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Journal of Entomology and Zoology Studies 2016; 4(2): 247-251
E-ISSN: 2320-7078
P-ISSN: 2349-6800
JEZS 2016; 4(2): 247-251
© 2016 JEZS
Received: 26-01-2016
Accepted: 29-02-2016
Luzlexis Arias-Di Donato
Museo del Instituto de
Zoología Agrícola, Facultad de
Agronomía, Universidad Central
de Venezuela, Aragua,
Venezuela.
luzdv.arias@gmail.com
Jonathan Liria
A) Laboratorio Museo de
Zoología, Facultad Experimental
de Ciencias y Tecnología,
Universidad de Carabobo,
Carabobo, Venezuela.
B) Universidad Regional
Amazónica IKIAM, km 7 vía
Muyuna. Napo, Ecuador.
Jonathan.liria@gmail.com
Correspondence
Luzlexis Arias-Di Donato
Museo del Instituto de
Zoología Agrícola, Facultad de
Agronomía, Universidad Central
de Venezuela, Aragua,
Venezuela.
luzdv.arias@gmail.com
Vital Statistics of Chrysomya megacephala
(Fabricius, 1794) (Diptera: Calliphoridae) under
Different diets from Venezuela
Luzlexis Arias-Di Donato,Jonathan Liria
Abstract
The life history of an important forensic blowfly, Chrysomya megacephala (Fabricius) from Venezuela,
was studied at 28 °C, 47% RH and 12 h photoperiod in laboratory under two protein substrates: beef liver
and sardine. The data were analyzed using the age-stage life table method with TWO-SEX computer
program that considers the development rate among individuals and between sexes. The development
time was: 8 h from egg-1st larvae, 20 h 1st-2nd larvae, 28 h 2nd-3rd larvae, 56 h 3rd-pupa and 83 h pupa-
adult. The total development time was 200 h and 198 h, with liver and sardine respectively. Were found
significant differences (Kruskal-Wallis test), between instars duration and protein substrates, with
exception of egg-1st larvae and 3rd larvae-pupa. The specimens under liver showed high fecundity and
low generation time; however under sardine, the life expectancy and survival rate were high, in contrast
to low mortality and long generational time. Our study represents the first investigation in Venezuela that
determines the vital statistics in blowfly species.
Keywords: Chrysominae, life table, mortality, survivorship, forensic entomology
1. Introduction
The human or animal carcasses decomposition is attributed to biological, chemical and physics
process that emitted compounds that attract several arthropods; some species in the Order
Diptera occurs in these decomposition substrates and the immature staged feed directly on the
carcasses [1]. The Calliphoridae are the most important flies associated to forensic studies,
because the immature stages development are used to estimate the length of time (Post
Mortem Interval) between death and corpse discovery [2, 3]. Determination of the Post Mortem
Interval is a crucial and fundamental step in any death scene investigation when a death is not
witnessed [3]. Zied et al., [4] stated that the life table of a population gives the most
comprehensive description on the growth, survival and fecundity. Therefore, a basic
demographic study (instars duration, mortality, fecundity, etc.) in blowflies and other insects
of forensic importance, is a fundamental and crucial aspect to support medico legal death
investigations. Some investigations focused on the life-cycle, colonization, reproductive and
population parameters of Calliphoridae species has been carried out. Zied et al., [4] and Gabre
et al., [5] from specimens collected in Egypt, estimated the life table of Lucilia cuprina
(Wiedemann) and C. megacephala (Fabricius), respectively. Later, Rueda et al., [6] studied the
vital parameters of Lucilia sericata (Meigen) from Colombia reared under two artificial diets.
Recently, Pinilla et al., [7] determined in Colombia, the life-cycle, reproductive and population
parameters of Sarconepsis magallanica (Le Guillou) under different diets, and Saleh et al., [8 ]
estimated the life table of Lucilia sericata collected in Iran. Finally Sanei-Dehkordi et al., [9]
determined in Iran, the experimental colonization and life table of Calliphora vicina
(Robineau-Desvoidy). Chrysomya megacephala is a common blowfly species in Venezuela [10,
11], with medical and forensic importance [12, 13]. Due to this, the main purpose of this work was
to establish under laboratory conditions a colony of C. megacephala, from samples of adult
specimens collected in Venezuela, to build life tables and to evaluate two protein substrates.
2. Materials and Methods
2.1. Sampling specimens: The laboratory colony of C. megacephala used in this study was
initially established in March 2012, from adult collections in the surroundings of the
Departamento de Biología at the Universidad de Carabobo, Valencia – Venezuela.
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2.2. Maintenance of blowflies in the laboratory: The adults
were kept in cages (25 x 35 x 25 cm) with white cloth “doppio
velo” type; each cage contain 10 specimens (eight females and
two males) at 28 ºC ±1, 47% RH and 12 h photoperiod.
2.3. Diets and life cycle: Adults were supplied daily with
granulated sugar, water ad libitum supplied in a petri dish with
cotton; another petri dish containing the protein substrate: one
cage with 20 gram of beef liver, and other with 20 gram of
sardines. From each cage/diet were taken 100 eggs, and
subsequently placed individually to with 5 gram of protein
source (liver or sardine) in bottles covered with doppio velo
and secured with a rubber band. Each hour the individuals
were revised, and the stage development and mortality were
registered. At the prepupal stage, were used dry paper napkins
as medium for pupation. In the adult emergence, females and
males were transferred to cages with 5 gram of protein
substrate and a petri dish with water; finally, for fecundity
evaluation, were counted the eggs hatch until the last female
die.
2.4. Life table and data analysis: For the life table study, the
raw data from 200 specimens (100 for each diet and two
replicates) were analyzed using the age-stage, two sex life
table method [14, 15] with the TWO-SEX computer program.
