Abstracts - uni-regensburg.de · sense if relatives benefit. In insect societies workers of are...

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Supported by Regensburger Universitätsstift

Supported by Regensburger Universitätsstiftung

Abstracts

Central European Workshop of MyrmecologySeptember27‐29,2019Regensburg,Germanywww.cewm2019.eu

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Invited talks

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Understanding the evolution of social insect colonies from first Hamiltonian principles

Jacobus (Koos) Boomsma

University of Copenhagen, Denmark

e‐mail: [email protected]

In our century of data‐driven biology it is too little appreciated that biology has an

encompassing theory of adaptation. This theory emerged after William D. Hamilton and

George C. Williams independently established the ‘gene’s eye view of adaptation in the

1960s. Hamilton’s version, known as inclusive fitness or kin selection theory, explained

reproductive altruism as a logical consequence of the expression of selfish genes, a

metaphor coined by Richard Dawkins.

The logic is summarized in Hamilton’s rule, a simple inequality saying that any gene inducing

reproductive altruism (helping someone else to reproduce) would spread if brs > cro. Here,

cro is the gene‐level opportunity‐cost of not having offspring to which one is related by ro

(usually 0.5), and brs is the benefit in gene copies passed on to future generations via the

offspring of siblings (or lesser kin) to which one is related by rs. Inclusive fitness theory

makes many testable predictions of the kind of social traits that could generally evolve (and

of those that could not possibly evolve) and these predictions have been confirmed with

very high consistency in animals, plants, fungi and microbes.

Social insects have been prominent testbeds for inclusive fitness theory because their

workers remain often or always unmated, which leads to forms of sterility that only make

sense if relatives benefit. In insect societies workers of are only conditionally unmated, but

permanent unmatedness was a necessary condition for evolving beyond society, i.e. for the

origin of superorganismal colonies characterized by what Darwin coined ‘neuters’. I will

discuss the causal mechanisms that have induced evolutionary transitions from society to

superorganism and highlight the close analogies with reproductive altruism among somatic

cells in multicellular organisms.

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Robustness of social structures to environmental changes

Mathieu Molet

Institute of Ecology and Environmental Sciences, Sorbonne Université, 4 place Jussieu, Paris, 75005

France

e‐mail: mathieu.molet@sorbonne‐universite.fr

In a context of global climate change and increased anthropization and urbanization, understanding

how environmental changes impact the living is of primary importance. Populations can go instinct,

unless individuals can disperse, or adapt genetically or in a plastic way. How group living can

influence the response to environmental changes is mostly unknown. Societies may have robustness

and resilience properties that buffer environmental variations and shield individuals from the

external world; but large disturbances could also trigger societal collapse. We conduct a series of

experiments that aim at improving our knowledge of how societies are impacted by environmental

changes, using the small acorn ant Temnothorax as a model species.

Our three questions are:

1. How do individual and group traits of social organisms change in response to environmental

changes?

2. What are the fitness consequences of these changes in traits?

3. What are the mechanisms underlying these changes in traits?

We specifically address the topic of urbanization. We are particularly interested in the relative

contributions of individual and social dimensions to the response. We also explore the robustness

properties of human societies.

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Polydomous ant colonies: from self‐organized networks to group‐level cooperation

Elva J. H. Robinson

University of York, York, United Kingdom


Among the most successful and ecologically dominant ant species, many have colonies that occupy

multiple socially connected nests: polydomy. Polydomous colony organization challenges many

traditional ideas of what an ant colony is and how it behaves. For some polydomous species,

relationships between nests of the same colony are characterized simply by mutual tolerance, but for

other species, active cooperation between nests, in the form of resource sharing, emerges. Using

examples from a long‐term study on wood ant polydomous nest networks, lab experiments on a

range of polydomous ant species, and models of distributed nesting, I will discuss the development,

function and ecological implications of polydomy. I will explore the role of polydomy in the success of

invasive ant species and some of the most ecologically dominant non‐invasive ants, and discuss the

challenges polydomy poses to the concept of the social insect colony as a unit of selection.

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Ecological genetics in fragmented landscapes – lessons from an ant

Liselotte Sundström

Organismal and Evolutionary Biology, Faculty of Biological and Environmental Science, University of

Helsinki, 00014 Helsinki, Finland


Social insects are keystone species in many habitats, making up a considerable fraction of animal

biomass in habitats as diverse as tropical rain forests and boreal taiga forests. The size of social

insects colonies can exceed 100 000 individuals, creating a picture of abundance, which is misleading.

In fact, the number of reproductive individuals that contribute to the gene pool of populations can

be very low. Thus the effective population size, decisive in the maintenance of genetic diversity, can

be very low – sometimes just a few individuals. Furthermore, the propensity to disperse crucially

influences the ability of a species to colonize new habitat patches, as well as the degree to which

inbreeding may become an issue.

In my presentation I will draw upon data from 23 years of monitoring of a fragmented population of

the ant Formica exsecta. In this population limited dispersal and inbreeding is rife, with considerable

effects on key fitness parameters. With the available demographic, genetic, and colony‐specific

productivity data I will discuss fitness consequences of inbreeding in conjunction with environmental

stress, such as pathogen exposure, and changes in the genetic structure and patterns of gene

expression.

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Contributed talks

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Nutrition as a modulator of the longevity/fecundity trade‐off in ants

Abel Bernadou1, Mathilde Vidal1, Audrey Dussutour2, Jürgen Heinze1

1 Zoology / Evolutionary Biology, University of Regensburg, 93040, Regensburg, Germany

2 Research Centre on Animal Cognition, Toulouse University, CNRS, 31062 Toulouse, France


In social insects, queens ensure the reproduction while workers take over all non‐reproductive tasks.

Several studies have highlighted the effects of environmental factors and in particular nutrition on

the development of individual traits and caste determination. However, it remains unclear how food

affects fecundity, longevity and task allocation in social insect colonies. Clonal ants, such as

Platythyrea punctata, are a suitable model to study direct effects of nutrition while avoiding any

other confounding factors. Despite their clonality, colonies have a well‐ordered reproductive division

of labor based on rank orders established through fighting. Each colony contains only one, rarely

several, reproductive workers, while the majority of individuals has inactive ovaries. In this study, we

investigated how different diets influenced life history traits in P. punctata workers and in particular

fecundity and longevity. Contrary to solitary insects, we found that ants confined to a high‐protein

diet lived longer but also laid more eggs than ants raised on a low‐protein diet. When we induced a

nutritional bias between same‐aged workers, ants fed with a high‐protein diet became dominant and

had better developed ovaries than workers on a low‐protein diet. This study shows the importance

of nutrition in task allocation and highlights the mechanisms that might lead to the evolution of life

history traits in social insects.

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Separating adaptability from conserved signaling in cuticular hydrocarbon profiles of the super

colony forming invasive Argentine ant Linepithema humile

Jan Buellesbach1,2, Neil D. Tsutsui 2, Wenwen Diao3, Thomas Schmitt4, Leo Beukeboom3

1 Institute for Evolution & Biodiversity, University of Muenster

2 Department of Environmental Science, Policy & Management, University of California Berkeley

3 Faculty of Science and Engineering, University of Groningen

4 Department of Animal Ecology and Tropical Biology, University of Würzburg

e‐mail: buellesb@uni‐muenster.de

Cuticular hydrocarbons (CHC) form the basis for a wide array of chemical communication systems in

insects while primarily functioning as desiccation barrier. In ants, CHC have been shown to be the

main mediators of nestmate recognition, with CHC profile uniformity appearing to be a key factor for

maintaining colony identity. In the highly damaging unicolonial Argentine ant Linepithema humile, a

recent unparalleled invasive expansion has led to cooperation between vast super colonies spanning

hundreds to thousands of miles, whose individual colony members still retain the capability to

recognize each other as nestmates. However, CHC uniformity as basis for this vastly extended

nestmate recognition behavior would largely conflict with the desiccation barrier function, expected

to display considerable flexibility in adapting to fundamentally different environments across their

expanded range. To shed light on these seemingly contradictory selective pressures, we deciphered

and isolated the particular CHC compound classes correlating with environmental factors most

closely associated with humidity and desiccation. In contrast, we found that the conserved colony‐

specific CHC signatures clearly override the more flexible CHC patterns correlated with

environmental flexibility. This delivered intriguing first hints at the hierarchy of CHC functionality

integrating both desiccation resistance and the maintenance of colony identity over immense

geographic distances. Interestingly, comparing our results for the Argentine ant with the

cosmopolitan, solitary Hymenopteran jewel wasp Nasonia vitripennis, where CHC function as

universally recognized female‐specific sex pheromones, we could reveal striking similarities despite

the actual communicated information varying so widely between both species. This suggests that the

main signaling properties in CHC profiles can be evolutionary conserved over vast phylogenetic

boundaries, delivering the first hints at elements of a unified, common “chemical language”.

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An inquiline ant uses both chemical and vibro‐acoustical mechanisms to integrate into its host

colonies

Luca Pietro Casacci1,2, Piotr Ślipiński1, Francesca Barbero2, Magdalena Witek1

1 Museum and Institute of Zoology, Polish Academy of Sciences, ul. Wilcza 64, 00‐679 Warsaw, Poland

2 Department of Life Sciences and Systems Biology, University of Turin, Via Accademia Albertina 13,

10123 Turin, Italy


Social parasitism represents a peculiar type of parasitic interaction in which a parasite exploits an

entire society instead of a single organism. One of the most fascinating forms of social parasitism is

the "inquilinism". In this association a parasitic queen without a worker caste coexists with the

resident queen in the host colony and produces her own sexual offspring, which is raised by the host

workers. To bypass the recognition system of the host colony members, thus achieving full

integration in the colony hierarchy, inquilines have developed a repertoire of deceptive strategies. In

our study, the mechanisms of chemical and vibro‐acoustic deception used by the inquiline Myrmica

karavajevi (Arnoldi, 1930), which exploits the colonies of Myrmica scabrinodis Nylander, 1846, were

investigated. The analysis of cuticular hydrocarbon (CHC) profiles of colony members showed that M.

karavajevi uses chemical mimicry to integrate into the host colony. Indeed, M. karavajevi gynes

possess CHC profiles similar to those of M. scabrinodis queens and the similarity increases if only

methylated alkanes are considered. The vibro‐acoustic signals produced by the inquiline gynes were

more similar to those emitted by the host queens than by workers and in playback experiments the

parasite vibro‐acoustic signals elicited the same degree of attention in the host workers than the

signals emitted by the host queen. Finally, in brood rescue experiments, the white pupae of M.

karavajevi were saved before the other brood categories of the host species. Our results suggest that

M. karavajevi has developed sophisticated strategies of deception involving multiple communication

channels, to increase his social status in the colony hierarchy.

This work has been carried out within the project VIBRANT (No. 2016/23/P/NZ8/04254) supported by

the Polish National Science Center under POLONEZ programme which received funding from the

European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska‐

Curie grant agreement No.665778.

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Inside Pandora’s box: development of the lethal myrmecopathogenic fungus Pandora formicae

within its ant host

Enikő Csata1,2, Johan Billen3, Lucian Barbu4, Bálint Markó1

1 Hungarian Department of Biology and Ecology, Babeş–Bolyai University, 400006 Cluj‐Napoca,

Clinicilor 5‐7, Romania

2 Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI),

Université de Toulouse, CNRS, UPS, Toulouse, 31062, France

3 Zoological Institute, University of Leuven, B‐3000 Leuven, Belgium

4 Department of Biotechnology and Molecular Biology, Babeş–Bolyai University, 400006 Cluj‐Napoca,

Clinicilor 5‐7, Romania


Parasites are assumed to modify their host’s appearance, behavior, and physiology to a certain

extent. Many of these modifications are seen as purposefully manipulative, serving solely the

parasite’s interest. Particularly endgames are intriguing, where the death of the host is required for

the parasite to develop further on. Summit or treetop disease is one of such spectacular examples of

parasite induced death: the host dies attached to an elevated part of the vegetation. Many different

organisms induce summit disease, amongst them fungi, as e.g. Ophiocordyceps and Pandora species

that belong to distant groups. Evolutionary convergences are generally assumed in all these cases

with regard to the mechanisms of parasitic manipulation. In the frame of the current study we

analyzed how Pandora formicae develops inside its Formica exsecta host’s body. Our findings show

that the fungus invades the ant’s body much faster than Ophiocordyceps species, while also

consuming its muscles and central nervous system. Differences and similarities between the two

fungal organisms are also discussed with regard to the extent of parasitic manipulation.

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Ants’ nutrition: who is pulling the strings?

