Shown here, the kiwikiu is a small Hawaiian honeycreeper endemic to Maui and is critically endangered. Populations of the kiwikiu and other honeycreepers on the islands have been decimated by avian malaria, a mosquito-borne disease to which these birds have little to no resistance. Scroll through the gallery to see more. Robby Kohley
According to CNN
In June, thousands of biodegradable packets dropped over Hawaii’s forests, each containing about 1,000 mosquitoes. Importantly: these insects do not bite people – they are laboratory-reared males carrying the Wolbachia bacterium, which causes eggs not to hatch when mating with wild females. The goal of such releases is to reduce the invasive mosquito population and protect local birds, especially honeycreepers.
Honeycreepers – key pollinators and seed dispersers, and important to Hawaiian culture. Historically in Hawaii there were more than 50 species of these birds, but today only 17 remain, and most are now threatened with extinction. In 2022 some species disappeared from the wild forever.
According to Dr. Chris Farmer, director of the Hawaii program of the American Bird Conservancy (ABC), the “significant threat” is avian malaria carried by mosquitoes.
“The mosquito that carries avian malaria differs from the one that carries human malaria.”
The insects are not native to Hawaii; they first appeared in 1826, likely unintentionally brought by whalers. Farmer notes that they have caused waves of disappearances among local birds.
Because mosquitoes thrive in the warmer tropical zones at lower elevations, the remaining honeycreepers sought refuge higher in the mountains, notably on Maui and Kauai; however climate change is forcing the population to shrink and move higher.
“Climate change is driving warmer temperatures, and we’re seeing mosquitoes move uphill in the mountains. In places like Kauai, bird populations there are simply collapsing.”
According to Farmer, it’s a long-running process: mosquitoes rise higher, and birds retreat further above survival zones. If we don’t break this cycle, honeycreepers could disappear forever.
“If we don’t break this cycle, we will lose our honeycreepers.”
Conservationists have been seeking solutions to control mosquito populations and save honeycreepers, but the use of pesticides could harm beneficial insects. One of the strategies under consideration is IIT – the infectious Wolbachia-based approach.
This method involves releasing male mosquitoes with a specific Wolbachia strain that makes eggs infertile after mating with wild females. Over time, through repeated releases, the wild population should decline.
In 2016, ABC, in partnership with Birds Not Mosquitoes and other organizations, began IIT research in Hawaii to apply it to mosquitoes that carry avian malaria. “The mosquito that carries avian malaria differs from the one that carries human malaria,” explains Farmer, so they tested different Wolbachia strains on local Hawaiian house mosquitoes to determine the most effective.
The process took years, thanks to a combination of scientific approach, community engagement, and regulatory steps. In 2022 they began scaling up production, breeding millions of mosquitoes with the chosen Wolbachia strain in a California lab. The following year they started releasing these mosquitoes into honeycreeper habitats on Maui, using helicopters and biodegradable packets that break down.
“We have an approximate estimate of the number of mosquitoes in the wild and are trying to release ten times more Wolbachia-infected mosquitoes so they meet females and can mate, after which their eggs will not hatch,” explains Farmer. “Right now we are releasing 500,000 mosquitoes per week on Maui and 500,000 on Kauai,” he adds, using both drones and helicopters.
According to Farmer, this is the first world-wide example of applying IIT for conservation. If the approach is successful, he hopes it could be applied in other countries as well. At the same time, he cautions that in Hawaii mosquitoes are an invasive species and do not play a significant ecological role, so in other countries there could be ecosystem consequences.
One of the main hurdles is remoteness and the rugged mountainous terrain where winds and weather are often variable. Therefore, releases are primarily conducted by aviation, but it is costly and limited, and also requires balancing with firefighting and tourism. That is why drones have become an important addition to the program. After extensive testing in challenging conditions, in June mosquitoes began to be distributed using drones. “This is the first known case of dispersing special mosquito packets with drones”, notes Adam Knox, ABC project manager for aerial mosquito deployment.
“We have greater flexibility in deployment timing in regions with unpredictable weather, and it’s safer because people don’t need to fly a plane to deploy mosquitoes,” adds Knox. This solution reduces costs, flight times, emissions, and noise, making deployment more accessible and sustainable.
Farmer expects that the first results will appear in about a year, and that IIT will help “buy time” for the birds’ recovery. A recent study by the San Diego Zoo Society and the Smithsonian Conservation Institute indicates a chance to save honeycreepers if IIT proves effective. Christopher Kyriazis, a postdoctoral researcher at the San Diego Zoo Society and lead author of the report, told CNN: “If we just wait a few years, the window of opportunity will quickly close.”
Although IIT is an ambitious step, which has not previously been applied at such scale for conservation, experts hope it can pay off. If we can control the mosquito population, honeycreepers will gain time to recover and increase genetic diversity – perhaps they will even develop resistance to avian malaria. But Kyriazis cautions that even with a protective mutation, its rapid spread through the population is unlikely to become possible.
Safer conditions will also allow reintroductions of some birds in captivity, notably akikiki; although they disappeared in the wild, they are now being raised at a Hawaii conservation center. For Farmer, being at the forefront of this initiative and witnessing bird losses is a “heartbreak,” but it is also a drive for action: “We have a chance to save these species. If we do not conserve the birds this decade, they probably won’t appear in the future. And so the chance to change the world motivates us all.”
