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Forensic entomology

THE HISTORY of Forensic Entomology Forensic entomology was first reported to have been used in 13th century China and was used sporadically in the 19th century and the early part of the 20th century, playing a part in some very major cases. However, in the last 20 years, forensic entomology has become more and more common in police investigations. In 1996, some of us developed the American Board of Forensic Entomology; a certification Board for Forensic Entomologists, similar to the Board certification available for forensic odontologists and forensic anthropologists. However, only in the last 30 years forensic entomology has been systematically explored as a feasible source for evidence in criminal investigations. Through their own experiments and interest in arthropods and death, Song Ci, Francesco Redi, Bergeret d’Arbois, Jean Pierre Mégnin and the German doctor Hermann Reinhard have helped to lay the foundations for today’s modern forensic entomology. Forensic Entomology can be defined broadly as the application of the scientific study to investigate insects and other arthropods biology to criminal matters in legal matters. A forensic entomologist will use insects to determine cause of death, drugs used and location of a crime.
Forensic entomology can also help detect abuse in children and also determine the location of an incident, and find the presence and time of the infliction of wounds. More specifically, the forensic entomologist estimates a portion of the postmortem interval based on the age of the insect present. The main subfields of forensic entomology is urban forensics (civil in nature and focuses on insect pest species typically concerns pests infestations in buildings gardens or that may be the basis of litigation between private parties and service providers such as landlords or exterminators when all points of possible infestation are examined in order to determine who is at fault), Stored-Product forensic (also civil in nature, and depending on the case may have a criminal aspect of insect the area concerns itself with insect contamination in food and beverage) and medico-legal forensic entomology it is generally criminal in nature and it focuses on the insects that colonize on human tissues in the postmortem interval.
Major steps of working during investigations  
Biological Process after Death of Insect
Death is commonly known as a physical shut down of the body of Insect and is determined when all of the body’s biological functions stop working.  It’s important to remember that in most cases of death, the functions of different organs in the body cease to work at different times. Today’s medical sciences have identified a few different types of death. Brain death is defined as when brain activity ceases even if other internal organs are functioning. In the process of death, cells and tissues are broken down in different stages. First, the body starts to cool down and biological tissues start to stiffen and become hard, this process is called rigor mortis. After all of the cells in the body cease to function the body starts to decompose as bacteria in the body begins to breakdown proteins, lipids, and other organic compounds. 
When Entomologist Starts Investigate the Dead Bodies?
Most cases that involve a forensic entomologist are 72 h or more old, as up until this time, other forensic methods are equally or more accurate than the insect evidence. However, after three days, insect evidence is often the most accurate and sometimes the only method of determining elapsed time since death. There are many different methods for determining time of death of a corpse. First is to take the temperature of the corpse. The body immediately begins to cool as blood ceases to pump through it. So starting with a normal body temperature and subtracting the temperature of the corpse can help in estimating time of death. If a body has been dead for quite some time, forensic entomologists use the presence and life cycles of Calliphoridae (flies) and Coleoptera (beetles) on the body to help determine time of death.
Movement of Corpses at Crime Scenes
After the cells in a body cease to function, certain insects (flies and beetles) and bacteria find the body immediately, and begin to colonize it. The space underneath the body also attracts these bugs and others.  It is when a forensic entomologist compares the environment of where the body was found with the information from the body (i.e. stages of rigor mortis and decomposition) that they may determine if the body had been moved after death.
Evidence Collection
Gathering evidence at a crime scene is essential in legal investigations. For forensic entomologist, without the evidence and the proper evidence collecting measures, their job is meaningless. The most important thing is to make visual observations and come up with ideas at the scene. They must then collect information about the climate of the scene.
Determining Cause of Death
Forensic entomology can be useful in finding out the cause of death in many different ways. Over time as a body decomposes, it becomes harder and harder to test blood and urine samples or examine stomach contents for traces of poison. However, because maggots feed on the dead body, it is possible to extract that information from dissecting the maggots themselves. 
What information can a forensic entomologist provide at the death scene?
Forensic entomologists are commonly called upon to determine the postmortem interval or “time since death” in homicide investigations. More specifically, the forensic entomologist estimates a portion of the postmortem interval based on the age of the insect present. The forensic entomologist can use a number of different techniques including species succession, larval weight, larval length, and a more technical method known as the accumulated degree hour technique which can be very precise if the necessary data is available. A qualified forensic entomologist can also make inferences as to possible postmortem movement of a corpse. 
Entomological evidence can also help determine the circumstances of abuse and rape. Victims that are incapacitated (bound, drugged, or otherwise helpless) often have associated fecal and urine soaked clothes or bed dressings. Such material will attract certain species of flies that otherwise would not be recovered. Their presence can yield many clues to both antemortem and postmortem circumstances of the crime. Currently, it is now possible to use DNA technology not only to help determine insect species, but to recover and identify the blood meals taken by blood feeding insects. The DNA of human blood can be recovered from the digestive tract of an insect that has fed on an individual. The presence of their DNA within the insect can place suspects at a known location within a definable period of time and recovery of the victims’ blood can also create a link between perpetrator and suspect. The insects recovered from decomposing human remains can be a valuable tool for toxicological analysis. The voracious appetite of the insects on corpses can quickly skeletonize the remains. In a short period of time the fluids and soft tissues needed for toxicological analysis disappear. However, it is possible to recover the insect larvae and run standard toxicological analyses on them as you would human tissue.
 
The writers are associated with the Department of Plant Pathology, University of Agriculture Faisalabad, Pakistan. They can be reached at <Zeeshansattar2206@yahoo.com>
 

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