Enikő Csata1,2, Alfonso Pérez‐Escudero1, Audrey Dussutour1

1 Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI),

Université de Toulouse, CNRS, UPS, 31062, Toulouse, France

2 Hungarian Department of Biology and Ecology, Babeş‐Bolyai University, 400006, Cluj‐Napoca,

Romania


Parasites and pathogens use a variety of bizarre manipulation methods to create an environment

that increases their own development, survival and transmission. While on one side the availability of

nutrients is a crucial constraint on parasite populations, on the other side, the host can increase its

resistance to parasites by increasing or modifying its food intake. In our study, we investigated how

parasites affect ant nutrition using the Geometric Framework (GF) approach. In the first step, we

defined independently the intake target of the parasite Metarhizium brunneum, the uninfected and

then the infected host Linepithema humile. In a second step, we studied how infected and uninfected

host performed when confined to diets offering varying amount of protein and carbohydrate. In a

third step, we offered both infected colonies and uninfected ones a choice between various diets to

decipher if parasites are manipulating the host foraging strategies to promote its own growth or if

the host is fighting the parasite to survive. Our state‐space modelling approach allowed us to

understand and unravel through an experimental method the nutritional requirements of the host

and its pathogen and how they interact with each other.

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Effect of TiO2 photocatalysts on an unusual group of test organisms, the ants

Zsolt Czekes1,2, Eszter Mátyás1,2, Zsuzsanna Nagy1, Kata Saszet1, Lucian Baia1, Emese Gál3, Klára

Hernádi4, Zsolt Pap1,4

1 Interdisciplinary Research Institute on Bio‐Nano‐Sciences, Babeș‐Bolyai University, Treboniu Laurian

42, Cluj‐Napoca, Romania‐400271

2 Hungarian Department of Biology and Ecology, Babeș‐Bolyai University, Clinicilor 5‐7, Cluj‐ Napoca,

Romania‐400006

3 Institute of Biochemistry Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt.

62, Szeged, Hungary‐6726

4 Hungarian Department of Chemistry and Chemical Engineering, Babeș–Bolyai University, Arany

János 11, Cluj‐Napoca, Romania‐400028

5 Institute of Environmental Science and Technology, University of Szeged, Tisza Lajos krt. 103,

Szeged, Hungary‐6720


Photocatalytic materials, and semiconductors generally are widely spread in different application

areas. Semiconductive materials which are desired to be applied in photocatalysis must have a high

charge carrier generation/separation rate, therefore they can produce reactive radicals which could

take part in the oxidation of compounds.

It is a basic requirement for all these materials, that they should be inert, stable and environmentally

friendly. The latter concept is, however narrowly considered in modern materials science as most of

the publications are using standard ecotoxicological tests, which are covering only short impact

effects, such as mortality, growth, etc. These tests however might not reveal the finer sublethal

effects. Despite the availability of these tests, none of them are covering long, ecologically significant

effect, therefore a potential knowledge void appeared.

In the present work an unusual set of ecotoxicological tests were created for different ant species,

ranging for simple mortality tests to behavioral tests which test the photocatalytic alteration of the

ants’ cuticular hydrocarbon (CHC) and pheromone‐based communication system. These tests proved

that a material usually marked as non‐toxic (in this case Evonik Aeroxide P25) can adversely affect

the ecological balance of our environment.

The present work was financially supported by the project coded PN‐III‐P1‐1.1‐TE‐2016‐1588

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Population genomic patterns and phenotypic variation in the invasive ant species Cardiocondyla

obscurior

Mohammed Errbii1,2, Jan Oettler2, Lukas Schrader1

1 Institute for Evolution and Biodiversity (IEB), University of Münster, 48149, Münster, Germany

2 Zoology/Evolutionary Biology, Universität Regensburg, 93053 Regensburg, Germany

e‐mail: merrbii@uni‐muenster.de

Biological invaders often have reduced genetic diversity due to extreme bottlenecks and inbreeding.

Yet they can rapidly adapt and colonize novel environments. The tiny ant species Cardiocondyla

obscurior is an example of a successful invader that established populations all over the tropics. Its

relatively small genome is characterized by local accumulations of transposable elements (“TE

islands”) and a high rate of recombination. The interplay of TEs and non‐allelic recombination can

rapidly generate novel genetic variants and thus increase the adaptive potential in otherwise

genetically homogeneous populations. In this study, we analyze the phenotypic as well as genetic

diversity among and within different populations of C. obscurior, to explore how de novo variation

evolves. By combining phenotyping (e.g. morphometric measurements, cuticular hydrocarbon

profiles, behavioral assays) and genomic approaches (population genomics, linkage mapping), we will

advance our understanding of genome dynamics in rapid adaptation and how it contributes to the

success of C. obscurior in colonizing novel habitats out of its native range.

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Behavioral specialization of workers with an external bacterial layer in the leafcutter ant

Acromyrmex octospinosus

Johannes‐Paul Fladerer, Franz Bucar

Institute of Pharmaceutical Sciences, University of Graz, 8010 Graz, Austria

e‐mail: johannes.fladerer@uni‐graz.at

Leafcutter ants live in symbiosis with fungi they grow for food and different bacteria they use for

protection against fungal parasites. Some workers are covered with a layer of bacteria, but the

behavior of these workers has been the subject of little research. In order to obtain a clearer

understanding of this phenomenon in Acromyrmex octospinosus (Reich 1793), two experiments were

conducted with majors, minors, workers with little bacterial layer and workers with a well‐developed

bacterial layer. In a first step, scan sampling was used to distinguish the preferred location in the nest

of workers with bacterial coats, compared to the preferences of their nestmates. Finally, 18 behavior

patterns of workers with a bacterial layer on their integument were investigated by focal

observations and compared to the behavior of their nestmates. Our findings suggest that workers

covered with a high amount of Pseudonocardia differ from their sisters in their preference of

location, in that they significantly prefer the bottom part of the nest and cannot be found outside the

fungus chamber in the feeding area or the waste area. Additionally, these ants show more fungus

grooming and are more often groomed by nestmates than the other workers.

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Individual and social immunity against viruses in ants

Anna Franschitz, Elisabeth Naderlinger, Sylvia Cremer

IST Austria (Institute of Science and Technology Austria), Klosterneuburg, Austria


Ants face a multitude of infectious pathogens, like fungi, bacteria and viruses. They defend

themselves against diseases at the individual (avoidance behavior, immune system) and colony level

(social immunity). Whilst fungal pathogens that infect their hosts externally via penetration of the

cuticle are very well studied, internal infections like viral infections upon oral uptake or wounds are

still little understood. We study virus infections in ants to understand their individual and colony‐

level defenses against pathogens that infect internally, replicate in a living host and may be

transmitted during social interactions in the colony. To this end, we established a model system to

investigate how Lasius ants fight the Cricket Paralysis Virus. We analyze (i) the pathogen load in the

living host over time, (ii) the ants’ immune response against the replicating virus in their bodies, as

well as (iii) potential behavioral changes of the infected individuals. Additionally, we study how virus

infections affect social interactions between nestmates to better understand the disease dynamics in

an ant colony.

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Quantifying the predatory effects of red wood ants (Formica rufa group) on herbivorous insects in

oak forests in Hungary

Ágnes Fürjes‐Mikó1, Csaba B. Eötvös1, Csaba Gáspár1, Imola Tenorio‐Baigorria1, Márton Paulin1,

Sándor Csősz2, Anikó Hirka1, György Csóka1

1 NARIC Forest Research Institute, Department of Forest Protection, Mátrafüred, Hungary

2 MTA‐ELTE‐MTM Ecology Research Group, Budapest, Hungary


Red wood ants, as generalist predators may play a significant role in forest protection. They prey on

many insects, which can significantly influence forest health. Red wood ant species obtain their food

mainly from tree canopies, so they can effectively reduce the herbivore pressure. Related studies are

mainly known from Germany (coniferous forests) and from northern countries (coniferous forests

mixed with birch), and there are only a few data known from Central European oak dominated

deciduous forests.

Therefore the main goal of our ongoing 4 years term project is to quantify the effects of red wood

ants on abundance of herbivorous insects, mainly defoliating caterpillars. Our sampling field is placed

in a mixed deciduous forest (Quercus petraea, Quercus cerris and Carpinus betulus), where we

compared herbivore pressure on trees close to anthills to that of on more distant ones. We

quantified the abundance of the most important defoliating insect group (Lepidoptera) with frass

collecting from spring to summer, and the abundance and the diversity of them with sticky belt traps

on the trunks from autumn until early spring. Compared the 2 habitats, there was no significant

effect in the frass amount. We have found significant difference in winter moth abundances between

the trees close and far from ant hills. In our ongoing project we keep quantifying herbivore prey

items carried by ant foragers via monitoring ant routes using small video cameras. By this

examination we hope to count the abundance and identify prey species.

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Citizen science meets rare alpine ant – results from a field study on the only population of the

Swedish Narrow Headed Ant (Formica suecica) in the Alps

Florian Glaser

Technisches Büro für Biologie Glaser, Walderstr. 32, A ‐6067 Absam


The subgenus Coptoformica contains several highly specialized species depending on oligotrophic

grasslands, bogs and heaths. Many of them are highly endangered at least in their Central European

range. One of them – the boreomontane Swedish Narrow Headed Ant (Formica suecica) shows an

extremely disjunct distribution with its main population in Scandinavia and Siberia in the North and

an isolated postglacial relic population in the Tyrolean Alps. The only known Alpine population

inhabits subalpine heaths with scattered Swiss Stone Pine (Pinus cembra) and high density of small

bogs in the inner Ötz valley. Previous knowledge of local distribution of the species was mainly based

on extensive surveys in the late 1990ies, in spite of growing habitat deterioration and destruction by

skiing industry. In 2014 a four‐year‐field‐study started mapping the ant distribution and collecting

nest samples and habitat parameters around colonies with the help of volunteers. The local

organization and support of this citizen science project was managed by the Naturpark Ötztal. Data

analysis and correct determination was conducted by a professional myrmecologist financed by the

regional department of nature of the Tyrolean government. Three subpopulations were confirmed,

two of them were previously documented by just single records. Parameter analysis demonstrated

specific habitat requirements of the species and provides important demands for future conservation

measures. The citizen science project additionally offered participants and a wider audience insight

in the necessity of nature conservation of invertebrates and the fascinating biology of ants.

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Ecology of ant communities on the alpine tree line ecotone

Elia Guariento1,2, Konrad Fiedler1

1 Department of Botany and Biodiversity Research, Rennweg 14, A‐1030 Wien

2 Institute for Alpine Environment, Drususallee 1, 39100 Bozen, Italy


Alpine ant communities are poorly studied from an ecological perspective, even in central Europe. At

five mountains situated in the Central Alps, elevational transects from the upper montane forest into

the alpine environment, crossing the tree line ecotone, were investigated focusing on the change of

community composition and the trophic position of dominant species. Fourteen ant species were

recorded. Species richness was found to be elevated directly at the ecotone, along with higher

functional diversity of the ant community. Both these results were mostly driven by a higher

abundance of Myrmicinae species directly at the ecotone. Mound‐building red wood ants dominated

numerically in the forest, while the subordinate alpine slave‐ant Formica lemani dominated in alpine

grassland. A constrained ordination of the ant community data revealed that shrub cover, soil humus

content and the density of wood ants influenced significantly the presence and abundance of all

other ant species. Feeding preferences were investigated experimentally (offering baits) and

analytically (using stable isotopes). Baiting revealed a high preference for sugar resources, therefore

likely the most limited resources for ants in subalpine forest as well as alpine grassland. Yet, feeding

responses of the ant community shifted over the ecotone towards an even higher sugar preference

in the alpine zone. The same shift was also found to occur intraspecifically in the two dominant ant

taxa (wood ants and alpine slave ant). Stable C and N isotope signatures of these dominant ants

likewise revealed a shift in the used resources, from a more herbivore‐like trophic position in

subalpine forest to a more carnivore‐dominated life style in alpine grassland. Further, wood ants

were found to occupy a higher trophic level compared to slave ants, although the contribution of

trophobiosis was initially expected to be higher for this latter subgenus. The lower trophic position in

the forest is most likely facilitated by strong trophobiotic associations with honeydew‐producing

homopterans that occur in far larger numbers on conifer trees in this habitat. The isotopic signature

of Formica ants changed over the gradient. To our knowledge, this is the first evidence that also

under natural conditions ants undergo shifts in their trophic niche. This finding contradicts a recent

assumption which forecasted the opposite.

