• blow fly
• Calliphora vicina
• forensic entomology
• forensic pathology
• Lucilia sericata
• sampling
• storage

Forensic entomology (FE) is one of the most important tools for estimating the time since death by analyzing the species composition and age of the necrophagous fauna on the dead body. Sampling, transferring and killing/storing of this insect evidence is a very important task in forensic entomology because different methods can influence survival and further rearing of the living samples in the laboratory or bias the morphological examination of the dead specimens. The majority of “Best Practices” and “Guidelines” in forensic entomology recommend that fly larvae, the most important group in FE, should kept under controlled or at least known conditions, most suitable at 2-6°C. They suggest in addition that larvae should be stored in vials with an air-permeable lid and that these vials should be equipped with coarse sawdust or paper for taking e.g. excretion liquids. Living samples should be then transport to an expert within 24 hours. While keeping the latter window of time is a realistic approach, cooling the samples or catering them during storage can be a difficult task for crime scene technicians or forensic pathologists. But neglecting guidelines or best practice recommendations could lead to a weakening of the entomological evidence at court or even its exclusion. However, so far it is not always clear whether and which of these recommendations are based on experiences, opinions or scientific proofed evidence.
What happens if there was no ventilation or no appropriate cooling and catering? Is there any unusual mortality or altered development when reared in the laboratory for estimating their age?
We stored all developmental stages of larvae (L1, L2 and L3) of the forensically relevant blow flies Lucilia sericata and Calliphora vicina at room temperature (~20°C) or in the refrigerator (5°C) for 16 hours without air, supply of food and sawdust. After that they were kept at 2-6°C in a Styrofoam box for 8 hours, simulating a transport situation. At the end of this treatment mortality rate was calculated and 25% of the surviving larvae were killed in hot but not boiling water, length measured and the remaining specimens were reared (25 °C) until all adults were hatched. A control group was created for every treatment.
Results showed that the mortality rate is higher in room temperature groups vs fridge groups and L2-L3 vs L1 and they could suggest that if it is strongly necessary storing alive samplings without air conditions or food, they should be stored in fridge instead of room temperature and the latter is recommended only for larvae with size L1-L2 stages (~ 1 cm).