The Ecology of Saldidae (Hemiptera-Heteroptera) Inhabiting a Salt Marsh, with Observations on the Evolution of Aquatic Habits in Insects

Abstract

In an estuarine salt marsh at Nether Hall, on the southern shore of the estuary of the River Stour, there is a zoning of spp. of Saldidae in the intertidal area and slightly above it in the following order from dry to wet Halosalda lateralis, Saldula pallipes adults, S. pallipes nymphs. Both adults and nymphs (especially the latter) of S. pallipes remained at the lower levels and were submerged by the rising tide, instead of retreating before it. Laboratory expts. involving enforced submergence showed that S. pallipes was able better to withstand submergence for longer periods without suffering permanent harm than H. lateralis. It is probable that S. pallipes is in the fore-front of an evolutionary tendency towards colonization of the water from the land. Two factors apparently limit the extent of the colonization of the intertidal zone: the period of time for which the Saldidae can withstand submergence; and the period of activity and feeding, which is apparently limited to the duration of exposure at low tide.