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In red wood ants, aphid milkers learn to avoid the nuisance of contacts with hoverfly larvae, and

hunters do not

Ivan Iakovlev1, Zhanna Reznikova1,2

1 Institute of Systematics and Ecology of Animals, Novosibirsk, Russia

2 Novosibirsk State University, Novosibirsk, Russia


The adaptive benefits of individual specialization and how learning abilities associated with task

performance are still far from being well‐known. Red wood ants are characterized by their huge

colonies and deep professional specialization. We hypothesized that red wood ants Formica

aquilonia form aversive learning after having negative encounters with hoverfly larvae differently,

depending on their task specialization. We tested this hypothesis, first, by examining whether

hunters and aphid milkers learn differently to avoid the annoyance of contacts with chemically

defended hoverfly larvae, and, second, by analyzing the difference between learning in ‘field’ and

laboratory‐reared (naive) foragers. During the first interaction with the hoverfly larva in their lives

the naive foragers showed a significantly higher level of aggressiveness than the members of a

natural colony. Naive foragers applied the ‘mortal grip’, ‘prolonged bites’, and ‘nibbling’ towards the

enemy with a significantly higher frequency, whereas members of both ‘field’ groups behaved more

carefully and tried to avoid encounters with the larva. The aphid milkers, who had a negative

experience of interaction with the larva, being ‘glued’ with its adhesive secretion, behaved much less

aggressively in the follow‐up experiments after ten minutes and even three days, thus exhibiting the

shaping of both short‐ and long‐term memories. However, both ‘field’ hunters and naive foragers

demonstrated no signs of aversive learning. As far as we know, this study provides the first link

between the natural aversive learning performance and task specialization in ants. We see two main

reasons explaining differences in the behavior of representatives of different task groups: (i) the

difference in the experience of previous encounters with chemically defended insects and (ii) the

manifestation of a set of task‐specific behavioral features. Given our previous results, we speculate

that scouts and aphid milkers are the most cognitively gifted specialists in red wood ant colony,

whereas hunters and guards are rather brave than smart.

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Six decades of dynamics in a Red Wood Ants (Formica spp.) colony in Romania: no decline but

relocation

Dietrich Klimetzek1, Petru T. Stancioiu2, Marius Paraschiv3, Mihai Daniel Nita2

1 University of Freiburg, Faculty of Environment and Natural Resources, Department of Biometry and

Environmental System Analysis, Tennenbacherstraße 4, D‐79085 Freiburg, Germany

2 Transilvania University of Brasov, Faculty of Silviculture and Forest Engineering, Sirul Beethoven 1,

Ro‐500123 Brasov, Romania

3 National Institute for Research and Development in Forestry "Marin Dracea", Closca Street 13, Ro‐

500040 Brasov, Romania

e‐mail: [email protected]‐freiburg.de

We tested the stability of the beneficial Red Wood Ant (RWA) populations, analyzing their colony

dynamics since the 1960's near Iași (Romania) in heterogeneous environments consisting of mixed

species stands. In 1960/61, a full inventory on 1870 ha contiguous predominantly broadleaved forest

contained 424 nests. We re‐sampled most of this area and some of their surroundings 2016 and

2018, finding 450 active nests. For comparison with present conditions, we rectified the old

inventory map and re‐adjusted the position of the nests by backdating (Kaim et al. 2016) based on a

CORONA satellite image. To assess present habitat conditions and to analyze how far nests were

located from edges, we produced a Normalized Difference Vegetation Index (NDVI) based on Sentinel

II satellite images and also inspected available forest management plans for stand structure

information. Based on the old data (map and species composition from the original report), we

derived maps on stand canopy conditions (light canopy vs. shade canopy). We also extracted the

potential favorable habitats from U.S. spy satellite images (produced by USGS, dated 1964 and 1966).

For the recent situation we derived maps on stand condition (canopy, age, species composition) from

forest management plans to analyze why original nests remained or vanished/moved. We also

identified on the NDVI map the habitat categories (different types of edges) as lines and calculated

the distance from nests to the identified edges. Cluster analysis was also performed on the two data

sets to assess the spatial pattern of the RWA colonies. All analyses were carried out in ArcGis (vers.

10.6). Results showed that RWA distribution was always clumped and changes in stand structure

(density, species, canopy cover) during stand development and after management activities

(cuttings, road building) have led to a shift in the distribution of the ant nests over the almost six

decades since original inventory. In the places where habitat conditions remained relatively

unchanged (such as next to roads or other permanent forest edges), the ant nests persisted at their

original locations. Otherwise, they seemed to have vanished from many locations inside the stands.

Intensive searches however confirmed that most of the times they have instead relocated to

adjacent places where they have found suitable habitat conditions.

22

Diversity of the myrmecophilous communities associated with the ectatommine ant genus

Ectatomma

Jean‐Paul Lachaud1,2, Gabriela Pérez‐Lachaud1

1 Departamento de Conservación de la Biodiversidad, El Colegio de la Frontera Sur, Chetumal 77014,

Quintana Roo, Mexico

2 Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de

Toulouse UPS, CNRS‐UMR5169, UPS, 31062 Toulouse Cedex 09, France

e‐mail: jean‐paul.lachaud@univ‐tlse3.fr

Despite the diversity of ant‐myrmecophile associations, few ant genera have been thoroughly

checked for an inventory of the myrmecophilous communities they host. Here we report on the

myrmecophiles associated with Ectatomma, a neotropical genus that contains only 15 valid species

along with 3 undescribed cryptic species of the complex E. ruidum, and which has been, for a long

time, considered unlikely to exhibit associations with other organisms. We also provide a brief review

of the interactions of these organisms with their hosts. We evaluated the organisms present within

ant nests or attended by foragers through exhaustive colony sampling and observations of two

species of Ectatomma (E. tuberculatum and E. brunneum) and one species complex (E. ruidum) over

more than thirty years of colony sampling and revised as much literature as we could find on all the

species of this genus. Contrary to what was expected according to the reduced number of species

concerned, the small size of their colonies and their aggressiveness, an amazing variety of associates

was found ranging from facultative mutualistic lepidopteran caterpillars to true primary ant

parasitoids, fungi and bacteria. At least 192 species belonging to 48 families from 18 orders are

involved in at least 265 associations. Half of them concern trophobiotic associations with Hemiptera.

Most of the myrmecophiles listed are rare, extremely specific, and exhibit highly specialized biology.

We discuss the limitations of the knowledge of their impact on individuals and host colony fitness.

Ectatomma ants, though being a small group, serves as a remarkable resource for the evolution of a

wide variety of myrmecophilous associations and the diversity of such communities might be much

more important than previously expected.

23

Myrmica and Lasius ants raise broods in bird nests

Marta Maziarz1, Grzegorz Hebda2, Luca Casacci1, István Maák1, Magdalena Witek1

1 Museum and Institute of Zoology, Polish Academy of Sciences, Wilcza 64, 00‐679 Warsaw, Poland

2 Institute of Biology, Opole University, Oleska 22, 45‐052 Opole, Poland


Ants are known to form associations with many organisms, such as plants or invertebrates, but the

relationships with nesting birds have been poorly recognized so far. Ants have been recorded to visit

active bird nests mostly searching for food, but records of ants raising their broods (eggs, larvae or

pupae) within songbird nests are rare. We present data for a previously unknown, but apparently

regular occurrence of Myrmica and Lasius ants and their broods within the active nests of a songbird,

the wood warbler Phylloscopus sibilatrix, which builds domed nests on the ground in European

forests. We aim to explain the reasons of this coexistence between nesting birds and ants by

comparing physical and thermal properties of bird and ant nests in the Białowieża Forest (Eastern

Poland) to detect potential advantages for ants from colonization of bird nests.

24

The risk of sexually transmitted disease in ants

Sina Metzler, Sylvia Cremer

IST Austria (Institute of Science and Technology Austria), Klosterneuburg, Austria


Mate choice is critical for the fitness of sexually reproducing individuals. In the context of disease,

careful choice allows to prevent contraction of disease during mating and may even allow to find a

partner conveying disease resistance to the offspring. Social Hymenoptera only have single mating

period early in life to make these decisions. As mating typically occurs on the wing, it can rarely be

observed, except for several species that mate inside the nest. We use the intra‐nest mating ant

Cardiocondyla obscurior to study how exposure to the obligate killing fungal pathogen Metarhizium

affects mating behavior and success of queens and males. We found that infectious sexuals still have

very high chances to mate successfully, bearing the risk of contaminating their mate partners. The

result of pathogen transfer is strongly dose‐dependent and can cause opposing effects, such as

disease or immunization against the pathogen. Importantly, even infected individuals at progressed

stages of disease engaged in mating, yet their mating success depends on surviving the disease and

retained sperm quality. Hence, contaminated or infected ant sexuals are still engaging in mating,

likely as a terminal investment strategy.

25

Caste differentiation in an ant with a sterile worker caste

Jan Oettler

Zoology & Evolutionary Biology, University of Regensburg, 93040 Regensburg, Germany


A fundamental feature of superorganismal species is reproductive division of labor between

reproductive queens and sterile workers. Workers exhibit disrupted development of the

reproductive organs, characterized by the lack of a spermatheca and reduced ovarian functionality.

Khila and Abouheif have coined this “reproductive constraints (RCs)”, and identified 5 distinct forms

of RCs. In my talk, I will discuss these RCs and propose a new order according to developmental

timing. I will further discuss an extreme form of RC which evolved several times in the myrmicine and

ponerine clades and once in the Dorylinae, and which results in workers as an extended phenotype

sensu stricto and a strict differentiation of soma and germ‐line. I will argue that these evolutionary

transitions are based on a novel interruption point in embryonic development involving signaling of

primordial germ cells and somatic gonad precursor cells, and thus represent a further step in the

evolution of superorganismality.

26

Experimental investigation of self‐organization while brood rescue in Myrmica

Sofia Panteleeva1,2, Sergei Zavrin2, Ulyana Zubairov 3, Zhanna Reznikova1,2

1 Institute of Systematics and Ecology of Animals SB RAS

2 Novosibirsk State University

3 Institute of Cytology and Genetics SB RAS


One of the vital tasks faced by ants is to save the brood after damaging the nest. We investigated

how ants optimize their group and individual actions. Laboratory experiments were carried out on

three colonies of Myrmica rubra, about 500 workers each. In the test arena (d = 15 cm) containing a

shelter in the center (d = 3 cm, h = 0.3 cm), we evenly distributed 18 larvae. We placed groups of 5

individually marked workers on the arena where they had to find and transport the brood into the

shelter, that is, to “rescue” it. We stopped filming after “saving” all the larvae or two hours after the

start of the experiment. With the use of The Observer XT (Noldus Ink.), we selected 9 behavioral

elements and obtained sequences of them for each ant. In sum, 20 tests were conducted (10.2 hours

of filming). In 18 tests (90%), ants in less than 64 minutes transported all larvae to the shelter. We

divided all ants into inactive (36.6%), spending 99.3% (98.2; 99.7) [Me (Q1; Q3)] of time in the

shelter, and active ones (63.4%) that moved in the arena, contacted with the larvae and with each

other, and spent in the shelter 48.1% (24.8; 70.2) of time. For active ants, we have described 4

behavioral tactics:

1) ants find larvae, but do not raise them;

2) find and stack clusters consisted of two or three larvae, but do not bring them to the shelter;

3) find larvae and bring them under the cover from the very beginning of the experiment (“true

rescuers”);

4) first act as inactive, or demonstrate other tactics, and after visiting the shelter become “true

rescuers”.

We then constructed an agent‐based model to simulate the process of brood rescue. We ran 1000

simulations and compared the parameters of “real” and model experiments. The model predicts that

сlustering the larvae makes it easier for “true rescuers” to find them, and thus plays an essential role

in the process of brood rescue.

27

Nutritional tolerance in ants: a comparative approach

Lina Pedraza1, Damien Gergonne1, Jürgen Heinze1, Audrey Dussutour2, Abel Bernadou1




The transition from small to large insect colonies has set a number of important changes at both the

individual (e.g. workers miniaturization and ovaries reduction) and group level (e.g. an evolution of

chemical communication). Whilst many aspects of the complexity of ant colonies are well

documented, the changes in the use of nutrients during social transition are still little understood. It

is commonly assumed that queens rely on proteins to lay eggs while workers use mostly

carbohydrates to fuel their daily activities. Ants feed on a wide variety of food sources; however,

most studies to date say nothing about the association between diet composition and colony

complexity. We therefore used the framework of nutritional geometry to determine the effect of

different food regimes on the longevity of workers across different ant species. Specifically we tested

the hypothesis that “cheaper” workers (sensu Peeters and Ito, 2015) have moved away from protein

diet and are therefore more tolerant to carbohydrates. Workers from different species, differing in

their colony size and/or in their capacity to reproduce, were isolated in Petri dishes on artificial diets,

varying in their composition of protein to carbohydrate ratios. The mortality rate on each diet was

recorded every day. We find that each species has its own optimal diet. We are now investigating the

link with colony complexity and worker “cheapness”.

