Tetanocera elata (Diptera: Sciomyzidae) Larvae Feed on Protected Slug Species Geomalacus maculosus (Gastropoda: Arionidae): First Record of Predation

The Family Sciomyzidae (Diptera) is one of the best studied groups of malacophagous insects containing some of the most important enemies of slugs. Larvae of the fly Tetanocera elata are known obligate feeders on slugs both as parasitoids and predators. We tested whether predatory larvae of T. elata can feed on the protected slug species Geomalacus maculosus, for which there appear to be no published records of natural enemies. Using an infra-red video camera, we recorded the behaviour of third instar T. elata in the presence of: 1) a single specimen of G. maculosus and 2) one specimen each of G. maculosus and Deroceras reticulatum, a known slug prey of T. elata. We describe the behaviour of the larvae where they killed and consumed G. maculosus and D. reticulatum in experiments 1 and 2 respectively. Since T. elata has been suggested as a potential biocontrol agent of pestiferous slugs, the possibility of predation on the protected species G. maculosus is discussed from this perspective.