Long-term changes in the adult density of Aedes albopictus (Diptera: Culicidae) in urban Tokyo: results of mosquito surveillance using a pair of dry-ice traps from 2003 to 2022

Mosquitoes were collected weekly using paired dry-ice traps in urban Tokyo from 2003 to 2022. A total of 27577 adults belonging to eight species in four genera were recorded, with Aedes albopictus and the Culex pipiens group being dominant. The annual number of Ae. albopictus increased from 2013 to 2018 and declined after vegetation around the trap site was cleared in winter 2018. To identify drivers of this long-term change, we modeled the summer abundance of Ae. albopictus (females and males separately) using a generalized linear model with a negative binomial distribution. Vegetation cover was the strongest predictor, showing a significant positive association with mosquito abundance. After accounting for vegetation, both daily average temperature and effective accumulated temperature were also significantly and positively associated with mosquito counts, whereas daily precipitation had no significant effect. These results suggest that vegetation growth at the study site from 2013 to 2018 provided a suitable resting habitat for Ae. albopictus, facilitating increased trap captures. Vegetation development, together with temperature-related factors, was therefore essential to the temporary rise in Ae. albopictus abundance observed during this period.