The distribution of an intertidal aphid, Pemphigus trehernei foster, on marine saltmarshes.

Abstract

The intertidal aphid, Pemphigus trehernei, is restricted to aster plants (Aster tripolium) growing near the edges of creeks and salt pans in low areas on tidal saltmarshes. Aphid populations in mid-marsh areas do not show an equivalent edge effect. In low-marshes the edge soil generally has more surface cracks and cavities which can accommodate aphids and a higher % air space than soil from regions away from edges. Adults and 1st instars can penetrate edge soil more readily than non-edge soil. Aphid abundance is positively correlated with % air space in low-marsh regions. Aphid populations established on potted asters were destroyed or reduced to very low levels when transferred to non-edge regions of low-marsh areas. It is suggested that aphid distribution is primarily limited by soil conditions, especially the extent of soil drainage.