Wolbachia is found in up to 60% of all insect species including the Cairns birdwing butterfly.
Wolbachia (green) in the ovaries of Aedes aegypti mosquitoes
High magnification image of Aedes aegypti cells with Wolbachia (green)
Wolbachia is found in moths, butterflies, ladybirds and the blue damselfly (pictured).

Wolbachia

Wolbachia is natural bacteria present in up to 60% of insect species, including some mosquitoes. However, Wolbachia it is not usually found in the Aedes aegypti mosquito, the primary species responsible for transmitting human viruses such as Zika, dengue and chikungunya.

For many years, scientists have been studying Wolbachia, looking for ways to use it to potentially control the mosquitoes that spread human diseases. The World Mosquito Program’s research has shown that when introduced into the Aedes aegypti mosquito, Wolbachia can help to reduce transmission of the above diesease to people. This important discovery has the potential to transform the fight against life-threatening mosquito-borne diseases.

Wolbachia is safe for humans, animals and the environment. It is naturally occurring bacteria already found in the environment, in many insect species. Two independent risk assessments have been conducted, both of which gave an overall risk rating of ‘negligible’ (the lowest possible rating) for the release of mosquitoes with Wolbachia.

 

The World Mosquito Program’s Wolbachia method

We release male and female Aedes aegypti mosquitoes with Wolbachia over a number of weeks. These mosquitoes then breed with the wild mosquito population, passing the bacteria from generation to generation.

Over time, the percentage of mosquitoes carrying Wolbachia grows until it remains high without the need for further releases. Mosquitoes with Wolbachia are less able to transmit diseases to people, so the risk of outbreaks in these areas is reduced.

The unique advantage of the WMP’s Wolbachia method is that in addition to helping to protect communities from mosquito-borne diseases like Zika, dengue and chikungunya, we are not posing a risk to natural ecosystems. Long-term monitoring shows that the WMP’s natural Wolbachia method is self-sustaining in almost all international project sites up to five years after our teams carry out releases.

How mosquito-borne diseases are transmitted and how Wolbachia blocks the transmission

Alternative uses of Wolbachia

Wolbachia bacteria can be used in several ways, including to suppress mosquito populations. Other research may involve the release of only male mosquitoes with Wolbachia. When these mosquitoes mate with wild female mosquitoes without Wolbachia, they are unable to reproduce.

This technique requires the release of a large number of male mosquitoes to reduce the overall mosquito population. As with insecticides, this technique would need to be reapplied over time as the population of mosquitoes gradually returns.

In contrast, the World Mosquito Program's Wolbachia method is unique because it is self-sustaining and does not need to be continually reapplied, making it an affordable, self-sustaining, long-term solution. Our method reduces the ability of mosquitoes to transmit dengue, Zika and chikungunya on to people, without suppressing mosquito populations and potentially affecting ecosystems.

We are currently adapting our approach for use in large, urban environments and targeting a cost of US$1 per person.