Colour preferences in sand dune insects found on ice plant flowers

Abstract

The ice plant (Carpobrotus edulis (L.), family Aizoaceae) is a succulent perennial native to South Africa that has been introduced widely around the world to prevent erosion of sandy or loose soils. At New Brighton sand dunes near Christchurch, dense mats of C. edulis now form part of a flora dominated by exotic plants, including marram grass (Ammophila arenaria L.), tree lupin (Lupinus arboreus Sims) and purple ragwort (Senecio elegans L.).

At New Brighton, a number of species of arthropods have been observed visiting ice plant flowers, including endemic Coleoptera (Lagrioida brouni Pascoe; Inophloeus rubidus Broun) and native arachnids (Cheiracanthium stratioticum Koch; Oxyopes gracilipes (White, 1849)) (Hodge et al. 2017). At least two colour forms of ice plant flowers occur at New Brighton: a common yellow form and a less common pink/purple form (Figure 1). This study compared overall arthropod occupation rates of the two flower colours and assessed whether individual insect species exhibited a preference for either colour form.