28

Engineering a novel lifestyle: Melissotarsus and Rhopalomastix ants chew tunnels in healthy wood

to accommodate their scale insect partners

Christian Peeters1, Roberto Keller 2, Adam Khalife 1, Evan Economo 3

1 Institute of Ecology and Environmental Sciences, Sorbonne Université, Paris, 75005 France

2 Universidade de Lisboa, Portugal;

3 Okinawa Institute of Science and Technology, Japan Paris,


Ants cannot eat leaves but they can feed on plants via sap‐sucking insects. Thousands of arboreal

ant species interact with scale insects, giving protection against predators and weather in return for

obtaining honeydew. Family Diaspididae is the most advanced and speciose among scale insects, yet

they engage in mutualisms with only two genera of ants, partly because they do not excrete

honeydew. Melissotarsus and Rhopalomastix are sister genera with minute workers exhibiting a

combination of unique morphological adaptations, including powerful mandibles and head glands

that secrete silk to secure tunnels. This lineage engineered a novel ecological niche: they live

permanently inside living trees, where adults and larvae feed on the diaspidids (meat and shield

secretions). In Melissotarsus, mid‐ and hindlegs are modified as anchors for tunneling, hence

workers cannot walk on flat surfaces. Such extreme specialization of ant workers is possible because

the queen caste can disperse by flight and walk on the outside of host trees during colony

foundation.

29

Honesty of larval begging signals is shaped by colony kin structure in Formica ants

Mélissa Peignier1,2,3, Tamara Pokorny4, Jürgen Heinze4, Rosanna Lindgren1,2, Heikki Helanterä1,2,5, Eva

Schultner4

1 Organismal and Evolutionary biology research programme, University of Helsinki, Helsinki, Finland

2 Tvärminne Zoological Station, University of Helsinki, Hanko, Finland

3 Comparative Cognition, Messerli Research Institute, Vetmeduni Vienna, Medical University of

Vienna, University of Vienna, Austria

4 Institute of Zoology, University of Regensburg, Regensburg, Germany

5 Ecology and Genetics research unit, University of Oulu, Oulu, Finland


Begging is one display commonly used by offspring to signal their nutritional state, however begging

behavior has received very little attention in social insects. Theory predicts that begging can be either

an honest (i.e. honest‐signaling strategy) or a dishonest (i.e. scrambling competition) signal of need,

with dishonest signals expected to be more likely when relatedness within the group is low. To

investigate the presence and honesty of begging, as well as the nature of the involved signals, we

used a comparative approach with four species of the ant genus Formica exhibiting differing degrees

of intra‐colony relatedness. We investigated the behavior of starved and non‐starved larvae of F.

aquilonia, F. pressilabris (both low intra‐colonial relatedness), F. exsecta (intermediate relatedness),

and F. fusca (high relatedness). In addition, we assessed the attraction of conspecific workers

towards odors extracted from these two classes of larvae and analyzed the larval cuticular

hydrocarbon profiles. We found that in species with high and intermediate levels of relatedness,

larvae signaled significantly more when starved. In contrast, larvae from one low relatedness species

signaled significantly more when they were non‐starved, while there was no significant difference in

the behavior of starved versus non‐starved larvae in the other low relatedness species. Our results

show that workers were not preferentially attracted to the odor of starved larvae, and we also did

not detect any differences between the cuticular hydrocarbon profiles of starved and non‐starved

larvae. Overall, this study demonstrates that larval hunger signaling can vary with colony kin

structure in ants and provides a first indication for the existence of dishonest behavioral hunger

signals in social insects.

30

Parasitoids of the poorly known Neotropical myrmicine ant Pheidole susannae

Gabriela Pérez‐Lachaud1, Jean‐Paul Lachaud1,2






Natural‐enemy diversity effects on host population dynamics are not well understood. Enhanced

host control is observed in diverse systems with different natural‐enemy groups complementing one

another temporally, but this is not always the case. Here we report on the co‐occurrence of dipteran

and hymenopteran parasitoids on a coastal population of Pheidole susannae Forel (Formicidae:

Myrmicinae) in southern Quintana Roo, Mexico. This Neotropical, opportunistic cavity nesting ant

occurs in various habitats including conserved seasonal dry forest and mature lowland rainforest

patches, and is also present in highly disturbed areas (city parks, hospitals). Pheidole susannae is

frequently reported as a dominant species along its geographical range, yet the species has been

poorly studied. Whole colonies or parts of colonies nesting in the soil under stones or inside

decomposing coconut shells were collected. Colonies are monogynous with about 400 workers and

800 immatures on average. Larvae and pupae were found parasitized by Orasema evansi

(Hymenoptera: Eucharitidae), a long known but only recently described wasp species, while adult

workers were observed being attacked by female flies of the Apocephalus grandipalpis‐group species

(Diptera: Phoridae) in the rainy season, during a nest emigration after disturbance. Colony‐level

distress was obvious when flies were present and threatening. Parasitism rate by Orasema

represented up to 12.5% of available brood. Though parasitism rate by phorids could not be

evaluated, these dipteran parasitoids can also have significant ecological implications for both the

host species and other interacting parasitoids, affecting host foraging patterns spatially and

temporally as well as changing dominance hierarchies in ant communities, but also disturbing

transport during emigrations including that of parasitized hosts. Though eucharitids may suffer a net

reduction in fitness via interference competition from phorids during host nest relocation, the effect

of both natural enemies on the host population appears at least partially complementary.

31

Grassland heterogeneity effects on evenness of ant communities in upland grasslands of Central

Germany

Antonio J. Pérez‐Sánchez1,2, S. Klimek1, Jens Dauber1,2

1 Thünen Institute of Biodiversity, Germany

2 Biodiversity of Agricultural Landscapes, Institute of Geoecology, Technische Universität

Braunschweig, Germany


The dynamic and composition of communities are influenced by the combined effects of

environmental filters, biotic interactions and neutral processes from local to global scales. In human‐

drive ecosystems, such as semi‐natural grasslands, the alteration of ant communities by

anthropogenic stressors (i.e. grassland management) not only alters the number of species, but also

their relative abundance and thereby dominance or evenness. The underlying mechanisms leading to

changes in ant species richness, abundance and community structure in Central European grasslands

are still not well understood. In fact, how grassland environmental heterogeneity could affect ant

communities in a local context is not completely clear. Although habitat homogeneity presumably

decreases species evenness and increases dominance, this pattern is spatially and temporally

dependent. Here, we assessed the effect of local abiotic conditions and management type on the

dominance‐evenness patterns in ant communities of upland grasslands of Central Germany. We

estimated local site variations in terms of climate (solar radiation, soil wetness, air temperature),

topography (elevation, slope, aspect), grassland management type (pastures, meadows), landscape

composition and grassland connectivity as proxies of grassland heterogeneity. Ant species richness

and nest density were surveyed in 33 grassland sites in the Thuringia Forest Nature Park. A total of 16

species, six genera and 465 nests were recorded. Mean richness per grassland site was four species

(min=1, max=9) and mean density was 7.9 nests/100 m2 (min=0.22, max=22.7). Cluster analysis

revealed differences in composition among grassland sites. Diversity profiles indicated higher levels

of species evenness in grasslands managed as meadows, while grassland sites managed as pastures

were mostly dominated by one or two species. Our results showed that ant dominance/evenness

patterns may be explained by an interplay of anthropogenic stressors (management type) and

grassland environmental heterogeneity at local scale. These findings have relevant implications for

further assessment of functional traits distribution in upland grassland communities and ecosystem

services provided by ants Central Europe.

32

Age‐dependent release of and response to alarm pheromone in Platythyrea punctata

Tamara Pokorny1, Lisa‐Marie Sieber 1, John Hofferberth2, Abel Bernadou1, Joachim Ruther1

1 Institute of Zoology, University of Regensburg, Germany;

2 Department of Chemistry, Kenyon College, Gambier, USA


Division of labor is the hallmark of social insect societies. Worker tasks such as brood care, nest

defense and foraging, are often performed by different workers. In many cases, task allocation

changes with worker age. Young workers fulfil tasks within the safe confines of the nest, while older

workers perform tasks outside of the nest. This age polyethism may involve not only task division,

but also differences in behavioral reactions to social signals, e.g. pheromones. The ponerine ant

Platythyrea punctata is an ideal model to study age polyethism due to its clonal mode of

reproduction, which minimizes genetic effects. The species’ pheromone communication, however, is

unknown, with studies so far reporting an unusual lack of volatile compounds. Contrary to this, we

found that P. punctata foragers would occasionally emit a lemon‐like odor when handled. Here, we

investigated the chemical composition and function of the putative alarm pheromone, as well as a

possible age polyethism in the production, emission and behavioral reaction.

33

Coloration variability in Formica rufibarbis group of ants within the local population

Tatyana Putyatina1, Alexey Gilev2

1 Faculty of Biology, M. V. Lomonosov Moscow State University, Russia

2 Institute of Plant and Animal Ecology, Yekaterinburg, Russia


Ants of the Formica rufibarbis group have the melanin‐based ornaments on their heads and thorax

parts. It is known that separate coloring elements, such as contrast of pigmentation bordering line on

the head, suggest as a systematic trait in this group. Types of insects’ coloring often appear to be a

marker of important biological features. A number of data show that the variability of coloring

pattern in this group may have an adaptive character. However the pigmentation has not been

sufficiently studied yet. The intercolonial coloring variability of the F. rufibarbis group has not been

studied at all. In this study we have analyzed the variability of ants’ coloring of the F. rufibarbis group

counting 31 colonies sample of which were collected on the territory of the Karlsruhe (Germany).

Based on the extensive analysis of the discrete coloring variation on different body parts we suggest

a unified scheme of coloring variability description for F. rufibarbis group. It has been revealed that

Formica rufibarbis differs in coloring types from Formica cunicularia. A significant phenotypical

differentiation of F. rufibarbis colonies has been discovered. The coloring variety caused by

composition of pigmentary spots and strips. When merging they give dark coloring. In an opposite

case the ant looks light. We have found colonies with prevalence of dark (in 70% of cases) and light

(in 30% cases) workers. The light‐colored colonies differ according to high and low varieties of

coloring variations. The possible morphological and ecological reasons of coloring variability of the

above mentioned observed variability are discussed.

34

Field and laboratory methods of studying ants' cognition

Zhanna Reznikova1,2

1 Institute of Systematics and Ecology of Animals Siberian Branch RAS

2 Novosibirsk State University, Novosibirsk, 630091, Russia


There are more than 12000 ant species in the World with different colony sizes, from tens to millions

of individuals, and different modes of social life and styles of cooperation, from single foraging to

mass recruiting. Ants use different ways of transferring information, from odor trails to distant

homing. Highly social ant species possess sophisticated and flexible communication based on

distribution of cognitive responsibilities among individuals in personalized teams. Members of these

“cognitive elite” species demonstrate the ability to solve problems at the level of dogs and monkeys.

In the talk experimental methods for studying individual cognitive skills in highly social ant species

are described, and the following questions are considered: How do ants recognize images? How ants

maintain individual and inter‐species hierarchical inter‐relations? Do ants display social learning?

How cognitive responsibilities are distributed within an ant family? Can ants transfer to each other

abstract information about location? Is it possible that ants grasp regularities and use them to

optimize their messages? Can ants count and use simple arithmetic rules? To answer these

questions we will follow ants in the wild and on laboratory arenas with our mazes and batteries of

tests.

35

How leaf‐cutting ants determine the size of their leaf‐fragments

Daniela Römer, Flavio Roces

University of Würzburg, Department of Behavioral Physiology and Sociobiology (Zoology II),

Würzburg, Germany

e‐mail: Daniela.Roemer@uni‐wuerzburg.de

As a central place forager, leaf‐cutting ants harvest fresh plant material and transport it back into

their nest. The optimal supply of a colony’s symbiotic fungus, and, in consequence, its brood, with

fresh substrate depends on thousands of individual workers cutting out leaf‐discs. Surprisingly, the

mechanisms by which these ants determine the size of their cuts are yet not understood. In our

study, we evaluated, whether leaf‐cutting ants use the position of their legs during the cutting

process to determine the size of their cuts. In laboratory experiments, using standardized leaves

made out of Parafilm®, we either manipulated leaf thickness or precluded feedback of the legs about

the position on the leaf by preventing leg contact to the leaf‐edge. Leaf‐fragment size was positively

correlated with ant body size, and negatively with leaf‐thickness. When cutting smaller fragments, a

worker’s legs were drawn closer to their body. Without feedback about the position on the leaf while

cutting, workers overall cut comparable leaf‐discs than workers with contact to the leaf‐edge.

