Ant Myrmica Research Articles

Alcon Blues: recent shifts in limiting habitat factors challenge the persistence of an endangered butterfly

Insect habitat specialists have declined more than generalists over the last decades. Understanding how habitat requirements and increased climate variability interact to explain persistence of populations is needed to enable effective conservation measures. Habitat specialists with a complex life cycle, such as myrmecophilous butterflies, are likely to be most vulnerable. Here, we explored to what extent the habitat factors explaining population persistence of the Alcon blue (Phengaris alcon), changed over a 25-year period in the Netherlands, contrasting the recent years 2018–2022 with extreme droughts with the preceding period 1998–2017 characterized by occasional climatic extremes. Population persistence of P. alcon over 1998–2017 as explained by historical habitat conditions was significantly higher in large heathland areas with large patches of its host plant Gentiana pneumonanthe. On the basis of current conditions, population persistence until 2017 was best explained by a combination of host plant area and quality. In contrast, persistence over the recent drought years was most closely associated with increasing occupancy of the optimal host ant Myrmica ruginodis and lower occupancy of competitive and predatory Lasius ants.Implications for insect conservation We conclude that critical habitat conditions change under increasing climatic extremes and that the availability of sufficient optimal host ants has become more critical than that of host plants. The results emphasise that both large-scale hydrological restoration and small-scale management for heterogeneity are necessary to preserve P. alcon and its habitat in the Netherlands. This is also likely to apply to other habitat specialists with complex life cycles from threatened habitats.

Fecal Deployment: An Alternative Way of Defensive Host Plant Cardenolide Use by Lilioceris merdigera Larvae

The brilliant red Lilioceris merdigera (Coleoptera, Chrysomelidae) can spend its entire life cycle on the cardenolide-containing plant Convallaria majalis (lily of the valley) and forms stable populations on this host. Yet, in contrast to many other insects on cardenolide-containing plants L. merdigera does not sequester these plant toxins in the body but rather both adult beetles and larvae eliminate ingested cardenolides with the feces. Tracer feeding experiments showed that this holds true for radioactively labeled ouabain and digoxin, a highly polar and a rather apolar cardenolide. Both compounds or their derivatives are incorporated in the fecal shields of the larvae. The apolar digoxin, but not the polar ouabain, showed a deterrent effect on the generalist predatory ant Myrmica rubra, which occurs in the habitat of L. merdigera. The deterrent effect was detected for digoxin both in choice and feeding time assays. In a predator choice assay, a fecal shield derived from a diet of cardenolide-containing C. majalis offered L. merdigera larvae better protection from M. rubra than one derived from non-cardenolide Allium schoenoprasum (chives) or no fecal shield at all. Thus, we here present data suggesting a new way how insects may gain protection by feeding on cardenolide-containing plants.

Infection with a non-lethal fungal parasite is associated with increased immune investment in the ant Myrmica scabrinodis

Social insects, such as ants, are preferred host organisms of pathogens and parasites because colonies are densely populated, and the number of potential hosts is high in the same place and time. Within a colony, individuals are exposed differentially to risks according to their function and age. Thus, older individuals forage and are therefore the most exposed to infection, predation, or physical stress, while young workers mostly stay inside the sheltered nest being less exposed. Immune investment is considered to be dependent on an individual’s age and pathogen pressure. Long-term exposure to a parasite could affect the immune activity of individuals in an intriguing way that interferes with the age-dependent decline in immunocompetence. However, there are only few cases in which such interferences can be studied. The myrmecopathogenic fungus Rickia wasmannii, which infects entire colonies without killing the workers, is a suitable candidate for such studies. We investigated the general immunocompetence of Myrmica scabrinodis ant workers associated with non-lethal fungal infection by measuring the levels of active phenoloxidase (PO) and total PO (PPO) (reflecting the amount of both active and inactive forms of the enzyme) in two age classes. The level of PO proved to be higher in infected workers than in uninfected ones, while the level of PPO increased with age but was not affected by infection. Overall, these results indicate that a long-term infection could go hand in hand with increased immune activity of ant workers, conferring them higher level of protection.

