Slugs (Deroceras reticulatum and Arion ater agg.) avoid soil treated with the rhabditid nematode Phasmarhabditis hermaphrodita

A series of experiments was done to determine whether the pest slugs Deroceras reticulatum and Arion ater agg. (Mollusca: Gastropoda: Stylommatophora) could detect the presence of and avoid soil treated with the parasitic nematode Phasmarhabditis hermaphrodita (Nematoda: Rhabditidae). One-half of the surface area of moist soil in experimental boxes was treated with infective juveniles of P. hermaphrodita at a density of 120/cm(2), The other half of each box was left untreated. Five discs of Chinese cabbage leaf were placed in each half of each box, Slugs (D. reticulatum or A. ater agg,) were added to each box and food consumption and resting sites were recorded over a 12-day period. Both slug species were more likely to rest and feed on untreated soil than on nematode-treated sea. A series of boxes was also prepared with one-half untreated and the remaining half treated with 1, 4, 12, 38, or 120 nematodes/cm(2), Slugs were less likely to rest or feed in the treated half of boxes containing 38 or 120 P, hermaphrodita/cm(2) but showed no preference between the untreated and the nematode-treated soil at lower nematode densities. A final experiment showed that there was little movement of P. hermaphrodita from the treated half to the untreated half of each box. a (C) 1999 Academic Press.