Finding Resistance in the Saliva of Crop Pests

Contrary to what many people think, plants don’t sit helplessly when attacked by insects. Tomato plants, for example, respond to injuries by producing hairs on their leaves that are sticky and contain toxic compounds to insects.

In response, insects have evolved attack mechanisms that turn off these defenses before they can get started. Gary Felton, PhD, is leading a project that explores the mechanisms of both the defenses and attack mechanisms—how they turn on and off—to devise tools that farmers can use to protect their crops.

“You may discover something in one insect and think it could apply to another. Sometimes it just doesn’t, even with closely related insects. There is so much diversity in insects; successful research does not involve generalizations.” – Gary Felton

When caterpillars attack tomato plants, proteins in the insect saliva disarm the tomato defenses. The bacteria in Colorado potato beetle oral secretions have a similar function. Some plants, however, defend themselves more effectively than others.

Dr. Felton and his colleagues have identified another set of proteins in caterpillar saliva that signal to tomato plants to raise their defenses. They are now searching for the receptors in tomato plants that are sensitive to the proteins. The next step will be to identify the genetic regions responsible for these receptors, which would boost efforts to breed resistance in the plants.

Reprinted from Penn State News