LABORATORY TESTS OF THE POTENTIAL OF ENTOMOPATHOGENIC NEMATODES FOR THE CONTROL OF FIELD SLUGS (DEROCERAS-RETICULATUM)

The entomopathogenic nematodes, Steinernema feltiae (UK 76) and Heterorhabditis sp. (North West European Group, UK 211), and the slug-parasitic nematode Phasmarhabditis hermaphrodita (UK 1) were tested for their ability to kill the slug Deroceras reticulatum using petri dish and soil bioassays. The entomopathogenic nematodes did not kill slugs in either bioassay at 14 and 23 degrees C, although they were shown to kill tenebrionid insect larvae (Tenebrio molitor and Zophobas morio) at 14 degrees C. The symbiotic bacteria of S. feltiae and Heterorhabditis sp. (Xenorhabdus bovienii and Photorhabdus luminescens, respectively) were injected in large numbers into the hemocoel of D. reticulatum. X. bovienii was found to be of low pathogenicity and P. luminescens was not pathogenic, whereas slugs were rapidly killed by injection of a strain of Pseudomonas fluorescens isolated from a cadaver of D. reticulatum. P. hermaphrodita killed D. reticulatum at 14 degrees C but not at 23 degrees C and did not kill T. molitor or Z. morio at 14 degrees C. It is concluded that S. feltiae and Heterohabditis sp. have no potential as biocontrol agents against slugs, whereas P. hermaphrodita is effective at the relatively low temperatures at which slugs are active. (C) 1994 Academic Press, Inc.