Developing a commercially viable system for biological control of light brown apple moth (Lepidoptera: Tortricidae) in grapes using endemic Trichogramma (Hymenoptera: Trichogrammatidae)

A native species of Trichogramma, Trichogramma (Trichogrammanza) carverae (Oatman & Pinto), has potential as a commercially viable control option for an Australian tortricid leafroller Epiphyas postvittana (Walker) in wine grapes. Four candidate species of Trichogramma were collected from E. postvittana egg masses in vineyards and assessed in the laboratory for their suitability for commercial use. This led to the isolation of a strain of T. carverae for putative commercial release. Inundative release trials using small blocks within commercial vineyards showed that >75% of the egg masses in the vineyard could be parasitized by T. carverae at release rates of 70,000 Trichogramma per hectare with as few as 30 release sites per hectare. Parasitism was higher around release sites within the first 2 d but was fairly evenly distributed over the 0.05-ha release blocks in the 4-5 d trials. The wasps moved upwind when there was little to no wind and downwind when wind speeds were higher (usually >5 km/h). Monitoring systems for E. postvittana were developed to help determine effective timing of releases. This study illustrates a relatively quick and inexpensive approach to the development of new strains of Trichogramma for commercial use that could be adapted for other agricultural systems.