Peach pest management programs impact beneficial fauna abundance and Grapholita molesta (Lepidoptera: Tortricidae) egg parasitism and predation

Abstract

We conducted timed visual observations of the peach canopy to monitor beneficial fauna diversity and abundance in orchards with reduced risk and conventional arthropod management programs. In addition, we placed sentinel Grapholita molesta (Busck) (Lepidoptera: Tortricidae) eggs in the peach canopy and determined egg parasitism, predation, and the total impact of natural enemies. Reduced risk orchards used minimal insecticide, G. molesta mating disruption, and managed sod ground cover to suppress Lygus lineolaris (Palisot de Beauvois) (Heteroptera: Miridae). Conventional orchards used organophosphorus and carbamate insecticides to control G. molesta, L. lineolaris, and other pests. Chrysoperla rufilabris (Burmeister) and C. plorabunda (Fitch) (Neuroptera: Chrysopidae), Coccinella septempunctata L. and Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), Orius insidiosus (Say) (Heteroptera: Anthocoridae), and Trichogramma minutum Riley (Hymenoptera: Trichogrammatidae) were the most frequently observed natural enemies in southern New Jersey peach orchards. Hippodamia convergens (Guerin-Meneville), Adalia bipunctata L., Coleomegilla maculata De Geer (Coleoptera: Coccinellidae), and T. exiguum Pinto et Platner (Hymenoptera: Trichogrammatidae) were observed less frequently. Beneficial fauna was more abundant in orchards with the reduced risk program compared with conventionally farmed orchards. The rate of G. molesta sentinel egg parasitism and predation was significantly higher in reduced risk orchards compared with conventional orchards. Overall, predators destroyed more sentinel eggs than did egg parasitoids.