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When a Mosquito Can’t Stop Drinking Blood, the Result Isn’t Pretty

engorged Aedes aegypti mosquitoes

An Aedes aegypti mosquito with an abnormally large blood meal (left) next to typical engorged mosquito (right) for comparison. (Photo by Perran Ross, Ph.D.

By Perran Ross, Ph.D.

Perran Ross, Ph.D.

Perran Ross, Ph.D.

An urban legend says that if you tense your muscle when a mosquito bites you and feeds on your blood, it can swell up and explode. With mosquitoes often cited as the most hated creature on the planet, the idea of being able to make them burst at will is perhaps an appealing one to many. But, having spent the better part of a decade feeding mosquitoes on my own arms for research, I can confidently say that it’s a myth. There is, however, a way to make mosquitoes actually burst; all it takes is a steady hand and some forceps.

The first ever exploding mosquitoes can be attributed to Robert Gwadz, Ph.D., in a discovery that was made through basic laboratory research over 50 years ago. He found that making an incision in the ventral nerve cord of a mosquito cuts off the signal to stop feeding, giving it an unquenchable thirst for blood. Mosquitoes that have undergone this procedure can drink in excess of four times their weight and may eventually burst. This led Gwadz to a hypothesis that blood ingestion is regulated by abdominal stretch receptors that prevent mosquitoes from (quite literally) drinking themselves to death.

Mosquito ventral nerve cord incision diagram

Severing or crushing the ventral nerve cord of a mosquito at the point shown by the green arrow leads to an unregulated intake of blood. (Image by Perran Ross, Ph.D.)

Although this research is fundamental to our understanding of blood feeding behavior in mosquitoes, the results have rarely been repeated. So, while running my own experiments involving blood-feeding mosquitoes, I attempted to replicate these findings using a simple procedure.

Female Aedes aegypti mosquitoes (only females feed on blood) were immobilized by placing them in the fridge for an hour. Then, under a dissecting microscope, I used a pair of forceps to pin the mosquito down on its side and a second pair to pinch the abdomen (pictured above), crushing the ventral nerve cord. The next day, I let the mosquitoes feed on my arm, as we do routinely in our laboratory. And then the magic happened.

Warning: Graphic content. Mosquitoes undergoing a simple operation are unable to sense when they are full, drinking blood until they burst. (Video by Perran Ross, Ph.D.)

The video above—which, be warned, may not be suitable for those squeamish at the sight of blood—shows some of the more dramatic results of the operation. Mosquitoes drank far beyond their fair share of blood and were rendered unable to fly or even walk. Others went even further, drinking so much that they eventually burst. Often, they would continue to feed long after their abdomen ruptured, unaware that what was going in was coming straight out the other end.

Although the results are dramatic, performing surgery on individual mosquitoes is not a practical way to control mosquito populations or reduce the incidence of mosquito-borne diseases. But this knowledge of mosquito biology and their blood-feeding mechanisms could have many unexpected applications and inspire future research. For instance, one group of researchers is exploring how mosquitoes discern between plant nectar and blood. And the discovery that diet drugs can suppress mosquito appetite came from simple curiosity. Although we probably don’t want blood from exploding mosquitoes raining down from the skies, sometimes it takes an absurd question for an important scientific breakthrough.

Perran Ross, Ph.D., is a postdoctoral research fellow in the School of BioSciences at the University of Melbourne, Australia. He is investigating ways to control insect pest and disease vectors with endosymbiotic bacteria. Twitter: @MosWhisperer. Website: https://blogs.unimelb.edu.au/pearg/. Email: perran.ross@unimelb.edu.au.

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