Experimental induction of autotomy in two potential model lumbricid earthworms Eisenia andrei and Aporrectodea caliginosa

Abstract

Mild electrostimulation of earthworms is commonly used for harvesting celomocyte-containing celomic fluid. We have noticed that frequent electrostimulations of worms can lead to the autotomy of posterior segments followed by their regeneration. Our present study aim was to develop an autotomy model in the eco-physiologically contrasting species, Eisenia andrei and Aporrectodea caliginosa, using direct current (DC), pulsating direct current (PDC), or immersion in the noxious anaesthetic MS222. A. caliginosa was clearly more susceptible to autotomy than E. andrei, with both electrostimulation regimes and MS-222 exposure inducing autotomy in the former species but only repeated PDC stimulations inducing segment loss in the latter. The observations lend credence to the hypothesis that autotomy in earthworms is caused by factors impinging upon the nervous system; they also indicate that repeated PDC stimulations could be an effective and reproducible means of facilitating segmental autotomy so that the fundamental cytological and molecular-genetic mechanisms underpinning the tissue loss event and subsequent regeneration can be studied in depth.