Caterpillars know how to eat poison to defend themselves from enemies

Swiss biologists have found that each plant species studied has the ability to synthesize substances that attract enemies of pests and pests and also find a way to cope with that ability.

According to Science Advances magazine, the caterpillar Spodoptera littoralis, who specializes in eating corn leaves, has found a way to overcome plant protection systems that know how to use odors to attract enemies of worms. Once you know about that danger, caterpillars begin to actively eat some separate parts of corn leaves that contain toxic substances and accumulate in their bodies. As a result, the worm is no longer an attractive bait for the enemy.

Moth Spodoptera littoralis (right) - (Photo: University of Neuchatel).

We think plants cannot respond positively to pest attacks, but not so.Plants have a number of active defense systems against lethal insects . In particular, to deal with mechanical damage in tissues, plants can release toxic substances. Moreover, some plants even know how to apply tactics depending on the specific enemy, for example, when reacting to substances contained in the caterpillar Spodoptera littoralis, corn leaves secrete indol attracting bees Microplitis rufiventris, specializing in hunting caterpillars.

In the new study, Swiss biologists found that caterpillars also participated in "arms race" and learned to combat these tactics. Bees are attracted by the smell of indole, but this substance in high doses is also toxic to both bees and caterpillars. At the risk of being attacked by bees, caterpillars actively eat the leafy parts of indole-rich plants and accumulate this toxin in their bodies.

Tests show that bees are no longer eager to lay eggs inside the body of caterpillars that have been eating a lot of indole, and later larvae are less developed.

This defense method of caterpillars is not harmless to the caterpillar itself, making them fatter, weaker, many die prematurely, not reaching the pupal stage. Swiss biologists also breed genetically modified corn with reduced indole content. In this case, caterpillars are no longer well protected and are at high risk of being a bee victim. In general, each plant species studied also has the ability to synthesize natural enemies of pests and diseases, but for the first time scientists have seen similar tactics.

New research shows how difficult it is for humans to improve plant self-defense systems because different species of nature interact with each other in a complex scheme.