POPULATION DYNAMICS OF SEPEDON FUSCIPENNIS (DIPTERA: SCIOMYZIDAE)

Abstract

AbstractAdults of Sepedon fuscipennis Loew were sampled periodically throughout the summers of 1969 and 1970 in a backwater habitat. Several overlapping generations of this common marsh fly were present during both summers, and its population density reached a unimodal peak both years. Population estimates based on mean number per sweep agreed well with mark–release–recapture data. These estimates showed a reasonably good fit to the negative binomial distribution and indicated that aggregation of the flies probably is due to some heterogeneity in the environment. Flies lived more than 3 months in laboratory cages, and each female laid an average of 191 eggs.Estimates were made of larval survival and net production for discrete cohorts followed in the field. The survival and production rates of larvae were greater when small snails were abundant in the habitat and much greater when the larvae were fed once before being released. Survival was not decreased perceptibly by the degree of larval crowding tested (50 larvae compared with 25 in an area of 254.34 cm2).