Sarcophaga ruficornis (Diptera: Sarcophagidiae) a …€¦ · · 2017-01-03The Journal of Zoology...
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The Journal of Zoology Studies
Vol. 3 No. 6 2016 Journalofzoology.com
Page 1
The Journal of Zoology Studies 2016; 3(6): 01-08
ISSN 2348-5914
JOZS 2016; 3(6): 01-08
JOZS © 2016
Received: 28-10-2016
Accepted: 06-12-2016
Kamal Adhikari
Post Graduate Student,
Gauhati University,
India.
Bulbuli Khanikor
Assistant Professor,
Gauhati University,
India.
Riju Sarma
Research scholar,
Gauhati University,
India.
Sudarshana Mahanta
Research scholar,
Gauhati University,
India.
Jatin Kalita Professor,
Gauhati University,
India.
Corresponding Author:
Bulbuli Khanikor
Assistant Professor,
Gauhati University,
India.
Study on the life history and protein content of Sarcophaga ruficornis (Diptera: Sarcophagidiae) a
forensically important insect
Authors: Kamal Adhikari, Bulbuli Khanikor, Riju Sarma, Sudarshana Mahanta, Jatin Kalita
Abstract
Since past few decades insects have been serving as an important tool in forensic entomology
i.e. in determining the time elapsed since death. The present investigation aims at studying one
of the primary colonizer of carcass namely Sarcophaga ruficornis (Diptera: Sarcophagidiae) in
Guwahati, Assam. The growth and development of S. ruficornis like other insects depends
strictly on the climatic conditions prevailing in the area and level of exposure of the corpse. For
laboratory culture of the flesh fly S. ruficornis, chick liver was taken as bait. The total protein
content of different developmental stages of S. ruficornis and the fresh as well as rotten chick
liver was determined by using the method of Lowry et al. The developmental time of S.
ruficornis was found as 25±3 days during the investigation period (23±1 days during May and
28±2 days during the month of February). The protein content of the liver was found to decrease
during its decomposition stage and the protein content of the developing stages of the fly was
found to increase linearly.
Keywords: Carcass, Sarcophaga ruficornis, Protein, Diptera: Sarcophagidiae, Insect
1. Introduction
Arthropods are among the most evolved groups of animals on earth. So they are found almost
everywhere on earth. Insects like other arthropods play a crucial role in different fields of
modern science like forensic entomology. Knowledge of the distribution, biology and behavior
of insects found at a crime scene can provide information on when, where and how the crime
was committed (Kashyap and Pillai, 1989 [1]
; Anderson and Carvenka, 2001 [2]
; Hall, 2008 [3]
).
Concepts of algor mortis, rigor mortis, and livor mortis play an important role during the first
few hours of death and hardly can be determined up to 3 days by these methods. However, all of
these parameters are affected by many other factors such as body size, age, illness, exertion
period to death etc. and become less valuable as time passes (Simpson and Knight 1985 [4]
;
Henssge et al, 1995 [5]
). Insects are never affected by all these parameters so they play a major
role in determining the post mortem interval, among which flies are of primary significance.
These insects feed on the corpse, oviposit and the larvae hatches into successive instars and
finally emerges as an adult. Blow flies and flesh flies are among the first colonizer (Luna et al.,
2001 [6]
; Bharti and Singh, 2003 [7]
). The study of their first mature maggots can provide the data
of time elapsed since death. Attraction of the arthropod species varies according to the
decomposition state of the corpse (such as fresh, bloat, decay, putrefaction, mummification, and
skelotization). A particular species never stay in the corpse during the whole process of
decomposition (Bornemissza, 1957 [8]
; Braack, 1981 [9]
). There is a succession of species of
arthropods. Each species stay only for a limited period of time (Anderson, 2009 [10]
).
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In the present study a forensically important species,
Sarcophaga ruficornis (Diptera: Sarcophagidae) was
chosen to study the life cycle by keeping them in a
close culture chamber and provided chick liver as bait
within the chamber.
