ARS | Publication request: Development of Spalangia cameroni and Muscidifurax raptor (Hymenoptera: Pteromalidae) on Live and Freeze-killed House Fly (Diptera: Muscidae) Pupae.

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 15, 2009
Publication Date: September 1, 2009
Citation: Kaufman, P.E., Geden, C.J. 2009. Development of Spalangia cameroni and Muscidifurax raptor (Hymenoptera: Pteromalidae) on Live and Freeze-killed House Fly (Diptera: Muscidae) Pupae. Florida Entomologist. 92(3)492-496.

Interpretive Summary: Parasitic wasps are among the most important biocontrol agents for filth flies, and there are several commercial insectaries that provide these wasps to farmers. One of the challenges that parasitoid producers face is dealing with fluctuating demands for their products because it takes a week to produce fly pupae for the parsaitoids and these live pupae only have a shelf life of 2-3 days. In this study, conducted by a scientists at the University of Florida and ARS’s Center for Medical, Agricultural and Veterinary Entomology, live house fly pupae were compared with pupae that had been killed by freezing and gamma irradiation for their ability to produce two species of parasitoids, Muscidifurax raptor and S. cameroni. Pupae were held in frost-free or non-frost-free freezers for varying lengths of time to determine whether the type of freezer conditions affected the quality of the pupae. M. raptor production on frozen hosts was not significantly different from production on live or irradiated hosts regardless of type of freezer or length of time that the pupae were kept frozen. S. cameroni performed poorly on frozen pupae of all types and was lower on pupae that were frozen for 5 months than on pupae frozen for two weeks. Measurements of weights of parasitized pupae over time indicated that freezing did not result in accelerated desiccation of hosts. These results document that the use of prolonged freezing and type of freezer minimally impacts M. raptor, but that commercial insectaries and researchers should be cautious in the use of frozen pupae when rearing or surveying for S. cameroni.

Technical Abstract: This study was conducted to determine if the reduced suitability of freeze-killed pupae for Pteromalidae, particularly Spalangia cameroni Perkins, is due to freezing, freezing duration or the type of freezer utilized. Processing pupae through freezing had a considerably greater negative effect on S. cameroni than on Muscidifurax raptor Girault and Sanders. Although freezing pupae did reduce M. raptor progeny production, there was no effect of length of storage or type of freezer used. Freezing pupae for 5 months resulted in significantly fewer S. cameroni progeny than freezing pupae for 2 weeks. Pupae held in the frostfree freezer produced more progeny than those in the non-frostfree freezer. Measurements of weights of parasitized pupae over time indicated that freezing did not result in accelerated desiccation of hosts. These results document that the use of prolonged freezing and type of freezer minimally impacts M. raptor, but that commercial insectaries and researchers should be cautious in the use of frozen pupae when rearing or surveying for S. cameroni.