Fun Plant Tricks with Smell

Have you ever been drawn in by a smell? The aroma of cookies fresh out of the oven, the fragrance of perfume, or the tantalizing scent of a flower? Smell can be a powerful motivator for all kinds of animals, from humans to lizards to insects. Recently, scientists here at the University of Utah unraveled the unusual secret of how one plant uses smell to its advantage.

The Plant
Meet Macrozamia lucida. This Australian wonder is a cycad, a primitive kind of plant that has been around since before the dinosaurs. If you're thinking it looks like a pine cone, you're right! Cycads, like pine trees and junipers, are gymnosperms, which means that they have seeds but not flowers. Instead, they produce cones.

Irene Terry, a biologist at the University of Utah, recently set off to explore just how Macrozamia lucida makes its way through life - particularly, how it reproduces. Like humans, individuals of this species are either male or female. To reproduce, male sexual cells (pollen) must reach and combine with female sexual cells (ovules). For a long time, people thought that the wind moved the pollen from the male cycad cones into the female cones, but in 1999, Terry discovered that small insects, called thrips, were responsible for carrying the pollen from plant to plant.

The Insects
This particular species of thrips spends its life inside the male cycad cones, laying eggs and munching on Macrozamia lucida pollen. The female cones, with no pollen in them to eat, aren't appealing to the thrips. But the plant needs the insects to move some pollen into the female cones so that it can reproduce. How does the plant get the thrips to do that?


The Trick
The answer, it turns out, has to do with the power of smell. The plants let off a special chemical that, in small doses, smells wonderful to the thrips and attracts them. In high doses, though, the chemical is toxic to the thrips and repels them. So, to make sure the insects don't just spend all their time eating pollen in the male cones, every afternoon the male plants burn some of their stored sugars to create energy and heat themselves up. The extra-hot male plants release a high dose of the chemical, driving the thrips away. Many of them fly towards the females, which have an attractively low dose of the chemicals even as the males are too strong. Later, the male plants cool off, and the thrips return to their tasty homes. The whole cycle starts again the next day "until the males wear out and the females are happily pollinated," Terry says.

Have you ever been manipulated by smell? What smells attract you? What smells would you avoid?

Bee Mystery: Scientists Get a Clue

Have you heard the buzz about bees? They're disappearing! All over the country, honeybees have been mysteriously vanishing from their hives.

Beekeepers first noticed the problem in 2006: they'd open a hive, and the worker bees would be gone! A hive could go from healthy to empty in just 2 weeks. No one knew what was causing the problem, but experts named it Colony Collapse Disorder (CCD).

So far, CCD hasn't made it to Utah. But without knowing how it's caused or spread, we can't be sure it won't get here. If it did come to Utah, bee keepers could lose up to 90% of their hives. That's a problem for more than just people who love honey; bees play an important role in producing much of the food we eat.

"People just don't realize how important pollination is," says Debbie Amundsen, a staff member at UMNH and an amateur beekeeper. According to the US Department of Agriculture, "about one mouthful in three in the diet directly or indirectly benefits from honey bee pollination." That includes almost 100 crops, such as almonds, peaches, and cucumbers. In Utah, bees also pollinate the alfalfa that is used to feed livestock.

The good news is, a team of scientists has just discovered an important clue to what causes CCD. They noticed that a new virus (first seen in Israel in 2004 ) is usually present in hives that suffer CCD. They don't think the virus is causing the collapse by itself, but teams up with other stresses to bring the bees down. "This research gives us a very good lead to follow," said Jeffery S. Pettis, one of the scientists working on the problem. Let's hope they solve this mystery before it's too late!


Talk to us! How might your life be different if there were no more bees? Click "Comment" below and let us know!

Old Flowers: New Evidence

Imagine what the earth was like 80 million years ago: the sights, the smells, the sounds.... I bet your mind didn't leap straight to orchids, did it? But scientists at the Harvard Museum of Comparative Zoology are buzzing about new evidence that the first orchids are old enough to have lived that far in the past, right alongside dinosaurs.

To what do we owe this newfound vision of T-rexes tromping along next to showy flowers? Why, to a bee! Lucky for us (though not for the bee), sometime around 15 or 20 million years ago a bee was covered in tree resin as it went about its daily business. Over millions of years, as the tree was buried, the sap hardened into amber with the bee trapped inside. Eventually, someone found the preserved fossil in the Dominican Republic and brought it to the Harvard Museum to study.

So how did a 15 million year old bee tell us about 80 million year old orchids? As it turns out, the amber preserved not only the ancient bee, but also the pollen grains it was carrying on its back. By carefully studying the pollen grains, the scientists were able to determine not only what kind of plant they were from but also how they relate to modern species.

This find was particularly exciting to scientists, because it's the first window into orchid evolution they've discovered. "It's absolutely fantastic," an orchid specialist told Nature magazine. "It's what the orchid community has been waiting for, for a long time."