GROWTH AND SURVIVAL OF LARVAE OF EPHYDRA-HIANS SAY (DIPTERA, EPHYDRIDAE) ON UNIALGAL DIETS

The algae Nitzschia latens Hustedt, Ctenocladus circinnatus Borzi, and two species of Oscillatoria were isolated from Mono Lake, which is ne ar Lee Vining, CA, and used to produce cultures containing only one al gal species (unialgal cultures). Survival to pupation and rates of lar val growth and development were compared among larvae of Ephydra hians Say, which were reared on one of these algal species or on a diet pre pared using the fish food Tetramin. It was found that larvae could be reared from the second larval molt to pupation when fed on a single sp ecies of algae. Larvae reared on Nitzschia showed significantly increa sed weight gain and survival compared with larvae reared on Ctenocladu s. Growth performance was always ordered Nitzschia, Oscillatoria, then Ctenocladus. Larvae reared on Nitzschia or Oscillatoria developed sig nificantly faster than those reared on Tetramin. The results indicate that single species of Nitzschia and Oscillatoria are adequate food so urces for E. hians growth. Although larvae of this fly appear to be ge neralist algal herbivores, food quality varies between algal species.