Distribution and abundance of natural parasitoid (Hymenoptera: Pteromalidae) populations of house flies and stable flies (Diptera: Muscidae) at the University of Florida Dairy Research Unit

Abstract

-From September 2001 through September 2002, house fl y and stable fl y pupae were collected weekly from three fl y habitats at the University of Florida Research dairy in northcentral Florida and evaluated for parasitism. Varying parasitism percentages were observed throughout the study but they were not affected by temperature, precipitation or fl y abundance. Of the 6,222 house fl y pupae and 1,660 stable fl y pupae that produced either a host fl y or a parasitoid, 26.9% and 26.7% were parasitized, respectively. Ten parasitoid species were recovered, with the genus Spalangia accounting for 85.7% of the total; the most common parasitoids attacking house fl y and stable fl y pupae were Spalangia endius Walker (33.9% and 27.3%), S. cameroni Perkins (27.9% and 40.6%), and S. nigroaenea Curtis (21.0% and 24.8%), respectively. Other parasitoids included one specimen of S. erythromera Förster and four specimens of Phygadeuon fumator Gravenhörst (Ichneumonidae). The percentage parasitism of pupae collected from bunker silos was higher than that of pupae from calf pens and open pastures. Spalangia cameroni was consistently recovered through the entire year.

Seasonal Abundance of Stable Flies and Filth Fly Pupal Parasitoids (Hymenoptera: Pteromalidae) at Florida Equine Facilities

“…These Þndings are similar to those of other studies in the United States (Petersen and Cawthra 1995, Petersen and Currey 1996, Weinzierl and Jones 1998. In Florida, stable ßy and house ßy parasitism was as high as 61 and 71%, respectively, depending on the substrate from which pupae were collected (Greene et al 1989, Romero et al 2010. However, parasitism rates in those studies was calculated using only pupae that resulted in a ßy or a parasitoid, resulting in increased values compared with the intact pupa method used in the current study (Petersen and Meyer 1985).…”

“…Although studies from Florida and other regions of the United States report the similar Þnding that these species made up a larger proportion of recovered parasitoids, collections also regularly contained a Muscidifurax spp. as well (Greene et al 1989, Meyer et al 1990, Jones and Weinzierl 1997, Romero et al 2010). In addition, these studies have been predominantly conducted at cattle feedlots or dairies (Meyer et al 1991, Romero et al 2010, and poultry facilities Axtell 1981, Kaufman et al 2001) where ßy breeding habitats can differ greatly depending on the cultural management practices of each farm (Legner andOlton 1971, Gilles et al 2008).…”

“…are active at Florida equine facilities has been similarly documented on Florida dairies (Greene et al 1989, Romero et al 2010) and may reßect a strategy to avoid competition by using a different temporal niche. This hypothesis is supported by previous Þndings that three Spalangia spp.…”

“…Although stable ßies can be collected throughout the year in Florida, activity is greatest between January and April (Gentry 2002, Romero et al 2010 depending on precipitation and availability of breeding habitats (Hogsette et al 1987). These observations are supported by our Þndings, in which stable ßy collections began to increase steadily in January, with peak collections occurring in April.…”

“…Increased stable ßy activity in Alberta, Canada, was later still, occurring during August and September (Lysyk 1993). In Florida, seasonal stable ßy activity is usually greatest between January and April, although stable ßies commonly occur throughout the year (Gentry 2002, Romero et al 2010. Multiple peaks in stable ßy abundance during these months can occur, depending on precipitation and available breeding habitats (Hogsette et al 1987).…”