Effects of adult Lumbricus terrestris on cocoons and hatchlings in Evans’ boxes

Interactions of juvenile Lumbricus terrestris with adults and their burrow systems in a two-dimensional microcosm

“…Glass-sided boxes (0.2x0.8x0.008 m) (n = 24) were constructed as described by Grigoropoulou et al (2008) based on the design of Evans (1947), and were fi lled with moistened (25-30%) sterilized soil (Boughton Loam & Turf Management Ltd., UK), with leaf litter as food source. Leaves (Acer pseudoplatanus, Betula pubescens, Betula pendula, Fagus sylvatica, Quercus robur, Tilia cordata, Tilia platyphyllos) were obtained from a deciduous woodland in autumn and were air-dried for three days before being rewetted and surface-applied to the boxes, occupying the upper 0.05 m. Large L. terrestris were collected from the same site and kept in darkness at 5 o C in a 25 L container with soil and leaves for fi ve days before use.…”

“…These and the eight unoccupied boxes were kept in darkness at a constant temperature of 17 o C, with regular additions of water and leaves, for two months. Thereafter, the adult L. terrestris were removed from eight randomly selected boxes using a tungsten lamp as heat source, to drive the earthworm upwards, as described by Grigoropoulou et al (2008). Juvenile L. terrestris previously maintained in culture were added to the experiment (one juvenile per box), which resulted in three treatments replicated eight times: juvenile L. terrestris in the presence of an adult in an inherited burrow system (ABJ); juvenile L. terrestris only, in a fully constructed inherited burrow from which an adult had been removed (BJ); juvenile L. terrestris only, in the absence of both an adult and a burrow system, i.e.…”

“…All of these factors could infl uence L. terrestris juveniles growth if they stay in close proximity to the parental burrow or midden soil. In previous work (Grigoropoulou et al, 2008), L. terrestris cocoons found in burrows were observed to be coated with fresh casting and the authors proposed that, besides functioning as a protective layer, these could also act as a potential food source for hatchlings on emergence. Moreover, possible regulation of temperature and moisture levels within the burrow could result in a more stable environment for hatchlings to grow (Butt & Nuutinen, 2005).…”

“…Moreover, possible regulation of temperature and moisture levels within the burrow could result in a more stable environment for hatchlings to grow (Butt & Nuutinen, 2005). Finally, the large amount of energy expenditure for burrow construction by L. terrestris has been proposed as a possible cause for the L. terrestris burrow reuse by conspecifi cs observed in laboratory experiments (Butt et al, 2003;Grigoropoulou et al, 2008). It could therefore be argued that the burrow-midden complex of an adult L. terrestris is likely to have a positive impact on the growth and development of hatchling and juvenile L. terrestris.…”

“…Laboratory studies (Lowe & Butt, 2002;Grigoropoulou et al, 2008) have shown that L. terrestris hatchlings will compete with adults for resources and space, and therefore would be expected to disperse before growing to a size where competitive interactions become intense.…”