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Experts: New mosquito birth control ‘game-changing’ for endangered avians

HANAPEPE — The last refuge of the island’s endemic forest birds is no longer safe.

Climate change has propelled mosquitoes and the deadly avian diseases they carry deeper into the endangered birds’ upslope habitat for years. The results have been catastrophic.

But a new film, “The Forest Birds of Kaua‘i: Mosquito Transmitted Diseases,” offers hope.

The five-minute video, produced by the Kaua‘i Forest Birds Recovery Project and the American Bird Conservancy, shows researchers reducing the island’s mosquito population by placing a naturally occurring bacterium, Bacillus thuringiensis subspecies israelensis (Bti), in island streams.

Bti is lethal to mosquitoes and some midge larvae. It is otherwise harmless. The federal Environmental Protection Agency recognizes its use by organic-farming operations.

However, Bti is a short-term fix at best. Experts say native birds’ salvation lies with a halt to climate change and another bacteria, Wolbachia, which naturally occurs in the guts of many insects in Hawai‘i.

“The idea is that we will rear male mosquitoes in labs and inject them with a different strain of Wolbachia than wild females carry, and release them in large numbers across the landscape,” KFBRP leader Lisa “Cali” Crampton says in the film, which premiered online Thursday. “Most of the females would end up with inviable eggs and we would have suppressed the mosquito population through birth control.”

Wolbachia-injected mosquitoes have been used on the mainland, but their introduction to Hawai‘i is still a few years away, experts said during a panel discussion and question-and-answer session that followed the premiere.

“To finally have a solution is just game-changing. This is really encouraging and energizing,” said Chris Farmer of the American Bird Conservancy. “We’re so close to getting all the pieces in place to save the wild forest birds … we’re all going incredibly hard because we know that we’re just so close.”

Farmer said conservationists will file the first necessary permit with the EPA later this year, and hope to complete preliminary trials in 2022. Small-scale usage of Wolbachia-injected male mosquitoes, which do not bite, would occur in 2023. Large-scale usage would not occur until 2024.

The reduction or eradication of island mosquito populations will do no damage, according to Farmer.

“Mosquitoes first arrived in Hawai‘i in 1826. On an ecological timescale, that’s not enough time to be integrated into any of the food webs or ecosystems,” he said.

Meanwhile, birds’ lives hang in the balance. The ‘akikiki is in particular danger, according to Crampton. Less than 500 individuals remain in the wild, and their territories have dwindled from 35 in 2015 to three this year.

“We are really, really worried currently about the fate of this species in the wild, and are spending a lot of time in emergency meetings,” she said Thursday. “Meanwhile, we have seen the numbers of mosquitoes increase on the plateau. We used to only see them in the fall months at the lower elevations — during the filming of this movie, for example — but now we see them year round.”

“The Forest Birds of Kaua‘i: Mosquito Transmitted Diseases” has been uploaded to the Kaua‘i Forest Birds Recovery Project’s YouTube channel, under the title “Last chance for Kauai’s forest birds: conservationists fight against Avian Malaria.”

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Scott Yunker, general assignment reporter, can be reached at 245-0437 or syunker@thegardenisland.com.
Source: The Garden Island

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