CSI PGS!

by Sampad Sengupta

This week, PGS unveiled a new club to add to its splendid range of co-curricular activities: the Experimental Biology Club. In a rare and privileged move, The Portsmouth Grammar School has formed collaboration with The University of Portsmouth to perform novel research, which will contribute towards worldwide biological understanding; in particular, the club will investigate the developing field of ‘Forensic Entomology’. 

‘Forensic Entomology’ translates as the use of insects to help in solving crimes, particularly in murder investigations. In the first session, Dr Katherine Brown visited from the University of Portsmouth to discuss the scientific basis behind ‘Forensic Entomology’ and introduce exactly how this ”biological clock” can be used to solve crimes. In the words of Dr Brown, forensic entomology is “really applicable… it’s current, it’s now”. It is something which gained importance in the late 90s and is now used widely across the world to help in investigations.

Samples of insects

The types of insects used in these cases are mostly flies and beetles. Insects usually colonise the crime scene in minutes and stay there, which is one of the primary advantages of using these techniques. Different types of insects would remain at the scene for different lengths of time and pupal casings can remain at a crime scene for millennia; such ‘puparia’ are now subjects of research at the university. These insects can be used to determine the manner of death, whether it be stabbing, gunshots or poisoning, following analysis in the laboratory. It also informs scientists of the post-mortem interval (PMI), which is used to estimate the time of death of the victim, by studying the lifecycle stages of the insects. The knowledge of ‘Insect Succession’ i.e. the estimated time of appearance of the different insects at the scene is applied in this case; the lifecycle and relative growth timings of insects is also taken into account.

Dr Brown went on to say what experiments and activities were going to be performed at the school. The club will begin by honing students’ molecular biology techniques, such as DNA extraction and analysis, and then move on to attempt to extract DNA from insect artefacts (vomit and faeces residue left by insects at the crime scene). In a world first, the club will then aim to use this technique to identify the victim the insects had been feeding on through DNA fingerprinting techniques.

In future, the club will therefore also need to rear flies and larvae in the laboratory. In doing so it will be essential to be able to observe and identify different types of flies, including the most common species in the UK ­­- Calliphora vicina, Calliphora vomitoria, Lucilia sericata and Protophormia terranovae – and become familiar with their forensic importance. Another major objective would be to test the principles of ADH (Accumulated Degree Hours), which is used to determine the age or stage in lifecycle of the insects by taking into account the temperature of the surroundings as that greatly affects their growth and development.

It is hoped that the club will provide students with a chance to be involved in novel research, improve their practical/experimental skills, develop analytical skills and perhaps even be able to publish their novel research. Wish us luck as we delve into the science of decay!