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Wildfeuer via Wikimedia Commons // CC BY 2.5
Wildfeuer via Wikimedia Commons // CC BY 2.5

Study Finds That Plant Emits the Scent of an Injured Honeybee to Lure Flies

Wildfeuer via Wikimedia Commons // CC BY 2.5
Wildfeuer via Wikimedia Commons // CC BY 2.5

Plants are liars. There, we said it. All right, fine, not all plants. But a lot of them. Meet the newest member of the botanical pants-on-fire club: a little flower that stinks like an injured bee in order to attract bee-eating flies. Researchers published a report today on the plant’s trickery in the journal Current Biology

Most plant deception is pretty crude. Consider the reeking corpse flower, or the bee orchid, whose lady bee-shaped flowers are irresistible to passing bee dudes. The male bees zoom in and get busy. Before too long they realize they’ve been had—but not before they’ve pollinated the devious, devious orchid.

Other plants employ slightly subtler devices. Plants in the Ceropegia family depend on flies for pollination. Their flowers are trap-shaped, so once a fly gets in, it will pretty much have to rub itself all up on the plant’s sexual parts in order to escape. But for that to happen, the fly first has to show up.

To catch a fly, you need to think like a fly. Fortunately, many of the flies that pollinate Ceropegia are fairly easy to predict. They like flying, buzzing, mating, and, most importantly, they like stealing other bugs’ food. Rather than hunting for its own honeybee, a kleptoparasitic fly waits until a predator like a spider has caught one, then buzzes down and digs in.

Flies could presumably follow spiders around until they made a kill. But it’s much more efficient to just sniff the air for the scent of a bee in trouble. It’s kind of the arthropod form of ambulance-chasing lawyers.

A team of European scientists suspected that the little South African flower Ceropegia sandersonii was using flies’ own trickery against them.

To find out, the researchers studied both the flowers and the bees. The first thing they noticed was that a spider-caught bee would eject its stinger, which released a droplet of venom. The team tested the venom and found it riddled with alarm pheromones, which, when released, would warn nearby bees to beat it.

A bee covered in kleptoparasitic flies. Check out the drop of venom at the tip of its stinger! Image Credit: Gernot Kunz

 
Next they captured and tested C. sandersonii’s oh-so-innocent floral fragrance, looking for chemical similarities with the bee venom. They found them. In an act of chemical mimicry, flowering C. sandersonii plants were in fact emitting what seemed to be appealing olfactory distress calls.

Biologist Daniel Janzen studies plant-animal relationships at the University of Pennsylvania. (He was unaffiliated with this study.) “Tropical nature is packed with these kinds of detailed eco-behavioral interactions,” he told mental_floss in an email. “It’s nice to have another one worked out.”

Know of something you think we should cover? Email us at tips@mentalfloss.com.

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Why Some Trees in Norway Are Missing Their Rings
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Dendrochronologists are experts at reading tree rings. They can learn a great deal of information—including past climate in an area and the age of the tree—by taking a tree core sample and reading between the lines (literally).

But as the BBC reports, one climate researcher was stumped when she discovered that many trees in the Norwegian village of Kåfjord were missing their rings. Extreme weather and invasive insects can cause some degree of damage to trees, but not enough to render them ringless.

Claudia Hartl, from Johannes Gutenberg University in Germany, knew that these trees dated back to 1945, but that alone wasn't enough information. Two other clues that helped Hartl and her colleagues solve the mystery were location and history. During World War II, Nazi soldiers moored the Tirpitz—the largest battleship of Hitler's navy—off the waters of Kåfjord to intercept vessels carrying Allied supplies to the Soviet Union. The Germans released an artificial smoke containing chlorosulphuric acid to conceal the ship's location, and this is believed to be the root of the trees' problem.

Artificial smoke could have damaged the needles of the trees, halting the photosynthesis process and stunting the trees' growth, researchers found. It takes time for the trees to recover, but it is possible. One tree saw no growth at all from 1945 to 1954, but after 30 years its growth had returned to normal. Hartl presented the findings at the European Geosciences Union General Assembly in Vienna this week [PDF].

"I think it's really interesting that the effects of one engagement are still evident in the forests of northern Norway more than 70 years later,” Hartl told BBC News. She believes her "warfare dendrochronology" will unearth similar findings elsewhere in the world.

[h/t BBC News]

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Palm Trees in Canada? It Could Happen, Thanks to Climate Change
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Human-caused global warming has the potential to transform coastlines, weather patterns, and entire populations. According to a new study published in Scientific Reports, the creep of palm trees into higher latitudes could be another sign that our planet is changing. If our climate continues to warm, the tropical flora could soon be spotted as far north as Canada.

In the new study, reported by Earther, researchers from Columbia University's Lamont-Doherty Earth Observatory and two Canadian institutions looked at the temperature tolerances of palm species best suited for chillier weather. Many varieties don't need a year-round tropical climate to thrive: As long as the average temperature for the coldest month of the year for the region is above 36°F, some palms can grow in northern latitudes. This is why you can see palm trees in Greenville, North Carolina, where average temperatures for January fall above 36°F, but not Washington D.C., where average January temperatures tend to dip below that number.

But that could soon change. As is the case with most northern states, average temperatures in D.C. are rising and winters are getting milder, which means it's shaping up to be an inviting habitat for palm trees. Not all palm species tolerate the same climatic conditions, and the effects of the species' competition with native and non-native plants in more northerly regions remains to be seen. But if the palms do migrate that far north in the coming years, the Northeast, Northwest, and even parts of Canada could be next.

A future of palm trees in Canada isn't as far-fetched as it may sound. Winters in these areas are already warm enough for people to plant palm trees in their gardens. In a controlled environment, these trees can flower and spread fruit, but average temperatures will need to climb a little higher before palm seedlings can survive in the wild.

[h/t Earther]

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