Aerial war targets avian malaria-spreading mosquitoes

ALAKAI PLATEAU — An aerial war is being waged above native forests on Kauai in an effort to save the near-extinct honeycreeper.

The honeycreeper, also known as akikiki, has long been under threat from avian malaria-spreading mosquitoes. To that extent, conservationists have been using a helicopter dubbed “Dusty” to spread a globally-used bacterium in forests inhabited by the honeycreeper.

The bacterium, known as Bacillus Thuringiensis Israelensis or Bti for short, naturally occurs in soils and waterways. Bti is harmless to other creatures and critters, but can suppress mosquitoes that carry avian malaria.

“It won’t affect any vertebrates like fish or birds, or your dog or your pig, or even you if you happen to drink water that this bacterium is found in,” said Dr. Lisa “Cali” Crampton, who is the project manager for the Kauai Forest Bird Recovery Project, in an update provided by the Department of Land and Natural Resources.

The aerial effort has been ongoing twice each month, three days at a time, since fall 2023 with the helicopter flying up to a 1,200-acre parcel on the Alakai Plateau. The helicopter is equipped with a boom that features dozens of nozzles used to spread Bti over land and streams.

Bti has proven effective, having been used for public health and control of mosquitoes, said Lindsey Nietman, the forest bird recovery project coordinator, in remarks made at a Board of Land and Natural Resources meeting in June.

“It’s EPA (Environmental Protection Agency approved, and you can buy it over the counter,” she told the board.

“It can be applied by truck, handheld broadcast sprayer or aircraft. We’re using a helicopter because we’re trying to target the millions of little ponds of water in Hawaii’s rainforests, where mosquitoes can breed.”

The initial phase of the project on Kauai found that water with BTi killed mosquito larvae at much greater rates than water without the bacteria, which led to the second phase.

“Like most mosquito control treatments, this is year-round suppression,” Crampton said. “We want to keep their numbers down to decrease disease transmission rates, so birds will not get infected as often by mosquito-borne diseases like avian malaria.”

The same applications are expected to begin next year in Maui where another tool is being used to control mosquito populations — Incompatible Insect Technique or ITT. ITT is scheduled to join BTi on Kauai at some point next year.

“I think the tricky question in conservation right now is that there is such a crisis and there is such a demand on financial and other resources, we’re all trying to figure out the best way to deal with our huge problems,” Crampton said.

She added, “Is it bringing all remaining individuals of at-risk species into captivity until we can get landscape-scale mosquito suppression? We need people to understand the importance of these tools and backing initiatives to employ all available tools.”