Evaluation of the augmentative effect of natural enemy releases under codling moth exclusion nets in apple orchards

Abstract: In orchards, native natural enemies (NE) tend to establish too late in the season to
provide effective aphid control. Augmentative biological control represents a promising
strategy to enhance early-season aphid regulation. However, it remains difficult to implement
in open-field due to released NE dispersal, intraguild interactions, and high dependency on
weather variability. This study aims to evaluate whether codling moth exclusion nets could
enhance the presence of NE after early releases of NE targeting aphids. Three netting strategies were compared: single-row, full block, and anti-hail nets as a control. Generalist predators (Chrysopidae and Forficulidae), and a specialist predator (Coccinellidae) were released. NE groups were monitored before and after releases to assess the occurrence and early arrival of NE. Analyses showed that neither the interaction between species released and netting nor netting alone affected NE group occurrence after releases. Chrysopidae releases did not show an increase in detection, whereas Coccinellidae releases enhanced both detection and precocity. Forficulidae were initially abundant, and the releases sustained high detection over time.