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Effect of sumithion on ovarian growth of a fresh water rice field crab (Oziotelphusa senex senex fabricius)
273
Toxicology Letters, 18 (1983) 273-276 Elsevier
EFFECT OF SUMITHION ON OVARIAN GROWTH OF A FRESH WATER RICE FIELD CRAB (OZIOTELPHUSA SENEX SENEX FABRICIUS) (Pesticide; crustacean; ovarian index)
P. SREENIVASULA
REDDY,
A. BHAGYALAKSHMI
and R. RAMAMURTHI
Department of Zoology, Sri Venkateswara University, Tirupati - 517502 (A.P.) (India) (Received
April 20th,
(Accepted
May 6th,
1983) 1983)
SUMMARY Sumithion
exposure
resulted
in a decrease
Oziotelphusa senex senex Fabricius
apparently
in the
ovarian
growth
of
the
by the release of the gonad-inhibiting
intact
female
hormone
crab, (GIH).
INTRODUCTION
Although increasing amounts of pesticides are being used to combat pests in or near fresh-water areas, little is known about how ‘non-target’ animals are affected by such compounds. Sumithion, a broad-spectrum insecticide, which is widely used in this area to control the rice stem borer, Tryporhyza sp. was used as a test chemical in the present investigation. The chemical nature, mode and site of action of GIH in different decapod crustaceans is well known [l-3]. In view of the fact that sumithion induces repetitive discharges in crustacean neurons [4, 51, it is conceivable that sumithion could produce secretion of GIH from the neurosecretory cells that synthesize it. This investigation was undertaken to determine (a) whether a sublethal concentration of sumithion can indeed inhibit ovarian growth in the female crab Oziotelphusa, and (b) if sumithion does have such an effect, whether it might involve stimulation or inhibition of the release of GIH.
Abbreviations:
0378-4274/83/$
GIH,
03.00
gonad-inhibiting
0 Elsevier
hormone;
GSH,
Science Publishers
gonad-stimulating
B.V.
hormone.
274
MATERIALS
AND
METHODS
Animals Adult, carapace
healthy female crabs of the species Oziotelphusa senex senex (30-32 g, width 32-35 mm) were collected from the rice fields and irrigation canals
(Tirupati). They were acclimatized to laboratory conditions (temp. 28°C; RH 75% and a light period of 12 h) for about 1 week before the start of the experiment. Crabs were kept singly each in 1000 ml of test or control solution at 28°C. The crabs were fed on earthworms ad lib. Twice weekly and transferred to fresh medium every day.
Pesticide The pesticide chosen for use in these experiments was technical grade (96% w/v) sumithion (fenitrothion; 0-0-dimethyl-0-(3-methyl-4-nitrophenyl) phosphorothioate) obtained from Rallis India Ltd (Bangalore). Sumithion was dissolved in ethanol and then diluted with tap water so that the final concentration was 0.1 mg/l containing 0.001% ethanol. The control crabs were kept in tap water containing the same ethanol concentration (0.001070).
Experimental design In Oziotefphusa the immature
ovary is white, whereas the mature ovary is orangered [7]. The ovarian color was recorded by making a hole in the carapace at the start of the experiment. After applying antibiotics, the holes were sealed with araldite (Ciba, India). In the present study only crabs having a white (immature) ovary were selected and put into five groups each of 30 crabs as follows: Group 1: initial control, killed at the start of the experiment.
TABLE
I
OVARIAN
COLOR
AND
DAYS OF DIFFERENT Group
INDEX
Treatment
I
Initial
2
Control
3
Intact
Color
control crabs
exposed
Destalked
CRAB,
OZIOTELPHUSA
SENEX
SENEX
AFTER
crabs
of the ovary
Ovarian
index
At the start of the
At the end of
experiment
the experiment
White (immature)
white
1.42 + 0.32”
White
white
1.44 + 0.41
White
white
White
Orange
red
0.82
-t 0.14
4.01
I
0.66
3.09 i
0.31
(mature) 5
“Values
Destalked sumithion
are mean
crabs
exposed
20
CONDITIONS
to
sumithion 4
OF THE
EXPERIMENTAL
to White
& S.E. of 30 individuals.
Yellow (maturing)
275
Group
2: control,
Group
3: intact
killed at the end of the experiment. crabs,
exposed
to sumithion
solution.
Group 4: Destalked crabs. Group 5: Destalked crabs, exposed to sumithion solution. The eyestalks of the crabs were excised without prior ligation but with cauterization of the stubs. Initial control crabs were killed at the start of the experiment and the remaining groups of crabs on the 20th day of the experiment as shown above. The ovaries were dissected out and the ovarian index was calculated by the formula: Ovarian
index
as described
Wet weight of~~ the ovary = Wet weight of the crab
earlier
x loo
[6].
