According to lead author Zhiyong Xi, a professor at Michigan State College's Division of Microbiology and Molecular Genetics, "In contrast to the approach to "producing insecticide, our objective is to make use of this method to construct a protected space that's illness vector-free."
How Do Radiation & Wolbachia Bacteria Control Mosquitoes?
The study employed two existing techniques, namely radiation-based sterile insect technique (SIT) and Wolbachia bacteria-based incompatible insect technique (IIT) to
stamp out the disease-carrying mosquitoes.
- In the SIT method, male mosquitoes sterilized by radiation are released into the environment to mate with wild female mosquitoes, resulting in the reduction of the mosquito population, since the female mosquitoes fail to reproduce
However, the radiation method alone can reduce survival and affect mating ability, thereby reducing the efficacy of this method.
- The IIT method uses Wolbachia bacteria, which mainly hinders the insects' ability to reproduce. Male bacteria are infected with Wolbachia bacteria, and following this, when they mate with female mosquitoes, the resulting eggs are not viable
Unfortunately, this method, when used alone is not effective if female mosquitoes also become infected (contamination rate of 0.3%). When both male and female mosquitoes infected by Wolbachia mate, it results in the production of female mosquitoes resistant to the bacteria rendering the method ineffective.
Combining Radiation & Wolbachia Bacteria Methods to Eliminate Mosquitoes
To overcome the drawbacks of each of the above methods used separately, the team decided to subject Wolbachia infected test mosquitoes to low-level radiation. This resulted in the sterility of female mosquitoes, but allowed the males to reproduce.
The above method enabled the research team to release more number of mosquitoes into the environment of more than 160,000 male mosquitoes per week per hectare.
Potential Demerits of the Method
The results were not successful universally. In areas with heavy traffic, close to construction sites or roads, etc., the numbers declined to a lesser extentcompared to that in remote areas, probably since mosquitoes migrated in from outside.
However, Xi states that the approach might be still effective if used in locations such as highways to control the migration of mosquitoes from outside.
Scope of Study & Future Plans
- Can be used against mosquitoes causing malaria as well
- Further research is needed to develop an effective mosquito release technique suited to urban locations
In summary, the technique combining both radiation and Wolbachia bacteria shows promise in controlling the number of disease-causing mosquitoes and preventing the transmission of serious diseases such as dengue and Zika. Reference :
- Incompatible and sterile insect techniques combined eliminate mosquitoes - (https://doi.org/10.1038/s41586-019-1407-9)