Coping with toxic plant compounds - The insect's perspective on iridoid glycosides and cardenolides

► Iridoid glycosides in the food plant unspecifically harm insects by crosslinking dietary and tissue proteins. ► Insects may avoid toxicity by suppressing gut enzymes that activate iridoid glycosides. ► Cardenolides act much more specifically by blocking an essential ion carrier, the Na+/K+-ATPase. ► Insects on cardenolide plants have repeatedly evolved target site insensitivity to prevent this toxic effect.