The chemical vocabulary of an insect requires specialized receptors that are exquisitely tuned and uniquely sensitive to chemical signals emitted by conspecifics and their hosts. Communication within a species is extremely important for resource utilization and reproduction; especially for specialized feeders such as the Colorado potato beetle (CPB) in which both immature and adult forms exist on the same host plant. Investigations into chemical communication by CPB have yielded little until recently when blends of chemicals emitted by potato plants were identified that were attractive to CPB and some of its predators (Dickens 1999; Dickens 2000a, b). However, the question of whether immature and adult CPB might communicate by way of chemical signals and the nature of this vocabulary remained unknown. Now we have determined textual differences among chemical signals emitted during larval and adult feeding on potato plants. These differences are detected by antennal chemoreceptors in adult CPB and their detection may result in attraction or avoidance of occupied host plants, as well as other behaviors. The messages are comprised of at least nine chemicals emitted as different blends during insect feeding. Behavior elicited by the chemical messages may be modified by previous experience. Thus, intraspecific communication occurs in CPB and is likely to be present in other species where larval and adult forms compete for the same resource. The expanded vocabulary inherent in these intraspecific “chemical conversations” demands a corresponding enhancement of receptor types, plasticity of the central nervous system, and a diversity of behaviors in response to overlapping syntax of the blends.

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