RESULTS
The results obtained with untreated, intact crabs and crabs that received various experimental treatments are presented in Table I. The ovarian index in eyestalkless crabs was significantly (PC 0.001) higher (+ 111.97%) than in intact crabs and also showed change in color of ovary from white (immature) to orange red (mature). Sumithion significantly (P< 0.001) decreased the ovarian growth in intact crabs but not in those without eyestalks. There was no significant change in ovarian index in both control groups. DISCUSSION
The data indicate the eyestalk removal can bring about an ovarian enlargement. Sumithion might have inhibited the ovarian growth in the intact crabs in several different ways, e.g., by triggering the release of GIH, by mimicking the action of this hormone, or even by directly acting on brain and thoracic ganglion, which is the source of GSH [7]. However, because sumithion was not able to inhibit ovarian growth in eyestalkless crabs, it seems most likely that sumithion exerted its ovarian growth-inhibiting effect by triggering release GIH from the sinus gland of the eyestalks. This also supports the hypothesis, that the sinus glands of this crab are the main release site for GIH.
in the eyestalks
ACKNOWLEDGEMENTS
The authors wish to thank Rallis India Ltd (Bangalore) for providing the technical-grade sumithion. Thanks are due to UGC and CSIR for the award of research fellowships to Bhagyalakshmi and Sreenivasula Reddy, respectively.
276
REFERENCES
1 K.G. Adiyodi
and R.G. Adiyodi,
Endocrine
control
of reproduction
in decapod
and IBH Publishing
Co.,
crustacea,
Biol. Rev.,
45 (1970) 121-165. 2 K.K. Nayar,
Invertebrate
3 R. Nagabhushanam, crustacea,
Natl. Acad.
4 A. Bhagyalakshmi,
Reproduction,
G.K.
Sci., Golden
P. Sreenivasula
duced hyperglycemia
Oxford
Kulkarni
and
R.
Jubilee Reddy,
Sarojini,
Reproductive
Commemoration
volume
V. Chandrasekharam
New Delhi,
endocrinology
1977. of
decapod
(1980) I-38.
and R. Ramamurthi,
Sumithion
in the fresh water field crab, Oziotelphusa senex senex Fabricius,
Toxicol.
in-
Lett.,
12 (1982) 91-93. 5 P. Sreenivasula fresh water 6 A.C. 7 R.
Reddy,
A. Bhagyalakshmi
rice field crab
Giese and J. Pearse, Gomez,
hydrodromous
Endocrine (Herbst),
and R. Ramamurthi,
Effect of sumithion
(Ozioklphusa
senex senex Fabricius),
Toxicol.
Reproduction
in marine
Academic
physiology Ph.D.Thesis,
of
moulting
Kerala
invertebrates, and
University,
regeneration India,
1967.
Lett., in
Press, the
on molting
of the
14 (1982) 2433246. New York,
crab,
1974.
Parutelphusa
Toxicology Letters, 18 (1983) 273-276 Elsevier
EFFECT OF SUMITHION ON OVARIAN GROWTH OF A FRESH WATER RICE FIELD CRAB (OZIOTELPHUSA SENEX SENEX FABRICIUS) (Pesticide; crustacean; ovarian index)
P. SREENIVASULA
REDDY,
A. BHAGYALAKSHMI
and R. RAMAMURTHI
Department of Zoology, Sri Venkateswara University, Tirupati - 517502 (A.P.) (India) (Received
April 20th,
(Accepted
May 6th,
1983) 1983)
SUMMARY Sumithion
exposure
resulted
in a decrease
Oziotelphusa senex senex Fabricius
apparently
in the
ovarian
growth
of
the
by the release of the gonad-inhibiting
intact
female
hormone
crab, (GIH).
INTRODUCTION
Although increasing amounts of pesticides are being used to combat pests in or near fresh-water areas, little is known about how ‘non-target’ animals are affected by such compounds. Sumithion, a broad-spectrum insecticide, which is widely used in this area to control the rice stem borer, Tryporhyza sp. was used as a test chemical in the present investigation. The chemical nature, mode and site of action of GIH in different decapod crustaceans is well known [l-3]. In view of the fact that sumithion induces repetitive discharges in crustacean neurons [4, 51, it is conceivable that sumithion could produce secretion of GIH from the neurosecretory cells that synthesize it. This investigation was undertaken to determine (a) whether a sublethal concentration of sumithion can indeed inhibit ovarian growth in the female crab Oziotelphusa, and (b) if sumithion does have such an effect, whether it might involve stimulation or inhibition of the release of GIH.
Abbreviations:
0378-4274/83/$
GIH,
03.00
gonad-inhibiting
0 Elsevier
hormone;
GSH,
Science Publishers
gonad-stimulating
B.V.
hormone.
274
MATERIALS
AND
METHODS
Animals Adult, carapace
healthy female crabs of the species Oziotelphusa senex senex (30-32 g, width 32-35 mm) were collected from the rice fields and irrigation canals
(Tirupati). They were acclimatized to laboratory conditions (temp. 28°C; RH 75% and a light period of 12 h) for about 1 week before the start of the experiment. Crabs were kept singly each in 1000 ml of test or control solution at 28°C. The crabs were fed on earthworms ad lib. Twice weekly and transferred to fresh medium every day.
