How does the sterile insect technique (SIT) work? Our mosquito reduction methods is based on the Sterile Insect Technique (SIT) developed in the 1950s and is delivered by releasing sterile male (non-biting) mosquitoes to mate with wild females of the same species. If the sterile males released successfully mate with a wild female, the eggs she then lays wont hatch, so reducing the Aedes aegypti population and in time, it is hoped removing the species from the landscape.
What method of sterilisation are you considering for the male mosquitoes? We considered several methods of sterilisation and found the most compelling method is using a natural bacterium called Wolbachia. These bacteria naturally occur in many insect species but not in Aedes aegypti. The Aedes aegypti mosquito can be infected by Wolbachia (originally through microinjection of eggs in the lab, the bacteria is than passed by the eggs to the next generation in the lab rearing process) and when males carrying this bacteria mate with females that do not have the Wolbachia bacteria, the eggs she lays will not hatch.
Won’t removing a species have ecosystem impacts? The mosquito we are targeting – Aedes aegypti, is an invasive species that has been introduced to Australia relatively recently and we don’t expect its removal to have any impact on the natural environment.There is no predator that is a specific mosquito feeder. Generalist feeders would include fish and dragonflies and some frogs, along with lizards, bats and birds. More broadly there are around 3,500 named species of mosquitoes in the world and over 300 in Australia. One of the reasons we’re looking at new population control methods like the Sterile Insect Technique is that more traditional approaches to mosquito control often involve chemicals or other methods that may affect non-target species and ecosystems.
Is this Genetic Modification? The Wolbachia method of sterilisation is not genetic modification.
Where else in the world is this sterile insect technique (SIT) being developed and tested? Researchers around the world are currently trialling this Wolbachia-based sterile insect technology including in the US, China, Malaysia and Singapore.
How does this research differ to the work being carried out by the World Mosquito Program (formerly Eliminate Dengue) in Queensland? The work that WMP has been carrying out in Queensland since 2011 is not identified as sterile insect technique (SIT) as that project’s method releases male and female mosquitoes that replace the wild mosquito population with mosquitoes that are unable to transmit diseases. The SIT method aims to reduce or remove mosquitoes that transmit diseases by releasing sterile male mosquitoes only.