In a scene that might seem like it was pulled from a horror movie, large drones are now soaring through the skies of Hawaii, dropping capsules filled with mosquitoes into remote forests.
While the idea of unleashing an army of mosquitoes may sound alarming, this initiative is part of a strategic plan to tackle a dire environmental crisis facing the Hawaiian islands.
Hawaii is grappling with an extinction crisis, having lost hundreds of species over the past two centuries, including many unique land snails and birds, primarily due to the spread of non-native animals such as feral pigs and stray cats.
This loss has left distinctively Hawaiian fauna teetering on the brink of extermination, prompting scientists to act swiftly to save the dwindling wildlife still in existence.
For Hawaii’s rare forest birds, particularly significant to Indigenous Hawaiian culture, the primary threat of extinction comes from malaria, a disease spread by mosquitoes.
These invasive insects were unintentionally introduced in the early 1800s via a whaling ship, rapidly multiplying and transmitting avian malaria, which is lethal to many bird species.
The disease has had devastating impacts on Hawaii’s forest birds, particularly the honeycreepers, a group of finch-like songbirds that once numbered over 50 species but now only 17 survive today.
The silence in Hawaii’s forests is telling; only a few honeycreepers manage to avoid malaria by residing in higher elevations that are too chilly for the mosquitoes.
However, as climate change continues to warm the islands, these insects are ascending into the birds’ remaining refuge areas, leading some experts to depict the situation as an “extinction conveyor belt.”
To counteract this situation, scientists are racing against time.
Enter the drone project.
For over a year, a coalition of environmental organizations has been deploying biodegradable capsules filled with mosquitoes into honeycreeper habitats in Maui and Kauai, initially using helicopters but now transitioning to drones.
These containers are designed without tops, allowing the insects to escape into the forest when they land.
Importantly, these are not ordinary mosquitoes.
All released mosquitoes are male—who do not bite—and have been bred in a laboratory.
Furthermore, they carry a strain of bacteria known as wolbachia, which disrupts reproduction; male mosquitoes that mate with local females will produce eggs that fail to hatch.
This innovative method, known as the incompatible insect technique (IIT), aims to significantly reduce the biting mosquito population responsible for spreading malaria, thereby protecting Hawaii’s vulnerable forest birds.
Chris Farmer, Hawaii program director at the American Bird Conservancy, emphasizes that there are minimal ecological ramifications from this project.
Since mosquitoes are not native to Hawaii, local ecosystems do not depend on them.
“What this does is it erects an invisible barrier so that these mosquitoes can’t get up to the forests where these birds remain,” says Farmer.
Since late 2023, the collaborative effort known as Birds, Not Mosquitoes has already released over 40 million male mosquitoes across Maui and Kauai.
Most of these releases were initially conducted using helicopters, which transport roughly 250,000 mosquitoes at once compared to about 23,000 for drones.
Despite the helicopters’ capacity, drones offer significant benefits as they reduce risk by being unmanned and are easier to deploy instantly.
Adam Knox, the drone pilot and project manager for aerial mosquito deployment at American Bird Conservancy, notes the advantages of using drones for such operations.
The unusual concept of distributing mosquitoes from drones may sound strange, but conservation experts like Marm Kilpatrick, an avian malaria specialist at the University of California Santa Cruz, assert it might be one of the most effective strategies available to aid Hawaii’s honeycreepers.
“The reason that it’s worth doing is that so far, we haven’t discovered anything else that can possibly do this better,” Kilpatrick said.
Although it is still uncertain if the release of sterile mosquitoes is effectively lowering the resident population of disease-carrying mosquitoes, ongoing research is dedicated to monitoring its impact.
Christa Seidl, mosquito research and control coordinator at the Maui Forest Bird Recovery Project, acknowledges that conclusive results are yet to emerge, as research continues.
Lessons from global health initiatives have been instructive for the project.
Other regions have successfully utilized the same reproductive disruption method to curb mosquitoes that transmit diseases to humans, like dengue fever, leading to significant decreases in illness.
“We’re standing on the shoulders of human disease,” Farmer remarked,
“The IIT we’re using for conservation was first developed for human health.”
The ultimate objective is not to eradicate mosquitoes that carry avian malaria entirely; that goal is deemed nearly impossible without launching an overwhelming number of lab-bred insects.
In the short term, the plan is to ensure a regular and ongoing release of these special mosquitoes into the forests that harbor endangered bird species like the kiwikiu, ‘ākohekohe, and ‘akekeʻe.
Assuming there are no regulatory or technical challenges, the deployment of drones will soon become a standardized process in this critical initiative.
“This is the last chance to save most of our remaining songbirds,” Farmer declared.
“When we’ve succeeded, the birds will come back.”
image source from：https://www.vox.com/down-to-earth/416699/hawaii-endangered-species-birds-mosquitoes
