Biology of the mayfly Leptophlebia cupida (Say) (Ephemeroptera: Leptophlebiidae)

Abstract

Leptophlebia cupida (Say) is a widely distributed and extensively reported mayfly species of North America. In the Bigoray River, a brown-water stream of Alberta, Canada, L. cupida is a univoltine species. The rate of progressing through the life cycle, i.e. predicted instar intervals, was found to be better correlated with the amount of cumulative degree days (water temperature) that the nymphs receive than with the cumulative calendar days of the life cycle. Leptophlebia subimagoes had a higher total potential fecundity per unit body size than any of the other Bigoray River mayflies.Nymphs are fine particle detritivores, ingesting about 96% detritus and 4% diatoms. Average particle size ingested was 38 μm. In the laboratory at 20 °C, there were 34 nymphal instars; but there is probably no fixed number of nymphal instars, the 34th being just one of several instars in which the nymphs, given the proper environmental cues, might transform. The first nine instars are figured.Using mainly laboratory data, we investigated the relative contribution that small individuals (< 1.5 mm) make to cohort production. This theoretical exercise indicated that the error which occurs in cohort production estimates by not adequately sampling the small individuals could be less than 10%.