Source: Zhongshan School of Medicine
Written by: Zhhongshan School of Medicine
Edited by: Wang Dongmei

The Sun Yat-sen University, in partnership with the Michigan State University, the Wolbaki Biotech Company, the Joint FAO/IAEA Division and others report the successful suppression of a mosquito vector population in Guangzhou, China, as part of efforts to use a nuclear technique to control the insect that spreads dengue, Zika and other diseases.

The results of this pilot trial were published in the journal Nature on July 17, 2019, showing that combining incompatible and sterile insect techniques (IIT/SIT) successfully enable near elimination of field populations of the world’s most invasive mosquito species, Aedes albopictus (Asian tiger mosquito) on two relatively isolated islands in the Pearl River, Guangzhou over a two-year period (2016-2017).

Almost 200 million irradiated mass-reared adult males of a mosquito line infected with Wolbachia were released. Community support for the IIT/SIT approach strongly increased following mosquito releases thanks to the decrease in nuisance biting. This successful field pilot demonstrated the feasibility of area-wide application of IIT/SIT for mosquito vector control.

The SIT, a form of insect birth control, uses radiation to sterilize male insects, which are then released to mate with wild females. As these do not produce any offspring, the insect population declines over time. Combining it with the cytoplasmic incompatibility conferred to the males by Wolbachia allows a reduced radiation dose to be used, which keeps the males more competitive while sterilizing the incidentally released females to avoid replacement of the target population.

The study predicts that the overall future costs of a fully-operational intervention using this environmentally friendly approach will be around 108-163 USD/ha/year which seems cost-effective in comparison with other mosquito control strategies.

China plans to test the technology in larger urban areas in the near future using sterile male mosquitoes from the mass-rearing facility operated by the Wolbaki Biotech company. This company uses advanced mosquito mass-rearing and irradiation equipment that has been developed in collaboration with the FAO/IAEA and can produce the required number of mosquitoes.

The push for the development of SIT to control mosquitos became more urgent following the worldwide Zika epidemic in 2015-2016. Moreover, dengue incidence is increasing every year with 390 million new infections estimated yearly.

The SIT has been used for over 60 years to fight agricultural pests such as the Mediterranean fruit fly and has only recently been adapted for disease-transmitting mosquitos. The insect control method can be particularly useful against human disease vectors that are difficult to manage using conventional techniques, or that became resistant to insecticides.

Link to the paper: https://www.nature.com/articles/s41586-019-1407-9