Efficiency of emergency conservation methods: a case study of the alcon blue butterfly (Phengaris alcon) and its specific parasitoid

A complicated life history and specific habitat requirements make the Alcon blue butterfly Phengaris alcon a very sensitive species to land-use change. Eggs are oviposited on some Gentiana and Gentianella plants, in whose flowerheads larvae initially feed, after which they continue their development as social parasites in the nests of specific Myrmica ants, once they have been adopted by workers. One of the main threats to their existence is mowing at a time when most individuals are still on gentians. In our research, we tested an emergency conservation method on a site of the butterfly subjected to this kind of pressure in the Białowieża Forest (NE Poland). Previous studies showed that the focal population (dependent on Gentiana pneumonanthe and Myrmica scabrinodis) was characterized by an extremely high density of adults as well as of Ichneumon eumerus, i.e. the rare and specific parasitoid of P. alcon. In mid-August 2020 we performed an unplanned experiment to save caterpillars present in freshly cut plants. We selected about 1800 shoots bearing the eggs or egg shells of the butterfly. Seven hundred and fifty preadoption larvae were transported to the site and placed close to the nests of host ants located in patches without G. pneumonanthe. In the following season we observed that the P. alcon infestation rate of experimental colonies was similar to a control patch, and proportions of parasited pupae did not differ, either.Implications for conservation. Our experiment proved that such actions can be highly effective as emergency conservation methods, and possibly also in (re)introductions of P. alcon.

First Record of the Introduced Ant Myrmica specioides In the Eastern United States

The ant Myrmica specioides Bondroit, 1918 (Hymenoptera: Formicidae) is first reported from the Eastern United States. This species is native to the West Palearctic region and has previously been known as an introduced species in Northwestern North America. It was found 2013 in the Boston metropolitan area. The species was identified by morphometric comparison to type specimens and DNA-barcoding. The distribution and invasive potential of M. specioides are discussed.

Adverse effects of the dietary supplement berberine studied on ants as models

An extract of Berberis plants is nowadays used as a dietary supplement as well as for treating several medical symptoms, e.g., mostly for regulating glycemia, lipid metabolism and central nervous system disorders. Few or no information has so far been reported about side effects of berberine on behavioral and physiological-linked traits. We thus investigated on the potential adverse effects of the alkaloid berberine by using the ant Myrmica sabuleti as a model. We found that berberine decreased the ant’s food intake, activity, locomotion, and sensory perception, but did not impact their social interactions, cognition, learning and memorization. The ants did not adapt themselves to the side effect of berberine on their locomotion. They did not develop strong dependence on berberine consumption. After weaning, the behavioral effect of a diet with berberine linearly decreased until it vanished in 15 – 18 hours. Researches to assess the effect of berberine on various associated behavioral and physiological traits in mammals and in humans are still needed in order to draw a complete safety profile of this substance.

Capability of Workers of the Ant Myrmica sabuleti to Categorize Numbers of Elements into Even and Odd

Categorizing numbers into even and odd is an ability held by humans that has recently been found to be also held by honeybees. We examined whether ants could also make such parity discrimination. Working on the species Myrmica sabuleti, we learned the ants of two colonies to associate 2 black circles with a reward and 5 of these circles with the absence of a reward, as well as learned the ants of two other colonies to associate 3 of these same cues with a reward and 4 of these cues with the absence of a reward. By collectively testing foragers of each colony in a separate tray in front of these cues, it was first verified during three days if they dully learned the ‘correct’ cue. Thereafter, while the ants continued to be trained, foragers of each colony were collectively subjected to nine successive choice tests, each day in front of a pair of cues different from the one used during the learning process. The cues used during these tests differed from those used to train the ants by the number and size of the dots, the cumulative surface of the dots, the perimeter of their area (surfaces and perimeters being maintained equal between the cues) and their layout. A ‘correct’ cue had the same parity (even or odd) as the cue learned during training. The tested ants each time consistently responded to the number that had the same parity as that of the number they learned during conditioning. This sensitivity to the number parity occurred from the number 1 until the number 7. Discrimination between 7 and 8 dots was beyond the ant capability.

Summary of Newly Found Ants’ Cognitive Abilities, and Their Occurrence in Humans

Authors studied the cognitive abilities of the ant Myrmica sabuleti Meinert 1861, and in addition to the separate publications of their findings, they also summarized them in until now three papers. Here, the authors summarize their eight last findings, and report similar abilities in humans as well as advices for acquiring and using them. The ants can associate visual cues, numbers of elements, and odors with the time periods of their occurrence, and do so taking into account the characteristics of the elements. Humans should do so for ameliorating their daily life. For adding two numbers, the ants must see them with a time gap not exceeding 8 minutes. The ants discriminate recent and previously perceived events, locating the recent but not the old ones on a ‘time line’. Humans must learn to evaluate the passing time, to have a ‘time line’. The ants’ time perception is underestimated when they are more active. This is true for humans, and must be considered while working, playing or doing nothing (e.g., elderly persons). The ants can navigate using a learned (memorized) sequence of odors. Humans must learn sequences of cues for finding their way. The ants discriminate even and odd numbers until the number 7. Humans are sensitive to numbers’ parity, and this should freely impact their choice. Shortly, the authors revealed four cognitive abilities in ants which should occur in humans, natively or acquired through experiences, at a more precise, complex and extended level, in order to provide them with an as comfortable as possible live.

