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.
After a severe brain injury, some people remain in a vegetative or minimally conscious state, unable to speak or move intentionally, and apparently unaware of the world around them. But in recent years, neuroscientists have found signs that some of these patients may still be conscious, at least to a degree. Now researchers have used a branch of mathematics called graph theory to search for neural signatures of consciousness.
Few parasitoids are more bizarre or disturbing than the wasps of the genus Glyptapanteles, whose females inject their eggs into living caterpillars. Once inside, the larvae mature, feeding on the caterpillar’s body fluids before gnawing through its skin en masse and emerging into the light of day. And despite the trauma, not only does the caterpillar survive---initially at least---but the larvae proceed to mind-control it, turning their host into a bodyguard that protects them as they spin their cocoons and finish maturing. Then, finally, the caterpillar starves to death, but only after the tiny wasps emerge from their cocoons and fly away.
From their new book A History of Life in 100 Fossils, Paul Taylor and Aaron O'Dea share the story of 10 incredible fossils
We love origin stories. When we see successful groups of animals and plants, we wonder where they came …
First research of its kind shows that tasers could impair a person's memory and thought process
Sometimes the most fascinating animals are the ones that are no longer with us. The oddly named sthenurine is no exception.
Australian banded stilts use mysterious cues to know when to head toward ephemeral lakes in the country’s otherwise dry interior
The intriguing story of how whale evolution was unpicked is told in The Walking Whales, revealing what it's like to be a globe-trotting palaeontologist
Cells derived from embryos appear to have improved vision in more than half of the 18 patients who had become legally blind because of two progressive, currently incurable eye diseases.
Oil rigs are rarely lauded by conservationists, but fish seem to love them – they have more fish living around them than natural rocky reefs do