Seasonal variation in toxicity of citral against sporocyst,
redia and cercaria larva of Fasciola gigantia
Dr. Kumari Sunita
Post Doctoral (UGC), New Delhi
Department of Zoology
D.D.U. Gorakhpur University, Gorakhpur
(UP) India 273009
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 Fasciolosis is the vector- born parasitic disease showing the
greatest latitudinal, longitudinal and altitudinal distribution
know.
 It is caused by two trematode parasite Fasciola hepatica and
Fasciola gigantica found in Asia and Africa.
 Fasciolosis has significant impact on growth, development and
productivity in domestic ruminants.
 The freshwater snail L. acuminata is an intermediate host of the
F. gigantica in northern parts of the India.
 According to WHO 2.4 million humans are infected with
Fasciola and a further 180 million are at risk of infection.
2
Release of molluscicide in aquatic system for their control to
kill the snails also affect the other non target organism.
 One way to reduce the incidence of fasciolosis is to destroy the
life cycle of Fasciola larval by in vivo and in vitro phytotherapy
of host snail L. acuminata at sublethal dose of molluscicide.
 It is a new approach to reduce the incidence of the fasciolosis
without killing the snails
 The use of plant product (Citral) Zingiber officinale are
effective, less expensive and eco-friendly.
3
Life cycle of Fasciola gigantica
Primary host (Definitive host)
•
•
•
•
Sheep
Cattle
Other Mammals Humans
Humans (Accidental)
Intermediate host
Lymnaea acuminata
Geographic Range
• Cosmopolitan; anywhere sheep and
cattle are raised
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Cercaria larva from Secondary Host Lymnaea
acuminata
Lymnaea acuminata
Immerging cercaria
Cercaria larva
5
Adult Fasciola gigantica from Buffalo Liver
Fasciola in Liver
Adult Fasciola gigantica
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OBJECTIVEs
The objective of the present study is to explore the use of plant
derived larvicidal component against different larval stages
(sporocyst, redia, cercaria) found in the intermediate host snail
Lymnaea acuminata.
1. Snails from different ponds in adjoining area were collected and
acclimatized to laboratory condition. There after, they were
dissected out under the microscope to observe the different
larvicidal stage in snail body.
2. Infected snails were divided in two parts. One part were counted
for larval infection without treatment (control) and second part
was treated with different concentration (less than the ten times
than LC50 value reported of snails) of Zingiber officinale and it
active components respectively. Now these treated snails were
dissected out after 2h, 4h, 6h, and 8h and number of dead and
live larva were counted each month of the year.
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3. In vitro treatment of plant derived molluscicides were studied
against different larval stage in water number of dead and live larva
will be counted in each month of the year.
4. On the basis of mortality data against different larvae LC50, g
value, heterogeneity factor, t- ratio and slope value were calculated
by the POLO computer programme of Robertson et al (2007)
(Bioassay with arthropods POLO computer programme for analysis
of bioassay data 2nd Edition 1-224).
5. Effective concentration for killing different larval stage
(sporocyst, redia, cercaria) were suggested without killing the
snails.
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Methodology
1.Toxicity study was done by the method of Singh and Agarwal
(1984).(J.Nat. Prod.47,702-705)
2. LC50, g value, Heterogeneity factor, slope, t-ratio was done by
the method of Robertson et al (2007, pp1-224) Bioassay with
arthropods
POLO computer programme for analysis of
bioassay data 2nd Edition 1-224
3. Product moment/ Rank correlation coefficient was done by the
method
of
Sokal
and
Rohlf
(1973)
(Introduction
to
Biostatistics,freeman,W.H San Francisco).
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Results
LC50 mg/ml
Sporocyst
90
80
70
60
50
40
30
20
10
0
2h
4h
6h
8h
March
April
May
Jun
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
MONTHS
Figure.1. In vitro toxicity (LC50 mg/ml) of
citral against sporocyst larva in different months of
year 2011-2012.
60
Redia
LC50 mg/ml
50
40
2h
30
4h
20
6h
10
8h
0
March
April
May
Jun
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
MONTHS
Figure.2. In vitro toxicity (LC50 mg/ml) of citral against redia larva in different months of
year
10
2011-2012.
LC50 mg/ml
Cercaria
50
45
40
35
30
25
20
15
10
5
0
2h
4h
6h
8h
March April
May
Jun
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
MONTHS
LC50 mg/L
Figure.3. In vitro toxicity (LC50 mg/ml) of citral against cercaria larva in different months of year
2011-2012.
100
90
80
70
60
50
40
30
20
10
0
40
Sporocyst
35
30
25
March April May
Jun
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
2h
4h
20
6h
15
8h
10
Temp
5
pH
0
DO
CO2
MONTHS
Figure.4. In vivo toxicity (LC50 mg/L) of citral against sporocyst and abiotic factors in different
11
months of year 2011-2012.
Redia
LC50 mg/L
80
40
70
35
60
30
50
25
40
20
6h
30
15
8h
20
10
Temp
10
5
pH
0
DO
0
March April May
Jun
July
Aug
Sept
Oct
Nov
Dec
Jan
2h
4h
Feb
CO2
MONTHS
Figure.5. In vivo toxicity (LC50 mg/L) of citral against redia and abiotic factors in different
months of year 2011-2012.
Cercaria
70
40
35
60
LC50 mg/L
50
40
30
30
2h
25
4h
20
6h
15
20
10
10
5
0
0
Mach April
May
June
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
8h
Temp
pH
DO
CO2
MONTHS
Figure.6. In vivo toxicity (LC50 mg/L) of citral against cercaria and abiotic factors in different
12
months of year 2011-2012.
Larvae
In vitro toxicity of citral
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
Nov
Dec
Jan
Feb
Sporocyst
Redia
Cercaria
 Highest toxicity of Citral
 Lowest toxicity of Citral
Larvae
In vivo toxicity of citral
Mar
Apr
May
June
July
Aug
Sept
Oct
Sporocyst
Redia
Cercaria
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Findings
In vitro and in vivo larvicidal activity of citral against the sporocyst, redia
and cercaria larvae of F. gigantica in different months of year 2011-2012 is
time and concentration dependent.
In vitro highest toxicity of citral against cercaria (8h LC50-0.006
mg/ml)/sporocyst (8h LC50-8.55 mg/ml) was observed in the month of July
and August.
Lowest toxicity was noted in month of January (10.12 mg/ml)/November
(15.49 mg/ml), respectively.
In in vivo 8h LC50 of citral against redia/cercaria and sporocyst larvae in
month of August and July (8h LC50-4.20 mg/L, 3.27 mg/L) was (8h LC501.23 mg/L), respectively.
The lowest mortality was observed in between January-February.
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Thank You
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