Insects
are among the oldest living organisms that inhabited the earth. Their
appearance dates back to time periods preceding human existence by millions of
years. They have shown an exceptional ability to adapt to a wide range of
environmental conditions, which enabled them to spread in various terrestrial
and aquatic ecosystems. This evolutionary success is attributed to the
structural, physiological, and behavioral characteristics they possess, which
enabled them to persist and reproduce with high efficiency, in addition to
their continuous vital activity and their persistent pursuit of obtaining food
resources (Goff, 2009)
Scientific
interest in insects of medical, veterinary, and forensic importance also
extends to deep historical roots, as the Chinese judge and scholar Song Ci in
the thirteenth century is credited with the first systematic documentation of
the use of insects in forensic detection, through his accurate observations of
the behavior of flies in identifying the crime tool, as mentioned in his book
The Washing Away of Wrongs, which is considered the cornerstone in the
emergence of this field
With the development of modern sciences,
entomology witnessed a qualitative shift represented by the formation of
precise specializations, the most prominent of which is forensic entomology,
which depends on analyzing the patterns of succession of insects associated
with corpses to estimate the time of death. Advances in molecular techniques,
especially DNA analysis and gene sequencing, have contributed to bringing about
a fundamental transformation in understanding the evolutionary relationships
among insects, which enhanced the accuracy of the forensic applications of this
science Forensic entomology is defined as an applied branch that
employs insects and arthropods in the service of legal investigations.
Estimating the minimum postmortem interval (PMI) is considered one of its most
important applications, as this is achieved through studying the developmental
stages of insects colonizing the corpse. Its role is not limited to this aspect
only, but also extends to include detecting the possibility of moving the
corpse from one location to another, or identifying the presence of toxic
substances or drug effects, in addition to its role in evaluating cases of
neglect (Amendt et al., 2011)
Ecological
studies have shown that a group of insects, especially in their larval stages,
depend in their feeding on decomposed tissues and are known as necrophagous
insects, whereas other groups use the corpse as a food resource during
different stages of their lives, which reflects the complexity of the food webs
associated with the decomposition process (Keiper & Casamatta, 2001;
Hobischak & Anderson, 2002)
Systematic
analysis of patterns of insect distribution, behavior, and developmental stages
at the crime scene provides a rich database. This enables researchers to
reconstruct environmental and temporal conditions associated with the incident.
This enhances reliability of forensic conclusions (Amendt et al., 2007)
The
process of corpse decomposition, as well as the dynamics of succession of
insect communities, is subject to the influence of a complex group of
environmental and physical factors, including temperature, relative humidity,
seasonal changes, and geographical location, in addition to the characteristics
of the corpse itself, such as size and the presence of clothing, as well as
surrounding environmental factors such as soil type and vegetation cover
density, and also the effect of chemicals and drugs (Kyerematen et al.,
2013).
With respect to
the taxonomic composition of insects associated with carcasses, necrophagous
species play a key role. They eat directly through decomposing tissues. In the
case of Entrance or Stringing flies, they might be the foremost colonizers
(Anderson, 2013) since they create a lunch of and bundle between tissues,
respectively.
Scientific
literature indicates that the families Calliphoridae, Sarcophagidae, and
Muscidae are the most common in association with human and animal remains. They
are often the first arrivals at the decomposition site (Chin et al.,
2011).
These are
followed by other groups including beetles from the families Staphylinidae,
Cleridae, Dermestidae, and Silphidae. Ants from the family Formicidae also
join, which may affect the remains and contribute to altering the course of the
decomposition process (Sikes & Venables, 2013; Pechal et al., 2014; Byrd
& Castner, 2019; Bonacci et al., 2022). The use of entomological evidence in
forensic investigations has gained increasing global attention. This is
particularly true in countries of the Northern Hemisphere, where systematic
studies have been conducted to develop this field and enhance its practical
applications (Williams & Villet, 2006)
Musca domestica
Sarcophaga africa
Necrobia rufipes