Friday, May 7, 2010

Leaves of the Carnivorous Plant Mimic Flowers to Trap Insects

A plant is not a flower, and some insects are learning at their expense. Biologists and chemists have shown that French carnivorous plants gave off the smell of flowers to attract their prey. The leaves of the Nepenthes rafflesiana, Found in Southeast Asia, biochemically mimic the flowers to mislead insects. They are attracted by a wide range of volatile smells mild and sweet compared to those given off by flowers and are trapped in the urn-shaped leaves of the plant.

The Nepenthes rafflesiana has leaves shaped urn containing a kind of sticky saliva to trap insects and prevent their escape. These leaves have developed traits in common with the flowers, like:
  • nectar
  • bright colors
  • guides ultraviolet
The researchers found that, depending on their position on the plant at ground level or height, the ballot boxes did not catch the same prey:
  • Urns of plant have a pleasant odor and trap a variety of insects such as flies, mosquitoes, moths, beetles, bees, wasps;
  • Urns land, low odor, captured mainly ants.
The researchers believe that this work can inspire discovery programs against insect pests or disease vectors cons involving mosquitoes.

The upper, or aerial, pitchers of the plant have a pleasant odor and trap a wide variety of insects, while pitchers at ground level emit little odor and mainly capture ants. The researchers compared in the field the insects that visited these two types of pitcher.

Aerial pitchers, even when they were placed on the ground, attracted more insects than ground pitchers, and notably a wide variety of the insects that normally consume flower nectar or pollen: flies, mosquitoes, butterflies, beetles, bees, wasps, etc. The team then performed olfactory experiments on the insects using olfactometers. Ants (normally visitors to leaves) and flies (normally visitors to flowers), had to choose between a control compartment containing only pulsed air, and another containing pulsed air and the scents of freshly cut pitchers. The researchers observed that in the absence of any visual stimulus, the insects preferred to visit the odorant compartment, and the flies were more attracted by the scent of aerial pitchers than that of ground pitchers.