Routes of penetration of the entomopathogenic nematode steinernema feltiae attacking larval and adult houseflies (Musca domestica)

The way in which Steinernema feltiae (Nematoda: Rhabditida: Steinernematidae) infects the housefly, Musca domestica (Diptera: Muscidae), was investigated. Adult flies were confined in petri dishes containing 1 million S. feltiae on capillary matting and individuals were dissected at hourly intervals. First, second, and third instar larvae were placed on filter papers with 100,000 infective juveniles, and then 2 larvae were examined at 30-min intervals. Infective juveniles were aggregated on the proboscis and anal aperture of male and female houseflies after 1 h. The nematodes penetrated female flies after 2 h by moving through the cloaca, then along the oviduct, and through the ovaries. Male houseflies were penetrated via the cloaca, and then S. feltiae entered the hemcoel by penetrating the wall of the ejaculatory sac. All larval stages were penetrated via the anal aperture. Nematodes then moved through the hind gut and penetrated the wall of the ileum, immediately posterior to the pylorus. Female nematodes were observed to penetrate housefly larvae before male nematodes. Male nematodes penetrated after 10 females had successfully parasitized a larva. Copyright 1998 Academic Press.