Student Symposium: Alternatives to Chemical Control of Insects: Scelionid Wasps as Biological Control Agents: A Review

David B. Orr


The Scelionidae is a large family of parasitic Hymenoptera whose members specialize in egg parasitism of insects and arachnids. Many of the characteristics considered most desirable in a natural enemy can be found within members of this family. Species have been studied which demonstrate high searching abilities and reproductive rates, lack of hyperparasitoids, have synchrony with host populations, have positive host-density responsiveness, have simple adult diets, and can be reared easily. The advancements made in rearing techniques for these natural enemies should prove valuable in the future both in classical biological control and in augmentative efforts. Research which has been done indicates that a variety of approaches are possible for augmenting scelionid populations. These range from simple innundative releases to manipulation of preferred nectar-bearing plants. Although fewer than 30 species have been used in classical biological control attempts, several of these have produced excellent results. The interaction of scelionid wasps with various insect management tactics is discussed. In general, scelionids interact well with insecticide applications due to the protective nature of host egg choria. The number of known scelionid species represents only a fraction of those estimated to be in existence. The results of biological control efforts undertaken with known species suggests that much potential exists within the Scelionidae.

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