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.
Fine-scale topographic complexity creates important microclimates that can facilitate species to grow outside their main distributional range and increase biodiversity locally. Enclosed depressions ...in karst landscapes ('dolines') are topographically complex environments which produce microclimates that are drier and warmer (equator-facing slopes) and cooler and moister (pole-facing slopes and depression bottoms) than the surrounding climate. We show that the distribution patterns of functional groups for organisms in two different phyla, Arthropoda (ants) and Tracheophyta (vascular plants), mirror this variation of microclimate. We found that north-facing slopes and bottoms of solution dolines in northern Hungary provided key habitats for ant and plant species associated with cooler and/or moister conditions. Contrarily, south-facing slopes of dolines provided key habitats for species associated with warmer and/or drier conditions. Species occurring on the surrounding plateau were associated with intermediate conditions. We conclude that karst dolines provide a diversity of microclimatic habitats that may facilitate the persistence of taxa with diverse environmental preferences, indicating these dolines to be potential safe havens for multiple phyla under local and global climate oscillations.
Fragmented natural habitats within human-transformed landscapes play a key role in preserving biodiversity. Ants as keystone species are essential elements of terrestrial ecosystems; thus, it is ...important to understand the factors influencing their presence. In a large-scale multi-site study, we surveyed ant assemblages using sweep netting and D-vac sampling on 158 ancient burial mounds preserving grassland habitats in agricultural landscapes in East-Hungary. We asked the following questions: (1) How do habitat factors and landscape composition affect species richness and functional diversity of ants? (2) Which ant traits are affected by habitat factors and landscape composition? Despite their small sizes, mounds as permanent and relatively undisturbed landscape elements could provide safe havens for diverse ant assemblages even in transformed agricultural landscapes. The complex habitat structure of wooded mounds supported high species and functional diversity of ant assemblages. Ant species on wooded mounds had small or medium-sized colonies, enabling the co-existence of more species. The effect of landscape composition on ant assemblages was mediated by habitat factors: steep slopes buffered the negative effect of the cropland matrix and enabled higher ant diversity.
Cannibalistic necrophagy is rarely observed in social hymenopterans, although a lack of food could easily favour such behaviour. One of the main supposed reasons for the rarity of necrophagy is that ...eating of nestmate corpses carries the risk of rapid spread of pathogens or parasites. Here we present an experimental laboratory study on behaviour indicating consumption of nestmate corpses in the ant Formica polyctena. We examined whether starvation and the fungal infection level of the corpses affects the occurrence of cannibalistic necrophagy. Our results showed that the ants distinguished between corpses of different types and with different levels of infection risk, adjusting their behaviour accordingly. The frequency of behaviours indicating cannibalistic necrophagy increased during starvation, although these behaviours seem to be fairly common in F. polyctena even in the presence of other food sources. The occurrence and significance of cannibalistic necrophagy deserve further research because, in addition to providing additional food, it may be part of the hygienic behaviour repertoire. The ability to detect infections and handle pathogens are important behavioural adaptations for social insects, crucial for the fitness of both individual workers and the entire colony.
Tool use by nonhuman animals has received much research attention in the last couple of decades. Nevertheless, research has focused mostly on vertebrates, particularly primates and corvids, even ...though tool use has also been documented in insects. One of the best documented examples involves ants using debris (e.g. sand grains, mud, leaf fragments) to collect and transport liquid food to their nest. However, little is known about the factors that determine the selection of materials to be used as tools. We investigated tool selection in two species of Aphaenogaster ants by giving them the choice between different kinds of potential tools (natural and artificial objects). Ant workers showed a clear preference for certain materials to be used as tool objects. Tool selection was also shaped by familiarity with the material as ants developed a preference for artificial tools with a good soaking capacity that cannot be found in their natural environment. Our results indicate that ants of this genus have evolved unique foraging strategies and show plasticity in their behaviour.
•Some ant species use debris as tools to transport liquid food to the nest.•When given the choice between different kinds of potential tools ants are selective.•They show preference for materials with optimal handling and/or soaking properties.•They can employ artificial materials novel to them, thus tool use is flexible in ants.
•Burial mounds maintain grassland habitats and biodiversity in transformed landscapes.•They are additional pillars for conservation and extend the border of protected areas.•Effects of the altered ...land use pose a considerable future threat for their existence.•Their small size and dispersed location calls for a new conservation approach.
In transformed landscapes, many populations of grassland specialist plant and animal species live outside the few protected areas and are often preserved on 'small natural features' (SNFs) such as road verges, field margins and rocky outcrops. In the steppe and forest steppe zones of Eurasia ancient burial mounds (kurgans) are widespread SNFs providing refuge for grassland species. Based on a large-scale botanical and zoological survey of 138 kurgans in Hungary, we compared the management regimes, the presence of threatening factors and the conservation potential of kurgans embedded in non-protected transformed landscapes and in protected areas. We found that kurgans extend the borders of the protected areas by maintaining populations of grassland specialist plants and arthropods (ants, orthopterans, true bugs and rove beetles) even in transformed landscapes. We revealed that the lack of proper management, the presence of anthropogenic disturbances and encroachment of woody species are the most considerable threats to the long-term maintenance of biodiversity on kurgans located outside the protected areas. For their effective conservation a new approach is needed, which can cope with the small area and dispersed localities of the kurgans and can integrate them into the network of other SNFs on a landscape-level. As the ecological importance of kurgans is disproportionate to their size conservation actions focusing on their protection offers a greater rate of return of the efforts than can be expected in case of larger continuous sites.
