Interaction between the dune aphid Schizaphis rufula and its host-plant Ammophila arenaria: a comparison of insect multiplication on different host-plant populations

Background/Question/Methods

Coastal dunes are large sand accumulations along the shoreline formed by sea currents, surges, wind or vegetation.  The vegetation provides dune stabilization, while creating suitable habitats for a large number of organisms including insects, crustaceans, reptiles and shorebirds.  Ammophila arenaria is a perennial grass that dominates mobile dunes (including both embryonic foredunes and foredunes) along the European shoreline.  Because of its easy collection, transplantation, propagation and adaptation to sand dunes, is commonly used in Europe and elsewhere for dune stabilization purposes.  The dune aphid Schizaphis rufula is a common species associated with this grass along the distribution range of the host plant.  Studies to gain insights into the interactions between A. arenaria and S. rufula are not only necessary to understand basic biological traits of these two species, but can also be useful to guide optimal management strategies on dune ecosystems.  The goal of this study was to study the multiplication of S. rufula on various genotypes of A. arenaria coming from the sites within the natural distribution range of this grass species.  We also aimed to evaluate whether S. rufula prefers local or allopatric genotypes.  Seedlings from Belgium, the Netherlands, United Kingdom and Portugal were exposed to one aphid population collected in Belgium.  After inoculation, aphids were allowed to multiply and feed on the plants for 21 days.  Aphid numbers were used to generate a population growth curve for each aphid-plant population combination.  Growth dynamics were compared between A. arenaria populations using a one-way ANOVA.

Results/Conclusions

The five plant-herbivore combinations tested revealed significant differences in multiplication among populations, with higher aphid reproduction on local (Belgium) populations and plants from Wales.  Therefore, plant population origin does influence aphid multiplication; nonetheless, no direct correlation with host plant geographic origin was discovered.  Other variables such as specific plant traits and defences must be further assessed to determine the mechanism behind the observed pattern.  Our study indicates that caution should be taken when choosing plant material for restoration purposes in coastal dunes due to the potential impacts on the associated fauna.