U.S. Grant Helps Optimize Nuclear Technique to Reduce Disease-Transmitting Mosquito Populations

Thanks to the U.S. grant, scientists have found a two-step process to tackle this problem. Using radiation, they trigger the emergence of natural characteristics unique to females or males, which will subsequently enable scientists to clearly differentiate males from females. In the case of Aedes aegypti, they have identified a genetic sexing strain that brings out red eye colour in females that has so far showed favourable results.

Second, a laser prototype that uses this difference in eye colour to sort the mosquito pupae by sex was tested on three species of the Aedes mosquito. It had excellent results, leading to a very high recovery rate for the males with an extremely low rate of female contamination, an important element to ensure that no females are accidentally released into the wild, Cardoso Pereira said.

Another challenge is scaling up and optimizing SIT technology, which is necessary to ensure the feasibility of large-scale implementation and cost effectiveness, Cardoso Pereira said. Testing the technology for mass-rearing conditions simulates how it will be used outside laboratory settings and reducing its costs will make it more affordable.

Certain core elements of SIT technology were made more cost-effective as a result of this research and development (R&D). As an example, the original designs of racks and cages to mass rear the Aedes mosquito used stainless steel, a relatively expensive material. Switching to aluminium and plastic frames greatly reduced the cost of the racks and the cages, without comprising performance, Cardoso Pereira said. It has decreased the cost per unit of the cages tenfold with no difference in the mosquitoes’ performance and made the racks three times cheaper without a change in production efficiency. Researchers were also able to reduce the cost of the larval diet for the mosquitoes by more than 50% by changing its composition using proteins derived from insects.

Funds from the grant were used to employ eight staff and to set up the appropriate infrastructure and equipment needed for the 34-month period between September 2016 and June 2019, over which this R&D was conducted.

Following the success of this R&D project, the U.S. Government provided an additional contribution of US$ 1.47 million starting in July 2019 to continue the project activities for another year, with a focus on transferring the technology from the laboratory to the field.