Activity and relative abundance of hymenopterous parasitoids that attack puparia of Musca domestica and Stomoxys calcitrans (Diptera : Muscidae) on confined pig and cattle farms in Denmark

A survey was conducted on 84 pig and cattle farms in Denmark between August and October 1996 and 1997. The aim was to describe the activity and relati ve abundance of parasitoids (Hymenoptera: Pteromalidae and Ichneumonidae) t hat attack puparia of Musca domestica Linnaeus and Stomoxys calcitrans (Lin naeus). In total, seven pteromalid species were recovered: Spalangia camero ni Perkins, S. nigripes Curtis, S. subpunctata Forster, Muscidifurax raptor Girault & Sanders, Pachycrepoideus vindemiae (Rondani), Urolepis I rufipes (Ashmead) and Nasonia vitripennis (Walker), an ichneumonid Phygadeuon fuma tor Gravenhorst, a diapriid Trichopria sp., and a staphylinid Aleochara sp. This is the first time that U. rufipes has been recorded in Europe. Spalan gia cameroni and M. raptor were the most frequently recorded species in all regions of the country, and accounted for the main parasitism of Musca dom estica and Stomoxys calcitrans puparia. The overall rate of parasitism per farm was low: 12.9% of the total number of fly puparia collected. Direct or dination, used to assess the habitat distribution of the parasitoids, showe d that Muscidifurax raptor mainly seeks fly puparia in outdoor manure heaps and especially in manure from pigs rather than from cattle, whereas Spalan gia cameroni mainly seeks fly puparia indoors, irrespective of livestock.