Plants and higher animals under stress from predation and disease, and also undergoing normal physiological changes such as hormone cycling, produce compounds released externally which have signalling roles with other organisms and within their own species. Plant receptors involved in these interactions are little understood, and such systems are difficult to exploit within higher animals because of welfare considerations and the disturbance caused to these organisms by invasive techniques. However, where such signals interact with insects, the highly developed techniques of electrophysiology used traditionally in identification of insect semiochemicals can be employed. Furthermore, relatively robust monitoring devices can be made using organ or whole organism preparations for exploiting the external signalling compounds in diagnostic systems. With the prospect of further exploitation by means of molecular genetics, in which over-expressed molecular recognition proteins will be used directly in biosensors, these aspects of insect chemical ecology are likely to have considerable bearing on areas as diverse as agricultural crop plant nutrition and human health and forensic science.

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