Unit 10 in Entomology
This is war.
Unit 10: insect and plant interactions.
What does the Cold War and insect/plant interaction have in common?
Believe it or not, plant/insect interaction is very much like the Cold War and the accompanying arms race
between the United States and the former Soviet Union.
However, plant/insect interaction began much
earlier than the beginning of the Cold War in 1945.
One has to go back approximately 400 million years
ago, when plants and animals first appeared on earth.
Plants evolved onto land before insects, and
when insects followed, they found plants to be a succulent food source.
To keep from being eaten,
plants had to combat insects with a variety of defenses which will be discussed within this unit.
to find out how this war turns out.
The objectives of this unit are to explain the connection between the rise of flowering plants and the
expansion of the number of insect species.
Using examples, explain how insects can protect and help
To describe the major ways in which insects gain nutrition from the plant and to
describe the ways plants protect themselves from herbivorous insects.
Plants and insects have both benefited and harmed one another throughout the ages.
provide sweet nectar as food to bees, wasps, moth, flies, butterflies, etc.
In return, these insects can
carry pollen caught on their bodies to other plants.
This aids their benefactor plants in the reproductive
On the other hand, harm may come to the plant as insects prey on the plant for food.
nice tender leaves are just too tempting and provide food for hungry caterpillars, the main consumer of
Plants can be defoliated in short order by these feeding machines.
In fact, more than half of all
insects are plant feeders.
It is not uncommon for insects to consume about 8.8% of the leaves in an
The major concern happens when there is an outbreak, like the biblical plagues of locusts.
There are outbreak conditions in which insects can defoliate entire plants or fields of crops, resulting in
major economic loss.
Throughout the rest of this unit you will learn about both kinds of plant/insect
relationships, beneficial and harmful.
Plants and insects have had a long, intimate relationship. Early in the world’s history, it is believed that
plants evolved onto land first and then insects followed.
The insects pressured the plants by feeding on
them, so the plants had to develop defenses to overcome the feeding.
The insects had to then evolve
ways to overcome the defenses, and so forth and so on.
This pressure back and forth accelerated
evolution of these two groups of organisms.
For example, insects may have first eaten plants on the
This selected for plants that thrived high up in trees.
However, insects that evolved wings
could then take advantage of these higher plants for forage.
Eventually some insects became more and
more selective and specialized regarding the kinds or parts of the plants they ate, such as being