Assessment of parasitism of house fly and stable fly (Diptera: Muscidae) pupae by pteromalid (Hymenoptera: Pteromalidae) parasitoids using a polymerase chain reaction assay.

Abstract The internal transcribed spacer (ITS) regions of the ribosomal DNA of house flies, Musca domestica L., the stable flies, Stomoxys calcitrans (L.), and four parasitoid species in the genus Muscidifurax (Hymenoptera: Pteromalidae) were characterized to develop a method based on the polymerase chain reaction (PCR) to better define the role of pteromalid parasitism of pupae of the house fly and stable fly. Two parasitoid-specific primers were designed to anneal to the 5′ end of the 5.8S rRNA gene in the parasitoid species. When paired with a universal primer at the 3′ end of the 18S rRNA, the primers amplified the target ITS1 region in 10 pteromalid species. PCR allowed detection of parasitoid DNA within 24 h after females of Spalangia endius Walker oviposited into house fly puparia. PCR failed to amplify parasitoid DNA or detect parasitism in puparia that were exposed to parasitoid oviposition, allowed to develop 7 d, then killed by freezing and held at 20–24°C for 4 d to allow DNA degradation. Dige...