The excision of polydnavirus sequences from the genome of the wasp Cotesiacongregata (Braconidae, Microgastrinae) is developmentally regulated but not strictly restricted to the ovaries in the adult

Cotesia congregata polydnavirus (CcPDV) is essential for the successful par asitism of Manduca sexta larvae by the braconid wasp Cotesia congregata. In the absence of PDV, parasitoid eggs are encapsulated. Molecular analysis h as demonstrated that polydnavirus sequences are integrated in the wasp chro mosomes, and an ultrastructural analysis has shown that PDV replication occ urs in the calyx region in the ovaries of the wasp. The bracovirus sequence s appear to be excised from the wasp genome in the calyx cells where the vi rus replicates. Following excision of the virus sequences, the flanking seq uences are rejoined. We analysed the production of two polydnavirus circles during wasp development and in different body parts of the adults of both sexes. Our study indicates that the excision of viral sequences is developm entally regulated, beginning in the pupal stage. In the adult wasp, excisio n occurs ubiquitously. However, regulation in the adult seems to occur only in diploid individuals, as no excision is detected in haploid males produc ed from virgin females.