However, fragments varied more in size. When cutting thick leaves, precluded leg feedback resulted

in an increased leg stretch and a loss of correlation between body size and leaf‐fragment area. Our

results indicate that leaf‐cutting ants use the plastic stretch of their hind legs, by which they hold

contact to the edge while cutting, to determine whether to cut smaller or larger fragments. Fragment

sizes resulting from the loss of leg feedback also suggests that workers can use more than just this

mechanism to determine fragment size, another possibly related to the head position of the ant

while cutting.

36

Influence of the individual personality on the task specialization in Camponotus vagus ants

Gema Trigos‐Peral, István Maák, Piotr Ślipiński, Magdalena Witek

Department of Social and Myrmecophilous Insects, Museum and Institute of Zoology, Polish Academy

of Sciences


Animal personality has been documented not only in vertebrates but also in social insects. Recently it

has become the focus of numerous ecological studies. However, the effect of the individual

personality on the task performance within the ant colony still remains unclear. The aim of our study

was to establish a relationship between the individual personality and the task performance of the

ant workers. To answer for this question, we carried out observations of the individual task

performance (brood care, social interaction, being active or inactive) of marked Camponotus vagus

ants coming from different colonies almost every day for a period of three months. We also tested

twice the aggression, exploration and boldness of the same marked individuals. Our results show a

positive relationship between the individual exploratory skills with the number of two types of task

performance, social interaction (z= 2.38, p < 0.02) and activity of ants within the nest (z = 5.12, p <

0.001). Exploration was negatively correlated with the number of events related with the care of the

broods (z = ‐ 2.93, p < 0.01). Moreover, the most active ants of the nest were also the boldest (z = ‐

2.38, p < 0.02). Our study shows the influence of the personality traits on the task performance of

the individuals and how it might contribute in the success of the colonies through individual

specialization. [email protected]

37

Is pro‐sociality of ants determined by their life expectancy?

Filip Turza, Krzysztof Miler, Marcin Czarnoleski

Institute of Environmental Sciences, Jagiellonian University, Poland


In this pilot study, our aim was to investigate whether the mean worker mortality is connected to the

level of proneness towards pro‐social behavior in distinct species of ants. We hypothesized that

species characterized by relatively lower mortality are relatively more pro‐social. Our study was

conducted on Borneo, where we located 12 easily distinguishable ant species with large numbers of

foraging individuals. We assessed mortality of workers belonging to each species as well as their

proneness to contact a nestmate during laboratory simulation of entrapment; contact is a

prerequisite of more advanced pro‐social behaviors such as rescue. In accordance with our

hypothesis, ants characterized by relatively lower mortality were relatively more prone towards

contacting their entrapped nestmates. Interestingly, signs of rescue behavior never appeared in

species with highest mortality but increased in frequency as mortality of species decreased. Our

results suggest that mortality can be a major factor dictating pro‐sociality among ants. Despite

numerous studies, differences in levels of pro‐social behavior in different species of ants are still not

properly understood and explained. Our study thus adds to our current knowledge on the subject

and opens up further research possibilities.

38

Effects of goldenrod invasion (Solidago canadensis) on ant assemblages (Hymenoptera:

Formicidae) from a rural area in Transylvania (Romania)

Ruxandra Văcărescu, Miruna Popa, Ioan Tăuşan

Lucian Blaga University of Sibiu, Faculty of Sciences, Sibiu, Romania


The Canadian goldenrod (Solidago canadensis) is a long‐lived perennial plant native to North America

but invasive in Europe, Asia, Australia and New Zeeland. The invasion of Solidago canadensis may

affect both plants and invertebrate species richness and abundance. Different organisms may exhibit

different responses to the invasion. Within the animal groups, ants are important components of

terrestrial ecosystems because they act as ecosystem engineers. We investigated ant assemblages

from a rural area in Transylvania (Romania). Sampling was carried out in invaded and non‐invaded

grasslands using pitfall traps in August 2018. Altogether, we identified 18 ant species. Most of the

species are common for the Romanian ant fauna. In terms of abundance the invaded plots were

characterized by the presence of Lasius alienus, L. niger and Tetramorium cf. caespitum whereas in

the case of the non‐invaded sites L niger was the most abundant, followed by L. alienus and Formica

cunicularia. Overall, the plots were significantly different, with lower values in terms of abundance in

the case of the invaded sites. However, our results show no significant differences between the

invaded and non‐invaded in terms of species richness (number of species or Shannon‐Wiener

diversity). The non‐invaded sites recorded 16 ant species, whereas the sites were Solidago

canadensis was dominant we recorded one species less (15). Despite the low effect on species

richness and diversity, the presence of Solidago canadensis may shape the ant community

abundance and composition by reducing the overall plant species richness.

39

Dominance relationships changes after wildfires in ant communities in southern Spain

José M. Vidal‐Cordero1, Elena Angulo1, Raphaël Boulay2, Xim Cerdá1

1 Estación Biológica de Doñana, CSIC, Sevilla, Spain

2 IRBI, Univ. François Rabelais, Tours, France


The role of fire as a natural disturbance in Mediterranean ecosystems is well known. During the last

decades fire regime and fire intensity have increased considerably in Mediterranean areas. Ant

community changes due to fire are mainly caused by the indirect changes in habitat structure,

microclimate, resource availability and competitive interactions. In this study we have analyzed the

effect of fire on the dominance relationships of the ant community of three burned areas burnt in

different years (2012, 2014, 2016) in southwestern Spain. We expected sequential changes in the

role and identity of the species of ant communities along the three post‐fire scenarios. Ant sampling

was made during May, June and July of 2017. We measured the outcomes of the aggressive

interactions between ant species at different types of baits (sugar, salt, water, tuna and sesame

seeds) during three periods of the day (morning, midday, evening) in two burned and two control

plots in each study site. Unburned plots of different areas presented similar species community

composition but different to burned plots. Otherwise, the top species in the ranking of dominance in

unburned areas were dominant ants such as Crematogaster scutellaris, Crematogaster auberti and

Tapinoma nigerrimum, while the top ranking positions in the burned areas were occupied by

subordinate ants such as Cataglyphis spp., Aphaenogaster senilis and Iberoformica subrufa. Burned

areas presented a community mainly composed by thermophilic and subordinate species (e.g., I.

subrufa and Cataglyphis spp.) and dominant species associated with open habitats (Messor spp.). On

the contrary, the unburned communities were composed by subordinate and dominant species

associated with a more developed vegetation.

40

Does temporary social parasitism exist in Tetramorium?

Herbert C. Wagner1 , Sándor Csősz2, Kadri Kiran3, Celal Karaman3, Birgit C. Schlick‐Steiner4, Florian M.

Steiner4

1 ÖKOTEAM – Institute for Animal Ecology and Landscape Planning, 8010 Graz, Austria.

2 MTA‐ELTE‐MTM, Ecology Research Group, H‐1117 Budapest, Hungary

3 Faculty of Science, Department of Biology, Trakya University, 22030 Edirne, Turkey

4 Department of Ecology, University of Innsbruck, 6020, Innsbruck, Austria


Social parasitism in ants has fascinated biologists for long. From the genus Tetramorium Mayr, 1855,

permanent social parasitism (i.e., slave‐making and inquilinism) is well known. In contrast, temporary

social parasitism has not been reported yet. Recently, a mixed colony of Tetramorium immigrans

Santschi, 1927 and Tetramorium aspina Wagner, et al. 2018 has been reported. The latter has been

described as putative social parasite without any details about its socially parasitic life history.

Meanwhile, we have detected several mixed colonies of Tetramorium moravicum Novák & Sadil,

1941 and Tetramorium ferox Ruzsky, 1903. Geographic distribution data, nest densities, the relation

between pure and mixed colonies, and morphological findings confirm the hypothesis of a temporary

social‐parasitic life history of the latter. Since temporary social parasitism might represent the

evolutionary link between independent species and slave makers, we consider our results as

fundamental for understanding the evolution of social parasitism in Myrmicinae.

41

Relative value perception in ants

Stephanie Wendt, Kim S. Strunk 2, Jürgen Heinze1, Andreas Roider3, Tomer J. Czaczkes1

1 Institute of Zoology & Evolutionary Biology, University of Regensburg, 93053 Regensburg, Germany

2 School of Business, Economics and Information Systems, Chair of Management, People and

Information, University of Passau, 94032 Passau

3 Department of Economics, University of Regensburg, 93053 Regensburg, Germany


Humans usually assess things not according to their absolute value, but relative to reference points –

a main tenant of Prospect Theory. For example, people rate a new salary relative to previous salaries

and salaries of their peers, rather than absolute income. We demonstrate a similar effect in an

insect: ants expecting to find low quality food showed higher acceptance of medium quality food

than ants expecting medium quality, and vice versa for high expectations. Further experiments

demonstrate that these contrast effects arise from cognitive rather than mere sensory or pre‐

cognitive perceptual causes. Social information gained inside the nest can also serve as a reference

point: the quality of food received from other ants affected the perceived value of food found later.

Value judgement is a key element in decision making, and thus relative value perception strongly

influences which option is chosen and ultimately how all animals make decisions.

42

Posters

43

Ants shape functional diversity and community assemblage of epiphytic lichens in montane Abies

alba forests

Renato Benesperi, Paride Balzani, Elisabetta Bianchi, Maria Beatrice Castellani, Luca Di Nuzzo, Filippo

Frizzi, Alberto Masoni, Federica Morandi, Giacomo Santini

Department of Biology, University of Florence, Florence, Italy


The Formica rufa group comprises several ant species which are collectively referred to as ‘red wood

ants’ ‐ RWA. These ants are usually numerically and ecologically dominant and may influence the

structure and dynamics of the habitats they colonize. Owing to these features, several RWA species

have been used as biological control agents. In Italy, nests collected from the Alps were transplanted

to various sites along the peninsula where they were formerly absent. However, the same features

that made these species interesting as control agents make them potentially dangerous for other

organisms, as is suggested by the literature on the ecological interactions of RWA within their native

range of distribution. Recent investigation on the fate and ecological impact of the populations of

one of these species (Formica paralugubris) clearly showed that this species has non‐negligible

detrimental effects on the local invertebrate fauna, but no information exists on the possible effects

on epiphytic communities. This study aimed to fill this gap, evaluating whether the presence of this

species could affect the structure of lichen communities. We selected two sites on the Apennine

mountains (Italy), where this species has been introduced more than 50 years ago. Lichen

assemblages on Abies alba trees located within the colonized areas were compared to those from

nearby, non‐occupied, areas. The results allowed to detect significant effects of ants on the structure

of lichen communities. Although there was no detectable impact on species richness, a significant

difference between impacted and control sites was detected by multivariate analysis. Furthermore, a

difference in functional diversity among sites emerged as well, probably as the consequence of

selective action of ants on some species.

44

RNAi in Cardiocondyla obscurior

Vera Ermer, Tobias Weichselgartner, Jan Oettler

Zoology / Evolutionary Biology, University of Regensburg, 93040, Regensburg, Germany

e‐mail: [email protected]‐regensburg.de

Polyphenism is the presence of multiple phenotypes in one population. This variance in phenotypes

can be either caused by the influence of external stimuli or complex gene regulatory processes.

Polyphenism is described in many species but is especially distinct between castes in social insects.

As discovered by Klein et al. (2016), the sex‐determining transcription factor doublesex (dsx) plays an

important role in the development of caste‐specific characteristics in the tramp ant species

Cardiocondyla obscurior (Myrmicinae). To identify the impact of dsx on caste‐specific traits a

previously established microinjection method is used. 3rd instar larvae and pupae will be injected

with small interfering double‐stranded RNA (dsRNA) against dsx specific spliceforms to knock down

their gene expression. By use of real‐time PCR and phenotype analysis the success of the attempted

knockdown will be evaluated.

45

Nutritional approach to locomotor activity and starvation resistance in ants

Damien Gergonne1, Lina Pedraza1, Jürgen Heinze 1, Audrey Dussutour 2, Abel Bernadou1




Almost each organism faces temporary problems of low food availability and quality. Starvation

resistance (SR) is an important phenotypic trait that reflects the ecological and evolutionary

capacities of individuals to cope with prolonged periods of food shortage in their environment.

