The effect of linear distance on the parasitism of house fly hosts (Diptera: Muscidae) by Spalangia cameroni (Hymenoptera: Pteromalidae).

Authors: MACHTINGER, ERIKA - University Of Florida; Geden, Christopher - Chris; LEPPLA, NORMAN - University Of Florida

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2015
Publication Date: 6/10/2015
Citation: Machtinger, E.T., Geden, C.J., Leppla, N.C. 2015. The effect of linear distance on the parasitism of house fly hosts (Diptera: Muscidae) by Spalangia cameroni (Hymenoptera: Pteromalidae).. PLoS One. doi: 10.1371/journal.pone.0129105.

Interpretive Summary: House flies and stable flies are important pests associated with House flies and stable flies are important pests associated with animals and humans and transmit a wide array of disease organisms. Biological control is an important element in successful fly management, and parasitic wasps that attack and kill fly pupae are the most commonly used fly biocontrol agents. Little is known about the distances that these wasps can travel, and this lack of knowledge has limited our ability to use appropriate spacing when releasing them on farms. In this study, scientists at USDA’s Center for Medical, Agricultural and Veterinary Entomology (Gainesville, FL) and the University of Florida conducted releases of one species of wasp (Spalangia cameroni) and measured how far they would travel over three days. Most of the wasps stayed within 5 meters of the release site, but some traveled as far as 60 meters. The results indicate that release points should be at most 20 meters apart to get good coverage and effective fly control.

Technical Abstract: Spalangia cameroni Perkins (Hymenoptera: Pteromalidae) is a common pupal parasitoid of pest flies in livestock facilities. Biological control for fly control using parasitoids has had variable success. The lack of efficacy in some trials may be a consequence of the insufficient knowledge of parasitoid behavior needed to write realistic release protocols, including optimal distance between parasitoid release stations. Knowing the distance a parasitoid will disperse from a release point is important for optimizing releases in augmentation programs. The purpose of these experiments was to assess the impact of linear distance on host parasitism by S. cameroni. House fly hosts were placed in a mixture of pine shavings soiled with equine manure, urine and alfalfa hay. The linear dispersal of S. cameroni at 6 distances ranging from 1 m to 60 m was evaluated. Releases of S. cameroni were made at a 5:1 host: parasitoid ratio in open fields with no previous livestock exposure. Spalangia cameroni females parasitized hosts at all tested distances. However, we found that S. cameroni was capable of dispersing and parasitizing hosts 60 m from a release site in the field. The highest rate of total parasitism (68.9%) was recorded from < 5 m from the release site. Results were analyzed in non-linear and linear models for best fit. The results suggest that releases of S. cameroni should be made in close proximity to host development areas. Additionally, releases may not be suitable in pasture situations where long-distance flight is required for control, but further testing is needed to examine the impact of density-dependent dispersal and diffusion of S. cameroni.