Exploring and exploiting the potential of the rhabditid nematode Phasmarhabditis hermaphrodita as a biocontrol agent for slugs.
Studies leading to the commercialisation, in 1994, of the slug-parasitic nematode Phasmarhabditis hermaphrodita as a biocontrol agent for use against slugs in the home garden market are described, together with ongoing investigations to exploit the potential use of this nematode for control of slug damage in a wide range of crops. The nematode is able to infect and kill all species of pest slug tested, as well as several snail species. However, larger species are thought to be susceptible only when young. Other invertebrates are not infected. The nematode is produced commercially in liquid fermenters. Infective larvae are harvested and, once formulated, they can be stored, under refrigeration, for several months. Infective larvae are applied to soil as a spray or drench at a rate of 3 × 109/ha. Slug feeding activity is considerably reduced shortly after infection, thus providing rapid protection from slug damage. The nematode is effective in protecting crops from slug damage, when it is applied as a drench or sprayed on to moist soil at, or shortly before, the stage when crops are susceptible. Efficacy in dry soil conditions can be improved by incorporating nematodes into the surface soil. Slugs avoid feeding or resting on areas of soil treated with nematodes, suggesting that it may be possible to target applications around individual plants or along crop rows. Despite its ability to kill a wide range of snail species, field studies indicate that it does not pose a threat to nontarget molluscs living in field margins and hedgerows adjacent to arable areas treated with the nematode.