Biological Warfare - Soil: Reflections on the Basis of our Existence - page 110

delicacies on the Australian menu. I think I can understand them, as I would not
stick to Swedish meatballs if I were on holiday in Greece, even if they were the
main dish on the hotel menu, but would choose souvlaki or octopus from the grill.
How on earth can one presume that a toad will stick to eating beetles if relocated
from one side of the world to the other?
In Sweden the most invasive species, at least in gardeners' eyes, is the Spanish
slug. I often see a man walking along the railway line near my home carrying a
bucket of salt. Every now and then he bends down and throws salt on a slug to kill
it. When I last stopped for a chat his tally stood at three thousand five hundred and
thirty-three slugs. First recorded in Sweden in 1975, Spanish slugs have spread
rapidly. They are rumoured to eat whatever they find in their path, including other
slugs, but the truth is that they merely eat dead ones. One could call them scaven-
ger cannibals. The problem is that they also eat a wide variety of plants. Dahlias
seem to be a favourite, in my garden at least. It does not take long after the first
dahlia shoots emerge in late spring for Spanish slugs to appear on the scene. Once
they have eaten the shoots they tunnel down to eat the stalk and roots, completely
ignoring the green shoots of pale globe-thistle and Allium alongside. A newly
sown row of salad will disappear in no time.
Perhaps we can combat the slugs with biological means. A new slug killer,
Nemaslug, contains microscopic nematodes that prey on slugs and are said to kill
up to ninety percent of the Spanish slugs in a garden within 4 weeks. But I doubt
we will eradicate them completely and in all likelihood we will just have to put up
with them. One wonders, too, what the nematodes will target if the slugs run out.
Who knows, slugs may not even be the nematodes' preferred food source.
Further Readings
Hopwood DA (2007) Streptomyces in Nature and Medicine, the Antibiotic Makers. Oxford
University Press, New York
Hölldobler B, Wilson EO (2009) The superorganism. WW Norton & Company Inc., New York
Nordbring Hertz B (2004) Morphogenesis in the nematode-trapping fungus Arthrobotrys oligos-
pora. An extensive plasticity of infection structures. Mycologist 18:125-134
Sandsk￤r B (red.) (2002) Biologisk bek￤mpning av skadedjur. Jordbruksverket