What type of feeding can cause leaves to curl?

Feeding that leads to leaf curling is primarily associated with piercing mouthparts, which are used by certain insects, such as aphids, whiteflies, and spider mites. These pests penetrate the plant tissue to extract sap, which disrupts the plant's physiological processes and can cause symptoms like leaf curling, yellowing, and wilting. The damage occurs because the removal of sap reduces the plant's ability to maintain turgor pressure, leading to cellular responses that cause the leaves to curl inward.

Chewing insects, such as caterpillars or beetles, typically cause damage in ways that manifest as holes or ragged edges on leaves, but not curling. Siphoning and rasping feeding methods are also less related to leaf curling. Siphoning refers to feeding through a straw-like structure, similar to piercing, but usually involves more liquid feeding behavior, while rasping involves scraping plant surfaces rather than penetrating deeply into the tissues. As such, the mechanism behind leaf curling is most accurately linked to piercing feeders.