2.0 MASS-PRODUCTION OF TRICHOGRAMMA MINUTUM RILEY ON FACTITIOUS HOST EGGS

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Abstract
A system was developed to produce large numbers (30 × 106 per week) of Trichogramma minutum Riley on eggs of the Angoumois grain moth, Sitotroga cerealella (Olivier). The parasitized host eggs were packaged and shipped in bulk for release against the spruce budworm, Choristoneura fumiferana (Clemens), and several other lepidopterous pests. Initial attempts to use the Mediterranean flour moth, Ephestia kuehniella (Zeller), as a host failed due to such factors as infestation by mites and parasitoids, low fecundity, long generation time, and the necessity for large labour inputs during moth collection. Eggs of S. cerealella, used to rear the host, remained viable when stored for up to 1 month at 9 °C, but eggs stored at 2 °C remained acceptable for parasitism for only 15 days. Rearing the host at high humidity (> 70% RH) gave better percentage emergence and infestation of grain than rearing at low humidity (< 30% RH). Developmental rates of T. minutum were determined over a range of temperatures and the developmental threshold and heat unit accumulations necessary for complete development were calculated. Using these values, Trichogramma were programmed, during the latter stages of production, to emerge within 24 h of exposure to light at room temperature. The programming facilitated shipment and handling of the parasitoids prior to their release.