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.