How parasitoid sex ratio, size and emergence time are associated with fruit tree cultivar, within-orchard tree position and ants

► Biocontrol-relevant parasitoid characteristics can vary within field populations. ► Parasitoid and host emergence time varied between apple cultivars (plant genotypes). ► Parasitoid size varied between apple cultivars and with distance to forest. ► Parasitoid sex ratio was related to fruit tree cultivar, tree position and ants. ► Cultivar selection and ant management may enhance biological control by parasitoids.