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Age and reprobiology of E.fetida and E.andrei


Sent by: Miguel Schuldt (Argentina) on June 02, 2010 hour 12:47:56:


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Updating of reprobiological parameters is necesarily. The full article is available on line in Rev.Museo de La Plata nueva serie Zoologia.

SCHULDT, M. A. RUMI y D. E. GUTIÉRREZ-GREGORIC, 2005. Determinación de “edades” (clases) en poblaciones de lombrices: implicancias reprobiológicas. Rev.Mus.La Plata n.s. zool., 17(170):1-10

ABSTRACT. The limitation of the time needed for the sexual maturation of individuals and
the link between this process and particular diets and culture management strategies are essential issues for vermiculture management. The aim of this work is to perform a critical analysis of the available information on the subject, as well as to advance
methodological approaches, to propose definitions and criteria, and to enhance the
opportunities for comparison between different experiences. The following results and
recommendations have arisen:
1) From an ecological viewpoint, Eisenia fetida presents prereproductive and
reproductive ages, and lacks a postreproductive age. For the purpose of the survey and
monitoring of populations, we suggest the recognition of the following life stages: cocoons
(1), juveniles (2), subadults (3) and adults (4). Ages 1-3 correspond to the prereproductive
stage. The adults are the effective reproductively active individuals (clitellated), and for
practical reasons, all animals that have lost the clitellum for any reason should be counted
as subadults. The use of weight or size (0.25 g or 2.5-3.0 cm) as the sole criterion for
prematurity-maturity transition is not sufficient.
2) Each substratum will admit a certain amount of individuals, according to the type and
age of its OM. Surveys performed in cubic 7.5 cm-sided sample units, taking 3 sample
units as sample size, are useful as tools for population monitoring. The results may be
conveniently expressed as nominal (dn) and effective density (de) per bed (L) of culture
(2 m2 surface area). dn is the number of animals/L; value 1 is assigned to cocoons for
this calculation (i. e., each cocoon holds a single embryo or earthworm), whereas de is
obtained by measuring the actual fecundity per egg-laying.
3) Diets based on manure from a single species permit greater growth than those based
on mixed manures from different species. It appears that sexual maturity is reached at
0.25 g independently of the diet. Therefore, a diet that allows faster growth implies
earlier sexual maturity, but doesn’t ensure higher cocoon production.
4) Cocoon production is subject to seasonal variations and decreases in older animals.
The degree of crowding has been proven to have such negative influence on the breeding
frequency that this factor is more important than any particular diet for population growth.
For comparison purposes, cocoon production it should be expressed as cocoons/adult or
cocoons/week/adult.
5) Earthworm fecundity varies between 0 and 9, and there are usually 2 to 4 individuals
per laying. At present no reliable correlations have been established between this variable
and any specific diet.
6) The Reproductive Potential R”= x(bnp) gives information on some significant events
such as escapes and substratum colonization, results of the crowding level that translate
into egg-laying fluctuations.
Key words: Eisenia fetida, ages, reprobiology.
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