LIHU’E — A team of researchers working to prevent the extinction of Hawai‘i’s endangered forest birds through the release of incompatible mosquitoes in Koke‘e are set to conclude a 10-day pilot project on Saturday, Nov. 4. The project is part of a nearly $7 million per year state plan to decimate mosquito populations, in an effort to stop the spread of avian malaria and give the birds a chance at survival.
The trial started on Thursday, Oct. 26, when a team of 12 individuals released 20,000 incompatible male mosquitoes at Koke‘e State Park, off a road on Alaka‘i Plateau. The mosquito deployment project was first announced by the state Department of Land and Natural Resources (DLNR) last week.
The department noted that female mosquitoes carrying avian malaria are moving higher and higher into honeycreeper habitats as temperatures warm, transmitting avian malaria, and killing many honeycreepers.
The 10-day pilot project on Kaua‘i to inform future mosquito releases, called the Mark-Release-Capture Study by the DLNR, costs $847,035, said Ryan Aguilar, a communications specialist with the DLNR, in an email response to The Garden Island.
The project is the initial phase of a long-term project aimed at stopping the extinction of at least four species of birds in the family called the Native Hawaiian honeycreepers.
It will cost approximately $6 million per year to implement the mosquito suppression method on the island, according to the DLNR. The department did not say how many years it intends to implement the project.
“We have applied for this funding from another federal source,” Aguilar said.
The Garden Island spoke on Thursday, Nov. 2, with Lisa “Cali” Crampton, the program manager for the Kaua‘i Forest Birds Recovery Project, who is overseeing the pilot project.
The Kaua‘i Forest Birds Recovery Project is part of Birds, Not Mosquitoes, a multiagency coalition made up of state, federal, nonprofit and private organizations working to protect Hawaiian forest birds by suppressing mosquito populations.
“Forest birds are essential to the very fabric of Hawai‘i’s culture,” said Crampton, who explained her organization’s work to prevent further decline.
Populations declining
In her interview, Crampton referred to three specific species of Native Hawaiian honeycreepers that are most threatened by avian malaria: the ‘akikiki or Kaua‘i creeper, the ‘akeke‘e or Kaua‘i ‘akepa and the i‘iwi or scarlet honeycreeper.
“For some of the other species, there are also other reasons (for population declines). But for these species, the main threat at the present time is mosquito disease,” Crampton said.
“(They) are very close to disappearing not only from Kaua‘i but from the whole planet because of these diseases.}
Both the ‘akikiki and ‘akeke‘e are state and federally listed as endangered, and the ‘anianiau is listed as vulnerable.
The ‘akikiki had an estimated wild population of 45 individuals in 2021, according to the U.S. Fish and Wildlife Service, who estimated at the time the bird would go extinct “most likely in 2023.” In July 2023, the DLNR reported there were only five ‘akikiki left in the wild, saying their chances of survival were slim.
Meanwhile, the ‘akeke‘e has decreased to 250 pairs, the DLNR reported in September 2023, noting that at one time its population was estimated at 150,000.
The i‘iwi species, while not considered endangered, has also rapidly declined on Kaua‘i, with a population estimated at 1,855 on the island, according to 2020 information from the United States Geological Survey. The species is still common on Maui and Hawai‘i Island, with a total population estimated to be around 600,000 in 2020.
Plan for bird recovery
Crampton explained the efforts to control mosquito populations, which are transmitting the deadly disease to native forest birds through the Incompatible Insect Technique (IIT)
In order for males and females to reproduce, they have to carry the same strain of Wolbachia, an intracellular bacteria that all mosquitoes in Hawai‘i naturally carry in their cells, she said.
If the male is carrying a different strain of the bacteria, the male’s sperm will be incompatible and the female will lay an inviable egg that can’t hatch.
The male mosquitoes are made to be incompatible through the lab manipulation of the strain of Wolbachia that they are carrying.
“Then we inject a different strain of a bacteria that is either carried by a different species of mosquito or like a species of fruit flies. So it’s just different and incompatible to the strains that wild females are carrying,” Crampton said.
“So almost all females will be with incompatible males and have unviable offspring. So that’s the long-term plan to control mosquitoes on the landscape,” she added.
Crampton noted the current small-scale study following the release of 20,000 males is meant to only track their survival and dispersal in the area.
“Depending on how far they move and how long they live, we will adjust our eventual control program to either release males more or less often depending on how long they live,” she said.
“We have to do the study first to figure out what our eventual parameters will be when we go to release lots more males on the environment to control mosquito populations.”
For the pilot project, the incompatible male mosquitoes were received from a private company in cardboard boxes. The researchers strung a bug dorm, a rectangular mesh enclosure used to house and study the bugs, as well as placed dozens of traps near the release site.
Following the end of the pilot project on Saturday, Nov. 4, the mosquitoes caught in traps will be sent to the lab for diagnosis to determine whether they are incompatible or compatible.
Crampton noted the team has been successful at catching mosquitoes in traps, which is a strong indicator that they are incompatible as wild males are rarely caught in traps.
The team plans to repeat the trial through a second version of the study in late November 2023.
Large-scale release to come
In the long term, the Kaua‘i Forest Bird Recovery Project is planning a large-scale strategy, as it plans to start releasing 500,000 incompatible males per week in more remote areas of the Alaka’i Plateau in about one year.
The plan is for the mass numbers of incompatible males to cause the mosquito populations to crash, stopping them from spreading the deadly virus to Native Hawaiian honeycreepers.
“As mosquito population crashes in those areas, then the disease will also virtually go away, and forest bird species will have better survival and begin to recover,” Crampton said.
Eventually, the goal is to treat 3,000 acres with hundreds of millions of incompatible male mosquitoes.
Crampton emphasized the importance of the birds to the country’s biodiversity and was hopeful about their eventual recovery.
“They live in the forest, and they need the forest. But the forest also needs them because it’s the forest birds that are eating the insects that would otherwise kill the trees,” Crampton said.
“The forest birds are integral to everything that makes a Hawaiian forest, a Hawaiian forest. And Hawaiian forests are the backbone of Hawaiian culture and watersheds.”
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Emma Grunwald, reporter, can be reached 808-652-0638 or egrunwald@thegardenisland.com.
