Nosema Disease of the Parasitoid Muscidifurax raptor (Hymenoptera: Pteromalidae): Prevalence, Patterns of Transmission, Management, and Impact

Microsporidia Biological Control Agents and Pathogens of Beneficial Insects

“…Dry et al (1999) examined M. raptor biweekly from poultry houses in Arkansas and report the prevalence of microsporidia in M. raptor as 13 and 5% in 1994 and 1995, respectively. In contrast to the observations made by Geden et al (1995), higher disease prevalence was not observed among parasitoids on farms where commercially reared M. raptor were released, and the authors conclude that released wasps are not a major source of the pathogen.…”

“…In many cases, microsporidia-infected beneficial arthropods exhibit a variety of symptoms, including reduced food consumption, prolonged larval and pupal development, deformed pupae and adults, reduced fecundity and longevity, and death (e.g., see Brooks & Cranford 1972;Siegel et al 1986b;Zchori-Fein et al 1992;Geden et al 1995;Bjørnson & Keddie 1999;Schuld et al 1999;Idris et al 2001;Steele & Bjørnson 2012). Microsporidia may have more noticeable effects when host insects are under stress (Kluge & Caldwell 1992), as is often the case in mass-rearings.…”

“…Zchori-Fein et al (1992) report that one-third of parasitoids collected from New York dairy farms in 1990 were infected with a microsporidium, later described as Nosema muscidifuracis (see Becnel & Geden 1994). Although microsporidia are common pathogens of parasitoids, N. muscidifuracis is one of only three known microsporidian pathogens that specifically infect a parasitoid and not its host (Geden et al 1995).…”

“…muscidifuracis also infects insectary-reared parasitoids. In a 1995 study, 86-100% of M. raptor obtained from a commercial insectary for biological control were infected with N. muscidifuracis (Geden et al 1995). N. muscidifuracis was found in 1.1 and 10.7% of indigenous M. raptor collected from New York dairy farms in 1991 and 1992, respectively.…”

“…Both known mechanisms of horizontal transmission involve cannibalism. Horizontal transmission occurs when uninfected M. raptor immatures feed on infected immatures within superparasitized host puparia or when adult parasitoids feed on the fluids of infected parasitoid immatures through wounds made by their ovipositors in the host pupae (Becnel & Geden 1994;Geden et al 1995). Horizontal transmission of N. muscidifuracis increases when parasitoids are overcrowded, resulting in the cannibalism of infected immatures by healthy ones within superparasitized hosts.…”