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Vital Statistics of Chrysomya megacephala (Fabricius, 1794) (Diptera: Calliphoridae) under Different diets from Venezuela


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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-1 st larvae, 20 h 1 st-2 nd larvae, 28 h 2 nd-3 rd larvae, 56 h 3 rd-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-1 st larvae and 3 rd 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.
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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,
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.
Luzlexis Arias-Di Donato
Museo del Instituto de
Zoología Agrícola, Facultad de
Agronomía, Universidad Central
de Venezuela, Aragua,
Vital Statistics of Chrysomya megacephala
(Fabricius, 1794) (Diptera: Calliphoridae) under
Different diets from Venezuela
Luzlexis Arias-Di Donato,Jonathan Liria
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.
Journal of Entomology and Zoology Studies
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
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
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.
Journal of Entomology and Zoology Studies
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).
Journal of Entomology and Zoology Studies
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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... The blowfly C. megacephala, commonly named as oriental latrine fly (Zumpt, 1965), is a species of widespread distribution in tropical and temperate climates (Badenhorst & Villet, 2018). Its life cycle has been well studied in America (Aguirre-Gil et al., 2015;Arias-Di Donato & Liria, 2016), in Africa (Prins, 1982;Gabre et al., 2005;Kamel et al., 2016) and in Asia (Wells & Kurahashi, 1994;Bharti et al., 2007;Ahmad Firdaus et al., 2009;Hu et al., 2010). It has medical importance because it is one of the most dominant Diptera species representing forensic entomofauna in Malaysia (Nazni et al., 2015). ...
... The life cycle of C. megacephala is well-known in different regions of the world such as America (Aguirre-Gil et al., 2015;Arias-Di Donato & Liria, 2016), Africa (Prins, 1982;Gabre et al., 2005;Kamel et al., 2016) and in Asia (Wells & Kurahashi, 1994;Bharti et al., 2007;Ahmad Firdaus et al., 2009;Hu et al., 2010). However, despite being one of the most common forensic indicator species, there is a lack of life cycle studies in Malaysia especially for the use in postmortem interval estimation (Ismail et al., 2007;Ahmad Firdaus et al., 2009;Kumara et al., 2010). ...
... Interestingly, the O. thoracicum results were similar to most studies carried on necrophagous dipteran larvae, where the diets tested (whether muscle or internal organ tissues) had no significant influence on the developmental time (e.g., Boatright and Tomberlin 2010, Donato and Liria 2016, Thomas et al. 2016, Bernhardt et al. 2017. However, in a few cases, the diet indeed had an effect (e.g., Clark et al. 2006, Ireland and Turner 2006, Warren and Anderson 2009, Thyssen et al. 2014. ...
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... Beef liver is a commonly used substrate for rearing forensically relevant Diptera [56][57][58][59]43]. While results of various studies indicate the effects of this tissue on larval development could be species specific [59,23,24,60], liver has been discussed as a suboptimal rearing medium [61][62][63]59]. ...
The secondary screwworm, Cochliomyia macellaria (Fabricius) (Diptera: Calliphoridae), is a carrion-breeding species of veterinary, medical, and forensic importance. It is very abundant in the Nearctic and Neotropical regions and is one of the most common colonizers of vertebrate remains in the southern United States. Therefore, it is of great evidential value in estimating the minimum time of colonization (TOC) of remains related to forensic investigations. So far, studies have investigated the effects of several biotic and abiotic factors on C. macellaria. However, no data on the specific impact of food source moisture on the larval development of this species are known to have been published. In this study, the effects of diet moisture on larval development time, larval length, and weight over time, as well as adult emergence and weight were investigated. Cochliomyia macellaria was reared on diets prepared from freeze-dried bovine liver with varying moisture content (0.0, 33.0, 50.0, or 70.8 %) at 25.6 °C, 77 % RH, and 14:10 L:D. Frozen-thawed liver was used as a control. Water content was found to significantly impact immature development time and corresponding life-history traits, both within and among developmental stages of C. macellaria. This result indicates moisture content of the carrion source should be considered when estimating time of colonization and identification of immature stage of flies in forensic investigations. Furthermore, as diet moisture content significantly affected the dry mass of emerging adults, the mass of adults collected at a crime scene could provide useful information as it could be an indicator of the condition the remains were in during time of colonization, including the moisture content of the tissue.
