The survival of the eggs of Austrosimulium pestilens Mack. & Mack. (Diptera, Simuliidae)

Abstract

AbstractEggs of Austrosimulium pestilens Mack. & Mack, were separated from sandy loam deposits in river beds in Queensland by washing the deposit through a 64·5 mesh/cm plankton sieve; the eggs were then picked off the surface of the sieve. Viable eggs were recovered only from permanently wet deposits; deposits above the water table contained only empty egg shells or dead eggs. Since eggs are laid directly into the water, their distribution in the river bed is related to its topography and the degree of scour and fill. Eggs stored in the laboratory in wet river deposits were still viable after 2½ years of storage, but died rapidly when exposed to relative humidities of 96% or less. Only a few eggs hatched from samples of riverbed deposits in water following up to four days' agitation with compressed air.