A study published online today in the journal Current Biology found that store-bought cabbage, lettuce, spinach, zucchini, sweet potatoes, carrots, and blueberries respond to light-dark cycles up to about a week after harvest.

And when the produce was kept on the same light-dark cycle as a predator—cabbage looper moth caterpillars (Trichoplusia ni)—it was better able to resist attacks.

Circadian clocks tell plants when the seasons change due to variations in day length, said Janet Braam, a plant biologist at Rice University in Houston, Texas. But the clock is also critical in plant defenses against insects.

"[Plants] know when the insects eat," said Braam, who is a co-author on the recent study, "so