Malaria mosquitoes go to work cautiously before landing on human skin and biting. Just before a mosquito lands, it reacts to both odours and heat given off by the human body. Researchers at Wageningen University came to this conclusion after studying images made with infrared-sensitive cameras. Their research was published in the scientific journal PLOS ONE on 2 May.
Most malaria mosquitoes prefer human blood. They fly in the dark while their host is sleeping. In order to locate a host, they focus on traces of carbon dioxide, released by all animals, and on characteristic human odours. At a distance of 1.5 m from their host, they mainly follow body odours. Just before they land, however, heat radiating from the human body also plays a significant role.
The researchers and technicians at  Wageningen University, which is part of Wageningen UR, worked with colleagues from Noldus Information Technology BV using video recordings and automated 3D image analyses to clarify how malaria mosquitoes find their host.
In order to investigate seeking behaviour in mosquitoes, the researchers placed the insects in a special dark wind tunnel measuring 60 by 60 cm, with a length of 1.6 m. The air stream had a constant temperature and humidity, and a speed of 20 cm/second. The flight of each mosquito (Anopheles gambiae) in the tunnel was filmed by means of infrared-sensitive cameras.
When human odours were absent, the mosquitoes continued to fly into the wind through the tunnel.
