Predation on the slug Deroceras reticulatum (Pulmonata: Stylommatophora) by Scarites anthracinus (Coleoptera: Carabidae)

The grey field slug Deroceras reticulatum has become a pest in no tillage sunflower (Helianthus annuus L.) and soybean (Glycine max L.) crops in the southeast of Buenos Aires province, Argentina. Ground beetles (Coleoptera: Carabidae) are an important component of the arthropod community in agricultural systems and have the potential to reduce pest populations. We tested the predation capacity of the carabid beetle Scarites anthracinus on Deroceras reticulatum individuals of different body mass (10, 20 and 30 mg) and on their eggs, in a controlled laboratory no-choice assay. We also tested its preference for juvenile slugs and the similarly-sized pillbugs (Armadillidium vulgare), under choice conditions. This beetle preyed upon both eggs and juvenile slugs, with the highest consumption rate on 20 mg body mass individuals. While preferring the pillbug during the first 24 h of the choice test, our results suggest that in field conditions, S. anthracinus might be a natural enemy of D. reticulatum, consuming slug eggs and juveniles of different body mass.