CH
FISHERIES RESEARCH BOARD OF CANADA
Translation Series No. 2831
Experimental Biology. Application of winter and summer
conditions, removal of the ocular peduncles, and action of an
ecdysterone on the adult female crayfish Orconectes limosus
R., during the anecdysis period: consequences on egg laying and
molting.
by Danielle Kracht
Original title: Biologie Expérimentale - Application de conditions
hivernales et estivales, épédonculation et action d'une
ecdystérone chez l'Ecrevisse femelle adulte Orconectes limosus
R., pendant la période d'anecdysis: conséquences sur la ponte et
sur la mue
From: C. R. Acad. Sc. Paris, Serie D, 275 : 1677-1680, 1972
Translated by the Translation Section
Department of the Environment
Department of the Environment
Fisheries Research Board of Canada
Biological Station
St. Andrews, N. B.
1973
11 pages typescript
F^,d
Experimental Biology.
c;263
Application of winter and summer conditions,
removal of the ocular peduncles, and action of an ecdysterone on the
adult female crayfish Orconectes limosus R., during the anecdysis period:
consequences on egg laying and molting,
Miss Danielle Kracht, presented by M. Louis Gallien.
C.R, Acad. Sc. Paris
275:1677-1680.
/
. î
We were able to interrupt the life cycle of the Crayfish, Oronectes
(1677)
limosus R 9 by three methods:
(a)
Artificial cold and warm periods can precipitate egg laying.
(h) The removal of the ocular peduncles can either invert the
egg-laying-molt succession, or will cause an early, egg
deposition. These eggs will develop normally.
(c)
The ecdysterone which always causes an exuviation.
For the last two years (August 1970 to July 1972) we have practised
weekly captures in the canal from the Marne R., to the Rhine: 563 mature
female Crayfish have been caught; at the sanie time, 25 mature females
(length of cephalothorax: 25-32 mm) have been placed in individual running
water tanks.
The water temperatures in the canal and in the laboratory are
checked regularly: they fluctuate in a similar pattern over the year, and vary
only slightly from one year to the next.
The canal Crayfish and the controls
are submitted to the saine thermal variations, which will be reported, with the
corresponding dates and observations.
In both the wild and the control animals, the eggs laid around April
15
hatch around May:115 (18 0 ). -The spring molt begins with
July (210 ) and the summer molt starts around the end of September (16°).
Between these two molts, the females may undergo one or
tHO
more molts.4
Among controls kept for a year: 12% molted 4 times, 44% three times and
44% twice.
The mature males of similar size molt only 2 or
3 times.
The period between molts varies greatly: from 20 to 60 days. A similar
variation exists for the long anecdysis period, between the summer and spring
molts (9-11 months).
_ 2 _
For two years, the various steps of, the biological cycle happen
-
very regularly both in the wild or captive stâ.te. Using the following methods,
we have looked for factors capable of disturbing the regularity of this cycle.
Artificial
temperature
conditions.
_
^..._,T,^..-,..._.............^_._.
The influence of,temperatureand,light
on the biologyof Decapoda has been studied:by various authors, specially Aiken (1)
who used Oronectes virilis. Aiken has shown that a Crayfish living in a cold
climate requires 4 to 5 months of low temperature and constant darkness to
insure the ovarian maturation.
Four series of experiments were done with Oronectes limosus, which is
found in temperate climates.
Early in the fall, the ovaries of thisspecies
have already-accumulated most of the vitelline stores„
The mature state.is
easily checked: at the border eephalothorax_abdomen, the large green-brown
ovocytes are easily observed in transparency.
1.
(1678)
40 females were placed at the end of August (19°) in running water
warmed to 200;
increasing.
As early as December, mortality starts and its rate keeps on
The ovaries are bright orange in colbur,_which indicates necrosis.
In January, 10 are left and placed in normal conditions again. The large orange,
ovocytes are slowly resorbed, and the molt takes place in July. Females raised
at 200 but without light behave the same way: maintaining summer conditions
does not improve longevity nor will it cause a_riormal ovariân cycle.
2.
12 females were harvested in early October (100) And submitted to cold
(40) and darkness for a'month. They were then kept at 20°: 6 of them laid eggs
in January.
3.
Early winter conditions will produce early egg laying.
20 females were harvested early in December.(100) and placed
.
^hty cl^ec^
immediately at 20°s
within a few days: the winter period was probably too
- 3 short, as experiments 2 and 4 tend to indicate.
4. 12 females were harvested at the end of January and placed at 209 .
The eggs are laid a month later. FeAundation and segmentation proceed
normally.
An artificial spring after a satisfactory winter period causes an
early egg laying. These eggs hatch early in March.
H:itir,experiments enabled us to precipitate egg laying by 2 or 3 months,
while in nature, this phenomenon underwent only minimal fluctuations in the
past 2 years.
Removal . of 'the ocular ueduncles.
The effects of the removal of the ooular peduncles on molt and ovarian
development of Decapoda have been known for a long time ( 2 ,3).
We have removed
the peduncles during the anecdysis period, under natural temperature conditions.