Nutritional status and dietary history are likely to influence the survival of individuals during periods

of food deprivation. For example, recent studies have shown that SR depends on nutrient

composition of food (i.e. protein and carbohydrate ratio, P:C). In Drosophila, SR increased at low P:C

ratios and decreased when the quantity of protein in the diet increased. But whether this pattern is

widespread among insects or whether it depends on the ecology and life histories of organisms

remains to be tested. Ants are a suitable model to understand the nutritional ecology and evolution

of SR. They are among the most successful insects in terrestrial ecosystems, have colonized almost

each biome and have extremely diversified lifestyles and social organization. In this study, we

investigated how P:C ratios influenced the locomotor activity and starvation resistance of ant

workers from different species. Ants were isolated in Petri dishes and confined to different P:C ratios

for two weeks. After this period of time, we tested in an empty arena the spontaneous locomotor

activity of workers. Individuals were then returned to their Petri dishes and we measured their SR.

We will discuss our results in the light of the colony size of species and the capacity of workers to

reproduce.

46

Biodiversity and life histories of the Cardiocondyla ants of Georgia

Nana Gratiashvili

Institute of Zoology, Ilia State University, Tbilissi, Georgia


The Caucasus is one of the regions on earth with the highest biodiversity. However, many endemic

species are highly threatened by urbanization, habitat fragmentation and the conversion of land to

agricultural use.

Ants are among the most abundant and most important invertebrates in terrestrial ecosystems. The

ant genus Cardiocondyla is particularly interesting genus, with its widely differed species in habitat

preference, nesting sites, queen number and mating frequency, and also male reproductive tactics.

Cardiocondyla ants are tiny with a body size of only 1.5–3 mm. Their small colonies, with only a few

dozen or hundred workers, live in the soil, rock crevices, or hollow plant material, such as folded

leaves, galls or dead twigs.

Previous investigations on Cardiocondyla have focused on species from Southeast Asia, Southern

Europe, and South Africa, and nothing is known about this genus in the Caucasus area. Today, more

than 12500 ants have been described, but only around 148 species are currently known from

Georgia. It can be expected that many more taxa wait to be discovered, given that close to 350

species are known from more intensively studied Turkey. According to a more recent analysis of ant

diversity, ten species of Cardiocondyla are known for Iran, eight for Turkey and three for Georgia (C.

elegans Emery, 1869, C. sahlbergi Forel, 1913, and C. stambuloffii Forel, 1892, Gratiashvili &

Barjadze, 2008). An accidentally collected sample from Georgia was recently identified by CO I

sequencing as a fourth species, C. koshewnikovi. Except for intensively studied C. elegans in France

(Lenoir et al., 2007) and a rather superficial description of the colonies of C. stambuloffii (Arnoldi

1926), nothing is known about the social structure, population biology and life history of Georgian

Cardiocondyla. Further detailed observations on the Georgian Cardiocondyla will certainly bring forth

valuable novel insights into this genus.

47

Invasive plant Rosa rugosa provides nesting habitats for hygrophilic ant species on coastal dunes

Irena M. Grześ1, Anna M. Stefanowicz2, Elżbieta Rożej‐Pabijan3, Marcin W. Woch3

1 Department of Environmental Zoology, Institute of Animal Sciences, Agricultural University, Al.

Mickiewicza 24/28, 30‐059 Kraków, Poland

2 W. Szafer Institute of Botany, Polish Academy of Sciences, Lubicz 46, 31‐512 Kraków, Poland

3 Institute of Biology, Pedagogical University of Kraków, Podchorążych 2, 31‐054 Kraków, Poland


The fauna of coastal dunes comprises unique ant communities represented mostly by xerophile and

thermophile species. Dune habitats in Europe are threatened by invasive plant Rosa rugosa that was

introduced from Japan in the 18th century as an ornamental plant. In contrast to native dune plants,

R. rugosa forms dense, perennial and highly productive woody shrubs, which may increase the

humidity of dune habitats. This study describes the community composition of soil‐nesting ants in

invaded and native habitats along the Hel Peninsula at the coast of the Baltic Sea in Poland using 25

native‐invaded paired plots. The ground of plots was scanned to find ant mounds; nest‐workers were

sampled and identified to species using standard microscopic methods. Jaccard's index of similarity

was applied to compare species composition between invaded and native plots. The average

similarity in species composition was relatively low and accounted for 37% (N=25; 95% confidence

interval: 0.20 ‐ 0.54). The dissimilarity between plots is likely due to the high representation of hygro‐

mesohygrophic Myrmica species in invaded plots. The result corresponds with another study

demonstrating that invasion of R. rugosa considerably increases the accumulation of soil organic

matter that potentially may change the dry nesting habitats of ants into the more humid ones.

The research was funded by the National Science Centre, Poland, under the project DEC‐

2017/01/X/NZ8/01805 and by the Ministry of Science and Higher Education of the Republic of

Poland.

48

Do Cardiocondyla obscurior ant queens age? A case study on gene networks

Mark Harrison1, Luisa María Jaimes Niño2, Jan Oettler2, Erich Bornberg‐Bauer1

1 Molecular Evolution and Genome Informatics, Institute for Evolution and Biodiversity, Westfälische

Wilhelms Universität Münster, Münster, Germany

2 Zoology & Evolutionary Biology, University of Regensburg, 93040 Regensburg, Germany


Signs of aging in social insects remain elusive. In its broadest terms, aging is defined as a loss in

vitality and fertility functions. Adult queens of the ant species Cardiocondyla obscurior exhibit an

increase in egg laying rate during life, with no signs of decreasing fecundity as expected in senescent

organisms. Furthermore, age‐related changes in gene expression have been shown to behave

oppositely to the non‐social species Drosophila melanogaster, supporting the hypothesis of

alternative regulation of conserved molecular pathways known to be related to aging. We wanted to

elucidate, by means of gene co‐expression network analysis (GCN), the pathways and co‐expressed

modules involved in the presumed lack of aging. We found that old ant queens actually exhibit an

age‐related higher extrinsic noise level (i.e. stochasticity of gene expression level), but, contrastingly,

a higher connectivity of gene expression (i.e. strength of correlations in a GCN) compared to younger

queens. The modules identified in the GCN are enriched for GO terms related with a higher protein

production and transcription regulation in old queens. Many hub genes upregulated in aged queens

were identified with functions related to protein homeostasis, gene regulation and stress response,

e.g. an ortholog of the histone deacetylase Sirtuin 6 in D. melanogaster. Interestingly, this gene,

downregulated with age in the fly, is important for the DNA repair and genomic stability during the

ageing process. These results indicate that C. obscurior ant queens may indeed experience signs of

senescence that are, however, combatted with effective compensatory mechanisms. Thus, allowing a

reversal of the fecundity/longevity trade‐off.

49

Built‐in disinfection: metapleural gland secretions and uses in a clonal ant.

Marc Hauber1*, Erhard Strohm2, Jürgen Heinze1, Gudrun Herzner2, Abel Bernadou1

1 Zoology / Evolutionary Biology, University of Regensburg, Universitätsstr. 31, 93053,

Regensburg, Germany. 2 Evolutionary Ecology Group, Institute of Zoology, University of Regensburg, Universitätsstr.

31, 93053, Regensburg, Germany.


Ant societies are exposed to a large number of detrimental microorganisms. Ants have

therefore evolved a great diversity of chemical and behavioral defenses to face such threats.

The metapleural gland (MG) is known to play a key role in sanitizing ant colonies. Previous

studies have mainly focused on the antimicrobial defenses of more derived ant genera like

Atta and Acromyrmex. Here we report on the function of the MG in the ponerine ant

Platythyrea punctata, a clonal species with simple social organization. Colonies of P.

punctata are small and, contain one, seldom more, reproductive workers that reproduce by

thelytokous parthenogenesis, while the majority of individuals has inactive ovaries.

Reproductive division of labor is based on rank orders established by young workers through

fighting. We analysed the MG content of P. punctata by gas chromatography / mass

spectrometry and found tryptophol (indole‐3‐ethanol) to be the major constituent.

Tryptophol proved to be active against a variety of microorganisms in vitro. Furthermore,

intranidal workers carried more tryptophol than foragers. Finally, tryptophol quantity

differed between reproductive and non‐reproductive workers.

50

High prey specificity and low niche overlap in an army ant community

P. Hönle, Christoph von Beeren

Ecological Networks, TU Darmstadt, 64287 Darmstadt, Germany


Army ants are among the top arthropod predators and considered keystone species in tropical

ecosystems. During daily mass raids with many thousand workers, army ants hunt live prey, likely

exerting strong top‐down control on prey species. Many tropical sites exhibit a high army ant species

diversity (>20 species), suggesting that sympatric species partition the available prey niches.

However, whether and to what extent this is achieved has not been intensively studied yet. We

therefore conducted a large‐scale diet survey of a community of surface‐raiding army ants at La Selva

Biological Station in Costa Rica. We systematically collected 3,262 prey items from eleven army ant

species (genera Eciton, Nomamyrmex and Neivamyrmex). Prey items were classified as ant prey or

non‐ant prey. The prey nearly exclusively consisted of other ants (98%), and most booty was ant

brood (87%). Using morphological characters and DNA barcoding, we identified a total of 1,105 ant

prey specimens to the species level. 129 ant species were detected among the army ant prey,

representing about 30% of the known local ant diversity. Using weighted bipartite network analyses,

we show that prey specialization in army ants is unexpectedly high, and prey niche overlap very

small. Besides food niche differentiation, we uncovered a spatio‐temporal niche differentiation in

army ant raid activity. We discuss competition‐driven multidimensional niche differentiation and

predator‐prey arms races as possible mechanisms underlying prey specialization in army ants. By

combining systematic prey sampling with species‐level prey identification and network analyses, our

integrative approach can guide future research by portraying how predator‐prey interactions in

complex communities can be reliably studied, even in cases where morphological prey identification

is infeasible.

51

The mitogenome of the endangered species Mycetophylax simplex (Emery 1888): comparative

genomic structure and phylogenetic analysis

Brenda Carla Lima Baldez1, Maykon Passos Cristiano1, Adriana Heloísa Pereira2, Evanguedes

Kalapothakis2, Danon Clemes Cardoso1

1 Departamento de Biodiversidade, Evolução e Meio Ambiente, ICEB, Universidade Federal de Ouro

Preto, Campus Morro do Cruzeiro, Ouro Preto, Minas Gerais 35400‐000, Brazil

2 Departamento de Biologia Geral, ICB, Universidade Federal de Minas Gerais, Campus Pampulha,

Belo Horizonte, Minas Gerais 31270‐010, Brazil


The mitochondrial genome, also known as mitogenome, can provide information for phylogenetic

analyses and evolutionary biology. We first sequenced, annotated, and characterized the

mitogenome of Mycetophylax simplex (Emery, 1888) through mitochondrial enrichment. The

complete mitogenome was 16,367 bp in length, comprising 37 genes in total, including 13 protein‐

coding genes (PCGs), 22 transfer RNA genes, two ribosomal RNA genes, and one non‐coding region (A

+ T‐rich region). There were three overlap locations and 32 intergenic spacer regions found

throughout the mitogenome of M. simplex, ranging from 1 to 158 bp. The A + T content in the

mitogenome was 81.51% (A=39.82%, T=41.69%, C=12.94% and G= 5.55%, which is consistent with

the pattern found in Hymenoptera. All PCGs used a standard ATN as a start codon, being nine (nad2,

cox2, atp8, nad3, nad5, nad4, nad4L, nad6 e nad1) with ATA and the remaining with ATG. Yet, TAA or

TAG was identified as the typical stop codon. All transfer RNA (tRNA) genes had a typical clover‐leaf

structure except for the Valine and Serine tRNA. Our comparative analysis of the sequences and

structural features of mitochondrial genomes reveals occasional rearrangements, mainly restricted

to changes on the tRNA positions. A phylogenetic analysis with another species of Formicidae was

performed using Bayesian inference, based on the amino acid sequences of 13 mitochondrial PCGs.

The phylogenetic reconstruction was consistent with the multilocus phylogenetic trees recovered for

Formicidae and Myrmicinae. However, since a small number of ant mitogenome are available it still

not feasible to trace a complete evolutionary scenario undergone ant mitochondrial changes.

52

How colony traits influence the collective behavior of Myrmica scabrinodis ants?

