Cold resistance of three species of earthworms (Oligohaeta, Lumbricidae) in Western Siberia

Abstract

We studied cold resistance of Lumbricus rubellus, Octolasion lacteum, Dendrodrilus rubidus tenuis earthworms of Western Siberia (Tomsk) populations. Worms of these species turned out to be not resistant to low temperatures (100% mortality at −3 °C), while cocoons, on the contrary, survived −35 °C (L. rubellus) or below −40 °C (D. rubidus tenuis). The worms’ populations under study do not have specific cold resistance. Their main characteristics are similar in Western Siberia and other geographically remote areas according to our studies. Due to their very high cold resistance, cocoons are indifferent to winter temperatures. Hibernation of the studied species of worms in the severe conditions of the West Siberian climate is possible only in the warmest habitats where minimum soil temperature in hibernation horizons does not fall below −2 °C. Apparently, the proportion of such habitats in the region is high as 5 out of 12 surveyed biotopes had minimum temperature above the maximum tolerated by worms at a depth of 15 cm.

Keywords:

• Earthworms
• Western Siberia
• Cold resistance
• Soil temperatures

Acknowledgements

The authors are deeply grateful to Professor D.I. Berman for his help in formulating the problem, discussing the results and editing the manuscript. This work was financially supported by the Russian Foundation for Basic Research [grants 07-04-00362-a, 13-04-00156-a] and by Tomsk State University Competitiveness Improvement Program.