|With a tiny "harmonic transponder" on its back, a bumble bee goes about its business (Photo by Ingrid Williams, IACR)|
An amazing little antenna teaches us how bees learn to fly
by Ric Getter
Some of natures smallest creatures are the source of some of sciences biggest mysteries. One of those mysteries has always been how honeybees can be such great navigators. Worker bees manage to fly straight back to their hive from flowers that are sometimes miles away. In fact, thats where the word "beeline" came from.
Unfortunately, honeybees are very hard for entomologists (the scientists who study insects) to track. They are rather small and quite fast (not to mention the fact that they tend to sting anyone who gets in their way). There are radar systems that are sensitive enough to track the little bees. But when they are flying only a few feet over the ground, too many things like trees and bushes get in the way of the radar. That "ground clutter" hides the bee from the radar.
What the scientists needed was something called a "transponder." Thats an electronic device that makes the reflected radar signal easier to identify. But even the smallest transponders, like the ones that were made to track migrating birds, were much larger than a bee could carry.
Then, Dr. Joe Riley, a radar scientist from the Natural Resource Institute in England, came up with a very clever idea. He invented a very small transponder that didnt need a battery. The little antenna was tiny enough to fit on the back of a bee. The antenna reflected the signal transmitted from one radar system in a way that could be clearly seen by another radar.
The portable radar uses two dish antennae. One activates the transponder, the other receives the signal. (Photo by Ingrid Williams, IACR)
The team of entomologists, led by Dr. Elizabeth Capaldi of the University of Illinois, was able to begin unraveling some of the mysteries. They discovered that the young bees flew a series of "orientation flights," learning more and more about the area around their hive. "Honeybees go through a division of labor based on their age," Dr. Capaldi explained. "When bees emerge as adults, they first perform tasks inside the nest. As they age, they switch to doing work outside the nest. We're learning what it takes to become a behaviorally mature, adult bee."
The entomologists also discovered that bees are skilled pilots as well as navigators. Somehow, they could zoom in and around the flowers without getting their new antenna tangled.
Dr. Riley is very happy with how his radar system is being used. He told NetSchools, "It has opened a whole new window on low-altitude insect flight...it's now become possible to study in detail the remarkable navigational performance of honeybees and of bumble bees." Dr. Capaldi told us that the most exciting part of the experiment for her is "the detection of something that no one has ever seen before. We're unraveling the mystery of where the bees are going on these early flights."
Farmers are very interested in these experiments, too. Some of their crops require visits from the bees to reproduce. Putting up big buildings on land that was once used for farming could get in the way of the bees valuable work. Learning how bees "commute" to their favorite plants could help toavoid problems in the future.
Soon, the radar entomology team plans to use their system to study the tsetse fly. Its a tiny insect that has been responsible for spreading a dangerous disease through parts of Africa. Learning more about how the tsetse fly migrates could help control the spread of the illness and possibly save peoples lives.
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Here are some places where you can find out more about radar entomology: