[Surveillance of the population density of adult Aedes albopictus in Guangdong Province from 2018 to 2023].

Objective: To investigate the fluctuations in the population density of Aedes albopictus and changes in the population density of Ae. albopictus in different geographical areas and different breeding habitats in Guangdong Province from 2018 to 2023, so as to provide insights into prevention and control of mosquito-borne infectious diseases in the province.

Methods: Ae. albopictus surveillance sites were assigned in 1 609 townships (streets) from 121 districts (counties) of 21 cities in Guangdong Province during the period between March and November from 2018 to 2023. The surveillance of the population density of Ae. albopictus was performed once a month in each surveillance site, and once a month in specific settings in cities where dengue were highly prevalent in Guangdong Province from December to February of the next year during the period from 2018 through 2023. Four streets (villages) were selected in each surveillance site according to the geographic orientation, and mosquito ovitraps were assigned in gardens, rooftops or public green belts at residential areas, parks, hospitals and construction sites. All mosquito ovitraps were collected, and the mosquito ovitrap index (MOI) was calculated. The population density of Ae. albopictus was classified into four grades in each surveillance site according to MOI, including no risk, low risk, medium risk and high risk. The risk classification of the Ae. albopictus density was analyzed in each surveillance site each year from 2018 to 2023, and the population density of Ae. albopictus was analyzed at different months and in different geographical areas and breeding habitats.

Results: A total of 118 241 Ae. albopictus surveillance sites were assigned in 21 cities of Guangdong Province from 2018 to 2023, and there were 68.26% of the surveillance sites with the population density of Ae. albopictus that met the requirements for dengue prevention and control, among which low, medium and high risk surveillance sites accounted for 23.61%, 6.67% and 1.47%. The risk classification of the Ae. albopictus density increased rapidly in Guangdong Province since April to May each year from 2018 to 2023, and then gradually reduced since September to October, with the peak during the period between May and July. The mean MOI was 4.21 at each surveillance site in Guangdong Province during the period from 2018 to 2023, with 4.69, 4.80, 4.38, 3.82, 3.38, and 4.33 from 2018 to 2023, respectively. The MOI was 4.35, 4.43, 3.53 and 3.58 in the Pearl River Delta region, and eastern, western, and northern Guangdong Province, respectively, and was 4.18, 5.44, 4.75, 3.24, 4.27 and 3.70 in residential areas, parks, construction sites, hospitals, waste collection stations, and other breeding habitats, respectively.

Conclusions: The population density of adult Ae. albopictus peaked in Guangdong Province during the period between May and July from 2018 to 2023, with a high density of Ae. albopictus in the Pearl River Delta region and eastern Guangdong Province. Targeted Ae. albopictus control measures are recommended to be implemented prior to the peak of the Ae. albopictus population density to reduce the development of mosquito-borne infectious diseases.