When faced with a predator, plants cannot get up and run away as an animal would do. Instead, they protect themselves with an arsenal of chemicals. One such chemical is a plant hormone called jasmonate. Increasing jasmonate levels drive the production of chemicals which deter herbivores, and also trigger the production of cellular machinery to repair damaged tissue.
The cabbage looper caterpillar is a common pest of cabbages. It has its own circadian rhythm, with the peak of its feeding behaviour happening in late afternoon. Remarkably, it has been shown that jasmonate production in plants is also under the control of the circadian clock. The plants synchronise their jasmonate production with the feeding behaviour, producing more deterrent chemicals when the caterpillars are more likely to be active.
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