Two-step learning involved in acquiring olfactory preferences for plant volatiles by parasitic wasps

► We found a novel mode of action in parasitoid learning. ► Olfactory response of Aphidius ervi is developed through two-step learning. ► First, potential base of preference is acquired in the prepupal period. ► Second is the actualization of the preference at emergence. ► An innate bias for host-related cues is found in the learning process.