumptious
blend of vital nutrients that
finicky bees just can't resist.
With a liquid diet, a machine already used by beekeepers would be able to easily pump the bee food into the hives, a far less labor-intensive approach, says Cohen. He recently retired from the ARS Biological Control and Mass Rearing Research Unit in Mississippi State, Mississippi. In the late 1980s, he was stationed at the Bee Research Center and worked with DeGrandi-Hoffman there.
Cohen started with an existing diet that he created for indoor rearing
of lygus bugs. It was patented by USDA in 2000. To meet the needs of
beekeepers, he converted the lygus bug food from solid to liquid, blending
ingredients that provide vital nutrients.
Cohen wanted to create a formula that would combine the sweetness of nectar and the nutritional punch of pollen into a digestible, absorbable food that bees would gobble up.
Nectar is rich in carbohydrates. Pollen is packed with protein, vitamins,
minerals, fats, and perhaps as-yet-undiscovered compounds essential
for bees' survival.
"What we didn't know is whether bees would be able to take a liquid
that combined the qualities of both nectar and pollen and process it
in such a way that the formula would be completely nutritious for them,"
says Cohen. "That was really one of the most exciting possibilitiesto
see whether we could essentially fool the bees' natural digestive mechanisms."
Cohen's classic recipe, modified slightly, thus became the Arizona
lab's starting point for a new menu option for domesticated honey bees,
With Cohen's formula in hand, DeGrandi-Hoffman and Gordon I. Wardell,
an entomologist and corporate collaborator at Tucson, mixed batches
of the creamy-white liquid for bees to taste-test.
The intent was to create an elixir so delectable that adult bees would
not only eagerly eat it but would also, as is their usual practice,
store some of it in the hive for nurse beesthe hive's round-the-clock
nanniesto feed to the colony's brood.
For the investigations, Wardell assembled 12 small hives, then enclosed
them with netting so bees couldn't sneak out during the tests to bring
their familiar foods back to the hive. Each hive housed about 3,500
to 4,000 bees. "We offered the bees one kind of foodeither
sugar-water, pollen, or the new liquid, which we poured into petri dishes,"
says Wardell. The bees ate little, if any, of the new concoction.
To make it more appetizing, the researchers launched a series of new
experiments, presenting variations of the baseline recipe for the bees'
approval. The scientists structured these experiments so that despite
natural variations from one six-legged taste-tester to the next, the
findings would be statistically sound.
After 5 months and nearly 80 reformulations, the team hit on an apparently
scrumptious creation that the finicky bees just couldn't resist. The
scientists then tested it in full-size hives, each accommodating about
30,000 bees. Wardell and co-worker Fabiana Ahumada-Segura fitted each
hive with a small window so that they could spy on the dining bees.
"At one point," says Wardell, "we saw 75 to 100 bees
jammed around a petri dish, pushing and shoving each other to get to
the food. In the commotion, some of the bees fell into the petri dish.
It was like a bee mud-wrestling match."
Adds Cohen, "This is somewhat historic because people have tried
for the past 50 years to develop diets for bees but were unable to get
the bees to continue to rear brood on those formulas. With the new diet,
bees have been able to rear continuous generations of brood."
To see whether the new culinary offering would please bees elsewhere,
Wardell sent samples to commercial beekeepers in Arizona, California,
Georgia, Maine, Michigan, New Mexico, and Pennsylvania. "All the
beekeepers reported that their bees liked this recipe," Wardell
says. "One beekeeper asked an assistant to take a ruler out to
a hive and measure how much food was left after the bees had about 4
hours to try it out. To their amazement, all the food was gone."
More work is needed, however, before the experimental food is ready
for commercial and hobbyist beekeepers to use. "We want to cut
the cost so the food is affordable," Wardell explains. "We're
using very pure, pricey ingredients, but we intend to substitute less-expensive
compounds." The scientists also aim to develop a dry mix. Lighter
than the liquid, it should be cheaper to ship.
Further fine-tuning of the formula may boost brood survival rates and
lengthen adult bees' typical 4-week life-span. Currently, both these
measures are about the same among bees reared on pollen patties and
those fed the novel food.
Another planned upgrade: compounds known as feeding stimulants that
may entice bees to eat even more. Though these are already standard
ingredients in other foods formulated for nourishing beneficial insects,
apparently no one yet knows which feeding stimulants would appeal to
This research is part of Crop Protection and Quarantine (#304) and
Crop Production (#305), two ARS National Programs described on the World
Wide Web at www.nps.ars.usda.gov.
"New Cuisine Wins Rave Reviews From Honey Bees " was published in the March 2003 issue of Agricultural Research magazine.