Parasitization by pteromalid wasps (Hymenoptera) of freeze-killed house fly (Diptera: Muscidae) puparia at varying depths in media.

Three laboratory experiments were performed to assess parasitization of freeze-killed house fly puparia, buried 0 to 6 cm in media, by Muscidifurax raptor Girault & Saunders, Muscidifurax raptorellus Kogan & Legner, Muscidifurax zaraptor Kogan & Legner, Trichomalopsis sarcophagae (Gahan) and Urolepis rufipes (Ashmead) (Hymenoptera: Pteromalidae). Virtually no parasitization occurred at depths greater than 1 cm in large arenas (988 cm2) with densities of 0.3 puparia and 0.008 female parasitoids per cm2. Parasitization was observed at depths as great as 4 cm for three of five species in small arenas (3 cm2) with densities of 6.4 puparia and 1.0 female per cm2. Combined across experiments, M. raptor achieved the highest level of parasitization, followed by M. zaraptor, M. raptorellus, U. rufipes, and T. sarcophagae. The greatest number of F1 females was produced by the gregarious species T. sarcophagae (834 female female) and M. raptorellus (708 female female), and then by the solitary species M. raptor (530 female female), M. zaraptor (365 female female) and U. rufipes (163 female female). High parasitization by M. raptor and high production of offspring by T. sarcophagae identify these species as being particularly attractive as biological control agents.