Abstract: 【Aim】 Ants have evolved a complicated association with microbes and, in particular, gut bacteria may have a strong impact on dietary evolution and species diversification of ants. Ants of the genus Camponotus are well known for harboring the endosymbiont Blochmannia and some other bacteria, which play an important role in the supplement of host nutrition. However, gut bacterial communities are sensitive to change of the food type, and such information might be useful to investigate the feeding activity of host ants in different seasons. In this study we aim to reveal whether the gut bacterial communities present seasonal characteristics in Camponotus ants. 【Methods】 The gut bacterial communities of foraging workers of C. japonicus collected from two colonies (colony 1 and 2) on four sampling dates (June 12, August 15, and October 10 in 2012, April 15 in 2013) were investigated using the 16S rRNA polymerase chain restriction fragment-length polymorphism (PCR-RFLP) method.【Results】 Seventeen bacterial genera and one unknown bacterium were found, dominated by Blochmannia in all the eight samples (67.1%-98.8%). Bacteria of Pseudomonas and Enterobacter were present in most samples, but other bacteria were distributed only sporadically in one to three samples with very low clone numbers. The gut bacterial communities in the two colonies did not show consistent change trend in the four months, and that they all harbored a low bacterial diversity. In colony 1, the bacterial diversity was relatively higher in April and October, but much lower in June and August, while in colony 2, the bacterial diversity was much higher in August than in April, June and October. The two colonies had similar bacterial communities in June and October, but were distinctly different in August and April.【Conclusion】 The gut bacterial composition and diversity in two colonies of C. japonicus can shift with seasons, but such changes have no consistent trend and no obviously season-specific characteristics have been acquired by this ant.

Key words: Camponotus japonicus, gut bacteria, 16S rRNA-RFLP, seasonal characteristics, bacterial diversity