Part of a lecture about how honeybees communicate with one another

Section 4. You will hear part of a lecture about how honeybees communicate with one another. First, you have some time to look at questions 31 to 35. Now listen carefully and answer questions 31 to 35. MAN: Good morning. Today I want to look at one of the most remarkable behaviours in the natural world: the way honeybees tell each other where to find food. When a single bee, a scout, discovers a good patch of flowers, she somehow passes on its exact location to her hive-mates, and she does it without sight, in the dark of the hive, and without sound as we understand it. She does it by dancing. MAN: This dance was decoded in the last century by an Austrian scientist, Karl von Frisch, work for which he later won a Nobel Prize. He found that the scout performs a movement now called the waggle dance. The bee walks in a straight line while rapidly shaking, or waggling, her body, then loops back and repeats it, tracing a shape rather like a figure of eight. MAN: What's astonishing is how much information this carries. The direction of that straight run tells the other bees the direction of the food, measured relative to the sun. And the distance to the food is encoded in the duration of the waggle, the longer the bee waggles, the further away the flowers are. So a very short run means the food is close by; a long one sends the others much further afield. Before you hear the rest of the lecture, you have some time to look at questions 36 to 40. MAN: Now, a natural question: what about cloudy days, when the sun is hidden? Remarkably, bees can still navigate, because they can detect the pattern of polarised light in the sky, which reveals the sun's position even through cloud. There is also a second, simpler message. Before dancing, the returning scout often shares a droplet of nectar with the bees around her, and the taste and smell of that sample tells them exactly which flower to look for. MAN: It's worth stressing why all this matters beyond the hive. Honeybees are among our most important pollinators, and a huge proportion of the crops we eat depend on them, so their efficiency in finding and sharing food has a direct effect on our food supply. When a colony can direct its workers precisely to the richest flowers, the whole hive gathers far more. MAN: Finally, a note of caution. In recent decades beekeepers have reported serious losses, and while the causes are complex, researchers point to a combination of factors, the spread of a parasitic mite, the loss of wildflower habitat, and the use of certain pesticides. Understanding how bees communicate is one small part of understanding how to protect them. That's where I'll stop today. That is the end of Section 4. You now have some time to check your answers.