The identification of chemical signals emitted by sweetcorn plants under attack from pests to attract beneficial insects and warn other plants to increase their defences may lead to the development of a new biological pesticide.

A study published by the USA's National Academy of Sciences says that chemical warning signals called green, leafy volatiles (GLV) are secreted into the air from the corn plant. These volatiles smell like cut grass which attracts caterpillar predators and parasitoids.

Also, when researchers exposed undamaged corn seedlings to GLV from damaged plants, the healthy seedlings sent up their own chemical signal. Furthermore, a stronger defensive reaction was triggered when seedlings were exposed to GLV purposely damaged and then treated with a beet armyworm caterpillar substance to imitate insect attack