Relative importance of honeydew and resin for the microbial activity in wood ant nest and forest floor substrate - a laboratory study

Wood ants maintain a stable, high temperature in their nests from spring to autumn. Much of the heat is generated by the nest's microbial community, which might be differently affected by the addition of available carbon (C) sources in spring, when the nest temperature increases, than in summer, when the nest temperature is maintained at a high level. We used an incubation experiment to examine the effects of honeydew and resin on microbial activity and biomarkers' contents in ant nest and forest floor substrates. The effects of resin lasted longer than those of honeydew. Microbial activity was higher in the ant nest substrate than in the forest floor substrate, indicating that the microorganisms in the ant nest substrate were better adapted to utilize both C sources. Although bacteria were expected to be dominant after honeydew addition, this was not the case probably because the available C from honeydew had been depleted by the end of the incubation. Fungal biomarkers dominated at 10 °C with both C sources probably because fungi are better able than bacteria to remain active at low temperatures.