Mosquitoes may have retained their annoying buzz in order to attract mates, says a report published online on December 31st in Current Biology.
“There’s no doubt many of us have wondered why it makes its presence so obvious,” said Gabriella Gibson of the University of Greenwich at Medway and one of the researchers on the study. “Surely, after all of these centuries of blood-feeding, selection should have favored a more stealthy approach that would leave mosquitoes less vulnerable to the defensive attacks of its unsettled host.” However, sounds to attract a mate of the right species would be under stronger selection than the ability to silently approach a host, she said.
The study’s results help to explain how genetically diverse mosquito forms manage to reproductively isolate themselves. The complexity of malaria control is due in part to the mosquito’s genetic plasticity, which enables it to survive in a broad range of habitats.
To establish the identity of mates, male and female mosquitoes harmonize with each other. “They can do this even if they each sing a different note, say a ‘middle C’ and a ‘G’ four tones higher,” said Ian Russell at the University of Sussex. “By listening and subtly altering their pitch to minimize the dissonance, they achieve their goal of ‘singing’ in a perfect harmony that we, but not they, can hear.”
The researchers have now shown that two mosquitoes don’t harmonize successfully if they are of the same sex or if they are not the same type of mosquito.