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FREQUENTLY ASKED QUESTIONS
Wolbachia-incompatible male mosquitoes applied across large landscapes have the potential to safely reduce the number of mosquitoes in the high-elevation forests of Hawaiʻi, decreasing the likelihood that our forest birds will go extinct due to avian malaria. However, this topic can get confusing because there are different mosquito species in Hawaiʻi and multiple tools that could be used for mosquito control.
We’ve provided answers to Frequently Asked Questions below.
What do mosquitoes have to do with the native birds of Hawaiʻi?
Twenty-three species of honeycreepers have gone extinct in Hawaiʻi since the first arrival of mosquitoes in the early 1800s, with many extinctions linked to avian malaria and pox.
Given Hawaiʻi's geographic isolation, its native forest birds evolved without the presence of disease and therefore have little to no immune response to illnesses like avian malaria. For the ʻiʻiwi, there is a 90% chance it will die after one bite from an infected mosquito. As our climate warms, mosquitoes are moving to higher elevations, and the available habitat for our native forest birds is disappearing.
A female mosquito bites the vulnerable skin of an 'i'iwi, potentially transmitting fatal avian malaria.
How does the Incompatible Insect Technique work?
The Incompatible Insect Technique (IIT) is a way to control insect pests, like mosquitoes, without using harmful chemicals. In Hawaiʻi, this technique involves releasing male mosquitoes that carry a different, incompatible strain of bacteria than what is present in the wild mosquito population. When these incompatible male mosquitoes mate with the wild female mosquitoes, the resulting eggs do not hatch, decreasing the mosquito population over time.
Learn more about the Incompatible Insect Technique here.
How do you know IIT's safe and won't affect other species or humans?
The release of Wolbachia-incompatible male mosquitoes requires rigorous testing and registration with the U.S. Environmental Protection Agency to demonstrate its safety and effectiveness. Additionally, it is considered a biological control agent, and its use must be approved by the Hawaiʻi Department of Agriculture. These public processes require the applicant to address potential environmental and human health safety issues. Moreover, this technique does not pose any known threat to humans or other species except for the targeted mosquitoes it intends to control. Additionally, there have been no reports of adverse effects on human and environmental health where Wolbachia has been used to influence mosquito populations.
The method of using Wolbachia to influence mosquitoes and disease transmission has been used for decades in over ten countries worldwide, including the continental US. In most places, these techniques have targeted Aedes aegypti (yellow fever mosquito) and Aedes albopictus (Asian tiger mosquito) for public health and quality of life purposes. There have been no reports of adverse effects on human and environmental health.
Wolbachia techniques have been proven safe in their world-wide applications for human health.
Does the Incompatible Insect Technique involve genetic modification?
No, the proposed technique does not modify any part of the genome of either mosquitoes or the Wolbachia bacteria.
What is Wolbachia?
Wolbachia is a naturally-occurring bacteria found in over half of all arthropod species worldwide. This includes insects, spiders, and other invertebrates such as crustaceans and nematodes. In Hawaiʻi, Wolbachia is already present in many insects, including mosquitoes such as the southern house mosquito and Asian tiger mosquito.
For many years, researchers have dedicated their efforts to examining Wolbachia to harness its potential to control mosquitoes that transmit human diseases. By incorporating these advancements in human disease control, our project strives to safeguard the native Hawaiian honeycreepers and prevent their extinction by using Wolbachia to suppress populations of the southern house mosquito.
Wolbachia (in green) within the ovaries of a mosquito.
Zhiyong Xi/ Michigan State University
Can Wolbachia be transferred from the southern house mosquito to my loved one/pet?
No, Wolbachia cannot be transferred from the mosquito to you or your loved one - it can only survive in arthropod species.
The project aims only to release male incompatible mosquitoes. Male mosquitoes do not bite, which means you will not be bitten by any mosquitoes released during the project.
Additionally, you have already been bitten by mosquitoes carrying Wolbachia. The southern house mosquito and the Asian tiger mosquito both already carry Wolbachia and have carried it since they were first introduced 125-200 years ago.
Are we introducing any new or foreign organisms to Hawaiʻi?
No, we are not introducing any new or foreign organisms to Hawaiʻi. The incompatible male mosquitoes reared in the lab are descendants of southern house mosquitoes initially collected in Hawaiʻi. Similarly, the strain of Wolbachia in the released male mosquitoes is also present in the bodies of another common mosquito in Hawaiʻi, the Asian tiger mosquito (Aedes albopictus).
