There’s an incessant murmur around us, one that is undetectable to human ears. Life-and-death battles are fought, and allegiances are forged. Our surroundings are a battlefield as plants wage a never-ending war against their perennial enemies, the herbivorous bugs. It’s a rivalry that started over 350 million years ago, and both sides have majorly improved their fighting skills since then.
10 Chemical Warfare
Leaves and other delectable plant parts are food for insects like caterpillars or beetles. But there’s no such thing as a free lunch, even in the bug world. Throughout time, plants have defied their static condition by developing numerous tactics to protect themselves from herbivorous insects. These vary from exterior armors (such as thorns, prickles, or toxic hairs called trichomes) to straight-up chemical defense systems.
These chemical responses are wide-ranging, and they can be activated one at a time or in a coordinated manner. Generally, when an insect starts feasting, the plant emits chemicals that can kill the insect or affect its growth. For instance, a plant will occasionally spice up its leaves with some bitter tannins, making it an unattractive lunch for the bug, not to mention somewhat indigestible.
So how do plants know they’re being attacked? Well, there are many different methods. However, the one that helps them respond the fastest involves “hearing” the insects chewing on them. Amazingly, a recent study found that a small flower named Arabidopsis can identify the vibrations triggered when a caterpillar is munching on its leaves, thus allowing the plant to increase its defenses accordingly.