In last week’s article I promised to tell you about a war that has been raging in nature since the beginning of time. This battle has endured and still rages on in every forest, meadow and planted field. It is a war with no truce, a war between plants and the predators that feed upon them.

When besieged by armies of voracious creatures, plants cannot run away or defend themselves physically, however through the years, there are plants that have developed defenses that include deadly poisons and toxic chemicals that give leaf-eaters serious indigestion.

Other plants produce compounds that interfere with the attackers’ growth cycle. There are insects that have developed responses to this chemical warfare by developing chemical defenses of their own.

A type of wild potato plant defends itself against aphids by manufacturing an ingredient that aphids release when they are under attack. The result is that aphids run away from the wild potato plant thinking that they are under attack.

Some insects, such as the monarch butterfly, develop ways to convert potentially harmful substances produced by the milkweed plants into both sources of nutrition and protection for themselves. The milkweed plant has a chemical defense that keeps most insects from eating its leaves, however, the monarch butterfly does feed upon the nectar of the milkweed flowers and then the female lays her eggs on the underside of the leaves.

After the eggs hatch into caterpillars they feed upon the leaves and digest the poison. This poison does not kill the caterpillars, but they become distasteful to other insects. Each monarch caterpillar then pupates into a butterfly that will also be poisonous, which discourages many predators from feeding upon them.

The adult viceroy butterfly is protected because its coloration mimics the monarch butterfly. Birds avoid viceroys if they have previously sampled a monarch. However, those birds that have never consumed a monarch will eat viceroy butterflies.

There are some plants, which when attacked, give off oils known as volatiles and terpenes that evaporate quickly. This evaporated oil will attract parasitic wasps that come to feed upon the insects which are attacking the plants.

When caterpillars begin munching on leaves from a corn stalk their saliva somehow activates the plant to begin emitting chemicals, such as terpenes, which is an active ingredient in turpentine. The wasps pick up this signal and look for the larvae to feed on. Cutting the corn stalk with a pair of scissors will not cause the corn plant to emit the terpenes, only the caterpillars’ mouthparts seem to set off the alerting terpenes mix.

The infested plant appears to recognize the value of the parasitic wasps that will kill the caterpillars attacking the plant. The plant will not begin emitting the chemical signal at night when the caterpillars start feeding, but rather delay the release until the following morning when the parasitic wasps are out hunting.

Also, research has found that the plant will release the chemical in sharp peaks that correspond with the time the wasps are at their hunting peak.

Potato and tomato plants fight back by creating chemicals that give their enemies indigestion, which prevent the caterpillars from digesting their food. The caterpillars continue to eat but being deprived of these vital nutrients will retard their growth. This gives the caterpillars’ predators longer to attack before the caterpillars pupate.

Native Americans smoked a plant known as the coyote tobacco plant. This plant when attacked by insects is able to pump its leaves full of nicotine tenfold, with a single leaf containing enough nicotine to kill ten rats.

There are plants that have the ability to go into a defense mode for protection against harsh weather or disease. This is good for the plant, but bad for the farmers growing the plants. It is bad when a plant acts to defend itself because its growth mechanism is turned off. Now, researchers at Michigan State have figured out how plants make the decision between growth and defense. The two key components of growth and defense programs physically interact with each other.

Plants are much like humans, with only a certain amount of energy to use and choices to be made on how to use this energy. Plants just as humans have learned to prioritize and use their energy for either growth or defense, realizing they can’t do both at a maximum level at the same time. Researchers have learned that they could help the plants strike a balance, keeping them safe from harm while also continuing to grow.

Researchers at the University of California are working on a vaccine for plants, in hopes that pesticides will not be necessary in the future.

Although the plant world has many weapons in its arsenal to defend them, the insects have also developed extraordinary capabilities. The war without a truce continues on.

Bill Bower is a retired Pennsylvania Game Commission Wildlife Officer. Read his blog and listen to his podcasts on the outdoors at www.onemaningreen.com.