Tricky little orchids

Orchids attract collectors all over the world. One of the things that draws us to these unusual plants is their Machiavellian approach to life. They unfeelingly employ deception to their benefit, usually practicing their art on unsuspecting members of the insect community. Research has revealed that one species of orchid, Anacamptis morio (or Orchis morio), or the green-winged orchid, lays its bold insect trap in an attempt to avoid a trap itself.

Inbreeding avoidance: not just for royalty

Although plants can do many things that most members of the animal kingdom cannot—self-fertilize or increase chromosome numbers in a generation—they’re still better off when reproductive measures result in an increase in genetic variation. As with most organisms, inbreeding is not a healthy thing for a plant, and many plants have mechanisms to avoid it.

The idea of inbreeding avoidance led researchers to a theory to explain the remarkable behavior of many orchids. These beautiful, much-coveted flowers attract humans and insects with their alluring fragrances and colors. For insects, some orchids add to the attraction by mimicking the female of the insect species, or wafting the scent of eau d’ dung for insects that prefer laying their eggs in such places. But of the 30,000 known orchid species, about 10,000 have nothing to offer the hapless insect in return: their flowers have no nectar.

Why keep coming back for nothing?

Researchers have sought to explain why insects would continue to visit such a stingy plant, and why the plants continue to get away with and employ their nectar-free strategy. The strategy itself seems in violation of so much of our understanding of the natural world, a place typically characterized by tradeoffs. In fact, orchids without nectar are not wildly popular among insects—it is difficult in many cases to witness a bee pollinating a green-winged orchid in the wild—but they still do manage to get pollinated.

Scientists investigated wild-growing green-winged orchids on a Swedish island and figured out why this species cheats insects so mercilessly. It’s about genetic variation. The flowers attract the bugs, but offer the foraging insects nothing, driving them on to explore other plants. Although the orchids have not provided food, they have given the unsuspecting insect a payload of a different kind: pollen. The bug—still on a quest for nectar—forages in other plants, pollinating as it goes along. Voila! No self-pollination. Plants that result from self-pollination are usually weak and unhealthy, and self-pollinating can be a waste of precious pollen.

Interviewing bees

Scientists detected this self-pollination avoidance by interviewing bees. They queried specific bees with plants that had been artificially dosed with nectar or with plants in their natural nectar-free state. The researchers found that bees stayed around the nectar-ful plants twice as long and investigated twice as many flowers on the same plant, which would promote self-pollination. Bees that found no nectar moved along to other plants, promoting cross-pollination.

One thing that could confound the interpretation of these results is that bees can remember how a plant smells. If a bee strikes out with one orchid, it will remember that orchid’s smell and not waste its time foraging around in other flowers that smell the same.

In separate research performed by a team in Switzerland, scientists found that the flowers of a nectar-producing orchid species all smell very much the same. But flowers on different plants of the green-winged orchid all smell different. A bee might have failure at one green-winged orchid and remember the smell, but then fly straight into another green-winged orchid plant because its smell is different. The unhappy bee falls into the orchid’s trap and gets nothing, but the deceitful orchid itself has had a great success: avoiding the trap of self-pollination.

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Wordless Wednesday: Dolphin diplomacy

(almost wordless…)

Move over, cockroaches. Dolphins have the communication game down to diplomacy:

(Credit: iStockphoto/Stephan Zabel)

Cockroaches are collective food critics

Collective communication guides cockroach dining decisions

Ever drive by a restaurant with an empty parking lot and avoid it yourself because, well, no one else was eating there? If so, you’re not much different from cockroaches. They also appear more attracted to food resources if other cockroaches dine there, as well.

Yes, cockroaches creep me out, too

They’re the only animal about which I’m phobic, but who could resist a story like this? A new study published in Behavioral Ecology and Social Biology has found that cockroaches communicate with each other about preferable food sources, much as people do.  Rather than doing it through visuals of empty parking lots or restaurants or via a critic’s recommendations, however, they probably use pheromones. So, there may be a cockroach pheromone or suite of the chemicals that says, “Hey, this pile of garbage is the best in town!”

The researchers who determined this used a couple of piles of food. The roaches collectively would spend more time and in greater numbers at one pile of food over another. Even more interesting–at least to cockroach researchers–the bugs would linger longer at the dining source if other roaches were there, too. Peer pressure, it appears, is not only a human phenomenon.

It’s not limited only to cockroaches in the insect world, either. There are many other examples of insect chemical communication guiding collective behavior. The most famous is probably the honeybee waggle dance, which the animals use to indicate which way to go to find the best food resources.

Why should we care?

Why would researchers go to the trouble of monitoring cockroach choices over piles of food? One reason is that if we identified the pheromone that communicates “good food pile” to cockroaches, we could use that to lure them into our little pest-control traps. Ever diabolical that way, we humans are. There are some things not even cockroaches can do.

Recorded “bee alarm” calls send pachyderms packing

Elephants are terrified of bees

Forget about the mouse freaking out the elephant. What these land behemoths fear most may be bees. Researchers report in PLoS ONE that African elephants live in such terror of African bees that the pachyderms have a specific alarm call that means “Bees!” Recordings of the call could send herds stampeding, even with no bees in sight or earshot.

Birds do it, prairie dogs do it, and so do elephants

Vulnerable vertebrates living in social groups often have calls specific to danger. Prairie dogs throw up little arms and let out a whoop that means “Hawk!” or “Snake!”. Some primates and birds also have vocalizations specific to certain threats. But why do elephants, with lions as their only non-human predator, fear bees so much? A swarm of angry African bees can sting their soft parts around the eyes and mouth, and the hide of young elephants isn’t tough enough yet to withstand the stingers.

Rumble in the jungle, er, savannah

When a bee threat is detected, the elephants emit a particular rumble (listen here), just one of the many vocalizations these social animals use to communicate with each other. Subtle variations in this rumble, which elephants may produce by small adjustments in lip and tongue, can send a pachyderm pack running as though a hive of angry bees were on their trail. But another small adjustment can leave most of them standing there, staring. These subtle changes may even cue the herd to the nature of a specific danger, as is the case with other vertebrate groups that sound alarm calls.

Other differences may not be so subtle. While bees get a rumble from the elephants, lions get an unmistakable elephantine reception that includes threatening roaring and trumpeting.

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