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Dendrobaena veneta -- For Bin, Bait, or Both |
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Written by Administrator
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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 |
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Last Updated ( Sunday, 18 September 2005 )
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