A native egg parasite, Trichogramma thalense, was mass-reared and released up to thirteen times against the eggs of the artichoke plume moth (Platyptilia carduidactyla) in three 5-acre biointensive artichoke fields along the northern Santa Cruz/San Mateo County coast in 1998 and again in 1999-2000. In 1998, a biorational pest management program (BIORAPP) utilized Trichogramma releases, pheromone-based mating disruption, double-cut control, and intensive monitoring of artichoke plume moth (APM) presence and damage. A management team comprising growers, an industry representative, and a university researcher monitored this program.

Mass-released parasitoids were recovered from APM eggs on only three occasions and in just one BIORAPP field in 1998, with low egg deposition elsewhere. No parasitoids were found in three adjacent, non-release conventional fields. In the second year, we shifted focus to mass trapping of APM due to poor results from parasitoid releases and challenges in mass rearing T. thalense. Rearing was transferred to Rincon-Vitova, a commercial insectary in Ventura, California, to improve colony quality.

The effects of BIORAPP management—Trichogramma releases, pheromone disruption, cultural control, and monitoring—were assessed from June 1998 through May 2000. The combination led to an insecticide-free production season in 1998-1999 for BIORAPP fields, aside from field B-2, treated with insecticide in March 1999. Although two BIORAPP fields and one control field surpassed the 4% bud damage threshold on certain dates, average seasonal damage remained below 4% through May 2000. Insufficient sampling in two fields hindered accurate damage assessment. In 1999, two organic artichoke growers joined the management team, and their fields experienced very low APM pressure throughout the season.