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United States Department of Agriculture

Agricultural Research Service


Location: Mosquito and Fly Research

Title: Host location by Spalangia cameroni (Hymenoptera: Pteromalidae) in equine associated substrates

item Machtinger, Erika
item Geden, Christopher - Chris

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2013
Publication Date: 1/23/2013
Citation: Machtinger, E.T., Geden, C.J. 2013. Host location by Spalangia cameroni (Hymenoptera: Pteromalidae) in equine associated substrates. Biological Control. 65:130-134.

Interpretive Summary: House flies and stable flies are important pests associated with animals and humans and transmit a wide array of disease organisms. Efforts to manage flies have traditionally relied on chemical insecticides, but flies have become resistant to most insecticides and there is increasing public demand to reduce pesticide use around animals. For many years, horse owners have been purchasing parasitoids that attack fly pupae as fart of their control efforts, but little is known about how effective this practice is. In this study, a University of Florida graduate student and a research entomologist with USDA/ARS’s Center for Medical, Agricultural and Veterinary Entomology (Gainesville, FL) examined the effectiveness of the parasitoid Spalangia cameroni at finding and killing house fly stable fly pupae in a wide variety of habitats that are commonly found on horse farms. The habitats included items such as horse manure, bedding, soil and their various combinations. Although the parasitoids showed some preferences for different substrates, the differences were small and only detectable when parasitoids were given large numbers of pupae to locate. House fly and stable fly hosts were equally vulnerable to attack. The results support field studies that suggested that S. cameroni was the most important species of parasitoid on horse farms. Results should encourage commercial parasitoid producers to provide this species to their horse-owning clients.

Technical Abstract: Biological control of filth flies with pupal parasitoids has become increasingly popular with horse owners (USDA 2006) but has not been evaluated on equestrian facilities. Little is known of the substrate preferences of filth fly parasitoids on equestrian facilities, but the success of release programs may be affected by microhabitat preferences. Spalangia cameroni Perkins, the most common naturally occurring parasitoid on equestrian farms in Florida, was evaluated for location preferences for parasitization of house fly and stable fly pupae in six substrates commonly found on equestrian farms in Florida. Substrates were evaluated at 20:1 and 5:1 host: parasitoid ratios. No differences were observed between hosts in any of the measured parameters. Significant effects of host: parasitoid ratio on host mortality and residual mortality were found but not on progeny production. Significantly more hosts were killed in the manure/shavings substrate than in shavings alone at the 20:1 ratio, no differences were observed at the 5:1 ratio. Additionally, no differences were found in progeny production by substrate at the 20:1 ratio, but higher reproductive success was observed in the hay and manure/shavings substrates at the 5:1 ratio. These results demonstrate that S. cameroni had substrate preferences but that these preferences were absent with reduced host density. This parasitoid species appears to be effective at parasitizing hosts in the common equine substrates of Florida.

Last Modified: 10/16/2017
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