Generally S. ruficornis is found abundant in carcass in
the early stage of decomposition. It is generally not
found after 3-4 days. It is a medium sized to large sized
fly. Front broad in the female somewhat narrower in
the male. Distal portion of the arista is bare. Abdomen
consists of 4 visible segments. External genitalia in
male are prominent. The puparium is reddish brown
and ovoid in shape. Mode of reproduction of
Sarcophaga is ovoviviparous, i.e. they lay first instar
maggot on the flesh.(Sukontason et al.,2014[11]
).
The purpose of studying the life cycle of a single
species was to get a more accurate and a firm report of
the life cycle. All the life cycle of the necrophagous
flies is more or less similar with the life cycle of
Sarcophaga ruficornis.
2. Methodology
2.1. Obtaining the specimen Sarcophaga ruficornis was collected by exposing a bait
of broiler. Flies were attracted to the bait. They
oviposit in the bait and the maggots grow into
successive instars and finally reached the pupal stage.
Pupae at this stage were collected in an insect proof
container and waited till they hatch.. After few days of
adult fly emergence, few other species of the family
Muscidae, Calliphoridae and Sarcophagidae that also
emerged simultaneously in the cage such as were
removed. Thus, a pure culture of Sarcophaga
ruficornis was achieved and maintained solely by
providing chick liver as bait. The species was
identified as Sarcophaga ruficornis by the experts from
Zoological Survey of India, Kolkata. In the present
study it was found that the species of Sarcophaga were
more abundant in the late winter than the species of
other forensically important insects. So their collection
was easier.
Fig 1: Broiler exposed for decomposition showing infestation and larviposition by flies.
2.2. Culture of S. ruficornis:
The first generation of the adults that emerged was
collected by allowing a bait for larviposition as
mentioned earlier. These adults were again provided
with the chick liver as bait to continue their life cycle.
The culture chamber was made of a glass container of
which the upper open portion was covered with a
mosquito net. Sufficient dry mud with sand was
provided at the bottom of the chamber so that the pre
pupa does not move to and fro in search of the suitable
place for pupation.
Fig 2: Culture chamber
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Fig 3: 2
nd instar maggot of Sarcophagaruficornis
growing in culture.
In this way, four such generations were maintained.
During the culture period no other insects were allowed
to mix with the culture.
During the experimental period broiler was also
exposed separately in the open condition and its
decomposition along with the infestation by different
flies were observed. The broiler was kept inside a wire
gauze of considerable perforation so as to prevent the
attack of other predators in open condition.
Here it was found that the fly life cycle was shorter in
wild than in culture in the laboratory. Due to its small
size the broiler was found to skeletonize after 8 days of
exposure period. After skeletonization, normal visitors
of the corpse disappeared.
2.3 Estimation of Protein
Estimation of protein content was done following the
method of Lowry et al., (1951) [12]
. The total protein of
1st instar larvae, 3
rd instar larvae, pupae and adults of
the fly were taken as the sample. Protein of fresh and
decomposing liver on 5th
day of decomposition were
also estimated following the same method.
2.4. Statistical Analysis
The Tukey test of the protein content of the meat
sample and different instars of S. ruficornis were done
with the help of SPSS (Version 16) software.
3. Results and Discussion
Fig 4: Life cycle of Sarcophaga ruficornis
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Table 1: Duration of different developmental stages of Sarcophaga ruficornis in different temperature.
S. no Time Average Developmental stages Total
Temperature 1st instar 2nd 3rd Pre- Pupa Adult lengh of
(0C) (Days) instar instar pupal (Days) (Days) Life
(Days) (Days) stage cycle(Da (Days) ys)
1 February 28±1 3±1 2±1 2±2 3±2 13±1 5±1 28±2
2 March 30±1.33 2±1 2±1 2±1 3±2 12±2 5±2 26±2
3 April 31±2 2±1 2±1 2±1 2±1 11±1 5±1 24±1
4 May 32±2 2±1 2±1 2±1 1±1 11±1 5±1 23±1
As shown in the table (Table1) above the
developmental period of the fly was found to strictly
dependent on the temperature and level of exposure of
the corpse. In the month of April and May when the
temperature was higher the developmental of the fly
was found to accelerate. Whereas in the month of
February when the temperature was lower the flies
took longer time to develop. This result was in
conformity with the findings of earlier researchers
(Byrd and Butler, 1997 [13]
; Wells and Kurahashi, 1994 [14]
; Boatright et al,. 2010 [15]
).
