István Maák

The effect of the invasive Asclepias syriaca on the ground-dwelling arthropod fauna.

Abstract The management of natural and seminatural systems often leads to disturbance associated with the appearance of non-native species. The spread of these species is increasing due to global environmental changes combined with local management interventions. These non-native species may establish self-sustaining populations influencing ecosystem functions, including the habitat use of native species. Here we explore the response of diplopods, spider and ant assemblages and the activity-density of individual species to the establishment of the non-native plant species, Asclepias syriaca in a disturbed poplar forest in Hungary. The relationship between the species richness of spiders and ants and the structural features of A. syriaca was weak. We found a significant relationship between the structural features of A. syriaca stands and the density and activity of the diplopod Megaphyllum unilineatum. We explain this relationship by the modified microclimate and litter quality of the habitats invaded by A. syriaca. The species composition of ant and spider assemblages was sensitive to A. syriaca. Asclepias syriaca had a negative local effect on the abundance of two spider species which were common in the studied forest. However, A. syriaca positively influenced the abundance of two ant species, most probably via indirect trophic relationships, as they feed on aphids living on A. syriaca. Our study shows that invasive plants can have mixed effects on local invertebrate assemblages. It is therefore crucial to understand how native assemblages respond to these changes in order to better manage these novel ecosystems and maximize their biodiversity benefits.

Tool selection during foraging in two species of funnel ants

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.

The effects of habitat parameters and forest age on the ground dwelling spiders of lowland poplar forests (Hungary)

Forest management has highly modified the structure of the European forests. Harvesting and post-harvest regeneration leads to a simplified forest structure. Our main objective was to detect the effects of habitat structure and forest age on the ground-dwelling spider diversity and assemblage composition of poplar forests at the Hungarian Great Plain. Our results demonstrate that the rarefaction diversity and the number of forest specialists closely correlated with the structural parameters of the forest floor, however, the age and canopy closure did not influence these parameters. According to redundancy analysis, the composition of spider assemblages was determined solely by habitat structure, with habitat structure having a major effect on the species composition and diversity of spider assemblages. A direct effect of forest age on the spider assemblages was not detected, due to the presence of different habitat types in the surrounding landscape, which may serve as suitable habitats for source-populations of spiders with different habitat requirements. Our results highlight the importance structural complexity of forests for maintaining forest spider diversity and preserving the regional species pool of spiders.

The effect of forest age and habitat structure on the ground‐dwelling ant assemblages of lowland poplar plantations

Intensive management causes significant changes to the habitat structure of forest stands and threatens forest specialist insect species. To assess and counteract the effect of periodic intensive forestry interventions, such as clear‐cutting and reforestation, it is important to adequately quantify the recovery rate and composition of the native biota. We aimed to characterize the above parameters for ant assemblages in forests with different structure and age. Epigeic ant assemblages were studied using pitfall traps in young (6–10 years old), middle‐aged (23–26 years old) and mature (35–37 years old) poplar forest plantations in the Kiskunság region of Hungary. Species richness of ant assemblages and the abundance of nonforest ants did not differ among the age classes. The abundance of forest specialist ants was, however, higher in middle‐aged and mature stands compared with young plantations. The assemblage composition of ants significantly correlated with habitat structure and forest age. We conclude that nonforest ant species can persist throughout the entire forestry cycle in poplar plantations with moderate tree density. The present study suggests that forest age and habitat structure together shape the ant assemblages of lowland poplar plantations.

Structure of ant assemblages in planted poplar (Populus alba) forests and the effect of the Common milkweed (Asclepias syriaca)

1MTA–DE „Lendület” Behavioural Ecology Research Group Department of Evolutionary Zoology, University of Debrecen H-4032 Debrecen, Egyetem tér 1, Hungary; E-mail: panka.somogyi@gmail.com 2Department of Ecology, University of Szeged, H-6726 Szeged, Közép fasor 52, Hungary E-mail: lorinczig@gmail.com 3Museum and Institute of Zoology, Polish Academy of Sciences Wilcza street 64, Warsaw, Poland; E-mail: bikmakk@gmail.com

Threat, Signal or Waste? Meaning of Corpses in two Dulotic Ant Species

Ant corpses, besides representing threat of infection by pathogens and parasites, can also be used during interspecific conflicts to inhibit the activity of the attacked colony, or they can be consumed as food. In the view of the former, the signal properties of corpses can be manifold. Besides discriminating nestmates and foes, the corpses of different ant species may act as cues for foragers, signaling the presence of other rival species, and triggering appropriate responses (e.g., alarm, retreat or foraging). In our study, we examined the responses of the facultative slave-maker Formica sanguinea and those of the obligate Polyergus rufescens towards corpses of nestmates, non-nestmate conspecifics, heterospecific slave-makers and their slaves, and corpses of non-enslaved host species under laboratory conditions. Both dulotic species responded differently to corpses of different origin. In F. sanguinea, the most intensive response was elicited by the corpses of P. rufescens and its slave, but also the corpses of non-nestmate conspecifics and their slaves elicited many adverse responses. In P. rufescens, the corpses of non-nestmate conspecifics and their slaves elicited the most adverse response. Both dulotic species distinguished corpses of their slaves from corpses of non-enslaved hosts. Based on our results, ant corpses are not meaningless objects scattered in the field, but cues carrying information that trigger different behavioral responses, and in F. sanguinea they can even represent an important food source.

Which tools to use? Choice optimization in the tool-using ant, Aphaenogaster subterranea

Gábor Lőrinczi,a, Gábor Módra,a,b Orsolya Juhász,a,c and István Maáka,d aDepartment of Ecology, University of Szeged, Közép fasor 52, H-6726 Szeged, Hungary, bDoctoral School of Environmental Sciences, University of Szeged, Rerrich Béla tér 1, H-6720 Szeged, Hungary, cDoctoral School in Biology, Faculty of Science and Informatics, University of Szeged, Közép fasor 52, H-6726 Szeged, Hungary, and dMuseum and Institute of Zoology, Polish Academy of Sciences, Wilcza street 64, 00-679 Warsaw, Poland