Polydnaviruses (PDVs) are a group of insect viruses and symbiotic to some endoparasitoid wasps classified in to Braconidae and Ichneumonidae. Though a lot of PDV genes are identified and analyzed in the host-parasitoid molecular interactions, PDV replication is still far from our understanding. PDVs are replicated in the wasp ovary during late pupal stage. A PDV, Cotesia plutellae bracovirus (CpBV), is symbiotic to Cotesia plutellae. The C. Plutellae ovary was analyzed in transcriptome by 454 pyrosequencing. The ovarian transcriptome provided several major DNA polymerases including Pol α, Pol δ, and Pol ε. All contigs matched to these polymerases were expressed in C. plutellae. Especially DP1 contig homologous to Pol α was highly expressed during late pupal and female adult stages. Its RNA interference significantly suppressed CpBV viral titre in the ovary. This study suggests a hint that CpBV replication uses a host DNA polymerase, in which Pol α may play a specific role in the viral replication in the ovary.