Identification of Human DNA from Degraded Mosquito Blood Meals Over Time

Hematophagous mosquitoes are considered among the biological evidence that can be collected at the crime scene to identify missing persons, perpetrators, or victims. This study is to simulate what might be expected at a crime scene with an insect that took a human blood meal and then died after various time intervals of post-feeding and remained at the crime scene for more periods. It aimed to analyze the DNA profiling of the Culex pipiens human blood meal stored at room temperature for a week after 24-, 48-, 72- and 96-hours of post-feeding. The two hypervariable regions (HV1 and HV2) of the mtDNA D-loop region were also used to define the possible period for identifying a person at the crime scene. The DNA concentration showed degraded amounts between 8.9 to 0.00 pg/µL due to the long storage. A complete STR profile was possible by direct PCR at 48 hours of post-feeding, while a partial profile was obtained 72 hours of post-feeding. It was possible to amplify HV1 & HV2 up to 96 hours of post-feeding. A gradual decrease of STR allele appearance and mtDNA with time course of post-feeding was recorded. MtDNA is more efficient than STR as HV1 & HV2 regions were possible to be amplified up to 96 hours blood meal of post-feeding. Thus, we conclude that mtDNA is an efficient molecular marker for time course identification of human DNA from blood meals taken by the mosquito. Examination of the blood meal of insects collected from the crime scene over a sufficient period, potentially aids in the identification of suspects and victims.