Effects of density and temperature regime on respiratory activity of the epigeic earthworm species Lumbricus rubellus and Dendrobaena octaedra (Lumbricidae)

Earthworm population densities vary strongly in space and time, and it has been hypothesised that the metabolic activity of the epigeic species Lumbricus rubellus and Dendrobaena octaedra is influenced by the presence of conspecifics. Carbon dioxide production of mature earthworms of these two species kept separately or in groups of two (L. rubellus) and three individuals (D. octaedra) were measured at constant and diurnally fluctuating temperature regimes. In L. rubellus respiration rates at constant and fluctuating regimes did not differ between specimens kept individually and in groups. In contrast, in D. octaedra both respiration rates and reproduction were significantly lower in earthworms kept in groups as compared to specimens kept individually.