Flies oviposit only when the carcass is fresh (Archer,
2003 [16],[17]
; Hall et al., 1993 [18]
). This has been found
true in the present study. But in the favorable season, in
case of the small carcass the fly infestation was
recorded maximum and therefore the oviposition rate
was also found maximum. The huge number of the
larvae was found to feed on the carcass voraciously
and skeletonize it within a very short period of time.
Moreover, the oviposition time was observed upto
early bloated period. Flies were observed to visit the
carcass till later part of the early bloated stage but they
were not found to deposit maggot on it. The flies were
rarely seen in the late decay phase and almost never
seen on the dry phase.
During the investigation period, the culture of the flesh
fly Sarcophaga ruficornis was almost successfully
completed. The adult fly lived for 3-7 days during
which it deposit maggot in the bait until it was fresh.
After 3-4 days the flies were resting on the wall of the
culture chamber and avoided the bait. Life cycle
depended on the temperature and humidity. It was
observed that the life cycle which was studied in
February was longer than the life cycle that was
studied in May. Likewise with the advent of summer
life cycle shortened. The average life cycle in culture
was found to be 25±3.
It was also found that the fly grown in culture had a
longer life cycle than the fly growing in the wild.
3.1 Protein Estimation Proteins of different stages of S. ruficornis were
determined by following the method described by
Lowry et al., (1951) [11]
.
Table 2: Showing the protein content of developmental stages
Sl No. Sample Protein(mg/ml tissue ±SE)
1 Fresh Liver 9.8±0.08
2 Rotten Liver 8.4±0.01
3 1st instar 7.0±0.38
4 Last instar 11.84±0.05
5 Pupa 20.3±0.25
6 Adult 17.22±0.08
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Fig 5: Bar diagram showing the relationship between standard protein and optical density
Fig 6: Bar diagram showing the protein content of different developmental stages
Fig 7: Bar diagram showing the gradual decrease of protein content during decomposition and the increase of the
protein content in the developing stages of Sarcophaga ruficorins
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Table 3: Result of Tukey test for the protein content
Serial No I group J group Mean difference(I-
J) Significance
95% confidence intervel
Lower
bound
Upper
bound
1 Fresh liver
rotten liver 1.39333* .000 1.2587 1.5280
1st instar 2.73667* .000 2.6020 2.8713
Last instar -2.02333* .000 -2.1580 -1.8887
pupa -10.50333* .000 -10.6380 -10.3687
adult -7.41000* .000 -7.5447 -7.2753
2 Rotten liver
fresh liver -1.39333* .000 -1.5280 -1.2587
1st instar 1.34333* .000 1.2087 1.4780
Last instar -3.41667* .000 -3.5513 -3.2820
pupa -11.89667* .000 -12.0313 -11.7620
adult -8.80333* .000 -8.9380 -8.6687
3 1st instar
fresh liver -2.73667* .000 -2.8713 -2.6020
rotten liver -1.34333* .000 -1.4780 -1.2087
Last instar -4.76000* .000 -4.8947 -4.6253
pupa -13.24000* .000 -13.3747 -13.1053
adult -10.14667* .000 -10.2813 -10.0120
4 Last instar
fresh liver 2.02333* .000 1.8887 2.1580
rotten liver 3.41667* .000 3.2820 3.5513
1st instar 4.76000* .000 4.6253 4.8947
pupa -8.48000* .000 -8.6147 -8.3453
adult -5.38667* .000 -5.5213 -5.2520
5 Pupa
fresh liver 10.50333* .000 10.3687 10.6380
rotten liver 11.89667* .000 11.7620 12.0313
1st instar 13.24000* .000 13.1053 13.3747
Last instar 8.48000* .000 8.3453 8.6147
adult 3.09333* .000 2.9587 3.2280
6 Adult
fresh liver 7.41000* .000 7.2753 7.5447
rotten liver 8.80333* .000 8.6687 8.9380
1st instar 10.14667* .000 10.0120 10.2813
Last instar 5.38667* .000 5.2520 5.5213
pupa -3.09333* .000 -3.2280 -2.9587
* The mean difference is significant at the 0.05 level.
