Egg loads and egg masses

Inundative releases of <i>Trichogramma minutum</i> Riley were made in a commercial blueberry field in British Columbia, Canada, to determine the extent of dispersal of adult wasps, and to determine whether complete parasitism of eggs within egg masses of the target host [oblique-bandedleafroller (OBLR), <i>Choristoneura rosaceana</i>(Harris)] occurred. Three weekly releases of wasps were made from a single release point in the center of each field during the flight of first generation OBLR adults. Sticky trap, sentinel egg mass and target-host egg mass data all indicated only a limited range of dispersal of <i>T. minutum</i> within the field. In addition, only partial parasitism of egg masses of the target host occurred even in close proximity to the release point. We discuss the importance of determining the response of <i>Trichogramma</i> females to previously-parasitized eggs when using <i>Trichogramma</i> wasps for biological control of lepidopterous species that oviposit large egg masses. [Publisher abstract]