Histological observations on larvae of the eye gnat, Hippelates pusio (diptera: Chloropidae), infected with the flagellate Herpetomonas muscarum

Abstract

A flagellate from Hippelates pusio was cultured in artificial medium and identified as Herpetomonas muscarum. Flagellate infections were established in the lumen of the larval midgut at its anterior end following ingestion of infective stages of the protozoan and spread subsequently to the gastric ceca and posterior portions of the midgut. Infections progressed from heavy gut infections to light hemocoelic infections when flagellates penetrated the gut wall, probably in the gastric ceca or anterior midgut. A bacterial septicemia which followed the flagellate invasion of the hemocoel ultimately destroyed all flagellates and killed the larva. Flagellates were never found invading any tissue other than the gut wall. Axenic rearing of gnats was considered prerequisite to determining whether flagellates alone are capable of causing mortality. The importance of the duration of infection to establishment of hemocoelic infections and therefore larval mortality, was demonstrated.