Evaluation of the effectiveness of iron phosphate and the parasitic nematode Phasmarhabditis hermaphrodita in reducing plant damage caused by the slug Arion vulgaris Moquin-Tandon, 1885

Arion vulgaris is one of the most important slug pests of crop plants, and is extremely hard to control. We assessed the effectiveness of a slug pellets containing iron phosphate, compared with methiocarb- and metaldehyde-based molluscicides, and of the parasitic nematode P. hermaphrodita contained in the commercial bioproduct Nemaslug. The effect of various doses of these substances and the nematode in reducing slug damage to Chinese cabbage plants was evaluated in laboratory experiments. A reduction in slug numbers and plant damage was obtained following application of the molluscicides, and a reduction in plant damage following application of P. hermaphrodita (immersion of plant roots in the nematode-containing liquid). The results are of great practical significance, because they show that it is possible to reduce the recommended dose of iron phosphate (5 g/m2) by one half. Another important finding is that application of the nematode in the form of root immersion is more effective than spraying. The study demonstrates the usefulness of the nematode and of the iron phosphate molluscicide in protecting plants from A. vulgaris; this is of particular importance for crops on which the application of traditional molluscicides is not possible.