How light can ward off misquotes bites

Exposing malaria-causing mosquitoes to short pulses of white light during the night can prevent them from biting, scientists say. Critical behaviours exhibited by the Anopheles gambiae mosquito – the major vector for transmission of malaria in Africa – such as feeding, egg laying and flying, are timeofday specific, including a greater propensity for night-time biting.

Insecticide-treated bed nets and walls have helped prevent bites and reduce malaria, but researchers say mosquitoes are adapting to preventive conditions, leaving adults and children vulnerable in the early evening and early morning hours – when they are not under the nets or in the house.

“Anopheline mosquitoes are adapting to current preventive methods by developing resistance to insecticides and by shifting feeding to earlier in the evening or later into the early morning, times of the day when people are not in bed and therefore not protected by a net,” said Giles Duffield, associate professor at the University of Notre Dame in the US.

Researchers tested the mosquitoes’ preference to bite during their active hostseeking period by separating them into multiple control and test batches. Control mosquitoes were kept in the dark, while test batches were exposed to a pulse of white light for 10 minutes.

Researchers then tested the propensity of the mosquitoes to bite immediately after the pulse and every two hours throughout the night, holding their arms to a mesh lining that allowed uninfected mosquitoes to feed while remaining contained.

Results indicated a significant suppression. In another experiment, mosquitoes were pulsed with light every two hours, and using this multiple pulse approach the team found that biting could be suppressed during a large portion of the 12- hour night.