Impact of molluscicidal formulations of earthworm surfacing behaviour:a novel use of security cameras

Abstract: Earthworms are of paramount importance in many soil systems, often comprising thedominant fraction of the soil macrofauna. Their activities have positive influences on soilfunctioning, recycling nutrients and promoting plant root growth for example. Pelletedmethiocarb and, more recently iron phosphate, molluscicides can impact on earthwormpopulations. The Daniel funnel test was used to determine the impacts of an iron phosphate andmetaldehyde molluscicide on nocturnal surfacing behaviour and feeding of Lumbricus terrestris.This technique monitors the removal of pellets and food (leaf portions) from the soil surface, butlacks detailed information regarding the level of direct interaction between pellets andearthworms. Therefore, night vision security cameras were mounted above a number of burrowsand, with the help of motion detection software, earthworm activity was filmed. This allowedearthworm surfacing patterns and the frequency and duration of pellet contact to be documentedfor the first time. Metaldehyde was found to have no significant impact on earthworm behaviourwhilst iron phosphate significantly reduced surfacing behaviour and feeding frequency.