Submitted to: Society for Invertebrate Pathology Annual Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 15, 2000
Publication Date: N/A
Technical Abstract: Muscidifurax raptor, a pupal parasitoid of house flies and other muscoid flies, has been found to be infected with the microsporidan pathogen, Nosema muscidifuracis. The infection causes a chronic disease in adult parasitoids resulting in reduced fecundity and longevity. Studies were carried out to evaluate the effectiveness of heat and drug therapies to cure colonies of the disease. For heat therapy we used heat shock treatments as well as continuous rearing at elevated temperatures. Infected M. raptor were allowed to oviposit in Musca domestica pupae for 24 hours at a host: parasite ratio of 5:1. Groups of 400 pupae for each treatment were then subjected to heat shock at the parasitoid's eggs stage for 1, 3, 5, and 7 hours at 40 degrees C and 45 degrees C, and also at 50 degrees C for 15, 30, 45, and 60 minutes at high humidity. About 80% of emerged progeny were cured of disease when treated at 50 degrees C for 45 minutes while 60 minutes exposure at this temperature resulted in over 90% cure. Limited cure was obtained in the treatments at 45 degrees C, whereas the 40 degrees C treatments were ineffective. Continuous rearing of infected M. raptor colonies at 32 degrees C was effective in reducing the infection by the second generation. A 3% solution of albendazole or rifampicin in honey was fed to infected adult M. raptor, after which the parasitoids were given hosts for oviposition at successive intervals of 2, 4, 6, and 8 days after exposure to the drugs. Progeny from the third and fourth exposures showed a significant reduction in the infection rate for both drugs. The above strategies can be utilized to manage Nosema disease in infected colonies and could be incorporated into commercial mass production systems to produce healthy M. raptor.