Life history traits of Aporrectodea caliginosa in a 8-year laboratory experiment

Earthworms are key soil organisms used as bioindicators of soil health and in population dynamics modeling approaches in soil ecology and ecotoxicology. However, very little is known about the effects of environmental conditions on their life history traits such as their life span, growth and reproductive capabilities on long terms. The aim of this study was to bring new data and knowledge on the effects of different conditions of food resource and earthworm density on life history traits (i.e., survival, growth, reproduction) of Aporrectodea caliginosa individuals during a 8-year laboratory experiment conducted in France. For that, a cohort of 20 hatchlings A. caliginosa were synchronized from a breeding culture, fed with normal food conditions or ad libitum (three times the normal food conditions) and monitored individually once a month. Once adults, they were kept isolated or pooled at different densities. Individual weight and cocoons were assessed every 14 days the first year and then once a month. We here highlighted that the lifespan of A. caliginosa can exceed 8 years under laboratory conditions. We also put evidence on a longer life span of individuals pooled with congeners among those kept isolated. An individual kept alone and fed ad libitum from its birth kept growing continuously, with individuals reaching 10 times the regular body mass known for A. caliginosa. Pooled earthworms stopped growing and allocate their energy to reproduction. Pooled or isolated, individual body mass of earthworms was found to be a precise proxy of the amount of organic matter in the soil. These data on earthworms’ biology and ecology can have implications in life cycle modelling and functional ecology.