During heavy rain, the lid of Nepenthes gracilis pitchers acts like a springboard, catapulting insects that seek shelter on its underside directly into the fluid-filled pitcher, new research has found. The findings were published today, Wednesday 13 June, in the journal PLoS ONE.
Pitcher plants (Nepenthes) rely on insects as a source of nutrients, enabling them to colonise nutrient-poor habitats where other plants struggle to grow. Prey is captured in specialised pitcher-shaped leaves with slippery surfaces on the upper rim and inner wall, and drowns in the digestive fluid at the bottom. Under humid conditions, the wettable pitcher rim is covered by a very thin, continuous film of water. If an insect tries to walk on the wet surface, its adhesive pads (the 'soles' of its feet) are prevented from making contact with the surface and instead slip on the water layer, similar to the 'aquaplaning' effect of a car tire on a wet road.
However, researchers have now discovered a new, unique method of capturing insects by the pitcher plant Nepenthes gracilis.
The lead author of the paper, Dr Ulrike Bauer from the University of Cambridge's Department of Plant Sciences, said: "It all started with the observation of a beetle seeking shelter under a N. gracilis lid during a tropical rainstorm. Instead of finding a safe - and dry - place to rest, the beetle ended up in the pitcher fluid, captured by the plant. We had observed ants crawling under the lid without difficulty many times before, so we assumed that the rain played a role, maybe causing the lid to vibrate and 'catapulting' the beetle into the trap, similar to the springboard at a swimming pool."
To test their hypothesis, the scientists simulated 'rain' with a hospital drip and recorded its effect on a captive colony of ants that was foraging on the nectar under the lid. They counted the number of ants that fell from the lid in relation to the total number of visitors. They found that ants were safe before and directly after the 'rain', but when the drip was switched on about 40% of the ants got trapped.
Further research revealed that the lower lid surface of the N. gracilis pitcher is covered with highly specialised wax crystals. This structure seems to provide just the right level of slipperiness to enable insects to walk on the surface under 'calm' conditions but lose their footing when the lid is disturbed (in most cases, by rain drops). The scientists also found that the lid of N. gracilis secretes larger amounts of attractive nectar than that of other pitcher plants, presumably to take advantage of this unique mechanism.
Dr Bauer added: "Scientists have tried to unravel the mysteries of these plants since the days of Charles Darwin. The fact that we keep discovering new trapping mechanisms in the 21st century makes me curious what other surprises these amazing plants might still have in store!"
University of Cambridge: http://www.cam.ac.uk
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
Scientists circumnavigating the globe on a spartan racing catamaran will spend the coming year deploying drones to collect better data on plastic pollution
A patch of gold electrodes you can wear behind your ear for up to two weeks will track your brainwaves 24/7 and let you control devices with your mind
Scientists have peeked inside the brain of a man with tinnitus to identify the brainwaves that underlie the debilitating sensation of ringing in the ear
For extinct creatures like dinosaurs known only from fossils, it is notoriously difficult to differentiate the males from the females of a species because sex distinctions are rarely obvious from the skeletons.
The most complete genetic information assembled on woolly mammoths is providing insight into their demise, revealing they suffered two population crashes before a final, severely inbred group succumbed on an Arctic Ocean island.
More than 30 million crows fly around the country, but among all creatures, the birds may be among the least understood. Ben Tracy reports on new research into crows' brains.
Mouse study demonstrates method to target mutations in DNA inherited from mother
After consulting a "stud book," the Zoo brought a male panda's sperm back to D.C., setting an exciting precedent
Stegosaurs may have sported quite different shaped bony plates on their backs, depending on whether they were male or female, new research claims.
Targeting a protein that causes rampant growth of cells in retinal blood vessels could lead to new treatments for vision loss in older people