Why scientists in Hawaii are releasing thousands of mosquitoes to save endangered birds
By Daniel Boal, ITV News producer
Thousands of mosquitoes are being dropped into Hawaii by drone in a bid to save an almost extinct species of bird.
These aren't just any mosquitoes.
The ones being dropped are non-biting, lab-reared male mosquitoes which carry a bacteria meaning they cannot successfully mate with wild female mosquitos.
Scientists hope they will help control the archipelago's invasive mosquito population, which has decimated native bird populations including the rare Hawaiian honeycreepers.
The birds play a central role in Hawaiian ecosystems as pollinators and seed dispersers.
At one point, there were more than 50 known species of honeycreepers in Hawaii, but today there are only 17 left, the majority of which are now endangered.
One species, named the 'akikiki' became functionally extinct in the wild last year due to malaria-carrying mosquitoes.
With no resistance to mosquito-borne diseases, the birds are falling victim to fatal avian malaria.
While development and deforestation have also led to falling bird populations, experts believe avian malaria to be the main threat.
Mosquitoes aren't native to Hawaii, and were first reported in 1826 after being carried in by whaling vessels.
Speaking to ITV News' US partner CNN, Dr Chris Farmer, Hawaii programme director for the American Bird Conservancy (ABC), said mosquitos cause "waves of extinction."
The insects thrive in tropical climates with low elevation, forcing the remaining honeycreepers to find refuge in the mountains.
Farmer added: "With climate change, we are seeing warmer temperatures, and we’re watching the mosquitoes move up the mountains.
"(In places like Kauai), we’re watching the populations of birds there just completely plummet.
"It’s a constant march of mosquitoes moving up as the temperatures allow them, and the birds getting pushed further and further up until there’s no habitat left that they can survive in.
"If we don’t break that cycle, we’re going to lose our honeycreepers," he adds.
What are conservationists doing?
Experts have been trying to control the population of mosquitoes through various methods.
Pesticides, which would usually be used to control insects, affect them indiscriminately and would damage damselfly and fruit fly populations - both of which are vital to ecosystems.
Scientists have successfully bred male mosquitoes in a lab that carry a strain of naturally occurring bacteria, which causes non-viable eggs when they mate with wild females.
Over time, with repeated releases, the population of wild mosquitoes should fall.
Farmer said: "Whenever you say, ‘I want to release millions of mosquitoes in the forest,’ people have a lot of very legitimate questions.”
The method has never been used on this large of a scale before, but if successful in curbing mosquito populations, honeycreepers would have time to replenish populations with more genetic diversity, which may even develop their own resistance to avian malaria.
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