Australasian Science: Australia's authority on science since 1938

London’s Underground Mozzie Molests Us in Winter

By Stephen Luntz

The London Underground mosquito has been found in hundreds of locations in southern and central Australia.

If you thought Australia was already well-stocked with native mosquitoes, University of Sydney entomologist Dr Cameron Webb has warned of the dangers of an introduced species, the London Underground mosquito Culex molestus.

C. molestus is unusual. It prefers to breed underground and is active throughout the winter, rather than hibernating or surviving the colder months in egg form like species indigenous to southern Australia. Its preference for underground habitats turned it into a nuisance during the blitz when Londoners took shelter in railway stations.

“We are not sure if molestus evolved to breed in water in caves and took advantage of human constructions, the same way the dengue mosquito moved from tree hollows to water in pots round houses,” says Webb.

This choice of habitat means that molestus is common in urban areas and could thrive on grey water systems and other forms of water storage if they are not properly protected.

“We normally think of mosquitoes being a problem in the tropical regions of the world, but as the outbreak of West Nile virus in North America last year showed us, temperate regions of the world are at risk too,” Webb says. Molestus is known to carry West Nile virus.

Webb says no studies have been done to see if it can carry local diseases such as Ross River fever, but he fears the introduction of West Nile virus here. Molestus was a possible vector for the outbreak of a subtype of West Nile to horses in 2011.

“This is a very distinctive-looking mosquito, and there are no reports in Australia prior to the 1940s,” Webb says. The theory is it arrived with American troops in Melbourne in World War Two.

However, Webb says the Australian imports are more closely related to Asian varieties than their North American equivalents; molestus probably hitched a ride with the Japanese forces to the Pacific battlegrounds, where it thrived in the bunkers before changing sides and travelling south with the Americans.

Webb published 230 Australian locations where molestus has been found across southern and central Australia in The Australian Journal of Entomology. He hopes that raising awareness of molestus will encourage efforts to keep potential breeding sites secure.