Studies on a New Entomophthora Attacking Calyptrate Flies

SUMMARY

A new species of Entomophthorales (Phycomycetes) which destroys flies in epizootic proportions was found on two occasions near Lawrence, Kansas. The fungus has been described, illustrated, and named Entomophthora kansana Hutchison.

Species of Calliphoridae, Sarcophagidae, Muscidae, and Tachinidae (principally blow flies and flesh flies) were dying in large numbers at both sites. Various symptoms were displayed by infected flies. Many possessed white rings between sclerites. Others lost abdominal portions while still alive, due to the adherence of abdominal parts to the substratum by a gelatinous substance produced as a result of the disease. This gelatinous substance, which consisted of fungal hyphal bodies and digested insect tissue, could be found in large masses on the abdominal sternites of some dead intact specimens. The weather was cool and humid during both epizootics.

Serial sections revealed that the pathogen follows the general life cycle for other Entomophthoras. In the host, the pathogen digested tissues of the head, thorax, and abdomen. It was also found in the legs and wing veins. Certain host tissues appeared to be more resistant to destruction by the pathogen than others.

The parasite was carried through only one cycle on an artificial medium.

Hundreds of healthy house flies were introduced into cages with infected flies. After approximately 90 hours the previously healthy flies, which fell on moist toweling, soon became partially gelatinized by the fungus. Only those which were placed on moist soil produced conidia. The disease cycle was approximately 96 hours in the laboratory. The pathogen was highly virulent for four months, but for unknown reasons was abruptly lost.