Collection and rearing of earthworms

Earthworm experimentation requires a source of supply. This may come from field-collection, purchase from a supplier, or from breeding of stock. The mode of obtaining the animals may be determined by the type of experimentation, but must not compromise the experiment. Typical collection methods employ digging and hand-sorting of soil, addition of a vermifuge, application of an electrical current to the soil or combinations thereof. Each collection method has advantages and may target particular groups of earthworms more successfully than others. Rearing earthworms in the laboratory may be viewed as difficult but if control of factors such as soil type, moisture, temperature, food supply and stocking density are in place, it can be straightforward. Culture design will be determined by the experimental objectives

Addition of earthworms to soils in soil ecological field experiments

Over recent decades experiments have been undertaken to reveal the optimum method for introducing earthworms into soils so the animals have greater chances of survival and are able to produce sustainable populations. This article describes development of the Earthworm Inoculation Unit (EIU) technique, its advantages over more traditional introduction methods and how it has been used. EIUs provide the means for sustainable earthworm population development even under harsh soil conditions, such as restored sites. However, certain circumstances dictate that this technique is not appropriate as digging in the soil/turf is unacceptable. Here more traditional methods can still be of value

Isle of Rum Earthworm Conference

In collaboration with Scottish Natural Heritage (Isle of Rum) and the University of Rzeszow, the Earthworm Research Group (ERG) from UCLan organised a conference in the Inner Hebrides in May 2014. This involved oral and poster presentations, field visits and discussions over a period of 3 days

Basic Research Tools for Earthworm Ecology

Earthworms are responsible for soil development, recycling organic matter and form a vital component within many food webs. For these and other reasons earthworms are worthy of investigation. Many technologically-enhanced approaches have been used within earthworm-focused research. These have their place, may be a development of existing practices or bring techniques from other fields. Nevertheless, let us not overlook the fact that much can still be learned through utilisation of more basic approaches which have been used for some time. New does not always equate to better. Information on community composition within an area and specific population densities can be learned using simple collection techniques, and burrowing behaviour can be determined from pits, resin-insertion or simple mesocosms. Life history studies can be achieved through maintenance of relatively simple cultures. Behavioural observations can be undertaken by direct observation or with low cost webcam usage. Applied aspects of earthworm research can also be achieved through use of simple techniques to enhance population development and even population dynamics can be directly addressed with use of relatively inexpensive, effective marking techniques. This paper seeks to demonstrate that good quality research in this sphere can result from appropriate application of relatively simple research tools

Dispersal of Calluna vulgaris(L.) Hull. seeds on a severly burnt upland moorland

From natural and manipulated experiments at 460 m a.s.l., traps were used to record the dispersal range of Calluna vulgaris seeds on an unvegetated post-wildfire site. Seeds were trapped to 50 m from source, although most (73%) were deposited within one metre of the parent plant. C. vulgaris seeds were not dispersed as far in these experiments as recorded in previous workers’ experiments on lowland grassland

Cocoon viability and evidence for delayed hatching by the earthworm Lumbricus terrestris in a laboratory-based study.

Clitellate Lumbricus terrestris, obtained from 5 commercial suppliers (A-E) and also field collected (F) - grassland in Preston, Lancashire, UK, were kept under controlled environmental conditions (15 °C and 24 h darkness) in a sterilised loam soil and surface-fed with horse manure. Survival, biomass and cocoon production was monitored every 4 weeks over 1 y. Collected cocoons were maintained in water-filled Petri dishes on filter paper. Time to hatch and cocoon viability was recorded over a 2 y period. Cocoon production ranged from 15.1 – 32.2 ind.-1 y-1. Cocoon production was initially low followed by a period of high production (12-36 weeks) and then fell (36-52 weeks). Time for cocoon hatching ranged from 132-731 days. Hatching success after 2 years was 58–90% across treatments, with a total viability (including cocoons dissected after the 2 year period) of 88-94%. Evidence of 2 distinct hatching peaks was recorded, separated by a period of approximately 12 months in treatments of most of the commercially obtained earthworms. Cocoon incubation periods are in excess of those previously recorded under similar laboratory conditions (e.g. 90–280 days). Furthermore, viability is also higher than previously recorded (e.g. 67.9–83%). These differences are mainly attributable to the extended length of cocoon observation. Origin, age, unknown pre-treatment (in A-E) and experimental conditions (e.g. a constant temperature regime) may have influenced incubation times. However, it is suggested that asynchronous and delayed hatching within cohorts and ability for cocoons to remain viable for extended periods allows this K-selected species to maximise reproductive potential. This proposed “bet-hedging” strategy is worthy of further laboratory and field-based investigation