The differences between instar development time and protein
substrates were analyzed with a Kruskal-Wallis test, in the
PAST statistical computer program [16].
3. Results and discussion
Table 1 shows C. megacephala development time for each
instars and protein substrates (beef liver or sardine): egg to 1st
larvae (8 h with liver; 9 h with sardine), 1st to 2nd larvae (21 h;
20 h), 2nd to 3rd larvae (28 h; 30 h), 3rd to pupa (56 h; 56 h) and
pupa to adult (87 h; 83 h); the total development time was 200
h and 198 h, with liver and sardine respectively. The instars
development time and protein substrates showed significant
differences (Kruskal-Wallis X2=1674; p<0.001), with
exception of egg to 1st larvae and 3rd larvae to pupa. Our
findings were different to others studies, Goodbrod & Goff [17]
studying the effect of larval densities in the development at
23.5 °C of C. megacephala and C. rufifacies (Macquart),
found for 2 larvae/g of beef liver a duration of 150 h. Later,
Sukontason et al., [18] reported 108 h from 1st larvae to adult,
from a cohort of C. megacephala growth in 28 °C and using
pork liver. Recently, Aguirre-Gil et al., [19] studying the larval
development of C. megacephala under different diets and
larval densities, found for 1 larvae/g of beef liver, a duration of
7.65 days (or 186.6 h) at 25 °C.
In relation with the life table parameters, the specimens under
beef liver substrate, obtained high values of intrinsic rate of
increase (r=0.41) and finite rate of increase (λ=1.51), short
generation time (T=15 days) and low net reproductive rate
(Ro=264), in contrast those specimens under sardine diet
obtained low values of r=0.37, and λ=1.45, long T=17 days,
and high Ro=558. The longevity obtained was different
between both protein substrates, 47 days under beef liver diet
and 57 days for sardine. Later, the fecundity (eggs/female) was
high under beef liver (82.02) and low in sardine (67.06). The
age-stage mortality in females was high at 40 days in beef liver
and 56 days with sardine; the high mortality was obtained
under beef liver at 11 days (62.5%) in the larval stages, and
63.5% in sardine at the same time, but in the pupa stage. The
age-stage survival rate (Figure 1) showed a low value in
female specimens under beef liver (41 days), in contrast those
in sardine (57 days); the age-stage expectancy life (Figure 2)
in female showed 58 days and 42 days, under sardine and beef
liver respectively. These results differ from Gabre et al., [5],
those report 32 days longevity in C. megacephala females at
26 °C under beef liver, 41 to 43 days for male and female
survival rate respectively, and fecundity 48 eggs/female. The
age-stage reproductive value under beef liver (Figure 3) was
high (149.3) in flies with 17 days in comparison with the diet
under sardine; similar results correspond to Gabre et al., [5]
with 161.2 in 19 days. On the other hand, the reproductive
value was lower than reported by these authors. This can be
explained because the 17 days females, compared to other age
groups, offer a high physiological potential that contributed to
the population.
Carvalho & Von Zuben [20] estimated demographic aspects of
C. megacephala maintained under laboratory conditions, with
different larval densities (100 to 800) in temperature-
controlled chambers at 25 °C. They found variations in the life
expectancy from 49.5 days (in 100 larvae density), 61.83 days
(in 200 larvae), 51.02 (in 400 larvae) 39.6 days (in 800 larvae);
in relation to fecundity, these author reports differences in the
total fecundity and net fecundity, the greatest values obtained
were found at density 100, followed by 200 larvae, while the
smallest values were found on 800 larvae. The main
differences between vital parameters among these studies,
could be attributed to the life table estimation; in our
investigation were used the two-sex life table method [14, 21].
According to Zied et al., [4] and Gabre et al., [5], the traditional
age-specific life table, ignored the male population and the
variable developmental rates among individuals. Furthermore,
because only the age was taken into consideration, the age-
specific life table cannot describe the stage differentiation of
insect population. Finally, following to Gabre et al., [5] for a
detailed understanding of the population dynamics of blowflies
species, data appropriate for life table studies must be
collected on different diets under both laboratory and field
conditions. And this information can be useful in determining
the Post Mortem Interval, especially if the stage structure of
Calliphoridae population on the corpse is recorded in a death
investigation. Our study represents the first investigation in the
country, that determine vital statistics in blowfly species using
life table methods. However are necessary studies in other
important forensic species, for example C. albiceps
(Wiedemann), Lucilia eximia (Wiedemann), L. cuprina,
among others, that consider different protein sources and a
wide temperature range.
Table 1: Development time (in hours) mean and standard deviation
of Chrysomya megacephala, from egg to adult under two protein
substrates (beef liver or sardine)
Stage Liver
(n=200) Sardine
(n=200)
Egg - 1st Larvae 8 ± 0.62* 9 ± 0.74*
1st Larvae - 2nd Larvae 21 ± 3.39 20 ± 1.93
2nd Larvae - 3rd Larvae 28 ± 5.63 30 ± 2.67
3rd Larvae - Pupa 56 ± 7.75* 56 ± 4.30*
Pupa-Adult 87 ± 10.14 83 ± 4.35
(*) Indicated non-significant differences with Kruskal-Wallis test.
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Fig 1: The age-stage specific survival rate of Chrysomya megacephala, from egg to female under
two protein substrates (sardine or beef liver).
Fig 2. Life expectancy of each age-stage group of Chrysomya megacephala, from egg to female under
two protein substrates (sardine or beef liver).
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Fig 3: Reproductive value of each age-stage group of Chrysomya megacephala, from
egg to female under two protein substrates (sardine or beef liver).
4. Acknowledgments
We are grateful to the staff of Departamento de Biología de la
Universidad de Carabobo, for the laboratory materials and
insectary facilities.
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