Scientists have discovered a secretive and exotic species of mosquito, which, unlike others of its kind, do not require a blood meal before laying eggs. Researchers found that rather than breeding in ponds, pools or wetlands, the culex molestus mosquito has adapted to life underground, particularly in septic tanks and disused stormwater pipes. Unlike other mosquitoes, this species can also develop their eggs without first requiring a blood meal.
“The curious biological trait of this underground-dwelling mosquito shows that people in cities need to take mosquitoes’ amazing adaptability into account when designing water storage systems,” said Cameron Webb, medical entomologist from University of Sydney Medical School, who led the study, the Journal of Vector Ecology reports.
“We have spent the last two years chasing the species, which has adapted superbly to life beneath our cities. Finding this mosquito isn’t easy. Instead of wandering through pristine wetlands, we were snooping around stormwater drains and other polluted structures,” said Webb, according to a Sydney statement.
“However, the toilet blocks in urban parklands were where we really struck gold. The disused septic tanks associated with these structures are where this mosquito is commonly found,” said Webb.
While the majority of pest mosquitoes require blood to develop their eggs, the female of this species can develop and lay a batch of eggs using nutrients stored earlier in its life cycle. This phenomenon is known as autogeny and has been documented in a number of mosquitoes.
“The breakthrough with our study is that if this mosquito is offered a blood meal, it won’t bite until its first batch of eggs has been laid. We believe this is the only Australian species to exhibit this behaviour,” Webb said.
“Once that first batch of eggs has been laid, they are on the hunt for blood and can be severe nuisance-biting pests.”
“One of the major implications of this work is that we must be mindful of the mosquito risks when designing subterranean water storage systems in our cities so we do not create new opportunities for mosquitoes,” said Webb. Culex molestus is thought to have been introduced into southern Australia in the 1940s, hitching a ride with travelling US servicemen.