IIT distinguishes itself from other biocontrol efforts (like the mongoose releases) because no new species or organisms are being brought into the islands. Even the incompatible Wolbachia strain is already present!
Can this have an adverse effect on the overall environment?
Suppressing mosquitoes should not harm the overall environment in Hawaiʻi. Our native birds, plants, and insects evolved over millions of years without mosquitoes, which were first introduced to Hawaiʻi about 200 years ago. As a result, they are not a necessary part of the diets of any native species, aren't needed to pollinate native plants, and don't serve any other known ecosystem function in Hawaiʻi.
What has to happen before you release any incompatible male mosquitoes?
We have to comply with all state and federal regulations, including permit requirements, and ensure that the public knows about the project and has the opportunity to provide input.
How will male and female mosquitoes be sorted prior to release?
Mosquitoes can be separated by sex using several techniques. Males and females are different sizes at various life stages, with females being larger as pupae and adults. The first method filters out females using mechanical sieving that only allows the smaller male pupae to fall through. The second technique uses automated sorting via imaging to scan adults and separate them by physical features. For example, male mosquitoes have fuzzier antennae and smaller abdomens than female mosquitoes. Ongoing monitoring will occur for quality assurance and control in the lab and release environments.
Male mosquitoes (left) are visually distinct from females (right) with bushier antennae, different mouthparts, and smaller bodies.
What if female mosquitoes are released?
Highly technical and rigorous processes are in place to sex-sort mosquitoes. While best efforts are taken to ensure only males are released, no system is perfect and the EPA allows for a small number of female mosquitoes to be released into the environment alongside the males (specifically, the EPA defines a female release rate of 1:250,000 as acceptable, meaning it will have no negative impact). However, if released, females pose no risk to human health or the environment.
The Wolbachia strain used in these mosquitoes is the same strain that occurs naturally in other mosquito species in Hawai‘i. Wolbachia cannot be transferred to humans, pets, or other vertebrate species, is not harmful when ingested, and has been living alongside us on the islands for hundreds of years without ill effect.
The reason for sex-sorting mosquitoes is to maximize the success of the BNM project by using incompatible males that cannot reproduce with the female mosquitoes already on the landscape. The females that might be released are also incompatible with wild males, so would be unable to successfully reproduce with them. While there is a small chance that a released male and a released female could mate and reproduce, their offspring would be highly unlikely to establish a population because they would be outnumbered by the wild mosquito population. In the unlikely event a population did become established, there would be no impact other than reducing the overall effectiveness of the project’s goal: reducing mosquito populations.
Why do you continue to use other mosquito control methods now that the Incompatible Insect Technique (IIT) is in progress?
Landscape management of mosquitoes is complex, especially in the dense, remote forests of Hawai‘i. We need to use every tool available to protect these critically endangered, irreplaceable birds. IIT is one of the management tactics implemented by BNM partners. Each tactic targets a specific need. Reducing mosquito breeding areas is essential, and in forested areas for native birds, this includes removing ungulates such as pigs which create mosquito habitat. Each person can remove mosquito habitat around your home by emptying standing water. Spot-applying a natural bacteria, BTi, targets mosquito larvae where they develop in streams. The combination of all these methods will maximize the protection of Hawaiian birds.
Researcher in a native forest (PC:MFBRP)
Will the project happen fast enough to save our birds?
'Akikiki, a Kaua'i endemic, are functionally extinct in the wild as of 2024 (above). Mosquito-borne diseases decimated their population. 'Anianiau (below) are also declining quickly. PC: Jum Denny
We don't know if it can happen fast enough to save all our birds. Based on recent field data, some of the native honeycreepers on Kauaʻi and Maui may have only two to three years before extinction. That is why this project is so urgent. We want to stop the loss of more species.
And isn’t this the same as past failed “biocontrol” efforts (i.e., mongooses)?
This project is different from the introduction of the mongoose. The private sugarcane industry imported the mongoose to Hawaiʻi in 1883 without any regulatory oversight, approval, or community engagement. The first regulatory framework for evaluating this type of action was created in 1890 and, over time, has become increasingly rigorous. Since 1975, no biocontrol release in Hawaiʻi has caused unintended negative consequences because extensive testing and analysis are done before any release. This mosquito control project is subject to these State and Federal laws, regulations, and reviews.