Mosquitoes with Wolbachia for reducing numbers of Aedes aegypti mosquitoes

Entomologist checks mosquito larvae

Entomologist checks on mosquito larvae being raised in a laboratory.

Wolbachia (wohl-bach-ee-uh) is a common type of bacteria found in insects. Approximately 6 in 10 of all types of insects, including butterflies, bees, and beetles, around the world have Wolbachia. Wolbachia bacteria cannot make people or animals (for example, fish, birds, pets) sick.

In the United States, the use of mosquitoes with Wolbachia is regulated by the U.S. Environmental Protection Agency (EPA). Prior to release of mosquitoes with Wolbachia into an area, EPA must grant an Experimental Use Permit external icon(EUP).

Aedes aegypti mosquitoes spread viruses including dengue, Zika, and chikungunya. Aedes species of mosquitoes are common throughout many areas of the United States. EPA has registered mosquitoes with Wolbachia to evaluate how effective they are in reducing numbers of Ae. aegypti mosquitoes, not other types of mosquitoes.

Mosquitoes with Wolbachia are not genetically modified.

How mosquitoes with Wolbachia are used to control Ae. aegypti mosquitoes

  • Did You Know
    • Only female mosquitoes bite. They need a blood meal to produce eggs.
    • Male mosquitoes do not bite. They feed on nectar from flowers.

    Wolbachia bacteria are not found in Ae. aegypti mosquitoes.

  • Scientists introduced Wolbachia into Ae. aegypti mosquito eggs.
  • When male Ae. aegypti mosquitoes with Wolbachia mate with wild female mosquitoes that do not have Wolbachia, the eggs will not hatch.
  • Male mosquitoes with Wolbachia are released regularly into an area by mosquito control professionals.
  • Male mosquitoes with Wolbachia mate with wild female mosquitoes.
  • Because the eggs don’t hatch, the number of Ae. aegypti mosquitoes decreases.

How scientists “make” mosquitoes with Wolbachia

  • First, Wolbachia bacteria are introduced into male and female Ae. aegypti mosquito eggs.
  • From these eggs, new mosquitoes with Wolbachia are bred.
  • Mosquitoes are mass-produced in a factory.
  • Male and female mosquitoes with Wolbachia are sorted. Only males are kept.
  • Females are not released but may be used for breeding in the laboratory.

Effectiveness of mosquitoes with Wolbachia in reducing numbers of mosquitoes

  • Puerto Rico Evaluates Mosquitoes with Wolbachia

    The Puerto Rico Vector Control Unit is working with the Communities Organized to Prevent Arboviruses (COPA) project in Ponce, Puerto Rico to determine whether mosquitoes with Wolbachia reduce the numbers of Aedes aegypti mosquitoes, which spread dengue, chikungunya, and Zika.

    The Puerto Rico Vector Control Unit release mosquitoes with Wolbachia in Ponce, Puerto Rico.

    Communities in Texas and California that have released mosquitoes with Wolbachia report a significant drop in the number of Ae. aegypti mosquitoes. Mosquitoes with Wolbachia have been successfully used in Singapore, Thailand, Mexico, and Australia. Puerto Rico is releasing mosquitoes with Wolbachia in Ponce.

  • When mosquitoes with Wolbachia stop being released into an area, the Ae. aegypti mosquito population will slowly return to “normal levels.”
  • Mosquitoes with Wolbachia will only work to reduce numbers of target mosquito species, not other types of mosquitoes. Most communities have many types of mosquitoes.

Mosquitoes with Wolbachia and integrated mosquito management

Using mosquitoes with Wolbachia may be more effective if used along with other mosquito control methods as part of an integrated mosquito management (IMM) approach, including:

  • Educating the community about how they can control mosquitoes in and around their homes
  • Conducting mosquito surveillance (tracking and monitoring the number of mosquitoes, types of mosquitoes in an area)
  • Removing standing water where mosquitoes lay eggs
  • Using larvicides and insecticides to control mosquito larvae, pupae, and adult mosquitoes
  • Monitoring how effective mosquito programs are at reducing numbers of mosquitoes.

Release of mosquitoes with Wolbachia is not intended to stop an outbreak. However, releasing mosquitoes of Wolbachia over several months can reduce the number of a specific mosquito species, such as Ae. aegypti. We do know that the best way to control mosquitoes is to start before an outbreak happens.

Mosquitoes with Wolbachia and the environment

  • Wolbachia are very common bacteria found in insects throughout the world.
  • Approximately 6 in 10 of all insects around the world have Wolbachia.
  • Once an insect dies, the Wolbachia will also die.
  • The type of Wolbachia used in these mosquitoes are same types of Wolbachia found throughout the world in many types of insects. Every day, insects with Wolbachia are around us. They die and decompose in the environment.
  • There is no data to suggest that Wolbachia bacteria cause any harm to people or animals or the environment.
  • The EPA determined that mosquitoes with Wolbachia are not likely to harm the environment.

Mosquitoes with Wolbachia and other animals

Wolbachia bacteria cannot make people or animals (for example, fish, birds, pets) sick.

Permits are required for release of mosquitoes with Wolbachia in a community  

  • Release of mosquitoes with Wolbachia requires an EUP from the EPA.
  • Release of mosquitoes with Wolbachia requires approval from the EPA and local authorities.

EPA’s EUP for use of mosquitoes with Wolbachia