Influence of maggot mass temperature in the development of chrysomya megacephala in estimating post mortem interval (PMI) in Kelantan,Malaysia.
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Date
2011
Authors
Azlan, Nurhazirah Zainul
Journal Title
Journal ISSN
Volume Title
Publisher
Pusat Pengajian Sains Kesihatan, Universiti Sains Malaysia
Abstract
The major contribution of forensic entomology is in the estimation of postmortem
interval (PMI). Postmortem interval is the time elapsed since death, which can be used
for narrowing down the suspect's presence at the time the body was disposed thereby
linking the suspect with the crime. Determination of the PMI is based on two principles,
one by studying the life cycle of a specific species of insect and the other by studying
the succession of different species of insects.
As a poikilothermic (cold-blooded) organism, rate of growth of the larvae is a
function of temperature and time. In this research, the influence of maggot mass
temperature is evaluated as a factor affecting the rate of growth of the larvae. Maggot
mass is referred to larvae that grow in groups. The larvae when in a mass produce heat
that can be higher than the ambient temperature. In temperate countries, higher maggot
mass temperature can sustain continual growth despite low ambient temperature. The
range of variation between ambient temperature and maggot mass temperature in
temperate countries has been reported to be 17°C to 33°C. Due to the higher maggot
mass temperature, life cycle of insect is completed earlier. Research on the influence of
maggot mass temperature on development of dipteran flies in tropical countries like
Malaysia is lacking.
This research conducted at Universiti Sains Malaysia in Kelantan, Malaysia, a
tropical environment evaluated the influence of maggot mass temperature in the
development of Chrysomya megacephala in estimating the PMI in Kelantan, Malaysia.
C. megacephala is chosen as it is the most prevalent fly of forensic importance in Malaysia. The experiments were designed to cover both sunlit habitat and shaded
habitat. The development of maggots in mass was studied in relation to the
development of scarce maggots in the same environment.
The animal model decomposed was beef meat and as it was covered using a
slotted plastic basket, the temperature inside the basket was considered the ambient
temperature and five replicates of the experiment were carried out. The results indicated
that the difference in the mean maggot mass temperature ranged from -0.1 to 6.9 °C
when compared to the basket temperature.
The time taken for the larvae to attain the three instars which are the first, second
and third was formal to be similar irrespective of whether they are in a mass or are
sparse. However, the maggots in mass were always longer than there in sparse. The
results indicate that maggot mean temperature has to be taken into consideration while
estimating PMI.
Description
Keywords
Forensic entomology