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The blowflies (Diptera: Calliphoridae) comprise a group of medical and forensic importance because some species are responsible for myiasis and immature stages of several species feed on corpses and show preference for certain stages of decomposition. In both cases, the correct taxonomic determination is a crucial aspect for a medical or forensic investigation. The geometric morphometrics is a recent tool that describes the shape variation, although this technique has been used in adult blowfly, it has not been evaluated in immature. The goal of this study was to analyze the variations on cephalopharyngeal morphometrics, to support the identification of forensic immature flies. For this we photographed a total of 101 cephalopharyngeal skeletons from Chrysomya albiceps (n=34), C. megacephala (n=34) and Lucilia cuprina (n=33). Landmark coordinate (x, y) configurations were registered and aligned by Generalized Procrustes Analysis. Canonical Variates Analysis (CVA) were implemented with proportions of reclassified groups and MANOVA. Statistical analysis of variance found significant differences in centroid size (Kruskal-Wallis). The CVA showed significant separation, and a posteriori re-classification was 100% correctly assigned. The main differences between the three species were localized on: base of parastomal bar, apical tooth, clipeal arc, concavity of the pharyngeal sclerite, and union between hypostomal sclerite and the mouth hook. These differences could be useful as additional tools for larvae taxonomic identification; however, more studies are needed that include a more complete species representation in Calliphoridae.
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Life cycles of insects play a fundamental role in their subsequent activities. This study was designed to establish a colony of two medically important flies in the laboratory to construct their life tables and to compare baseline parameters of their survival. Adult blowflies, Lucilia sericata were collected from different slaughterhouses and meat processing plants. Adult house-flies Musca domestica were collected from different poultry farms and dairy plants. Both species were kept in rearing cages at 28±2°C average temperature, 50±5% relative humidity and 12 h photoperiodicity. Baseline parameters of their life cycles were recorded and life tables were developed for both species. Total survival rate were measured as 73.76±2.47 and 72.83±1.98% for L. sericata and M. domestica, respectively. Net reproduction rates for L. sericata and M. domestica were obtained as 3.398 and 2.206, respectively. The survival curve of both species was classified as type IV. The results confirmed the efficiency of applied diets for optimum development of both species. Based on these results, it could be concluded that both populations may be reared simultaneously to reduce extra labour and costs.
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La entomología forense surge como apoyo técnico-científico a la investigación criminalística, aportando información sobre la data de muerte. Un método comúnmente utilizado es la sucesión de la entomofauna cadavérica sobre el cuerpo, sin embargo, la mayoría de los estudios se realiza empleando cadáveres de animales. Debido a esto, el presente estudio pretende utilizar como biomodelo vísceras de res, para determinar la secuencia de sucesión de las especies de importancia forense en el Estado Carabobo. Se emplearon pulmón e hígado, y la entomofauna fue colectada e identificada durante ocho días. Se obtuvieron 127 individuos adultos del Orden Diptera, pertenecientes a las Familias: Calliphoridae (67,9%), Muscidae (23,1%), Piophilidae (5,3%) y Sarcophagidae (3,7%); en Coleoptera se obtuvieron 7 ejemplares adultos de Dermestidae y Cleridae. Las especies reportadas fueron Chrysomya megacephala, Lucilia cuprina, Chrysomya albiceps y Cochliomyia macellaria, para Calliphoridae; Dermestes maculatus y Necrobia rufipes en Dermestidae y Cleridae, respectivamente. La mayor riqueza y abundancia de insectos se encontró en los primeros días de descomposición, seguido de la aparición de larvas que degradan de forma progresiva los tejidos y la presencia de coleópteros. El patrón de sucesión coincide con otros estudios realizados en los Estados Aragua y Carabobo, los cuales contemplaron el uso de cadáveres de conejos y roedores, respectivamente. La implementación de este biomodelo permitirá el desarrollo de protocolos de muestreo con el fin de generar una base de datos que relacione las fases de descomposición con listados de especies de importancia forense.
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A comprehensive, but simple-to-use software package for executing a range of standard numerical analysis and operations used in quantitative paleontology has been developed. The program, called PAST (PAleontological STatistics), runs on standard Windows computers and is available free of charge. PAST integrates spreadsheettype data entry with univariate and multivariate statistics, curve fitting, time-series analysis, data plotting, and simple phylogenetic analysis. Many of the functions are specific to paleontology and ecology, and these functions are not found in standard, more extensive, statistical packages. PAST also includes fourteen case studies (data files and exercises) illustrating use of the program for paleontological problems, making it a complete educational package for courses in quantitative methods.
