Venezuelan Pitcher Plants Use Wettable Hairs to Trap Insects
A pitcher plant in Venezuela is using its hairs to trap insects, reveals a new study.
Pitcher plants are carnivorous plants that are found in the Guyana Highlands in Southern Venezuela. They can grow up to 7 inches tall and more than 2 inches wide. They have the ability to trap insects like ants using their hairs.
Normally, hairs on plants, called trichomes (outgrowths on plants), are used to repel water. But a team of researchers from Cambridge University, U.K., found that the pitcher plants (Heliamphora nutans) have downward pointing hairs that are wettable. The research team wanted to test if the wetness in hairs is related to trapping insects.
They found that the plants use their hairs to trap insects by creating a water slide. The wetness in hairs increases the slipperiness of the trap on which the insects slip and fall to their death.
The capture rate of the ants was 88 percent when the hairs were wet, compared to a 29 percent capture rate when the hairs were dry, said the researchers.
Further, during the study, experts found how exactly the hairs trap insects. They noticed that the wetness in hairs affected the adhesive pads of the insects, while the directional arrangement of the hairs was effective against the claws. This makes the insects lose their grip, slip and fall to death.
"When the hairs of the plant are wet, the ants' adhesive pads essentially aquaplane on the surface, making the insects lose grip and slip into the bowl of the pitcher. This is the first time that we have observed hairs being used by plants in this way, as they are typically used to make leaves water repellent," Ulrike Bauer, lead author of the paper from the University of Cambridge, said in a statement.
When pitcher plants become dry, they use a wicking method to get moisture from the plant's bowl to the trapping surface of the hair. This could help them capture insects when there is no rain.
The findings of the study appear in the online journal of the Proceedings of the Royal Society B.
Insect-trapping plants obtain nutrients by catching and digesting their prey. These carnivorous plants use different strategies to capture prey. For example, rare sundew plants (Drosera glanduligera) take a different approach to catch insects.
The sundew plants have spoon-shaped trap leaves with two types of tentacles to snap the prey in a fraction of a second. These plants have a life span of less than a year and grow quickly. They require more nutrients for their growth and hence consume more insects.