The Influence of Illumination Regimes on the Structure of Ant (Hymenoptera, Formicidae) Community Composition in Urban Habitats

The reliance on visual cues can vary among ant species living in different habitats, and is mostly influenced by the level of ambient illumination and the morphological adaptations of ant species that can determine their period of daily activity. Thus, different illumination regimes might affect ant community composition in habitats with different ambient illumination intensities. Despite this, in the literature, information is scarce about the effects of ambient illumination on ant activity. In the present study, we investigated the effect of ambient illumination intensity on the activity of ant species and their community composition under herbaceous and woody plants in 24 localities from Kyiv and Kyiv region, Ukraine. Our results showed that the ambient illumination properties of the habitat type affect the presence of ant species and the activity of their workers. In open habitats, the maximum ambient illumination had a negative effect, whereas in closed, woody habitats the maximum ambient illumination and tree circumference generally had a positive effect on the number of non-dendrobiotic ant individuals found on individual plants. The dendrobiotic species were less affected by the maximum illumination intensity. Although, in closed habitats, the effect of the previous variables and their interaction had species-specific aspects. Based on the former, we can tell that more structured forest habitats can provide broader illumination intensity ranges, allowing more ant species to coexist. However, similar illumination intensity ranges can lead to overlaps in the activity of ant species under the same illumination conditions, especially in open habitats. The outcomes of these interactions are highly influenced by larger trees that besides lowering illumination intensities, can enhance ant worker activity and promote species coexistence

Comparison of foraging tool use in two species of myrmicine ants (Hymenoptera: Formicidae)

Many ant species are known to exhibit foraging tool use, during which ants place various debris items (e.g., pieces of soil, leaves, pine needles, etc.) into liquid food, and then they carry the food-soaked tools back to the nest. In the present study, we compared the tool-using behavior in captive colonies of two closely related myrmicine ants with different feeding preferences: Aphaenogaster subterranea, an omnivorous species, and Messor structor, a mainly granivorous seed-harvester species. We supplied foraging ants with honey-water baits and six types of objects they could use as tools: sand grains, small soil grains, large soil grains, pine needles, leaves, and sponges. We found that the workers of A. subterranea both dropped more tools into honey-water baits and retrieved more of these tools than the workers of M. structor. While A. subterranea preferred smaller tools over larger ones, tool preferences for M. structor did not differ significantly from random. In addition, tool dropping was significantly faster in A. subterranea, and both the dropping and retrieving of tools began significantly earlier than in M. structor. For Aphaenogaster species that regularly utilize and compete for liquid food sources, the ability to efficiently transport liquid food via tools may be more important than it is for seed-harvester ants. Dropping tools into liquids, however, may still be useful for seed-harvester species as a means to supplement diet with liquid food during periods of seed shortage and also to serve as a means of getting rid of unwanted liquids close to the nest

The effects of intensive logging on the capacity of karst dolines to provide potential microrefugia for cool-adapted plants

Dolines are local depressions of karst surfaces. They can be considered potential microrefugia for various species. We investigated the species composition and vegetation pattern of two medium-sized dolines in Hungary before and 10 years after logging, and analysed how different species groups (oak forest species, beech and ravine forest species and disturbance-tolerant species) were affected. The cover and number of oak forest species and disturbance-tolerant species increased, while the cover and number of beech and ravine forest species decreased within dolines due to logging. Therefore, their species composition and vegetation pattern have changed substantially, and dolines have partially lost their capacity to act as safe havens for plant species adapted to cooler conditions