Forensic scientists recover human DNA from mosquitos

July 10, 2017, Nagoya University
Stereomicroscopic images of two mosquito species at taken at different times after feeding on human blood. The upper and lower images respectively show Culex pipiens pallens and Aedes albopictus at different stages of digesting a human blood meal. (a) Unfed, and (b) 0 h, (c) 24 h, and (d) 72 h after-feeding. Credit: Toshimich Yamamoto

Nagoya University research team shows that human blood extracted from mosquitos remains viable for DNA analysis up to two days after feeding.

Most people would agree that painful mosquito bites are an especially annoying part of summer. Except perhaps forensic scientists, who can examine human blood from a mosquito's stomach and match the DNA to determine who was bitten. This technique can help police work out who was at a and in the future, might provide evidence that can be used to convict offenders. But questions remain about how long it takes a mosquito to digest and how long before the DNA becomes unrecognizable.

Now a team of at Nagoya University has answered these questions.

"We asked several volunteers to let mosquitos bite them", explains first author Yuuji Hiroshige. "After allowing the mosquitos 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."

Polymerase chain reaction, or PCR, is a standard tool in forensics for amplifying a minute amount of DNA. A single DNA fragment can be multiplied many thousands or even millions of times. The team can then use the amplified samples to find out how much DNA is left after the mosquito feeds and who it belongs to.

By examining DNA in blood digested by two different species of mosquito over a range of times after feeding, the team was able to trace back blood samples to individual volunteers, even after two days of digesting in the mosquito. After roughly three days the mosquitos completely digested the blood.

Group leader Toshimichi Yamamoto says, "Ours is the first study to systematically apply modern DNA profiling techniques to the challenging forensic analysis of mosquito blood meal. We hope this will help 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 ' blood feeding with even greater accuracy."

Explore further: Trapped Amazonian mosquitos reveal their last meals: humans, birds, and small mammals

More information: Yuuji Hiroshige et al. A human genotyping trial to estimate the post-feeding time from mosquito blood meals, PLOS ONE (2017). DOI: 10.1371/journal.pone.0179319

Related Stories

Antibody test gauges mosquito exposure

December 1, 2016

How many mosquitoes live in your neighborhood? How many mosquito bites have you and your neighbors gotten this week? Answering these questions—and gauging how mosquito populations change over time or after a control strategy ...

Recommended for you

Why bioelectrodes for energy conversion are not stable

May 25, 2018

Researchers at the Ruhr-Universität Bochum have discovered why bioelectrodes containing the photosynthesis protein complex photosystem I are not stable in the long term. Such electrodes could be useful for converting light ...

Simulations show how beta-amyloid may kill neural cells

May 25, 2018

Beta-amyloid peptides, protein fragments that form naturally in the brain and clump into plaques in Alzheimer's disease patients, are thought to be responsible for neuron death, but it hasn't been clear how the substances ...

The changing shape of DNA

May 24, 2018

The shape of DNA can be changed with a range of triggers including copper and oxygen—according to new research from the University of East Anglia.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

winthrom
not rated yet Jul 10, 2017
And Jurassic Park mosquitoes ???

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.