Release density of Uscana senex Grese (Hymenoptera: Trichogrammatidae) for control of Bruchus pisorum L. (Coleoptera: Bruchidae).
The effect of release densities of U. senex on parasitism rates of B. pisorum eggs and B. pisorum damage reduction in pea seeds was assessed. The release densities were 1.92, 3.84, 7.68 and 15.2 millions of U. senex/ha. U. senex individuals were released twice a week at the beginning of flowering until pea pods were completely filled. The rate of parasitism obtained fluctuated between 49.8 and 82.1%. U. senex exhibited dispersion abilities. As the distance from a release point increased, the level of egg parasitism decreased. The highest U. senex release density reduced pea seed damage to approximately 10%, equivalent to a 70% reduction in seed damage.