Abstract / Introduction / Summary:
The activity of foraging ants was studied at two study sites in southern part of warm temperate region, Ibusuki-shi, Kaghoshima-ken, southwest Japan, i.e., Ibusuki port and a hotel flower bed. The survey was conducted once a month throughout a year from April 2020 to March 2021. Fifty honey bait traps were set up at each site once a month (600 baits in total). Further- more, as a supplement to the above a combination of honey bait trapping (10 baits) and manual collecting was conducted at a nearby site (grassland edge) only during the winter (December to March) once a month. Seventeen ant species belonging to 11 genera in 3 subfamilies were collected in this study. Of the 17 spe- cies, 7 (41.2%) were alien ant species. The dominant species in each study site was estimated by the fre- quency of occurrence of each species to all of honey baits (600) throughout the year. At Ibusuki port, Tapi- noma melanocephalum (0.25) was the most dominant ant, followed by Tetramorium bicarinatum (0.17) and Monomorium chinense (0.14). On the other hand, at the flower bed, the most dominant ant was M. chinense (0.46), followed by Pheidole parva-complex (0.41) and T. melanocephalum (0.15). The foraging of ants was seen throughout the year. The activity level was constantly high from April to November, and low in the winter from December to March. In the winter season the foraging activity level of worker ants was much lower, with the lowest in January. In the winter nine species were sampled, of which 6 (66.7%) were alien and only 3 native (Paraparatrechina sakurae, M. chinense and M. in- trudens). Interestingly, during the winter the activity level of P. sakurae and M. chinense was higher than that of alien species, e.g., Pheidole megacephala and Ph. parva-complex. They might represent native spe- cies active during the winter in the disturbed area of the southern part of warm temperate Japan. Two alien ant species, Ph. megacephala and Ph. parva-complex, were confirmed to have been estab- lished in Ibusuki-shi by 2019. Although the activity level of these ants was significantly low in the winter, foragers would come out from their nests during the daytime responding to the rise of the temperature on the ground surface and in shallow soil.