The leaves of tobacco protect from parasitic insects by releasing a chemical signal, inducing production in adjacent cells of a compound toxic to invertebrates.

When cells within a tobacco leaf are touched by an external force, stretch receptors cause them to release calcium ions. The signal spreads into adjacent cells in a propagating wave triggering the release of more calcium ions and the subsequent production of a chemical called GABA. Tobacco leaf parasites that ingest GABA suffer tremors, excitablilty, paralysis, and death.

Last Updated August 23, 2016