An investigation into the growth and reproduction of the earthworm <i>Lumbricus terrestris</i> L. under controlled environmental conditions

Earthworm inoculation for soil amelioration has been shown to be valuable in a range of experiments. At present, inoculation on a large scale is limited by the supply of larger deep-burrowing species of earthworm. This work aimed to assess the feasibility of intensively producing deep-burrowing earthworms for soil amelioration projects. Lumbricus terrestris, whose behaviour is well documented, was chosen. The scientific literature was used to identify points within the life cycle of this earthworm where manipulation of conditions might lead to increased rates of production. Feed quality, environmental temperature, time of year, population density and age of breeding stock were all recognised as important variables. Experiments were performed to identify the optimal conditions for L.terrestris reproduction, cocoon development and growth. Results suggested that reproduction would occur throughout the year and mean annual figures of 37 cocoons per worm were recorded from intensively produced earthworms. Recently matured worms showed greatest levels of cocoon production. As previously reported seasonal variation in reproduction was found even at constant temperature. Cocoon development was most rapid at a temperature of 20°C, taking 70 days, with a cocoon viability of 83%. Growth from a mean hatchling weight of 53mg to sexual maturity at 5g, took twelve weeks. Growth at constant temperatures of 15 and 20°C was not significantly different. A synthetic feed, with a carbon to nitrogen ratio of 40:1, created from paper waste and yeast extract, led to greatest recorded figures for both growth and cocoon production. The results suggest that an intensive production system is technically feasible, and the economic viability needs to be tested

Earthworm dispersal of plant litter across the surface of agricultural soils

When we observed earthworms (Lumbricus terrestris L.; the dew worm or nightcrawler), foraging on patchily distributed plant residues in the laboratory, we noticed an exceptional interaction in their acquisition of dead organic matter. We review this original observation and then relate a subsequent finding which indicates the importance of the phenomenon in the field

An oasis of fertility on a barren island: Earthworms at Papadil, Isle of Rum

The Isle of Rum, Inner Hebrides, has an impoverished earthworm fauna as the soils are generally acidic and nutrient-poor. Species associated with human habitation are found around deserted crofting settlements subjected to “clearances” in the mid-19th century and at Kinloch, where a large volume of fertile soil was imported from the mainland around 1900. Earthworms, and the dew worm Lumbricus terrestris L. in particular, were investigated at Papadil, an abandoned settlement and one of the few locations on Rum where a naturally developed brown earth soil is present. The small (1.5 ha), fertile location is isolated, so was also suitable for field experimentation. Visits over six years allowed dew worm distribution to be assessed within low lying grassland and woodland and also within an adjacent sloping broadleaved woodland. The factors limiting dew worm distribution at the site were investigated with associated translocation to adjacent uninhabited areas. Small scale spatial dynamics were studied with density manipulation and containment experiments where Visual Implant Elastomer marking of individuals was utilised. Translocations from streamside woodland to adjacent grassland was successful over a short period (5 months), but the colonies did not persist over a longer term (5-6 years). Field trials with earthworm tagging were successful, but highest tag recovery rate was 25%. Where adults/sub-adults were removed, recruitment of juveniles was notable. Exceptionally large (>12 g live mass) individuals were found in soils of terraces on wooded slopes, suggesting that dew worms may be long lived at this location, where food is abundant and relatively few terrestrial predators are present

Evaluation of digital photography as a tool for field monitoring in potentially inhospitable environments

Efficient and accurate vegetation monitoring is essential for successful assessment of upland moorland restoration. Working conditions on open moorland may be difficult, and surveying and monitoring of vegetation problematic. Image capture by digital photography, with subsequent computer analysis, was used to monitor Calluna vulgaris post-wildfire. Problems, for example picture warp, associated with close range photography of quadrats, were overcome. Digital imagery measurements of vegetation cover showed no significant difference compared with a traditional point quadrat method