Developmental analysis of Ganaspis xanthopoda, a larval parasitoid of Drosophila melanogaster.

Ganaspis xanthopoda is a solitary larval parasitoid wasp of the fruit fly Drosophila melanogaster. The life cycle of Ganaspis xanthopoda in the wild-type and developmental mutant ecdysoneless strains of Drosophila melanogaster is described. The female infects a second-instar host larva. The parasitoid embryo hatches into a mobile first-instar (L1) larva. The L1 parasitoid has fleshy appendages and, while mobile, it remains confined within the wandering larval host. The second-instar larva (L2) is an endoparasite within the host prepupa and lacks appendages. The L2-to-L3 molt is dependent on pupation and marks the transition of the endoparasite into an ectoparasite. The third-instar larva (L3) is a sessile ectoparasite, develops an extensive tracheal system and consumes the host as it progresses through its prepupal and pupal stages. A single adult male or female emerges from the host puparium. The developmental analysis of Ganaspis xanthopoda reveals a tight synchrony between host and parasitoid development which is, at least in part, dependent on the ecdysone levels of the host.