Dynamic study of the burrowing behaviour of Aporrectodea nocturna and Allolobophora chlorotica: interactions between earthworms and spatial avoidanceof burrows

The behaviour of earthworms belonging to two different species and ecologic al types (Aporrectodea nocturna and Allolobophora chlorotica) was studied u sing two-dimensional (2D) terraria. Two experiments were set up to gain ins ight into the nature of interactions between these earthworms. Firstly, the evolution of the burrow systems was analysed with the density of the earth worms varying from one to five individuals. Secondly, a burrow system was f irst established by using one earthworm which was then. removed before the introduction of a second earthworm. This second earthworm therefore encount ered a burrow system created either by a conspecific earthworm or by an ear thworm of the other species. These experiments showed that: (1) intra- and interspecific interactions occur between earthworms, (2) these: interaction s are dependent on the physical presence of the earthworms, and (3) spatial avoidance can occur (A. chlorotica avoiding burrows created by A. nocturna ). The results suggest that earthworm burrow systems art: "'individual stru ctures", rarely used by other earthworms when inhabited. When abandoned, th e burrows may be recolonised depending on the ecological type of the earthw orm under consideration.