Diapause induction in aphid parasitoids

Diapause is one of the adaptations that insects have evolved for the synchr onisation of their life cycle with seasonal climatic changes and resources. In aphid parasitoids, univoltine species have an obligatory, genetically d etermined diapause. Polyvoltine species, on the other hand, use a variety o f abiotic (temperature, photoperiod) and biotic (host insect or/and host pl ant) signals for the induction of diapause. We present an overview of the r ole of these environmental cues in diapause induction in specialist and gen eralist aphid parasitoids, and discuss possible endocrine factors that may be involved in diapause induction.