Chemical Warfare in the Plant World

We mentioned yesterday that plants use scents to attract friendly and helpful insects and animals. They also use fragrances to protect against unfriendly visitors. Seemingly passive plants have secret weapons against insect invasions. We call it chemical warfare in the plant world.

A good example is the lima bean. Spider mites attack lima bean plants, but other predatory mites eat spider mites. When spider mites attack a lima bean plant, it floods the area with a chemical signal that attracts the predatory mites. This chemical odor also causes other lima bean plants to emit the same chemical. When the spider mites are gone, the plants stop secreting the chemical.

Some plants, such as tobacco and corn, protect themselves from destructive caterpillars by sending off a signal to attract wasps. Research has shown that plants customize the signal to attract a particular species of wasp. The wasps can tell the difference between the chemical signal of plants attacked by tobacco budworms and corn earworms, and different chemicals attract a different wasp species. So far, cotton, corn, and beets have been shown to have different emissions as they call for protection.

We previously mentioned wasps that kill and eat the caterpillars of certain butterflies. In that instance, ants have a symbiotic relationship with the caterpillars to protect them from the wasps in exchange for food. The U. S. Department of Agriculture is looking to find ways to cause one insect to combat another. This research is necessary because it can help us find ways to protect crops.

Chemical warfare in the plant world shows that God has equipped plants to protect themselves against different insect scourges. Because of that, we can survive on a planet where insects hopelessly outnumber us. The design that the Creator put into living systems is truly amazing.

— John N. Clayton © 2020