Listening to Slugs: Acceptability and Consumption of Molluscicide Pellets by the Grey Field Slug, Deroceras reticulatum

SIMPLE SUMMARY: The Grey Field Slug, Deroceras reticulatum (Müller), is a common crop pest worldwide. To control slugs, chemicals, such as metaldehyde are incorporated into pellets which are toxic to slugs when consumed. Our aim was to compare slug feeding on new pellet types with those already commercially available. Novel pellet types included silica-coated commercial metaldehyde pellets where metaldehyde is released more slowly. An audio sensor was used to record the individual slugs feeding on a variety of pellet types, including toxic (metaldehyde and ferric phosphate) and non-toxic (cereal) pellets. Two types of experiment were conducted: shorter laboratory trials and longer arena trials. The length of each bite and the total number of bites were recorded. There was no difference in the length of the bites between pellet types in laboratory trials. Novel pellets were not consumed more than commercial pellet types. Commercial pellet types did not differ in consumption. ABSTRACT: Gastropod damage to crop plants has a significant economic impact on agricultural and horticultural industries worldwide, with the Grey Field Slug (Deroceras reticulatum (Müller)) considered the main mollusc pest in the United Kingdom and in many other temperate areas. The prevailing form of crop protection is pellets containing the active ingredient, metaldehyde. Metaldehyde can cause paralysis and death in the mollusc, depending on the amount ingested. The paralysing effects may result in reduced pellet consumption. A greater understanding of metaldehyde consumption may reveal an area that can be manipulated using novel molluscicide formulations. Novel pellet types included commercial metaldehyde pellets coated so that metaldehyde is released more slowly. In both laboratory and arena trials, an audio sensor was used to record individual slugs feeding on a variety of pellet types, including commercially available toxic pellets (metaldehyde and ferric phosphate) and novel metaldehyde formulations. The sensor was used to record the length of each bite and the total number of bites. There was no significant difference in the length of bites between pellet types in laboratory trials. Novel pellets were not consumed more than commercial pellet types. Commercial pellet types did not differ in consumption.