From result of Tukey test (table 3) for the protein
content of fresh and rotten liver along with the
different developmental stages of S. ruficornis, the
values were found significantly different from each
other.
The amount of protein content in these flies was found
to totally dependent on the protein content of the
carcasses. We know that liver contains relatively more
proteins than other macromolecules (Guinez et al.,
2011 [19]
)
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The protein content of insects depends on the
metamorphosis stage; adults usually have higher
protein content than other instars (Ademolu et. al.
2007) [20]
.
But in the present study the result did not match
exactly with the findings of Ademolu et al. (2007) [20]
From the experiment it was found that the pupal stage
contained the highest amount of protein among all the
developmental stages. Sarcophaga ruficornis has an
ovoviviparous mode of reproduction, in which eggs
hatch into first instar maggot in the female
reproductive system and the 1st instar maggots are
deposited in the carcass. Generally S. ruficornis adults
feed on the sap of the flesh (as the fly is in the culture
chamber). The carcass in the summer dries up very
fast. So, possibly it may happen that the carcass was
not in the state in which the flesh fly feed (Byrd and
Castner, 2001)[21].
First instar maggot after being laid
on carcass feed voraciously and attained successive
instars. During this feeding period they store sufficient
nutrients for the adult stage. From the experiment it
was found that the total protein contents accumulate in
the larvae gradually and reach its peak during the pupal
stage (Fig.6 and Table.2).
When a graph was plotted to show the total protein
content of different developmental stages of S.
ruficornis it was found that the total protein content
rose linearly till the pupal stage and again fell to some
extent in the adult stage. From this finding, it can be
inferred that the quantity of protein that was lost in
adult was utilized during the pupal to adult
transformation process.
An attempt was also made to correlate the protein
content in the fresh liver where the first instar maggots
were usually thrive and rotten liver where the last
instar maggots were usually found. From the
experiment it was found that protein content of the
liver degraded gradually during decomposition process
and the protein content of the developing stages of the
flies increased gradually during development period.
The total protein content of pupa was found to be
20.3±0.25, which was relatively higher in comparison
to the other developmental stages (Fig.6 & Fig.7).
From these findings it can be inferred that the protein
content of different developmental stages of the flies
was dependent on the protein profile of the carcass.
4. Conclusion
Forensic entomology is evolving as an inevitable
branch of forensic studies. The insects that colonize the
carcass serve as clock for the estimation of post
mortem interval. Here in the investigation life cycle of
a forensically important insect Sarcophaga ruficornis
was studied. To quantify the amount of protein present
in the carcass and the growing larva, protein of various
developmental stages and the larvae were estimated
using the method of Lowry et al., (1951). The results
of the investigation reveal that the time required for the
development of a fly varies within a narrow range of
25±3 during the study period. Protein content of the
developing stage increased linearly till pupa and in the
adult it slightly decreased. The result signifies that
heavy infestation of the fly of interest was abundant in
the earlier time, i.e. when the carcass was fresh.
Gradually adult disappeared and maggots began to
grow. The most important tool here is the growing
larvae through which the time of death can be
estimated. The developmental stages of the fly did not
vary much during the time period. The gradual increase
in the protein content of the developmental stages till
pupal stage and slight reduction on adult stage was a
clear indication that the adults feed on the sap of the
flesh (as the fly was in the culture chamber). The
carcass in the summer dries up very fast. So, possibly it
might happen that the carcass was not in the state in
which the flesh fly feed. Further, it is important in
poultry farm to feed the chick with a proteinaceous
diet, so the last instar or the pupal stage can be
recommended as a protein rich source.
5. Acknowledgement
The authors are very much grateful to the UGC for
their financial assistance and the head of the
Department of Zoology Gauhati University, Prof. Dr
Jatin Kalita and Prof. R. K. Bhola for their guidance
and help. The authors also express their heartfelt
gratitude to ZSI, Kolkatta for their help in
identification of the specimens.
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Adhikari K, Khanikor B, Sarma R, Mahanta S, Kalita J. Study on the life history and protein content of Sarcophaga ruficornis (Diptera:
Sarcophagidiae) a forensically important insect. Journal of Zoology Studies. 2016; 3(6):01-08.
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