Coll's Unusual Worm

Brian Boad. Dundee

One of the advantages of my kind of work, being a scientist at the Scottish Crop Research Institute is that I can mix work with pleasure. I am interested in the distribution of both animal and plant-parasitic nematodes sometimes called "eelworm" (they are small microscopic animals (1 - 15 mm long) and the potential damage they can do to animals and crops. Five soil samples collected in 1984 and 1985 from Coll indicated the presence of Longidorus vineacola, an eelworm usually measuring up to llmm in length. It was found from farmland as far apart as Sorisdale in the north east to Breachacha in the south west. This worm had only previously been found in Scotland on Tiree (in 4 samples) and from a single soil sample collected from the island of Berneray south of Harris by members of the Macaulay Institute for Soil Research, Aberdeen. From over 10,000 soil samples collected during the last 20 years from throughout Great Britain and Ireland this worm had only been recorded on two previous occasions, once from a garden in Ireland and once from a barley field in England.

This worm is relatively common in Europe having initially been described from the roots of vines in Germany but having subsequently been recorded from Belgium, France, Italy, Israel, Greece and The Netherlands. The unusual distribution of Longidorus vineacola in Great Britain, i.e. its virtual absence from the mainland and concentration in the Hebrides has lead to the suggestion that it was introduced by man after the last ice age 10,000 years ago. Close examination of the different populations from the islands and the rest of Europe support this idea since all of Scottish populations have significantly shorter tails and bodies than those from the other countries. This suggests a single introduction into the Hebrides from which it was subsequently spread both between and within the islands. It has been postulated that birds may have brought the worm in soil stuck to their feet but the large distances involved, over 800km. (500 miles), makes this explanation improbable. It is likely that L. vineacola was introduced by man since the islands have been inhabited continuously for nearly 5,000 years and there have been many conatacts between the islands and the continent, e.g. missionaries and Vikings. However, there may be other more probable explanations and I would be glad to receive them.

Brian Boag. Dundee.