Too sticky to steal: species-specific influence of seed mucilage on ant-mediated dispersal

Abstract Aims Seed mucilage plays a crucial role in plant ecology and survival strategies. The mucilage, which has high adhesive forces, can be very effective as defense mechanism against ant-mediated seed predation. Especially harvester ants are known to collect seeds and therefore influence seed dispersal and seed survival. To get a better understanding in ant-mediated seed predation, this study investigates the protective properties of seed mucilage of Plantago ovata and Ocimum basilicum seeds as we hypothesized that the composition of this mucilage influences the protection against ant-mediated dispersal. Methods For this purpose, we performed field experiments with the harvesting ant Messor wasmanni and observed seed survival rates of freshly hydrated and dried-in-contact seeds on two different surfaces. Results The results demonstrate that seeds of P. ovata had a higher resistance to removal by ants (with 90% and 75% seeds left at the experimental site) than those of O. basilicum (with 5% and 0% left at the experimental site) on solid substrates (concrete and stones, respectively) and an overall faster removal of O. basilicum seeds. These findings indicate a better protection of P. ovata seeds against ant-mediated dispersal than of O. basilicum seeds. Conclusions This study provides an insight into species-specific adaptations to seed defense. This can contribute to understand the importance of seed differences and mucilage compositions on seed ecology and plant defense mechanisms with potential implications for plant population dynamics, evolution and industrial and agricultural applications for seed protection.