A new advertising billboard in Rio de Janeiro targets not a human audience, but Brazil's population of Zika-spreading mosquitoes.
Developed by Brazilian ad firms Posterscope and NBS, the Mosquito Killer Billboard emits both carbon dioxide and a fine mist containing traces of lactic acid. These respectively simulate the breath of a sleeping mammal and human sweat, drawing Aedes aegypti mosquitoes, the primary infection vector for the Zika virus, to the billboard from as much as 4 kilometres away. Fluorescent black lights also help to attract the insects.
A catch mechanism is positioned at the bottom of the raised billboard to target the mosquitoes which, on average, fly 1.2 metres off the ground. The mechanism involves a hole through which a mosquito can enter and a cage with an isolation filter that keeps them from getting out again. Trapped inside the billboard, the insects die of dehydration. The agencies say that one billboard can kill hundreds of mosquitoes every day.
The design of the billboard has been licenced under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 and put online for anyone to download, share and make. The plans are slightly lacking in details of some aspects of the billboard's construction, such as how the isolation cage is built, but they provide clear specs for most of the equipment involved.
"It's impressive how many mosquitoes you can trap and how many lives you can save with this idea," Posterscope's Otto Frossard told the BBC, adding that the boards cost "a few thousand Reals" (several hundred pounds) to make.
The Zika virus has been given global health emergency status by the World Health Organisation and is particularly prevalent in Brazil, where it has been linked to birth defects and neurological diseases such as Guillain-Barré syndrome.