Quantifying the economic impact of Peristenus relictus establishment on host Lygus hesperus populations in California organic strawberry

Lygus hesperus is a key pest in California-grown strawberries, in part because it lacks specialized natural enemies. In response, the specialist European nymphal parasitoid Peristenus relictus was released, and subsequently established, along the California Central Coast. A simulation model, based on field-collected L. hesperus immigration rates and 16 years of parasitism data, compared simulated pest populations with and without parasitism by P. relictus. After 10 years, L. hesperus population reductions exceeded 95% in weeds and alfalfa, and 70% in strawberry. These simulated results were in agreement with field-based P. relictus longitudinal studies. The averted value loss associated with L. hesperus, due to the establishment of P. relictus, is estimated at $1,901 per acre in organic strawberry.