May 03, 2010

Elizabeth Capaldi Evans, associate professor of biology and animal behavior.

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By Julia Ferrante

LEWISBURG, Pa. — Illustrations in the classic Winnie the Pooh often show Pooh carrying a gray paper-like nest on a tree branch — with honey bees flying around it. Fond childhood memories aside, there's a fundamental problem with this picture.

"Winnie the Pooh liked honey and he always got the honey from a thing that was supposed to be a bee nest," said Elizabeth Capaldi Evans, an associate professor of biology and animal behavior at Bucknell University. "But the picture of the 'bee nest' was in reality a picture of a wasp nest. So we don't really know what he was eating." 

This portrayal is just one of many common misconceptions about bees, which eat only pollen and nectar from plants while wasps eat insect larvae, spiders and plant materials, said Evans, who explores the various aspects of bee behavior, their importance in human food production and other bee facts in a new book, Why Do Bees Buzz? Fascinating Answers to Questions about Bees (Rutgers University Press 2010), co-authored with Carol A. Butler.

From bee biology to killer bees
The book, which is set up in a question-and answer format, answers more than 100 basic and complex questions for beekeepers, scientists and others interested in bees. The subjects range from basic bee biology to the aggressive nature of killer bees and a mysterious condition, colony collapse disorder, which is threatening bees' very existence.

Why Do Bees Buzz? is part of a series of question-and-answer books published by the Rutgers press. Others in the series, also co-authored by Butler, answer questions about butterflies, bats, hummingbirds and salt marshes. The bee book includes photographs by Debra Cook-Balducci, an instructional technologist at Bucknell, and illustrations by Bucknell alumni Julie Dlugos and John Cullum, both Class of '08.
Evans, who has a bachelor's degree in biology from Trinity College in Hartford, Conn., and a Ph.D. in zoology from Michigan State University, became interested in bees after college. She began studying the orientation and navigation of bees during graduate school, studies that continued when she worked as a post-doctoral research scientist at the University of Illinois Urbana-Champaign. Evans joined Bucknell in 2000, shortly after she published a paper in Nature demonstrating for the first time that bee flight may not be dependent on age but on flight experience.

Intriguing insects
Evans did not always have an affinity for bees but through her research she developed respect for them. 

"I was scared of and intimidated by bees when I started my graduate work but saw how powerful an organism they are and how complicated they are," she said. "Bees have some interesting behaviors like the use of a dance-like movement to recruit nestmates to find profitable food sources. The way they do this waggle dance is based on the position of the sun's azimuth and opposing gravity. They are great navigators and can communicate about where to find food outside in the world, from inside the dark of the nest."

Evans has found that many others are fascinated by bees as well. She most often is asked about bees' "waggle dance," allergies — which often are related to wasps rather than bees — and killer bees.

Killer bees are a more aggressive type of honey bee that resulted from the cross-breeding of two subspecies from Africa and Europe. Originating in South America in the 1950s, they have been found along the southern border of the United States but are not a major threat in most parts of the country.

"Cross-breeding causes different behavior," Evans said. "Killer bees have a higher sensitivity to alarm and disturbance. Their venom is exactly the same as the European varieties. When they sting they leave behind a perfume that makes the other bees react and become aggressive, too. You are marked by the venom and stinger. You may get 1,000 stings from African bees where you might only receive a few stings from the European bees. The chemical is exactly the same."

Evans noted, however, that beekeepers have been managing killer bee colonies for years after proper training, so people should not fear bees because of the reputation of the killer bees.

Colony collapse disorder
One of the more pressing matters facing bees is the emergence of colony collapse disorder (CCD), which is decreasing the honey bee population exponentially. Considering that one in three bites of food is ultimately dependent on insect pollination, the far-reaching effects of CCD could be catastrophic.

The immediate causes of CCD, which was discovered by a central Pennsylvania beekeeper, are unknown. There are many potential factors involved, including diseases, colony management strategies or pesticides in the environment, Evans said. Parasitic mites are believed to be transmitting viral infections, which contribute to colony stress and ultimately kill the bees.

"In general, the average person doesn't know much about bees, which is a shame," Evans said. "If you're a beekeeper or you use bees for research or teaching you are intimately connected to what affects their health. Long before colony collapse disorder was identified, beekeepers had complained about 'fall dwindling disease.' Beekeepers and researchers noticed their bees were sick in the fall season."

'Social' insects
One of the reasons that diseases are challenging beekeepers is because when one bee is sick, it affects the whole colony. Honey bees are social insects. They differ from other bees because they have cooperation in their colonies. As such, they also are models of social behavior.

"They have a social stomach, meaning if one bee is hungry, they will signal a sister and she'll be obliged to share her food," Evans said.

Bees also divide the labor needed to maintain their hives and, contrary to "Bee Movie," starring Jerry Seinfeld, bees do not choose one job and stick with it; they change jobs throughout their lives. Worker bees also are female, not male, as the movie portrays.

The queen bee
Another intriguing fact about worker honey bees is that they know within 20 minutes if their queen is gone from the hive, Evans said. Because workers need a queen to maintain their colony, they will quickly rear a new queen from an egg laid by the queen.

"As the egg grows into larvae, the workers feed it 'royal jelly' from special glands in their heads, which turns the larva into a queen," Evans explained. "Without royal jelly, female bee larvae grow into workers."

Rather than wait for the workers to rear a new queen, a beekeeper can take control of the re-queening process, Evans said.

"If you take the queen out of a hive and put another one in immediately, the worker bee will kill it," she said. "If you take the queen out for 24 hours and then just put a new queen in, they will mostly not accept her as the new queen. They get agitated because she doesn't smell like their mom. But, if you put the queen in the hive within a screened cage stoppered by sugar candy, by the time they eat through the candy to free the queen, they will most likely accept the new queen as the head of the colony, even though she may not be related to the rest of the family. It's quite fascinating."

Evans hopes her book will provide a resource for those who are curious about bees in the general public so that more people will understand their importance.

"We can't leave all the information about bees, pollination and food production to scientists, farmers and beekeepers," Evans said. "We all share our dependence on these insects, so we need to know about their biology and how to keep them healthy."

Contact: Division of Communications