Ask the Experts: Elizabeth Capaldi Evans on bees
Elizabeth Capaldi Evans, associate professor of biology and animal behavior biology.
Posted: March 25, 2010
LEWISBURG, Pa. — Welcome again to "Ask the Experts," a regular web feature that highlights the expertise of various Bucknellians in a range of topics related to current news events and other timely subjects. || Ask the Experts archive
This week, we asked Elizabeth Capaldi Evans, an associate professor of biology and animal behavior, to talk about bees, how they benefit the ecosystem and how a mysterious condition called colony collapse disorder is threatening their existence. Evans' research focuses on bee learning and potential impacts of disease on bee behavior. She is the co-author of a new book, Why Do Bees Buzz? Fascinating Answers to Questions about Bees (Rutgers University Press, 2010).
Q: Where do honeybees come from and how do they benefit the ecosystem?
A: Honeybees live in North America because they were brought here by European colonists. They were physically brought here by people because every community needed to have a source of honey and wax. Prior to the manufacture of cane sugar, honey was the only sweetener, so honey was an important part of early American households. There is some evidence bees were brought here by Vikings, but we know that the Puritans and colonists had honeybees on their ships.
Bees are found throughout our habitat, so bees and people overlap with where they live. Bees are quite beneficial for us in our native habitats because they are pollination vectors and they are essential for plant reproduction. One in three bites in an average American diet is dependent upon insect pollination and so the biology of bees should be a cause of concern for a lot of people. Crops like tomatoes, apples, oranges, almonds, cherries, pears and blueberries all are completely dependent on the action of bee pollinators. Without the pollinators, none of those foods would be on your plate.
Q: When "Bee Movie" was released, you took a class to see the movie and asked them to assess its biological accuracy. What are some common misconceptions about bees illustrated in this movie and in general?
A: The first misconception about bees is probably that they are malicious, that they somehow are aggressive unnecessarily, although the "Bee Movie" didn't have this problem. Usually, bees sting when they perceive threats, either to themselves or to their colony. The second thing is that most people have a bad experience with a stinging insect and it's a wasp and not a bee. Wasps are much more aggressive and much more assertive about their aggression, so bees get a bad rap because of the actions of wasps. Another misconception is that bees have paper nests. Those are wasp nests. Most bees nest in the ground or in wooden cavities.
The "Bee Movie" came out during a semester when I was teaching my class "Social Insects." We asked the Watsontown Theatre to open for us to see it as a group, and the students had to write a movie review, a biologically correct movie review in the tone of a newspaper article. They had to review the movie and the biology included in it. That was a really successful writing assignment for them because they had to convey to me both their appreciation for the art form and Jerry Seinfeld's humor, but they also had to make commentary about how they could have done it differently to make it biologically correct.
You can overlook things like the bees speaking English and wearing sneakers for artistic expression, but the whole theme of the movie, which is that a bee has to pick one job and stick with it for the rest of its life, is also wrong. Social insects are unique because they have a change of jobs throughout their lives as they age. The biggest problem with the movie from a biologically correct perspective is that all worker bees are females. In the movie, they were all male; the only female bee character in the movie was Jerry's mother.
Q: What is colony collapse disorder, how was it discovered and how has it affected the bee population?
A: Colony collapse is a disorder of bee colonies that has a yet-unidentified origin. A local beekeeper named David Hackenberg, who brings his colonies from Pennsylvania to Florida and California annually, discovered in the fall of 2006 a catastrophic loss in the population of his individual colonies. Beekeepers have been dealing with a seasonal dwindling of their population for years, but this was on the order of magnitude that hadn't been seen before. The discovery initiated a series of studies and new research to figure out why colony populations crash.
People need to know that without sufficient individuals in the colonies, they can't survive the winter. There isn't a single magic bullet to explain the phenomenon. There are a number of different factors that are shown to be involved. Right now, there's no statistically validated, biological evidence that has been scientifically demonstrated to show that it is the result of a single cause. It's not because of a new insecticide. It's not because of a new virus. It's because those and other factors are interacting and affecting the health of the bee.
This has primarily been a problem for beekeepers who have a large number of colonies, and it's much less dramatic of a problem in hobby beekeepers or smaller operations. Colony collapse is one major cause of overwintering mortality, when between 50 percent and 75 percent of a beekeeper's colonies don't survive over the winter, but it's not the only one. This problem is hugely important for the business of beekeeping, but it also means the spring population service is substantially lower. There are fewer bee bodies available in the spring to do the pollination.
Q: Are there any known causes of colony collapse and what is being done to combat it?
A: There are numerous factors involved. One is that we need to know that the bees have adequate nutrition. We also have to make sure that they are not exposed to pesticides in the environment. Honeybees harbor a parasitic mite that functions like a tick on mammals, and the mite itself transmits viral disease. The virus is not something that we can treat chemically, but we can modify the way we keep the bees to affect the mite populations. If we can control the mites, then we can lower the amount of disease within the colony.
Q: Bats in the northeast are being devastated by white-nose syndrome, a mysterious condition that causes them to leave hibernation early, deplete their reserves and starve to death. Is the fact that white-nose syndrome is killing off bats at the same time bees are dying as a result of colony collapse compounding these problems?
A: Both white-nose syndrome and colony collapse are thought to have an impact on the host animals' immune system. So white-nose syndrome is affecting bats because the bats are not able to fight off the infection. With colony collapse, it's not a single cause but we know that the ability of the bees to withstand environmental change has been lowered, so it could be multiple causes. Both bees and bats are immune compromised in some way, and we don't know exactly how we can treat that, but I don't think the two are related beyond the fact that we are dealing with some form of an exotic disorder that is having an influence on the population. Both problems are truly bad news for the environment.
Maybe I see a little bit too much of the silver lining with environmentally sensitive issues, but one thing that has been beneficial about the press attention that the bee issue has created is that people are paying attention to where their food comes from — and that's a good thing — whether it is to promote environmental awareness or attention on buying food that is grown locally or grown in the back yard. When people are concerned about bees, it means they are thinking about the consequences of not having bees, and that can only be good for our communities.
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