Post-Oviposition Development of Eggs of South Australian Mayflies

Abstract

Eggs of Atalophlebia australis, Nousia inconspicua, N. fuscula and Baetis soror from South Australia were incubated under constant temperature conditions in the laboratory (Range 4- 24 degree C). For each species the relationship between length of incubation period (Y) and incubation temperature (T) for the initial hatch (Hi) and mean egg hatch (Hx) was given by the equation Y = aT-b. The rate of development (V) was given by the equation V = bT + a. Photoperiod length had no effect on the incubation period. Embryonic development occurred at all temperatures, but hatching did not occur below 12 degree C for A. australis below 15 degree C for N. inconspicua and below 5 degree C for N. fuscula and B. soror . Two strategies of egg development for the South Australian mayflies are proposed on the basis of these experiments and field life cycle studies: (1) a direct relationship between temperature and incubation period (N. fuscula and B. soror ) and (2) a direct relationship between temperature and incubation period with a temperature enforced quiescence (A. australis and N. inconspicua )