Non-lethal fungal infection could reduce aggression towards strangers in ants

Many parasites interfere with the behaviour of their hosts. In social animals, such as ants, parasitic interference can cause changes on the level of the individual and also on the level of the society. The ant-parasitic fungus Rickia wasmannii influences the behaviour of Myrmica ants by expanding the host’s nestmate recognition template, thereby increasing the chance of the colony accepting infected non-nestmates. Infected ants consistently show an increase of the alkane tricosane (n-C23) in their cuticular hydrocarbon profiles. Although experimental application of single compounds often elicits aggression towards manipulated ants, we hypothesized that the increase of n-C23 might underlie the facilitated acceptance of infected non-nestmates. To test this, we mimicked fungal infection in M. scabrinodis by applying synthetic n-C23 to fresh ant corpses and observed the reaction of infected and uninfected workers to control and manipulated corpses. Infected ants appeared to be more peaceful towards infected but not uninfected non-nestmates. Adding n-C23 to uninfected corpses resulted in reduced aggression in uninfected ants. This supports the hypothesis that n-C23 acts as a ‘pacifying’ signal. Our study indicates that parasitic interference with the nestmate discrimination of host ants might eventually change colony structure by increasing genetic heterogeneity in infected colonies.

The Pattern of Social Parasitism in Maculinea teleius Butterfly Is Driven by the Size and Spatial Distribution of the Host Ant Nests

The parasitic relationship between Maculinea butterflies and Myrmica ants has been extensively studied but little information is available on the spatial occurrence of Maculinea larvae. We searched for the presence of Maculinea teleius in 211 ant nests at two sites in two crucial phases of its life cycle, i.e., in autumn, during the initial larval development, and in the following late spring, before pupation. We assessed variations in the proportion of infested nests and factors correlated with spatial distributions of parasites in Myrmica colonies. The parasitism rate in autumn was very high (∼50% of infestation rate) but decreased in the following spring. The most important factor explaining parasite occurrence in both seasons was the nest size. Further factors, such as the presence of other parasites, the Myrmica species or the site, concurred to explain the differential survival of Ma. teleius until the final development. Irrespective of the host nest distribution, the parasite distribution changed from even in autumn to clumped in late spring. Our work showed that the survival of Ma. teleius is correlated with colony features but also with the nest spatial distribution, which therefore should be taken into consideration in conservation strategies aiming at preserving these endangered species.

The Workers of the Ant Myrmica sabuleti can Learn and Use a Sequence of Four Odors to Navigate between Nest and Food Site

The ant Myrmica sabuleti uses essentially odors for navigating. It has also several skills which presume that it could learn, memorize a sequence of odors and afterwards use it for navigating. By training (operative conditioning) then testing forager workers, we demonstrate that these ants are able to soon learn and memorize a sequence of four odors, i.e., thyme, lavender, basilica, and orange zest, linearly set during training between the nest entrance and the food site, and a simple additional experiment showed that the trained ants effectively used the learned sequence of odors for moving between the nest and the food. Moreover, as workers of this ant can associate odors with the time of the day during which they perceive them, they should be able to use a memorized sequence of odors at appropriate time periods in order to optimize a safe navigation. As this ant is known to use visual cues, odometry, area marking, and deposition of the trail pheromone to navigate, it is also liable to combine these strategies with that of following odor sequences.

When Associating Numbers of Elements With Their Time Period of Occurrence, the Ants Take Account of the Characteristics of the Elements

After having shown that the workers of the ant Myrmica sabuleti can associate amounts of elements with their time periods of occurrence and knowing that these ants do not take into account the characteristics of elements when counting but take them into account when adding the elements, we wondered if, when associating amounts with their time periods of occurrence, these ants take or do not take account of the characteristics of the elements. Working on six colonies and using three kinds of visual cues during training and these three cues modified as for their size (small, large), color (blue, yellow) or shape (triangle, star) during testing, we revealed that, when associating amounts of elements with their time periods of occurrence, the ants take into account the characteristics of the elements. We checked if, without changing the elements characteristics, the ants effectively associated the perceived amounts (1 – 3, 2 – 4, 3 -5) of elements (squares, blue circles, triangles) with their time periods of occurrence (8 – 19 o’clock, 20 – 7 o’clock), and they did. We also made a complementary experiment on newly collected colonies using a slightly different protocol, and we obtained identical results which leaded to the same conclusion. So, the present work confirmed our previous results and solved the last asked question on the subject.   

