From chemical to population ecology: Infochemical use in an evolutionary context

The marriage of chemistry with ecology has been a productive one, providing a wealth of examples of how chemicals play important roles in the loves an d lives of living organisms. At first the marriage may have been a simple a nd monogamous one with the major scientific aim of making proximate analyse s of chemically mediated, individual level interactions. But times have cha nged and chemical ecology is broadening, embracing different approaches and disciplines. There is, for example, increasing appreciation of variability in the systems under study and an increase in evolutionary thinking. Anoth er promising development is greater recognition of the potential importance of chemically mediated interactions for population dynamics and for struct uring communities and species coexistence. The latter is an utterly underex plored area in chemical ecology. The field of chemical ecology of insect pa rasitoids shows some of these promising developments. Responses of parasito ids to infochemicals are increasingly studied with an integrated approach o f mechanism and function. This integration of "how" and "why" questions sig nificantly enhances the evolutionary and ecological understanding of stimul us-response patterns. The future challenge in chemical ecology is to demons trate how chemically mediated interactions steer ecological and evolutionar y processes at all levels of ecological organization. To reach this goal th ere is a need for interdisciplinary collaboration among chemists and ecolog ists working at different levels of organization and with different approac hes, with other disciplines as partners.