István Maák1, Jessica Camera2, Luca Pietro Casacci1,2, Francesca Barbero2, Gema Trigos‐Peral1, Piotr

Ślipiński1, Simona Bonelli2, Michele Zaccagno2, Magdalena Witek1

1 Museum and Institute of Zoology, Polish Academy of Science, Wilcza 64, 00‐679 Warszawa, Poland

2 Department of Life Sciences and Systems Biology, University of Turin, via Accademia Albertina 13,

10023 Turin, Italy


Collective behaviors are the outcomes of interactions among several individuals without central

control. Eusocial insects are ideal models to study group behaviours performed by cooperative

individuals at caste or at the colony level. In addition to the ecological constraints, such as the

resource fragmentation or the costs of maintaining the interaction patterns, also the social structure

might affect the collective behavior of ants. We investigated the effect of Myrmica scabrinodis colony

traits, i.e. the number of queens, colony size and colony age‐structure, on four major collective

behaviours: nest defense, necrophoresis, foraging and colony relocation. Our results showed that the

number of queens and the colony size did not affect the level of aggression against non‐nestmate

intruders while the efficiency of corpse removal was positively influenced by both traits. The age

structure of the colony influenced both the aggressiveness and the hygienic behaviours. Sub‐colonies

containing a higher proportion of young individuals were more aggressive against non‐nestmates and

less efficient in corpse removal. Foraging activity was affected by all the studied traits, suggesting

that it is one of the most important behavior in colony life. According on our results we concluded

that some of the ant collective behaviours, like foraging, are determined by many traits and their

interactions, while others are mostly determined by one or a few major traits. Overall it seems that

individual tasks forming collective behaviours depend from different intrinsic colony traits allowing a

prompt and appropriate behavioral response in any situation.

53

Mating frequency and colony genetic structure analyses reveal unexpected polygyny in the

Mediterranean acrobat ant Crematogaster scutellaris

Alberto Masoni, Filippo Frizzi, Chiara Natali, Claudio Ciofi, Giacomo Santini

Department of Biology, University of Florence, 50019, Sesto Fiorentino (Firenze), Italy


Among eusocial Hymenoptera, ants represent an unrivaled example of diversity in queen number

and mating systems. Ant colonies may have one (monogyny) or several queens (polygyny) which can

mate once (monoandry) or several times (polyandry). In this study, we analyzed the genetic structure

and breeding system of the Mediterranean acrobat ant Crematogaster scutellaris. Despite its

widespread distribution and pivotal role in regulating arthropod communities, many details of the

biology of this species have yet to be fully investigated. According to previous, not unequivocal

studies based on few observations, C. scutellaris is monogynous and monandrous with a claustral

foundation phase. We assessed the mating frequency and the number of queens in 40 colonies using

highly polymorphic, species‐specific nuclear DNA microsatellite loci. The number of queens in each

colony was directly inferred from workers relatedness. Moreover, in order to determine the

proportion of multiple matings by queens, we performed both parental reconstruction analysis using

offspring data and direct analysis of the sperm stored in the queen’s spermathecae. We investigated

relatedness between queens and their mated males. The results showed that although the majority

of the colonies were monogynous, polygyny may also occur at an unexpected frequency of 10 % in

the four populations analyzed. Monoandry was the norm as we found evidence of multiple paternity

in just two out of 40 colonies. Finally, no relatedness was found between queens and their mate,

indicating that the latter were from different colonies. This work is the first description of the genetic

structure of colonies of C. scutellaris and provides new insight for further investigation on the social

organization, behavior and ecology of Mediterranean acrobat ants.

54

Photocatalytic effect of TiO2 on the foraging behavior of Lasius niger

Eszter Mátyás1 , Zsuzsánna Nagy1,2,3, Kata Saszet4, Zsolt Pap4,5, Zsolt Czekes1,4


Romania‐400006

2 Institute of Biochemistry Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt.

62, Szeged, Hungary‐6726

3 Faculty of Science and Informatics, University of Szeged, Közép fasor 52, Szeged, Hungary‐6726



5 Environmental Chemistry Research Group, Institute of Environmental Science and Technology,

University of Szeged, Tisza Lajos krt. 103, Szeged, Hungary‐6720


Nanoparticles are a group of materials used largely in different industries. One of the most

commonly used nanoparticle is TiO2 (Titanium‐dioxide), a transitional metal oxide, which can be

found as a natural mineral. It is used widely as a pigment, in the pharmaceutical industry, food

industry, cosmetics, electronic, and also in water treatment. Although, it has lots of beneficial uses, it

could also be harmful, as it can cause pneumonia and lung cancer in rodents, but ecotoxicological

data is scarce. Although rarely considered in toxicological testing, due to the fact, that ants are

spread worldwide, can be kept easily, they are good organisms for ecotoxicological tests. They have a

well‐developed foraging system which involves trail pheromones. Due to the fact that the

photocatalytic activity of nanomaterials degrades a wide range of organic compounds, it is expected

that these pheromones can be degraded by these photocatalysts. In the current study, we observed

if TiO2 can affect negatively the foraging of Lasius niger. In the experiments, we used paper bridges

with two equal branches between ant nests and food sources. One of the braches was treated with

TiO2 aqueous suspension (1g/L) and the other with water, to observe the effect of TiO2. Our results

showed, that TiO2 reduces the foraging efficiency of Lasius niger ants.

55

If acorn ants need dead wood?

Sławomir Mitrus

Institute of Biology, University of Opole, Opole, 45‐052, Poland


Acorn ants inhabit cavities mostly in fallen twigs and hollow acorns. Such places, e.g., dead wood,

provide an attractive living resource for many groups of microorganisms, like fungi and bacteria,

which could be important for ants. However, during experiments in laboratories, acorn ant colonies

typically are kept without dead wood. During laboratory experiments, I have checked if the ant

Temnothorax crassispinus prefers nest sites with pieces of dead wood and if the presence of such

wood influences productivity and the sex ratio of colonies. The ant colonies preferred nest cavities

with pieces of dead wood vs. empty nest cavities. When cavities were filled with pieces of wood or

with pieces of wood formerly sterilized (72 hours, 70°C), colonies preferred the unsterilized zones.

However, during a three‐month‐long laboratory experiment, I have found no influence of availability

of dead wood in colony growth and the production of sex individuals. Thus, the ants prefer cavities

with pieces of wood, but the lack of availability of dead wood during a several‐month‐long

experiment has no influence on life history parameters.

56

The tight ant genomes: C‐value diversity, base pair composition and ancestral state reconstruction

of Formicidae

Mariana Neves Moura1, Danon Clemes Cardoso2, Maykon Passos Cristiano2

1 Departamento de Biologia Geral, Universidade Federal de Viçosa (UFV‐MG), 36.570‐000, Viçosa,

Minas Gerais, Brazil

2 Departamento de Biodiversidade, Evolução e Meio Ambiente/ICEB, Universidade Federal de Ouro

Preto, Campus Morro do Cruzeiro, Ouro Preto, Minas Gerais 35400‐000, Brazil


Genome size or C‐value is a basic feature of the genome of an organism and varies more than

200,000‐fold in eukaryotes. There is still a lack of knowledge about which are the mechanisms that

drive the change and variation of this trait among organisms. In ants, the patterns and processes

regarding this issue are overclocked and few species were studied. So, the aim of the present study

was to access the diversity of genome size (C‐value) on ants (Hymenoptera, Formicidae by flow

cytometry in order to evaluate the patterns of distribution, variation and base composition among

taxa. Further, we provide a phylogenetic perspective on genome size evolution across the family

under the reconstruction of the ancestral states. New estimates were present for 99 species of ants,

91 of which corresponding to new taxa and the mean genome size of Formicidae family was 0.38 pg.

The AT/GC ratio obtained for Formicidae was AT = 62.40% and GC = 37.60%. As expected, our

phylogeny recovered the monophyly of Formicidae with a high value of posterior probability with an

ancestral genome size of 0.38 pg according to the Bayesian Inference and 0.37 pg according to

Maximum Likelihood and Parsimony methods. Significant differences in genome size were observed

between the subfamilies sampled. Our results suggest that the changes in genome size in Formicidae

were likely due to the loss and accumulation of non‐coding regions, mainly due rearrangements on

transposable elements, and in some specific ant lineages would be possible the whole genome

duplication. However, the processes and constraints behind these genome expansions and shrinking

still need to be understood. It has been suggested by intraspecific studies that changes in DNA

content are related to the new colonization events could trigger genome changes in response to the

challenges imposed by new environments.

57

Accumulation of Zn and Cd in Lasius niger workers is colony dependent

Mateusz Okrutniak, Irena M. Grześ

Department of Environmental Zoology, University of Agriculture in Krakow, al. Mickiewicza 24/28, 30‐

059 Krakow, Poland


Ants may build reproductive colonies even in highly disturbed habitats, including metal polluted

areas. The colonies of ants are stationary and perennial, which limit the mobility of colony members.

Therefore, ants may be expected to accumulate higher amounts of metal than other insects. The

number of recent studies shows that many biological aspects diversify the colonies. Our previous

studies showed that traits mediating evolutionary response to pollution are usually not related to the

pollution level, but they are colony‐specific. In the present study, we focused on zinc and cadmium

accumulation in workers of common garden ant (Lasius niger, L. 1758). We expected that the

efficiency of metal detoxification should differ between colonies. We collected the ants on four sites

located on the industrial wastelands around the zinc and lead smelter in southern Poland. We took

nest‐samples of workers from 40 nests. Total body concentration of zinc and cadmium was measured

using standard analytical methods. The accumulation varies significantly between the colonies

(P<0.0001). The results clearly showed the variability of metal accumulation, however, it is still

unknown which colony traits behavioral or genetic or other contribute mostly to the obtain variation.

This Research was financed by the Ministry of Science and Higher Education of the Republic of

Poland, BM 2202/2018.

58

Phylogenetic analyses of the proteins involved in encapsulation signaling pathways in ants

Kincső Orbán‐Bakk1,2, Bálint Markó1,2, Ferenc Kósa1

1 Hungarian Department of Biology and Ecology, Babeş‐Bolyai University, Clinicilor 5–7, 400006, Cluj‐

Napoca, Romania

2 Center for Systems Biology, Biodiversity and Bioresources, Babeş‐Bolyai University, Clinicilor 5–7,

400006, Cluj‐Napoca, Romania


The cuticle plays an important role in the defense system of insects. If pathogens manage to pass this

barrier, cellular and humoral immune responses will be elicited. Encapsulation makes part of the

cellular immune response, and it is one of the most important immune defense mechanisms. There

are two signaling pathways (Toll and Jak/Stat), that result in the expression of specific immune genes,

which, on their turn, encode peptides, proteins and activate innate immune responses like

encapsulation. The main aim of my study is to elucidate the phylogeny of the proteins involved in

these signaling pathways. Furthermore we also study the evolutionary differences in the proteins

domain structure, and the potential ecological background of the revealed variations. Altogether we

analyzed 14 proteins, while searching for the homologue sequences in six social insect groups, as

termites, ants, bees, crabronid wasps, sweat bees, and social wasps, and in three solitary insect

groups, as fruit flies, ichneumonid wasps, and megachilid bees. We found that the proteins involved

in encapsulation signaling pathway can be found in different social and solitary insect. In the studied

families the studied proteins’ domain structure show clear differences, and ants form clearly

separate clades in the phylogenetic tree. However, there are ant species that group separately in

certain cases. Potential underlying factors are discussed.

59

Does snow‐making on ski slopes affect ants? Preliminary results from a study from the Czech Giant

Mountains

Lenka Petrakova, Jiri Schlaghamersky

Masaryk University, Faculty of Science, Department of Botany and Zoology, Brno, Czech Republic


Snow‐making is increasingly used at ski resorts to extend the ski season and to provide more stable

conditions for the preparation of ski runs. Artificial snow has somewhat different properties to

natural snow, for instance in regard to the insulation of the underlying soil and the content of

nutrients. Together with higher amounts of snow and thus a prolonged thawing period and possibly

higher water infiltration this can affect biota above and below ground. Within a project investigating

the effect of artificial snow on vegetation and invertebrate fauna, we compared ant assemblages on

six pairs of grasslands serving as snow runs – with and without snow‐making – in the montane zone

of the Giant Mountains (Krkonoše, Czechia). Our preliminary results are based on two methods:

Kempson extraction of soil samples (625 cm2 surface area, ca 10 cm depth) taken once in spring and

once in autumn 2018 and pitfall traps exposed from May to early August and from early August to

the end of October 2018. For both methods there were five replicates per site and date. At the

moment of abstract submission only the ants obtained from soil samples were identified (1011

specimens). Based on these data, a total of eight species were present. Ant assemblages on all sites

were dominated by Myrmica scabrinodis NYLANDER, 1846. At some sites also Myrmica rubra

(LINNAEUS, 1758) and Myrmica ruginodis NYLANDER, 1846 were abundant. Other species, Myrmica

lobicornis NYLANDER, 1846, Myrmica rugulosa NYLANDER, 1849, Lasius niger (LINNAEUS, 1758),

Lasius flavus (FABRICIUS, 1782), and Formica sp. LINNAEUS, 1758 were rarely found at some of the

study sites. Total ant abundances in soil samples did not differ between sites with and without snow‐

making. We are going to finish identification (pitfall trap material) and the analyses in the coming

months.

