•Social environment during ontogeny can have strong consequences on mate preference.•Prior work found variation in insect mate preferences reared in isolation vs. in aggregations.•Playbacks to nymphs reared in isolation partly rescued the effect of rearing them in aggregations.•We pinpoint interactions during development as a cause of signal ontogeny in an insect.•Signalling interactions from early life are essential for the development of adult communication even in insects. We recently discovered that there is a social ontogeny of signals and preferences in Enchenopa treehoppers. Nymphs signalled throughout their development; some signal features changed gradually and in sexually dimorphic ways throughout ontogeny; and some adult male signal features and female mate preferences differed between individuals reared in isolation or groups. In this paper, we investigate whether signalling interactions during ontogeny are a cause of plasticity in mating signals and preferences. We subjected Enchenopa nymphs to treatments of either: rearing in aggregations (the natural condition), in isolation, or in isolation with playbacks of nymph signals. We then described variation in the signals and mating preferences of individuals that developed in those conditions. The playback treatments partially “rescued” the signal and preference phenotypes, resulting in phenotypes either similar to those that result from rearing in aggregations, or intermediate between those that result from rearing in isolation or in aggregations. These results pin-point signalling interactions during ontogeny as an important cause of plasticity in signals and mate preferences.