Pesticide The pesticide chosen for use in these experiments was technical grade (96% w/v) sumithion (fenitrothion; 0-0-dimethyl-0-(3-methyl-4-nitrophenyl) phosphorothioate) obtained from Rallis India Ltd (Bangalore). Sumithion was dissolved in ethanol and then diluted with tap water so that the final concentration was 0.1 mg/l containing 0.001% ethanol. The control crabs were kept in tap water containing the same ethanol concentration (0.001070).
Experimental design In Oziotefphusa the immature
ovary is white, whereas the mature ovary is orangered [7]. The ovarian color was recorded by making a hole in the carapace at the start of the experiment. After applying antibiotics, the holes were sealed with araldite (Ciba, India). In the present study only crabs having a white (immature) ovary were selected and put into five groups each of 30 crabs as follows: Group 1: initial control, killed at the start of the experiment.
TABLE
I
OVARIAN
COLOR
AND
DAYS OF DIFFERENT Group
INDEX
Treatment
I
Initial
2
Control
3
Intact
Color
control crabs
exposed
Destalked
CRAB,
OZIOTELPHUSA
SENEX
SENEX
AFTER
crabs
of the ovary
Ovarian
index
At the start of the
At the end of
experiment
the experiment
White (immature)
white
1.42 + 0.32”
White
white
1.44 + 0.41
White
white
White
Orange
red
0.82
-t 0.14
4.01
I
0.66
3.09 i
0.31
(mature) 5
“Values
Destalked sumithion
are mean
crabs
exposed
20
CONDITIONS
to
sumithion 4
OF THE
EXPERIMENTAL
to White
& S.E. of 30 individuals.
Yellow (maturing)
275
Group
2: control,
Group
3: intact
killed at the end of the experiment. crabs,
exposed
to sumithion
solution.
Group 4: Destalked crabs. Group 5: Destalked crabs, exposed to sumithion solution. The eyestalks of the crabs were excised without prior ligation but with cauterization of the stubs. Initial control crabs were killed at the start of the experiment and the remaining groups of crabs on the 20th day of the experiment as shown above. The ovaries were dissected out and the ovarian index was calculated by the formula: Ovarian
index
as described
Wet weight of~~ the ovary = Wet weight of the crab
earlier
x loo
[6].
RESULTS
The results obtained with untreated, intact crabs and crabs that received various experimental treatments are presented in Table I. The ovarian index in eyestalkless crabs was significantly (PC 0.001) higher (+ 111.97%) than in intact crabs and also showed change in color of ovary from white (immature) to orange red (mature). Sumithion significantly (P< 0.001) decreased the ovarian growth in intact crabs but not in those without eyestalks. There was no significant change in ovarian index in both control groups. DISCUSSION
The data indicate the eyestalk removal can bring about an ovarian enlargement. Sumithion might have inhibited the ovarian growth in the intact crabs in several different ways, e.g., by triggering the release of GIH, by mimicking the action of this hormone, or even by directly acting on brain and thoracic ganglion, which is the source of GSH [7]. However, because sumithion was not able to inhibit ovarian growth in eyestalkless crabs, it seems most likely that sumithion exerted its ovarian growth-inhibiting effect by triggering release GIH from the sinus gland of the eyestalks. This also supports the hypothesis, that the sinus glands of this crab are the main release site for GIH.
in the eyestalks
ACKNOWLEDGEMENTS
The authors wish to thank Rallis India Ltd (Bangalore) for providing the technical-grade sumithion. Thanks are due to UGC and CSIR for the award of research fellowships to Bhagyalakshmi and Sreenivasula Reddy, respectively.
276
REFERENCES
1 K.G. Adiyodi
and R.G. Adiyodi,
Endocrine
control
of reproduction
in decapod
and IBH Publishing
Co.,
crustacea,
Biol. Rev.,
45 (1970) 121-165. 2 K.K. Nayar,
Invertebrate
3 R. Nagabhushanam, crustacea,
Natl. Acad.
4 A. Bhagyalakshmi,
Reproduction,
G.K.
Sci., Golden
P. Sreenivasula
duced hyperglycemia
Oxford
Kulkarni
and
R.
Jubilee Reddy,
Sarojini,
Reproductive
Commemoration
volume
V. Chandrasekharam
New Delhi,
endocrinology
1977. of
decapod
(1980) I-38.
and R. Ramamurthi,
Sumithion
in the fresh water field crab, Oziotelphusa senex senex Fabricius,
Toxicol.
in-
Lett.,
12 (1982) 91-93. 5 P. Sreenivasula fresh water 6 A.C. 7 R.
Reddy,
A. Bhagyalakshmi
rice field crab
Giese and J. Pearse, Gomez,
hydrodromous
Endocrine (Herbst),
and R. Ramamurthi,
Effect of sumithion
(Ozioklphusa
senex senex Fabricius),
Toxicol.
Reproduction
in marine
Academic
physiology Ph.D.Thesis,
of
moulting
Kerala
invertebrates, and
University,
regeneration India,
1967.
Lett., in
Press, the
on molting
of the
14 (1982) 2433246. New York,
crab,
1974.
Parutelphusa