Effect of release point density of Trichogramma pretiosum Riley (Hymenoptera:Trichogrammatidae) on control efficacy of Keiferia lycopersicella (Walsingham) (Lepidoptera:Gelechiidae) in greenhouse tomato

Controlled environment studies have shown that the egg parasitoid Trichogramma pretiosum Riley is a promising biological control agent for tomato pinworm (TPW), Keiferia lycopersicella (Walsingham). The present study examines the dispersal ability of T. pretiosum from single and multiple release points in a greenhouse tomato crop. Daily distances travelled from a single release point by an individual female T. pretiosum ranged from 0.67 to 0.9 m during the 4 days post-introduction. Parasitoid-induced mortalities to Ephestia kuehniella Zeller (sentinel host) eggs after 4 days post-introduction decreased from 94% on the plant next to the release point to 7% on plants 2.3 m away from the release point. T. pretiosum-induced mortalities to K. lycopersicella eggs were 66, 46, and 34% after 4 days post-introduction when the parasitoids were introduced at release point densities of one release point every 1, 2, or 8 m2, respectively. Based on these results, recommended release point densities for T. pretiosum for control of K. lycopersicella are one release point every 1–2 m2 for full-canopy greenhouse tomato crops.