Wood-pastures harbor critical natural and social values and are among the most ancient land use forms of Europe. The crucial conservation value of these silvopastoral systems is generally contributed ...to their characteristic landscape elements, the solitary trees, which provide microhabitats for a variety of organisms. However, by accommodating four habitat types (grasslands, solitary trees, forests, and forest edges) on a relatively small spatial scale, wood-pastures might host functionally and compositionally distinct arthropod communities, thus enhancing the landscape-level biodiversity. To test this, we assessed the fine-scale microclimatic conditions of the four different habitat types of three wood-pastures and investigated the effects of these conditions on ant activity and community organization patterns. Besides microclimate, niche breadths (quantified by four-dimensional niche hypervolumes), niche overlaps, and interspecific interactions were also considered to assess the importance of interspecific competition in shaping the studied ant communities. The four habitat types showed notable differences in the previous aspects, which resulted in different patterns of ant activity and community organization. Posing ideal conditions (high solar irradiance and temperatures above 25 °C) for ant activity, the grasslands were monopolized by usually 2–3 dominant species with large hypervolumes, while the subordinates mostly occurred under environmental extremities. Despite their vicinity to the grasslands, solitary trees showed a different pattern, where in total 8 subordinate species associated with specific microclimates were present. The forest edges hosted the most species-rich communities, with 18 species in total, where interspecific interactions played a major role in shaping the activity patterns. A similar result was obtained for forests, although the mild environmental conditions of these habitat types resulted in low overall ant activity. Our results unveil that by posing various microclimatic and structural conditions, wood-pastures enable the coexistence of four ecologically and functionally distinct communities, which makes them ideal targets for biodiversity conservation.
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•Wood-pastures accommodate four different habitat types on a small spatial scale.•We showed that the habitat types differ in a range of microclimatic parameters.•These peculiar microclimatic conditions shaped the ant interspecific interactions.•This led to unique ant activity and community organization patterns.•Complex landscapes can host distinct communities and promote biodiversity.
In the genus Aphaenogaster, workers use tools to transport liquid food to the colony. During this behavior, ants place or drop various kinds of debris into liquids or soft food, and then, they carry ...the food‐soaked tools back to the nest. According to some authors, this behavior is not "true" tool use because it represents two separate processes: a defense response to cover the dangerous liquid and a transport of food. Here, we investigated the debris dropping and retrieving behavior of the ant Aphaenogaster subterranea to establish which of the two hypotheses is more probable by conducting manipulative experiments. We tested the responses of eight colonies (a) to liquid food (honey‐water) and nonfood liquids (water) in different distances from the nest and (b) to nonthreatening liquids previously covered or presented as small droplets. We also tested whether the nutritional condition of colonies (i.e., starved or satiated) would affect the intensity and rate of debris dropping. Our results were consistent with the tool‐using behavior hypothesis. Firstly, ants clearly differentiated between honey‐water and water, and they directed more of their foraging effort toward liquids farther from the nest. Secondly, ants performed object dropping even into liquids that did not pose the danger of drowning or becoming entangled. Lastly, the nutritional condition of colonies had a significant effect on the intensity and rate of object dropping, but in the opposite direction than we expected. Our results suggest that the foraging behavior of A. subterranea is more complex than that predicted by the two‐component behavior hypothesis and deserves to be considered as "true" tool use.
In the genus Aphaenogaster, workers use various materials to transport liquid food to the colony. According to some authors, this behavior represents two separate processes: a defense response to cover the dangerous liquid and a transport of food. Our results with Aphaenogaster subterraneasuggest that this behavior is more complex than that predicted by the two‐component behavior hypothesis and deserves to be considered as "true" tool use.
A decrease in habitat amount and connectivity causes immediate or delayed species extinctions in transformed landscapes due to reduced functional connections among populations and altered ...environmental conditions. We assessed the effects of present and historical grassland amount and connectivity as well as local habitat factors typical of the present landscape on the current species richness of grassland specialist and generalist plants and arthropods in grassland fragments. We surveyed herbaceous plants, ants, orthopterans, true bugs and rove beetles in 60 dry grassland fragments in Hungary. We recorded the area of the focal grassland, the slope and the cover of woody vegetation. By using habitat maps of the present and historical landscape, we calculated grassland amount and connectivity for four time periods covering 158 years (1858–2016). We found evidence for an unpaid extinction debt in specialist plants, suggesting that they have not come to equilibrium with the grassland amount and connectivity of the present landscape yet. This localised and typically long-lived group responded slowly to the landscape changes. Specialist arthropod taxa with short generation times responded much faster to habitat loss than plants and did not show an extinction debt. Generalist plants and animals adapted to a wide range of habitats were affected by the landscape-scale decline of grassland habitats. Despite decreased habitat connectivity, grassland fragments with dry environmental conditions and high environmental heterogeneity can sustain specialist plants in transformed landscapes. Unpaid extinction debt should be considered an early warning signal: Restoration of grassland connectivity is necessary to halt ongoing extinction processes.
The nymphs of the cixiid planthopper, Reptalus panzeri (Löw, 1883), were found cohabiting with the myrmicine ant Aphaenogaster subterranea (Latreille, 1798) in a sub-Mediterranean oak forest in ...mid-western Hungary. Except for a few cases, nymphs were recorded only in the nests of A. subterranea, or were recorded with foragers of this ant from neighbouring colonies. Adult planthoppers were also found in nests of A. subterranea in the emergence period. Neither field nor laboratory studies revealed direct or unambiguous interactions between this ant and the planthopper nymphs that would indicate a trophobiotic relationship, however the fact that nymphs do not try to escape from the ants, which do not attack the nymphs, indicates some kind of mutualistic relationship between them. The main food plant of R. panzeri nymphs in this habitat is likely to be the roots of manna ash (Fraxinus ornus). PUBLICATION ABSTRACT
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