Mosquito ‘Birth Control’ Aims to Protect Native Birds

DLNR courtesy photo.

A safe, targeted and efficient mosquito control method to reduce the population of mosquitoes has been adopted and proven successful around the country and the world.

A similar method has been used in Hawaiʻi for decades to control fruit fly pests which are harmful to local agricultural products.

Now, researchers from the University of Hawaiʻi are teaming up with the DLNR Division of Forestry and Wildlife and the U.S. Fish and Wildlife Service to adapt this “birth control method” for mosquitos to protect Hawaiʻi’s unique, imperiled native birds.

Mosquitos are a nuisance and a hazard both to Hawai‘i’s people and its native birds, which are in danger of extinction from decades of habitat loss, predation and diseases like avian malaria and avian pox.

Scientists from the UH at Mānoa and UH at Hilo are taking the first steps to adapt this mosquito control method, known as “Incompatible Insect Technique,” to reduce the population of the disease-carrying mosquitoes that harm the state’s native birds.

IIT acts like a birth control method for mosquitoes and it has already been adopted and proven successful around the country and the world. A similar method has been used in Hawaiʻi for decades to control fruit fly pests which are harmful to local agricultural products.

Mosquitoes arrived in Hawai‘i accidentally in the 1800s and are one reason why about two dozen species of Hawai‘i’s remaining native birds are threatened or on the brink of extinction.

Today, most of these birds survive at higher elevations where it’s too cold for mosquitoes. But as the climate changes, mosquitoes are moving uphill and bringing disease with them.

“We are already seeing the loss on Kauaʻi of the safe havens of higher elevation forests for our native birds,” said Cynthia King, an entomologist with DLNR/DOFAW. “Mosquito-spread diseases are decimating bird populations and if we do nothing we could lose several more species in the next 10 years.”

Just one of the six types of mosquitoes found in Hawaiʻi harms native birds — Culex quinquefasciatus.

Scientists and conservationists are working together to use a bacteria that is naturally occurring in fruit flies in Hawaiʻi, called Wolbachia. The research, which will be done in controlled laboratory settings, involves giving the male mosquitoes a different strain of Wolbachia than is normally found in them, to prevent them from producing offspring. To reproduce, most mosquitoes carry a type of this Wolbachia in their system. When male mosquitoes with the different strain of Wolbachia try to mate with females, there are no offspring.

“The process for mosquitoes is very similar to techniques that have been used for many decades in Hawaiʻi to control pest fruit flies for the benefit of agriculture,” said King. “It doesn’t eradicate the insect, but helps to safely reduce the population on a landscape scale without the use of pesticides and without harming any other species.”

The technique will not impact the other five mosquito species present in Hawaiʻi, though researchers hope to learn more in the process about control methods that could be applied to the mosquito species that affect human health. If tests are successful, the team will evaluate how to safely apply this method to Hawaiʻi’s remote native forests where birds still reside.

DLNR and its partners will also continue to evaluate other control options to expand tools available to control mosquitoes in Hawaiʻi.

“Controlling mosquito populations will greatly benefit our endangered native birds,” said Suzanne Case, DLNR chair. “Mosquitos have only been here for about 200 years, and our native wildlife has evolved without them over millions of years. While some native species may eat small amounts of mosquitoes, there are no species that depend on them, as even bats are documented to prefer larger prey. Reducing mosquitos is good for nature and people in Hawaiʻi.”