David Y Ige | DLNR Press Release – MOSQUITO SURVEYS UNDERWAY TO PROTECT BIRDS FROM DISEASE

DLNR Press Release – MOSQUITO SURVEYS UNDERWAY TO PROTECT BIRDS FROM DISEASE

Posted on November 7, 2022 in Latest Department News, Newsroom

(PU’U MAKA’ALA NATURAL RESERVE) – This high-altitude wildlife refuge is one of six locations on the island of Hawaii where teams from DLNR’s Department of Forestry and Wildlife (DOFAW) and the University of Hawai’i Pacific The Cooperative Studies Unit (PCSU) traps mosquitoes to detect the presence of avian malaria.

It’s the disease that’s on the cusp of wiping out at least two species of native Hawaiian honeyrunners forever, potentially within the next two years, with several other species being endangered within five years.

The population surveys will help partner organizations involved in the birds, not mosquitoes initiative, of which DLNR is a part, to determine where best to start using potentially male mosquitoes that are incompatible with wild female mosquitoes to try to roll back their ability to infect birds with the deadly disease. These field surveys will provide information on the presence of disease and would be part of the planning process for a potential mosquito control project, which would also include an environmental assessment.

On a typical rainy morning in Pu’u Maka’ala, Cara Thow, the DOFAW/PCSU avian disease research director for the island of Hawaii, and her team of three begin checking mosquito traps stretched across the damp and mossy forest floor.

“We are only interested in female southern house mosquitoes because they are the big villains in terms of avian malaria history,” Thow explained. “Once a female bites a vulnerable bird, there is a 90 percent chance she will die.”

This mosquito species, like all others, is not native to Hawaii and entered ship bilges or water supplies in the early 1800s. Hawaiian honeyrunners evolved in the absence of mosquito-borne diseases like avian malaria and have little to no natural immunity. Now field studies have begun for potential future projects to reduce their numbers in forests on Hawaii Island, Maui and Kaua’i, where avian malaria is prevalent. Due to warming caused by climate change, mosquitoes have been moving higher and higher into native bird habitats, the reason for catching in locations between 4000 and 6000 feet elevation.

The collection teams use two types of traps. One is baited with carbon dioxide and is designed to attract female mosquitoes looking for a blood meal. The second, known as the Gravid Trap, lures the insects into a small container of stagnant, smelly water. Both traps eventually catch mosquitoes in webs.

“The gravid traps are a bit tricky because the mosquitoes have so much room to move around,” Thow said. Using plastic hoses and tubes, members of the investigation team suck (suck) the insects out of the nets, where they are then placed in a small vial of ethanol for preservation.

The collected mosquitoes are then sent to one of two labs: Northern Arizona University or a US Geological Service (USGS) lab in Honolulu, where further work to detect malaria is being conducted.

On days when the animals are not collected, the field team rings and blood tests the birds to expand the data available and to support management decisions on where to release the incompatible males after all permits and regulatory approvals have been obtained.

Thow added, “The truth is that mosquitoes are not native to Hawaii and do not play a role in the environment that other insects cannot fill, so there are no downsides to eliminating them. What is being proposed (introducing males that are incompatible with wild females) will not eliminate them entirely, but will hopefully push back populations enough to give these critically endangered native birds some breathing room.”

There are no laboratory results yet. Over 200 mosquitoes have been sent to labs for testing since collections began last November. The majority comes from the Pu’u Maka’ala Conservation Area, which sits at an elevation of 4,000 feet.

Thow said monitoring must continue even after the incompatible insect technique is implemented to determine if the released incompatible mosquitoes are sufficient to push back populations.

“The entire team (Kupu members and RCUH/PSCSU contract employees) is absolutely proud to be a part of this work,” added Thow. “It is an honor to work towards solutions that will result in these birds persisting and being enjoyed by our children and grandchildren in the future. It really makes sense to be a part of it.”

This is the third publication detailing ongoing groundwork ahead of potential mosquito control projects in Hawaii, Maui, and Kaua’i. See links to previous versions below.

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RESOURCES

(All images/videos courtesy: DLNR)

HD Video – Mosquito Collection on the Island of Hawaii Media Clips (July 21, 2022):

Photos – Mosquito collecting on the island of Hawaii (July 21, 2022):

https://www.dropbox.com/sh/d4umy1lux6djw8w/AAD5T43ysndyZWwbYhlFYNRLa?dl=0

Past Releases –

Maui Mosquito Survey Teams Give the Voiceless a Voice (10/13/22):

https://dlnr.hawaii.gov/blog/2022/10/13/nr22-153/

Kaua’i mosquito survey teams at the forefront of avian malaria detection (9-7-22):

https://dlnr.hawaii.gov/blog/2022/09/07/nr22-134/

Media contact:

Dan Dennison

Senior Communications Manager

Hawai’i Department of Land and Natural Resources

[email protected]

Ryan Aguilar
communication specialist
Hawaii Department of Land and Natural Resources
[email protected]
808-587-0396

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