Parasitism of the house fly parasitoid Spalangia cameroni on Norwegian pig farms: local effect of release method

Abstract

Mass release of parasitoids (Hymentoptera: Pteromalidae) is one possible control method of house flies (Musca domestica L.) on livestock farms. To improve the success of this method, however, there is a need for more detailed recommendations. In the present study, parasitism was evaluated in and around pens following release of the parasitoid Spalangia cameroni Perkins by hand and from containers. The study was conducted at conventional Norwegian pig farms with scattered breeding grounds for house flies. The experiment was carried out twice, with a total of seven trials of each release method followed by four weeks of monitoring parasitism by house fly sentinel pupae. No significant difference was found between the two release methods. Parasitism decreased with temperature (range 18-23°C) and was low on farms with few sites for the parasitoids to hide.

Life history parameters of two geographically separated populations of Spalangia cameroni, a microhymenopteran pupal parasitoid of muscoid flies

“…Although we cannot exclude the possibility of laboratory-induced differences between the populations, a genetic component might also explain the differences. A far less accurate estimation of sex ratio from mass-produced S. cameroni that originated from the Danish strain yielded 60-62% female (Birkemoe et al 2009;Birkemoe and Øyrehagen 2010), which is fairly close to the present results. A study of the two populations under mass-rearing conditions is needed to determine whether the differences are maintained.…”

“…One plausible explanation for these differences in development time and survival could be the different adaptations to thermal regimens in the two populations' home ranges. The Norwegian population of S. cameroni was obtained from a confined pig production unit with moderate fluctuating indoor temperatures (17-24°C) from spring in April to autumn in September (Birkemoe et al 2009;Birkemoe and Øyrehagen 2010) and indoor temperatures of approximately 17°C in the winter months, according to farmers. The Danish population of S. cameroni originated from relatively open dairy cattle units with larger yearly fluctuating temperatures of 7-10°C in winter and 10-23°C in spring through the summer and autumn periods (Skovgård and Nachman 2004;Skovgård 2004).…”

“…In the release studies conducted in Norway, a Danish parasitoid population was applied (Birkemoe et al 2009;Birkemoe and Øyrehagen 2010). Numerous studies of fly parasitoids have shown important differences in activity between geographical populations (Legner 1988 and references therein).…”

Comparison of the Olfactory Preferences of Four of Filth Fly Pupal Parasitoid Species (Hymenoptera: Pteromalidae) for Hosts in Equine and Bovine Manure

“…To our knowledge, Birkemoe & Oyrehagen (2010) conducted the only study comparing the 2 methods and found no significant effect on house fly parasitism by S. cameroni on Danish pig farms. They suggested that any disadvantages of the scatter method were compensated for by the short distance that parasitoids needed to travel to find hosts (Birkemoe & Øyrehagen 2010). Our results support the practice of scattering parasitized puparia in that the presence of formerly parasitized hosts does not interfere substantially in the ability of S. cameroni and M. raptor to locate and parasitize live puparia.…”

Linear Dispersal of the Filth Fly Parasitoid Spalangia cameroni (Hymenoptera: Pteromalidae) and Parasitism of Hosts at Increasing Distances

“…The lack of efficacy in some of these trials may be a consequence of insufficient knowledge to develop release protocols, including optimal distance between release sites or stations. Two common parasitoid release methods are scattering parasitized host puparia on the ground near fly development sites [ 22 – 24 ] and allowing parasitoids to disperse from artificial devices placed in or near known fly development areas [ 16 , 21 , 22 – 23 ]. In some release studies, the distance between release stations is not given or the method of release is not disclosed.…”