Pitcher plant in Borneo.
Carnivorous pitcher plants get an assist from Mother Nature in capturing their insect prey, according to a study published in PLoS ONE.
Botanist Ulrike Bauer of the University of Cambridge and colleagues report that the lid of the Nepenthes gracilis pitcher plant “acts like a springboard, catapulting insects that seek shelter on its underside directly into the fluid-filled pitcher,” according to a press release from Cambridge. The insect then drowns and is broken down by digestive fluid in the pitcher.
To discovery was made through observation.
“It all started with the observation of a beetle seeking shelter under a N. gracilis lid during a tropical rainstorm,” Bauer said in a press release. “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.”
This is an N. gracilis pitcher with a visiting Polyrhachis pruinosa ant. (Courtesy of Bauer et al 2012)
The scientists then tested the mechanism in the lab and found that about 40 percent of ants were trapped when they simulated rainfall using a drip system.
Insects are attracted to the lid of the pitcher both for apparent protection from the elements and nectar secreted by the plant.
The researchers said they were surprised by the discovery. Pitcher plants are a popular research subject for their charismatic appearance and unusual feeding behavior.
“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!”
Citation: Ulrike Bauer, Bruno Di Giusto, Jeremy Skepper, T. Ulmar Grafe, Walter Federle. With a Flick of the Lid: A Novel Trapping Mechanism in Nepenthes gracilis Pitcher Plants. PLoS ONE, 2012; 7 (6): e38951 DOI: 10.1371/journal.pone.0038951