Molluscicides and mechanical barriers against slugs, Vaginula plebeia Fischer and Veronicella cubensis (Pfeiffer) (Stylommatophora: Veronicellidae)

Thirteen molluscicides containing metaldehyde, three molluscicides containing metaldehyde plus carbaryl, one molluscicide containing metaldehyde plus methiocarb and one molluscicide containing methiocarb alone were tested for efficacy against the brown slug, Vaginula plebeia Fischer, and the two-striped slug, Veronicella cubensis (Pfeiffer). With the exception of Corry's Liquid Slug, Snail and Insect Killer against V. plebeia, all tested molluscicides caused significant mortalities against both species. Selected molluscicides were further evaluated for persistence under simulated rainfall; Deadline One Last Meal for Slugs and Snails, Deadline 40, Deadline Bullets and Slug and Snail AG Pelleted Bait, all of which contain metaldehyde as the active ingredient, consistently produced high mean percentage mortalities against both species. Efficacy of certain molluscicides decreased steadily with time, whereas efficacy of other molluscicides increased initially before declining. Mold grew on the majority of molluscicides after application. Liquid paste and liquid formulations were more resistant to mold development than pelleted, granule or coated granule formulations. In a separate study, physical barriers composed of copper or fiberglass screens repelled both slug species. (C) 1997 Elsevier Science Ltd.