Each week we solve one of London’s great mysteries (as submitted by you, the reader). This week Tom Dodd from Shoreditch asks: ‘is it true that the London Underground has its own species of mosquito?’
This is not a belated April Fool: it’s true! Back in 1999 geneticists Kate Byrne and Richard Nichols analysed the phenomenon in a research paper, ‘Culex pipiens in London Underground Tunnels: Differentiation Between Surface and Subterranean Populations’. The study found that London Underground had its very own family of mosquitoes- a unique species that is alive and well and has most likely been commuting with us for years.
Most of us have been irritated by pests on the tube at some point in our travelling lives. But surely the Underground is far too hostile a place for any living thing to thrive for long? We tracked down Byrne at the London Institute of Zoology to find out more about this subterranean sucker. ‘My assumption is that they have been there as long as the Underground has existed,’ said Byrne. ‘They were certainly present during the war, when people were frequently bitten while using the Underground as an air raid shelter.’
The mosquitoes are unique, Byrne explained, because ‘they have adapted to a manmade environment, changing their biology in the process, and have become reproductively isolated from surface mosquitoes.’ The insects are able to survive in this environment due to the damp nature of Underground tunnels. ‘Mosquitoes require water in which to lay their eggs,’ she said. ‘Water in the Underground is full of nutrients, which come from everything from discarded sandwiches to shed human skin. Nutrient-rich water means large, healthy mosquitoes, and it importantly means that females are able to lay at least one batch of eggs without needing a blood meal.’ We asked Byrne if the mosquitoes have a favourite tube line. She explained that, even within the system, there are distinct populations on the different lines, ‘presumably because it is easier to move up and down tunnels on the same line than from one line to another’. It turns out everybody in London has an opinion on the best line to travel on – even those pesky mosquitoes. Clare Considine
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