Our results are presented, and they take into account the temperature variations.
1.
Removal of the ocular peduncles in September (18 0 ) October (140 ) of
24 females (cephalothorax: 28-45 mm).
- 10 large crayfish die during exuviation at the end of December (40 );
low temperature, they do not succeed in getting free of the exuviae.
- 10 medium sized crayfish molt one month after ocular peduncle removal
(10-7° ), lay eggs and die one month later.
- 2 crayfish molt one month after the operation, and one lays its eggs.
Both molt again in December (7 0 ) and die soon after.
One animal
underwent two molts without laying.
- 2 animals molt one month after the operation, lay their eggs and survive
winter. Their second molt takes place early in May(6° ).
2.
Removal of the ocular peduncles in 35 females in December (5 0 )
and January (40).
(1679)
In both cases, eggs were laid before molting.
Within one or two months
of the operation, in January (70) and February (100) all the crayfish had laid
their eggs.
In 19 of the 35 females, the eggs become fixed to the pleopods
and become segmented:
-4 crayfish dieJshortly after the eggs were laid;
- 13crayfish moltdin March or April (12°). The eggs are shed with the
exuviae.and exhibit an advanced embryon. ► c
development.
- 2 crayfish molt at the,ènd of May .(200). The eggs hatched about May 15;
and the youngs molt twice under their mother.':
The results vary greatly depending on the date of the operation. The
first series of operations show that the ovary is influenced by a factor
which is probably thermal, and different from the peduncular inhibition. In
the second series, the operation was done during cold temperature. Egg
laying always preceded molting, and when the eggs were fertile, théy evolved
slowly until hatching (4 months instead of one month). Whatever the date of the
operation during the anecdysis period, the.crayfish do not molt more than twice.
After one or two molts, death comes quickly-even under mild conditions.
Utilization of ecLsterone.
Ecdysterone crystals (4) are introduced during winter into the abdomen
of 30 adult female crayfish (cephàlôthorax: 20_27 mm) at the dose of 40 to'
50 )tg.
Ten were "implanted " in December, 10 in January, 10 in February. None
of our crayfish underwent a complete molt, as opposed to the results obtained
with Procambarus (5).
Each group is submitted to 150 after the introduction of the hormone.
Ten days'later, our crayfish become almost completely immobile for 2 days and die.
The study of the exuviation stage reached show either the stage D2(presence.
of new bristles) D3 (resorbtion of the exuviae,,the shell is easily removed,)
The.same resul.ts were obtained using large juvenile females, The same treatment
was repeated in April, using females'almost ready to lay or already bearing eggs:
the results were the same.
The dose used may not be large enought;to_ cause a complete exuviation. It
may also be that the crayfish,.which are in 'a resting state at this time of the
year, and are not physiologically able to realize a complete exuviation within
such a short period. However, these experiments show that (a) during the
anecdysis period, moltings may be triggered by a synthetic,hormone,(b) that
egg laying.cannot be induced, even if its normal time is near; (c) that
exuviation may be induced, as is the case of Orchestia gammarell& (6), in the
ovigerous females.
Conclusion.
Using our experimental protocols, we were able to induce
some important variations of the biological cycle of the adult female érayfish.
The use of artificftl seasons influences mostly the time factor, causing early
egg laying, hatching and molt. The removal of the ocular peduncles can, undér
some conditions, invert the egg-laying-molt sequence, while ecdysterone at à
similar time results always in a molt,
(*) Séance du 18 septembre 1972.
(1) D. E. AIKEN, Canad. J. Zool., 47, no 5, 1969, p. 931-935.
(2) N. DEMEUSY, Thèse, 1958.
(3) H. H. SCUDAMORE, Biol. Bull. U. S. A., 95, 1948, p. 229-237.
(4) Ecdystérone fournie par les Mann Research Laboratories, New York, USA.
(5) A. KRISHNAKUMARAN et H. A. SCHNEIDERMAN, Geu. comp. Endocrinol., 12, 1969, p. 515-518.
(6) M. F. BLANCHET et H. CHARNIAUX-COTTON, Conlptes rendus, 272, Série D, 1971, p. 307-310.
Laboratoire de Biologie Animale I,
Université de Nancy-I, .
C. O. no 72, 54-Nancy, Meurthe-et-Moselle.
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TITLE IN ENGLISH:
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Application de conditions hivernales et estivales,
epédonculation et action d'une ecdysterone chez
l'Ecrevisse femelle adulte.Orconectes limosus R.,
pendant la periode d'aneedysis: conséquences sur
la ponte et sur la mue
LANGUAGE:
C. R. Acad. Sc. Paris Serie D
TITLE IN ORIGINAL LANGUAGE:
JOURNAL (title)
IN ORIGINAL
2.75
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2
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PP•16771680
Pages containing -fables, drawings
Year: 1 972
Bibliography
Reference reprint in English
REQUESTED BY:
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Dr. D. E. Aiken
Fisheries and Marine S ervice
Biological Station
St. Andrews, N.B.
DATE
A. T. Reid
.Sélelitifid.toeumentation
Nov. :13; 1973
DATE OF REQUEST
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