[The following is an exact transcript of this podcast.]
Animals rely on all sorts of cues to find their next meal. Monkeys and birds are attracted to the colors of ripe fruits and berries. And snakes find their prey by sensing heat. Now a team of Canadian scientists finds that some insects can do the same thing, sensing the infrared radiation emitted by, of all things, pine cones.
These seed-eating bugs are not the first known to home in on heat when they’re looking for food. Some blood-sucking bugs can sense the temperature of their warm-blooded hosts. But this study, published on October 22nd in the Royal Society journal Biological Sciences, is the first to find that insects can use infrared to find their favorite plants.
Pine cones, it turns out, run about 15 degrees warmer than the pine needles that surround them. In fact, the cones radiate so strongly in the infrared that they show up like candles on a Christmas tree. The bugs, which nosh on conifer seeds, can locate the toasty, seed-bearing cones thanks to special infrared receptors on their abdomens. When the scientists covered up those receptors, the insects couldn’t see the forest or the trees. And the male insects probably won’t even stop to ask for directions.