Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2002
Publication Date: N/A
Interpretive Summary: Parasitic wasps are important tools for managing house flies and stable flies on livestock and poultry farms. Wasp releases can reduce fly populations and save farmers money while reducing the amounts of insecticides needed for their fly control programs. To meet the demand for these biocontrol agents by American farmers, several commercial insectaries snow produce and sell wasps for farmers to release. The quality and effectiveness of these commercially-produced wasps is significantly compromised if they are infected with protozoan parasite in the genus Nosema. In this study, conducted by a graduate student and scientists working at USDA's Center for Medical, Agricultural, and Veterinary Entomology (Gainesville, FL), it was found that wasps that have Nosema disease take longer to develop from egg to adult than healthy ones. By documenting this difference at different temperatures, the researchers found that the disease can be managed by discarding any wasps that emerge 1-2 days after the emergence of the first individual at 20-25 degrees C. This provides a simple method that commercial producers can use to clean up infected colonies so that they are selling the highest quality biocontrol product possible.
Technical Abstract: Muscididfurax raptor (Hymenoptera: Pteromalidae) is a pupal parasitoid of house flies and other filth flies and serves as a host for the microsporidium Nosema muscidifuracis. To determine the effects of infection on development times, uninfected and infected adult M. raptor were allowed to parasitize pupae of the housefly (Musca domestica L.) for 24 hours. Exposed pupae of the two groups (infected and uninfected) were then held i chambers maintained at 15, 20, 25, 30, 32 and 34 degrees C wth 75-80 percent relative humidity. Infected colonies produced about half as many progeny as healthy colonies and had substantially male-biased sex ratios. Infected M. raptor took significantly longer to develop at all temperatures than uninfected parasitoids, with infection resulting in about a 7 percent extension of development time in most cases. The differences in development time provided narrow windows for collecting uninfected M. raptor females. This window was greatest at 20 degrees C, with large proportions of uninfected females emerging for nearly 48 hours after emergence of the first uninfected females.