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Insects play a fundamental ecological role in the decomposition of organic matter. It is the natural tendency for sarcosaprophagous flies to find and colonize food source such as cadaver as a natural means of survival. Sarcosaprohagous fly larvae are frequently encountered by forensic entomologists in death investigations. The most relevant colonizers are the oldest individuals derived from the first eggs deposited on the body. The age of oldest maggots provides the precise estimate of post mortem interval. With advancement in technology various new methods have been developed by scientists that allow the data to be used with confidence while estimating the time since death. Forensic entomology is recognized in many countries as an important tool in legal investigations. Unfortunately, it has not received much attention in India as an important investigative tool. The maggots of the flies crawling on the dead bodies are widely considered to be just another disgusting element of decay and are not collected at the time of autopsy. They can aid in death investigations (time since death, manner of death). This paper reviews the various methods of post mortem interval estimation from Calliphoridae to make the investigators, law personnel and researchers aware of the importance of entomology in crime investigations. The various problems confronted by forensic entomologists in estimating the time since death have also been discussed and there is a need for further research in field and in the laboratory. Correct estimation of post mortem is one of the most important aspects of legal medicine.
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The life-history raw data of the Australian sheep blow fly Lucilia cuprina (Wiedemann) were collected in the laboratory conditions and analyzed based on the age-stage, two-sex life table to take into consideration both sexes and the variable development rates among individuals. The intrinsic rate of increase (r) is 0.236 d-1, while the finite rate of population increase (λ) is 1.266 d-1. The net reproductive rate (R0) is 106.1. The mean generation time (T) is 19.8 days. The population parameters suggest that L. cuprina population is r-strategist.
Estimation of the postmortem interval (PMl) using faunal diversity, development and succession in human death investigations is based on a number of assumptions. Investigators should not be overly dependent on the few baseline studies currenlly in use to estimate the PM!. This paper reviews a number of problems to be considered when using inse<:ts to estimate the PMI: 1. Insect activity in inclement weather and at night. 2.1'iming of blow fly oviposition. 3. Mixed fly populations and staggered broods. 4. Seasonal efTects on maggot-generated heat. 5. Effect of maggot-generated heat. 6. Impact of species arriving out of sequence. 7. Availability of gravid blow ny recruits at the scene. 8. Effect of drugs, toxins, and parasitoids on maggot development. A discussion of these problems is presented along with some approaches to their solution. KEY WORDS Forensic entomology, interval, COl-pSC, insect fauna, blow nics, Calliphoridae, Diptcra. The major contribution made by a forensic entomologists in a homicide investigation is an estimate of the duration of the postmortem interval (PMI). Some added contributions include indication of movement of the corpse, and possibly the manner of death. Estimating the PMI involves the setting of the maximal and minimal probable time interval between death and corpse discovery (Fig. 1). The maximal limit is determined by the species of insects present, and the "weather windows" available for activity of these species. The habits and mix of species can be used to give a crude estimate of the earliest time of corpse exposure. 'Weather windows are intervals of conditions, usually warmer tempel'atures and sunshine, when carrion-seeking species are likely to be active. The minimal limit is determined largely by estimating the age of developing immature insects at the time of corpse discovery. The relationship between the age of immatures and the PMI is determined from a few published baseline studies with rates adjusted by interpolation t.o include the influence of climate, season, weather, and location.
Sarconesiopsis magellanica is a forensically relevant necrophagous blowfly that can aid in determining the post-mortem interval (PMI) as it is the first to colonise decomposing corpses. The blowfly has been reported in several South-American countries including Colombia, in high-altitude regions ranging from 1200 to 3100m above sea level. The present study reports this blowfly's life cycle and an analysis of its reproductive and population parameters under laboratory conditions for the first time. Six successive generations of flies were produced with an average of 65.38% adults emerging with respect to the total number of puparia. The shortest life cycle from egg to adult emergence was found in individuals fed on a lyophilised liver (LL) diet, while the longest one was found in individuals fed with an egg-powdered milk (E-PM) diet; intermediate values were found when the pig liver (PL) diet was tested. The greatest adult longevity was achieved when the PL diet was used, the LL diet giving the shortest. The population parameters based on the horizontal life table were: net reproductive rate (Ro)=447.752±9.9, mean generational time (Tc)=18.18±0.38, natural population increase rate (rm)=0.145 and finite population increase rate (λ)=1.398. This blowfly colony represents a valuable asset for both basic and applied studies. Members of the S. magellanica colony so established were used for analysing the life-cycle, reproductive and population parameters, and further medical and forensic application studies are currently underway.