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Dendrobaena veneta -- For Bin, Bait, or Both E-mail
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Written by Administrator   
Sunday, 11 September 2005

by Kelly Slocum, from our issue #22

Search the vermicomposting forums on the Internet for the hot topic of the day and you’ll likely find the worm species Dendrobaena veneta generating a lot of discussion. Reclassified by taxonomists to the genus and species Eisenia hortensis, and commonly referred to as the European or Belgian nightcrawler, this species has suddenly emerged as the hot worm to try in today’s vermicomposting and vermiculture systems.Dendrobaena veneta is one of the handful of earthworm species studied in detail for use in vermicomposting. Doctors Adrian Reinecke and Sophie Viljoen conducted detailed studies on the reproduction and maturation rates and environmental requirements of this species in the early 1990s, which confirmed studies conducted on this species by Dr. Clive Edwards in the late 1980s. The researchers found D. veneta to be a large worm with a low reproductive rate and slow maturity rate compared to Eisenia fetida, Perionyx excavatus and Eudrilus eugeniae; findings which suggest this species is the least suitable for vermicomposting of those studied. Even so, D. veneta has demonstrated some value in vermicomposting. Studies demonstrate that this species performs better in excessively wet environments than the other species used for vermicomposting, leading to its use in some large-scale European vermiprocessing systems remediating paper sludges. Observations of small-scale vermicomposting and vermiculture systems using mixed cultures of Eisenia fetida and Dendrobaena veneta show that E. fetida tends to remain in the upper, dryer regions of the bin and D. veneta to populate the lower bedding areas where moisture concentrations are highest.

Some U.S. worm growers have become fans of Dendrobaena veneta and dispute the research data, believing the worm to reproduce and grow as rapidly as Eisenia fetida in their vermiculture and vermicomposting systems. Their observations are compelling and, coupled with the great size of this worm, are likely responsible in part for the sudden popularity of the species. Many home vermicomposters are interested in a larger worm species for use as fish bait which can be raised on household food scraps.

While there are questions surrounding the use of Dendrobaena veneta in general vermicomposting systems, there is no denying that this species is a top notch bait worm. This species is much larger than Eisenia fetida, making it easier to fit on a hook, but not so large as Lumbricus terrestris (common nightcrawler), which is sometimes considered to be too large. Claims of D. veneta secreting enzymes highly attractive to fish are unsubstantiated, but many anglers swear by this large, robust worm.

The current challenge to those interested in this species is finding a supplier with enough worm stock that they are willing to sell. The interest D. veneta is generating has gotten the worm into the U.S., but worm growers need time to build their breeding stock. The slow reproductive and growth rates of this species make this an even more time-consuming process than for some of the other cultured earthworms. As such, many growers who have the worm are not yet ready to sell it. Some of those who are selling the worm are selling mixed cultures of D. veneta and E. fetida in an effort to get the worm into the market without depleting their breeding stock. It is believed these mixed cultures may be partly responsible for the disparity as regards breeding and growth rates between the research data and the observations of some growers.

Each worm species has its niche in nature. Likewise, those studied seem to have found their place in the vermiculture industry. While not the best choice for most vermicomposting systems, if one seeks a large bait worm which can be easily bin-cultured, Dendrobaena veneta fits the bill nicely.

From Life-cycle of the European compost Worm Dendrobaena veneta (Oligochaeta), published in the South African Journal of Zoology, 1991, 26(1) by Sophie A. Viljoen, A.J. Reinecke and L. Hartman:

“The life-cycle of Dendrobaena veneta was studied to assess the potential of this species in vermiculture. The development, growth and reproduction were investigated by rearing worms at 25°C on urine-free cattle manure with a moisture content of 80% over a period of 200 days. It was found that cocoons are produced at a mean rate of 0.28 cocoons per worm per day and production can be sustained for at least 200 days. The mean incubation period of the cocoons is 42.1 days with a very low hatching success. The mean number of hatchlings per cocoon that hatched was 1.1. Sexual maturity may be attained within 20 - 35 days but some worms take up to 130 days. Dendrobaena veneta grew well on cattle manure. This species seems to be less suitable than some other epigeic species for vermiculture, at least in terms of its reproductive capacity in the experimental climatic conditions.”

From Moisture Requirements of Dendrobaena veneta (Oligochaeta), a Candidate for Vermicomposting, published in Soil Biology and Biochemistry, Vol. 26, No. 8, pp. 973-976, 1994 by N.Y.O Muyima, A.J. Reinecke and S. A. Viljoen-Reinecke:

“...Juvenile worms were exposed to different moisture contents in glass flasks filled with cattle manure medium and kept at 15°C (59°F). The highest frequency for clitellate worms was between 77.9 and 78.7% while their moisture preferences ranged between 67.4 and 84.3%. For cocoon production the highest frequency was between 73.1 and 79.9%. The optimum moisture content for growth and maturation of juvenile worms was 75%. From the results it appears that this earthworm species could be utilized in organic waste with a relatively high moisture content. However, comparing the reproductive capacity and maturation time with that of other vermicomposting species, D. veneta seems to be a less successful earthworms species for vermicomposting.”

From The Influence of Temperature on the Life-Cycle of Dendrobaena veneta (Oligochaeta), published in Soil Biology and Biochemistry, Vol. 24, No. 12, pp. 1341-1344, 1992 by S. A. Viljoen, A. J. Reinecke and L. Hartman:

“The life-cycle of Dendrobaena veneta was studied at 15°C (characteristic of the animal’s natural habitat) and at 25°C (77° F — at which the life-cycles of other vermicomposting species have been studied in Southern Africa).

At 15°C the life-cycle was completed in 100 days and it took 150 to complete the cycle at 25°C. At 25°C maturation was quicker, worms started to produce cocoons at a younger age and more cocoons were produced (per worm, per day) than at 15°C. The incubation period and the number of hatchlings per cocoon were more at the lower temperature.”


Photo caption:
Dendrobaena veneta appears violet, purple or olive brown, sometimes with pale striping in segment furrows. Its clitellum is on segments 26-32, its first dorsal pores between segments 4/5, tuberculata pubertatis on segments 30 and 31, its prostomium is epilobic and its setae are widely paired.

Sidebar:
Classification:
Phylum: Annelida (segmented worms)
Class: Megadrilidae (large worms)
Order: Oligochaeta (few setae)
Family: Lumbricideae
Genus: Eisenia
Species: hortensis
Last Updated ( Sunday, 18 September 2005 )
 
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