Larval development of Anomala dubia (Scarabaeidae) in coastal dunes: Effects of sand-spray and Ammophila arenaria root biomass

摘要

In coastal dunes larvae of the Scarabid beetle Anomala dubia feed on roots of Ammopnila arenaria and other grasses. A. arenaria shows vital growth of roots if fresh wind-blown beach sand is being deposited. Due to increased atmospheric nitrogen deposition and active dune stabilisation Dutch dunes have become grass-encroached and sand-spray is strongly limited. Here, A. dubia is much less abundant than in pristine dynamic coastal dunes. A comparative study between Dutch and pristine Danish dune areasshowed that the density of larvae of A. dubia is highest if sand is deposited, A. arenaria is vital and fresh root biomass is produced. In these optimal conditions larvae probably complete their development within one year, whereas their development takes two years in less optimal conditions. In several Dutch coastal dune areas where restoration measures resulted in renewed sand-spray, larval densities were comparable to densities in pristine Danish dunes.