60

Bioturbation impact of the dominant ant Ectatomma ruidum sp. 2 (E. ruidum species complex) in

Andean coffee plantations

Carlos Santamaría1, Inge Armbrecht1, Jean‐Paul Lachaud2,3

1 Departamento de Biología, Grupo GEAHNA, Universidad del Valle, Cali, Colombia





e‐mail: jean‐paul.lachaud@univ‐tlse3.fr

Bioturbation by ants can deeply impact soil physical characteristics and plant growth in

agroecosystems, especially where ant nest density is high, but such an ecosystem service has rarely

been studied in plantations of economic importance. We aimed at evaluating the impact of a

dominant predatory ant belonging to the species complex Ectatomma ruidum, E. ruidum sp. 2, which

presents nest densities estimated between 568 and 1945 nests ha‐1 in Andean coffee plantations of

the Department of Cauca, one of the most important coffee producing areas in Colombia. A total of

120 experimental units (EUs), each containing two young seedlings of Coffea arabica, were

established in semi‐natural conditions in 20 shade or sun coffee plots. Sixty of them did not contain

ant colony (controls), while a colony of E. ruidum sp. 2 (70 individuals on average + 1 queen) was

added to the other EUs (treatments). The soil removed by ants and/or other organisms present in the

EUs was collected every two days during two months, oven dried and weighted. Various variables

concerning plant growth (plant height, stem diameter, plant dry weight), water infiltration, and

physical properties of the soil (apparent density, percentage of micropores and macropores, total

porous space) were also recorded for all EUs. On average, each E. ruidum sp. 2 colony removed 104.4

g dry soil during the two months of experiment (i.e., 1.58 g day‐1 colony‐1), about 13 times more

than the global soil removal performed by other invertebrates (arthropods, annelids or other ant

species) present on an equivalent surface during the same period of time (control EUs). Soil removal

was similar in sun and shade coffee plantations. A very conservative estimate of the global

bioturbation impact of this species in Andean coffee plantations was calculated at between 0.898

and 3.077 kg ha‐1 day‐1. This impact could be much higher in more natural conditions as, when

considering only those Ectatomma colonies fully active until the end of the experiment, bioturbation

was much more important, reaching up to 3.47 g day‐1 colony‐1. At the global level of the 60

colonies involved, E. ruidum sp. 2 seemed to affect only some of the variables related to seedling

growth or soil physical properties during the two months of the experiment. However, their presence

had a clear significant positive effect on all plant growth variables when only those colonies that

were active until the end of the experiment were considered. Conservation of soil nesting ants by

avoiding pesticides should be considered in the light of the functional role of these ants for

bioturbation in agroecosystems.

61

The effect of nest structure and space use on disease spread in ant colonies

Linda Sartoris, Erika Dawson, Christoph Sommer , Sylvia Cremer

IST Austria, Am Campus 1, Klosterneuburg 3400, Austria


Pathogens can spread quickly through the close interaction networks in social insect colonies. For

each individual the risk of disease depends on pathogen spread within the colony. Contamination of

an individual can occur either directly through interactions with an infectious colony member or

indirectly by entering a contaminated area. We study the effect of spatial overlap of colony members

on their risk of directly or indirectly picking up pathogens from an infectious colony member. To test

this, we assess their space use by tracking them individually, and determine the pathogen load they

acquired. We ask whether nest structure induces compartmentalization of social interaction and

thereby reduces spatial overlap and, hence, pathogen transmission among colony members.

62

Comparative study on the toxic effect of synthetic nano‐ilmenite and natural ilmenite mineral on

Formica pratensis

Kata Saszet1, Eszter Mátyás2, Zsolt Czekes1,2, Enikő Almási3, Zsolt Pap1,3




Romania‐400006

3 Environmental Chemistry Research Group, Institute of Environmental Science and Technology,

University of Szeged, Tisza Lajos krt. 103, Szeged, Hungary‐6720


Although nanomaterial‐based applications are more and more widespread in the last centuries, their

effect on our environment is unclear. Even some environmentally friendly applications, such as

advanced oxidation processes for wastewater depollution use semiconducting nanomaterials whose

impact on nature is not yet investigated or it is well‐known to be harmful (e.g. FeTiO3, Cu2O). The aim

of the current work is to study the toxic effect of different ilmenite (FeTiO3) samples on Formica

pratensis ant species, comparing the synthetic samples with the natural ones, sourced from minerals.

For this we submitted the model species to mortality tests using commercially available nanomaterial

(Sigma‐Aldrich Iron (II) titanate, 99.9 % purity), a laboratory synthesized one (FeTiO3 and auxiliary

components via hydrothermal method) and natural ilmenite mineral. Each test lasted 7 days, the

survival of ants was investigated using Cox regression. Based on the results, it is possible to conclude

whether nano‐milled natural ilmenite minerals can be a safe alternative of synthetic nano‐ilmenite in

environmental applications.

63

Transgenerational effect of rifampicin on queen fitness

Ciğdem Ün, Eva Schultner, Jürgen Heinze, Jan Oettler



The ant species Cardiocondyla obscurior hosts two endosymbionts, Wolbachia and Candidatus

Westeberhardia cardiocondylae. To study the role of these bacteria, we use antibiotic rifampicin

treatment to eliminate the bacteria. Among various direct phenotypic effects on queens, such as

decreased productivity, here we report that F1 males from treated queens have shorter sperm

length compared to males from untreated queens. This suggests a toxic transgenerational effect of

rifampicin on spermatogenesis. In addition to the effects of rifampicin on prokaryotes, it has also

been shown to directly affect mitochondrial RNA synthesis. Mitochondria play a critical role in

spermatogenesis and thus sperm motility. This suggests a transgenerational toxic effect of the

applied antibiotic on male fitness. There is increasing evidence that environmental factors can induce

epigenetic change are transmitted to offspring. Together our data call for further investigation of

transgenerational effects of rifampicin on male reproductive success and life history traits.

64

Nest density and distribution in relation to the reproductive female at the head of Gnamptogenys

bisulca (Formicidae) colonies in neotropical forests

Diana Marcela Urcuqui1, Chantal Poteaux2, Janine Herrera‐Rangel1, Inge Armbrecht1

1 Universidad del Valle, Department of Biology, Calle 13 100‐00. Ed. E20, Off. 3025, Cali, Colombia 2

Laboratoire d'Ethologie Expérimentale et Comparée EA 4443, Université Paris 13, Sorbonne Paris Cité,

93430 Villetaneuse, France


The hunting ant Gnamptogenys bisulca (Formicidae: Ectatomminae) has shown to be a biological

indicator of habitat quality in Andean montane forests of Colombia, where it nests only in fallen

twigs within forest leaf litter. The ecological success of its populations within the fragmented Andean

forests could be related to the flexibility of its social organization marked by its capacity to switch

from queen to ergatoid ruled colonies, according to the ecological context. Therefore, this study

describes its local and regional spatial distribution in relation to the kind of reproductive females in

four differently fragmented Andean landscapes. In eight 100m2 plots located in four landscapes in

the western Colombian mountain range, the position of G. bisulca colonies was recorded. The 233

colonies collected showed a nest density ranging from 800/ha to 3000/ha, averaging 2259/ha with

no trend to be more or less dense in preserved forests. Their social composition was described and

classified into ergatoid or queen ruled colonies, and an effective monogyny was present in this

species, even in polygynous colonies. In general, a significantly negative relation between the

number of queens and ergatoids was found. At the local level, nest spatial distribution was random

no matter the kind of reproductive. However, at the landscape level, there was a correlation

between the proportion of colonies with ergatoids and the level of fragmentation in the landscapes

studied, while ergatoids were almost absent in the less fragmented landscapes, i.e., the Verdum

Reserve and El Brillante forest. Our results suggest that this species has a flexibility to switch to

ergatoid‐ruled colonies when ecological landscape conditions deteriorate.

65

Royal matchmaking: ant workers promote outbreeding by their sexual sisters by transporting them

to alien nests

Mathilde Vidal, Jürgen Heinze


e‐mail: mathilde‐[email protected]

Courtship and mating are typically associated with costs and risks and females are therefore

expected to mate only with one or a few males. Nevertheless, female multiple mating (polyandry) is

a common phenomenon in animals. In Hymenoptera, polyandry might be beneficial because it

increases the genetic diversity of the queen’s offspring, thus improving division of labor and

increasing pathogen resistance. Furthermore, multiple mating may counterbalance the negative

effects of eventual sib‐mating. Colonies of the ant Cardiocondyla elegans from Southern France

obligatorily contain only a single fertile queen (monogyny) and several wingless males. Mating occurs

within the nest between brothers and sisters, but to promote additional outbreeding workers may

transfer their female sexual sisters into alien colonies. In summer workers have been observed

carrying female sexuals over several meters and dumping them into the entrances of other nests. It

appears that sexuals are not randomly exported but transferred only to a subset of the locally

available colonies. In order to understand which parameters workers use to select particular colonies

we evaluate the relatedness between workers and the female sexuals they carried, their relatedness

to the source and receiver colony, and the population structure.

66

Coping with environmental change: interactions between an insect host and its microbial

symbionts

Jennifer Wallner, Jürgen Heinze, Jan Oettler, Eva Schultner



Understanding how organisms cope with environmental change is one of the most important

challenges facing humans today. Predicting the effects of extreme environmental conditions is not

easy because, in addition to abiotic factors such as temperature and humidity, organisms are

influenced by many biotic interactions. These include interactions with their competitors, predators

and microbial symbionts, who themselves are exposed to changing environmental conditions. We

used the ant Cardiocondyla obscurior to investigate how insects cope with changing environmental

conditions, and what role their microbial partners play in this process. This ant is a typical “tramp”

species: while it most likely originates from Southeast Asia, today it can be found in subtropical and

tropical habitats all around the world. To test how the ant and its microbial symbionts interact in

changing environments on a global scale, we sampled colonies from 10 locations and characterized

the genotype of the ant and its symbionts using sequence data. We then subjected colonies to

different temperature regimes and monitored productivity as a correlate of colony fitness. We find

that ants from different populations differ in their reaction to temperature change, and that these

changes are linked to both ant and symbiont genotype. This study will help resolve the global

distribution pattern of an invasive ant, and, more generally, will help explain how insect hosts and

their symbionts can interact to cope with environmental change.

67

Caste determination in Cardiocondyla obscurior

Tobias Weichselgartner, Jan Oettler



The development of ovaries in eusocial ants is a crucial point in setting the reproductive division of

labor between the queen and worker caste. In the polygynous ant C. obscurior workers lack ovaries

and queens are the only reproducing members of the colony. This makes C. obscurior a suitable

model to investigate how reproductive division of labor in a higher ant species via differential

gonadal development occurs.

Vasa is a member of the class of DEAD box proteins and is consecutively expressed throughout the

development of germ cells. Vasa is also found in cells that are involved in oogenesis and is therefore

considered germline specific. Consistent with this observation queen pupae show expression of Vasa

protein in nurse cells and pro‐oocytes of their developing ovaries. This makes Vasa a promising

marker to follow gonadal development in C. obscurior larvae. To identify active germ cells in

developing female larvae, expression levels of vasa were measured using quantitative real‐time PCR.

Confocal imaging in combination with an antibody against VASA was used to detect and identify

VASA expressing cells in C. obscurior queen larvae, showing that worker‐destined 3rd instar larvae do

not express VASA, while queen‐destined 3rd instar larvae show clear VASA expressing cells.

68

Overwintering in Formica fusca ants

Tomasz Włodarczyk

Dept. of Biology, University of Bialystok, Bialystok, 12‐245, Poland


Ant colonies living in regions with harsh weather conditions during winter have special adaptations

to survive this period. However, it is also crucial for a colony’s fitness to resume activity as soon as

suitable conditions appear. It was studied how F. fusca ants are distributed with respect to the depth

during a winter period. Moreover, data on the total colony size, the number of queens, and the

worker sizes were also collected. As a result, we obtained sociometric data on this species, free of

measurement bias caused by the differences in the progress of annual life cycle, which might be the

case when ant populations are sampled during activity season. We also tested whether ants localized

closer to the soil surface are more likely to undertake external tasks later during the season, as

compared to ants from the deeper parts of the nest.

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