July 11 (UPI) — New research proves human DNA can be successfully extracted from mosquitoes and sequenced two days after feeding.
Forensic scientists have previously suggested suspects could be placed at the scene of the crime if their DNA was recovered from a local mosquito population. But until now, researchers weren’t sure how long it takes mosquitoes to digest human blood and render DNA unrecognizable.
The new research — published this week in the journal PLOS ONE — suggests human DNA remains intact inside a mosquito’s stomach for at least two days after consumption.
“We asked several volunteers to let mosquitoes bite them,” Yuuji Hiroshige, a forensic scientist at Nagoya University in Japan, said in a news release. “After allowing the mosquitoes to digest the blood for a certain amount of time, we extracted the human DNA and used PCR techniques to amplify the sample for quantification and genotyping.”
Scientists used polymerase chain reaction to amplify DNA fragments in the mosquito blood. The technique allowed scientists to identify DNA fragments belonging to the study participants.
After three days, researchers found no recognizable DNA fragments, as the human blood had been completely digested.
“Ours is the first study to systematically apply modern DNA profiling techniques to the challenging forensic analysis of mosquito blood meal,” said lead researcher Toshimichi Yamamoto. “We hope this will help crime scene investigators collect reliable evidence that could be used to guide investigations and support convictions. Although we need to take some steps to improve our methods and obtain more data, with more accurate quantification methods, we might be able to estimate the time after mosquitoes’ blood feeding with even greater accuracy.”
