Ehler, L.E. 1995a Evolutionary history of pest-enemy associations.. Proceedings of the VIII International Symposium on Biological Control of Weeds. DSIR/CSIRO Melbourne 735 pp.

Notes: [Conference held at Lincoln University, Canterbury, New Zealand, 2-7 February 1992.] In an evolutionary context, there are at least four categories of pest-enemy associations, as opposed to just new versus old. "New" associations exist when the pest and enemy have no coevolutionary history; however, such associations should be considered "recent" after the pest and enemy have had the opportunity to co-evolve for some period of time. In "quasi-old" associations, a formerly coevolved pest-enemy system is reunited, but only after the pest has had the opportunity to evolve free of its natural enemy for a considerable amount of time. "Old" associations exist where pest and enemy have a long and continuous coevolutionary history. This classification can also be applied to multi-species assemblages of enemies (e.g., "new exploiter" associations). It is suggested that the type of pest-enemy association can have implications for introduction strategy in classical biological control of both insect pests and weeds, and that such strategies should be evaluated whenever possible. The introduction of Encarsia aurantii into California for biological control of obscure scale (Melanaspis obscura) is described and used to illustrate the concept of "target-specific" introduction strategy, in which a blend of induction, deduction, experience, intuition, and inspiration is employed to derive an introduction strategy to suit the particular needs of a given pest problem. Other scale species mentioned are Aonidiella citrina, Chrysomphalus aonidum, Dactylopius ceylonicus, Icerya purchasi and Melanaspis obscura.