英語(yǔ)時(shí)差:走開！
Don: Arghh. Stupid bees! Yaël: Are you sure those are bees Don? D: Well I'd say they're either bees or wasps. But I'm not sure. Y: Well I think most people couldn't tell wasps or bees apart by sound. And we're not alone! A study shows that some leaf-eating caterpillars can't tell the difference between wasps and bees by sound either. D: Bees don't usually hurt caterpillars, but don't some wasps eat those hairy little guys? Y: They sure do. And this study showed that when some caterpillars hear buzzing nearby they stop their leaf munching and head for the hills, because they don't know if the buzz maker is a harmless bee or a predatory wasp. D: That's too bad for the caterpillars, but it sounds like good news for the plant since the caterpillar doesn't munch on so many of its leaves if there's a bee nearby. Y: Exactly. The study found that fruitless plants sustained sixty- to seventy-percent less leaf damage by caterpillars when bees were around then when the caterpillars were left alone with the leafy greens. D: So bees are pulling double duty for plants: not only do they pollinate flowering ones but they also scare off plant eating bugs from plants within earshot of the bees'buzzing. Y: Indeed. And with this finding we might someday be able to improve food production;since if we could get more bees buzzing around our crops, scaring off pests, we might get higher yields using fewer pesticides.
