Insect digestive enzyme activates sugar-containing plant defence substance: Removing the sugar component changes the food plant chosen by cockchafer larvae

A cockchafer larva nibbles on the roots of its food plant dandelion. WWU - Meret Huber Plants are not entirely at the mercy of their herbivore enemies. Often, chemical defences 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' defence 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 ). In tackling the enemies that feed on it, the plant organism often uses a chemical trick: it binds a sugar component to the antigen and thus deactivates it. As a result, the substance is prevented from damaging the plant itself.