D. C. Steinkraus

Susceptibility of sixteen species of Diptera to the fungal pathogenEntomophthora muscae (Zygomycetes: Entomophthoraceae)

Sixteen species of Diptera from eight families were inoculated with conidia ofEntomophthora muscae (Zygomycetes: Entomophthorales). The following species were susceptible and became infected at the rates indicated:Musca domestica (100%),Sarcophaga haemorrhoidalis (86%),Phaenicia sericata (44%),Scatophaga stercoraria (30%),Drosophila melanogaster (11%),Aedes aegypti (3%), andStomoxys calcitrans (2%). The following species were not susceptible under the conditions of this study:Phormia regina, Calliphora vicina, Rhagoletis pomonella, Eristalis arbustorum, Eristalis tenax, Toxomerus geminatus, Sphaerophoria scripta, Syrphus sp. andAllograpta oblique. Differences in susceptibility were not related to the taxonomic affinities of the taxa tested; however, susceptibility may be related to interspecific morphological differences of hosts, such as, scales and hairs on the host or the degree of sclerotization of host integument.Each host-pathogen interaction was examined. Characteristics of the post-mortem growth of the fungus were similar within a host species but differed between host species. These differences in post-mortem growth of the fungus were related to the suitability of host species as a substrate for the pathogen. The incubation period of the mycosis was related to host species and not to host size, it varied from seven days for the relatively largeS. haemorrhoidalis to 17 days for the relatively smallA. aegypti.

Culture of Entomophthora muscae in vivo and its infectivity for six species of muscoid flies

A method for the continuous culture of Entomophthora muscae (Entomophthoraceae) in adult house flies (Musca domestica) is described. Using this method we have maintained the host-pathogen system in the laboratory for more than one year. The ability of this isolate to cause fatal infections in virtually all of the house flies at risk has remained constant. The face fly (Musca autumnalis), the onion fly (Hylemya antiqua), and the seed-corn fly (H. platura) are susceptible to this isolate. The stable fly (Stomoxys calcitrans), the black blow fly (Phormia regina), and the false stable fly (Muscina stabulans) are not.