ABSTRACT
Aphids are among the most important agricultural pests in the temperate regions of the north hemisphere (Dixon 1998), and are currently used as models for evolutionary and functional biological research. Because of their negative impact on agricultural production, aphids were among the fi rst organisms to be studied for their semiochemistry. Semiochemicals are chemical substances that carry a message from one living organism to another for the purpose of communication. The identifi cation of chemical cues that guide individuals according to their needs is now a major discipline, termed chemical ecology, studied in a wide range of organisms, especially insects (Thompson et al. 1999). The semiochemicals emitted and/or perceived by aphids have been extensively documented over the last 40 yr, with the fi rst sex and alarm pheromones being identifi ed in the early 1970s (Bowers et al. 1972, Marsh 1972).
