A simple plant is not capable of much, but it would be foolish to believe that nature has not endowed plants with the ability to defend themselves from injurious animals. A research team has recently discovered that certain plant species defend themselves from insect pests by recruiting the help of other insects that are predatory towards herbivores
The “large cabbage white butterfly” and female “gravid butterflies” are pests that feed off of various plants. The researchers found that when these two common herbivores feed off of plants while in the larval stage, the plant releases scents that signal other plants to action. Researchers are not exactly sure why this scent-signal is emitted, and how other plants respond to these scent-signals, but the researchers hypothesize that the plants are working together as a community to protect themselves from harmful foreign invaders.
Even more interesting was how parasitic wasps reacted to the scents emitted from plants once a plant-eating pests’ eggs are placed on the plant. The wasps react to the plant’s scent by attacking the plant pests while the pests are in the larval stage. The parasitic wasps will attack butterfly eggs as well as the caterpillars that feed off of the plant. This study showed that when plants are threatened by the presence of harmful herbivore larvae, the plants will respond by emitting a scent that causes nearby parasitic wasps to attack the herbivore larva, which, of course, results in the removal of the threat to the plant. It is interesting how a simple plant can make an insect work to protect the plant from harmful pests.
Do you think that there are alternate mechanisms, besides scent, that plants use to induce insects into protecting the plants from harmful herbivores?