Plants are not entirely at the mercy of their herbivore enemies. Often, chemical defenses ensure that the plants are inedible, or even toxic, and as a result insects and other hungry animals steer clear of them. A new study has shown, for the first time, that the degradation of plants' defense substances by insects' digestive enzymes can influence the insects' preference for certain food plants. Researchers at the University of Münster, the University of Bern (Switzerland) and the Max Planck Institute for Chemical Ecology in Jena investigated this phenomenon in the larvae of cockchafers (Melolontha melolontha) and the plant they feed on, dandelion (Taraxacum officinale).
source https://phys.org/news/2021-10-insect-digestive-enzyme-sugar-containing-defence.html