Developing Trichogramma (Hymenoptera: Trichogrammatidae) as a pest management tool

The egg parasitoid, Trichogramma (Hymenoptera: Trichograinniatidae), is used extensively around the world as a biological control agent for the control of lepidopterous pests. Wasps are either released to augment an existing population "inoculative release," or they are released in large numbers to coincide with maximum pest pressure "inundative release." Field releases however, have had variable success. This has been attributed to wasp quality and issues relating to the release and integration of wasps into an agricultural setting. Wasp quality can be split into genetic and environmental components. Here, genetic quality is discussed in terms of the identification and maintenance of species/strains most suited to the particular situation. Environmental effects that are thought to impact upon wasp quality include rearing host effects; rearing conditions i.e. under constant environmental conditions, or by acclimation; and storage conditions. Release and integration issues that are considered important for the development and maintenance of a successful IPM approach include host/parasitoid synchrony, pesticide choice and timing of application as well as weather conditions at the time of release. In this paper we focus on and discuss quality issues, both genetic and environmental, as well as consider information pertaining to optimal release conditions, in relation to the development and maintenance of Trichogramma as an effective biological control agent.