Mosquitoes are suckers for human blood. While much has been written about the reasons for the pesky insects’ bloodlust, the mechanism which drives this has remained a mystery — till now. A study published in the Proceedings of the National Academy of Sciences (PNAS) on July 1 suggested that a pair of hormones work in tandem to activate or suppress mosquitoes’ blood cravings.
Here is what you need to know.
What the study found
There are around 3,500 mosquito species in the world, spread across all continents with the exception of Antarctica. The females of these species consume animal blood to aid the development of their eggs. However, after their meal, female mosquitoes lose their appetite for blood till such time they lay their eggs.
Entomologist Michael Strand, of the University of Georgia in Athens, wanted to learn about the mechanism which controls this cycle. During his research, he saw that the levels of a certain mosquito gut hormone called F(NPF) spiked when they were looking for a host, and drastically dropped down once they were done feasting.
This motivated Strand to further analyse mosquito enteroendocrine cells, which are responsible for gut hormone production. He, along with his colleagues, found that the insects’ NPF levels shot up before they feasted on blood, and fell six hours later. The researchers also found that NPF levels dictated mosquitoes’ interest in humans — the insects did not care for human blood after their feast but “made a beeline” for it after laying their eggs.
The presence of another gut hormone, RYamide, was also found to influence mosquitoes blood lust. As NPF levels fell down after a blood meal, RYamide levels went up, and vice versa. The researchers thus surmised that NPF and RYamide work together to stimulate and suppress mosquitoes’ attraction to humans and other hosts.
Why this matters
“The discovery could provide new pesticide targets for preventing mosquito reproduction and disease transmission,” Zhen Zou, an entomologist at the Chinese Academy of Science’s Institute of Zoology in Beijing, told nature.com.
Mosquitoes are the deadliest animal on the planet. They act as vectors for diseases such as malaria, dengue, West Nile virus, yellow fever, Zika, chikungunya, and lymphatic filariasis, which together kill more people in the world than any other creature.
In fact, with climate change, mosquitoes are becoming ever-more prevalent, with diseases like dengue spreading to regions which previously were too cold for mosquitoes to survive.
Scientists are constantly working to better combat mosquito-borne diseases. This study will aid that effort.
