Dichogaster bolaui (Oligochaeta: Octochaetidae), an unusual invader in a swimming pool in Ireland

Abstract

The exotic octochaetid earthworm Dichogaster bolaui (Michaelsen, 1891) is reported from a heated indoor swimming pool in Cork, Ireland. The worms were noticed to emerge from drains in shower rooms and gaps between floor tiles almost daily for over a year. This is the first record of the species from Ireland or Britain. In the last two decades, this pantropical “tramp” native to central Africa has been in the limelight because of its ability to thrive and spread within the plumbing systems of urban buildings in Fennoscandia. It appears that a buffered microclimate and constant food supply (biofilm, organic residues) such as those found in domestic/sanitary sewers allow these worms to be active year‐round and prolific even at high latitudes. We also speculate that the prominent vascularization of the body wall and inner organs may facilitate their survival and spreading under flooded conditions. Earthworms are not known to act as vectors of human parasites or pathogens. However, control of indoor earthworm populations in households and public amenity buildings is desirable because of the loss of aesthetic value and perceived lack of neatness caused by their presence. In the present case, D. bolaui was controlled by repeated applications of concentrated salt solutions into drains and on to floor tiles and manual collection of the emerging worms.

Keywords:

• Dichogaster bolaui
• invasive species
• Ireland
• new record
• octochaetid
• tropical earthworm

Acknowledgements

We thank Mr Eamonn Hogan, Cork, for bringing this record to our attention and for collecting specimens.