Slugs (Deroceras reticufatum and Anon ateragg.) 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: Stylominatophora) 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. reticulaʹ turn 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 nematodetreated soil. 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.