Sod translocation to restore habitats of the myrmecophilous butterfly Phengaris (Maculinea) teleius on former agricultural fields.

In Europe, 50%–70% of former natural grassland area has been destroyed during the past 30 years due to land use changes, losses are expected to increase in the future. Restoration is thought to reverse this situation by creating suitable abiotic conditions. In this paper, we investigate the effects of sod translocation with specific vegetation to facilitate the restoration of a former intensive agricultural field into a wet meadow. First, starting conditions were optimized including modification of the local hydrology, removal of the fertilized topsoil, application of liming, and translocation of fresh clippings as a seed source. The second part aimed at restoring the habitat for the butterfly species Phengaris (Maculinea) teleius, one of the species that was especially affected by the loss of wet meadows. This species engages in a complex myrmecophilous relationship with one host plant, Sanguisorba officinalis, and one obligate host ant, Myrmica scabrinodis. We used sod translocation to create islands of habitat to promote host plant and host ant colonization. After 4 years following the restoration, we observed that plants spread from the transplanted sods to the surroundings. The vegetation composition and structure of the transplanted sods attracted colonization of Myrmica ants into the restored areas. Following the increase in vegetation cover and height, Myrmica ant colonies further spread into the restored areas. Therefore, sod translocations can be considered an effective restoration method following topsoil removal in the process of restoring wet meadows to provide a starting point for ant colonization and plant dispersion. With these findings, this paper contributes to the evidence‐based restoration of wet meadows on former agricultural fields, including complex interactions between invertebrates and their required ecological relationships.

Colony specificity and starvation-driven changes in activity patterns of the red ant Myrmica rubra.

Although the activity levels of insect societies are assumed to contribute to their ergonomic efficiency, most studies of the temporal organization of ant colony activity have focused on only a few species. Little is known about the variation in activity patterns across colonies and species, and in different environmental contexts. In this study, the activity patterns of colonies of the red ant Myrmica rubra were characterized over 15 consecutive days. The main goals were to evaluate the colony specificity of the activity patterns and the impact of food deprivation on these patterns. We found that the average activity level varied across colonies and remained consistent over 1 week, providing evidence that the activity level is a colony-specific life trait. Furthermore, all colonies applied an energy-saving strategy, decreasing their average levels of activity inside the nest, when starved. Starvation induced no consistent change in the activity level outside of the nest. An analysis of activity time series revealed activity bursts, with nestmates being active (or inactive) together, the amplitudes of which reflected the ants' degree of synchronization. Food deprivation increased the amplitude and number of these activity bursts. Finally, wavelet analyses of daily activity patterns revealed no evidence of any periodicity of activity bouts occurring inside or outside of the nest. This study showed that M. rubra ant colonies are characterized by specific activity levels that decrease in response to starvation with the adoption of an energy-saving strategy. In addition, our results help to understand the functional value associated with synchronized and/or periodic fluctuation in activity, which has been debated for years.

A new myrmecophilous genus of Falagriini from Colorado, USA (Coleoptera: Staphylinidae: Aleocharinae).

A new genus and species, Myrmecoagria hoebekei is described as the first known myrmecophilous representative of Falagriini in North America. The new species is believed to be associated with Myrmica ants based on an associated host specimen and label data. Ahn Ashes (1995) dataset is modified to investigate the placement of Myrmecoagria and evolution of myrmecophily within Falagriini. Sceptobiini, a long suspected close relative of Falagriini was included in the analysis and was recovered nested within Falagriini. Myrmecoagria was recovered distant to Myrmecopora, a genus with anatomical similarities.

Association, in an Ant, of a Quantity of an Element with the Time Period of Its Learning

The workers of the ant Myrmica sabuleti detain numerosity abilities, have a notion of the running time, and can acquire operant conditioning. The present work examines if, according to these skills and through conditioning, the workers of this ant can associate a learned quantity of a given element with the time period of its occurrence. We collectively trained such ants from 8 to 19 o’clock to a stand bearing a given quantity of an element and from 20 o’clock to 7 o’clock next day to a stand bearing another quantity of the same element, and we tested them in front of these two amounts at 16 o’clock and 4 o’clock next day. At 16 o’clock, the ants reacted essentially to the amount presented during training from 8 to 19 o’clock, and at 4 o’clock to the amount presented during training from 20 o’clock to 7 o’clock. They thus associated the learned quantity of an element with the period of the day during which this learning occurred. It may be argued that this association simply results from the three cognitive capabilities cited here above, and does not require any other more complex skill. In addition, the ants appeared to have better learned from 20 to 7 o’clock than from 8 to 19 o’clock, i.e., during the time of day corresponding to their period of highest natural activity.

Seed Dispersal by Ants in Three Early-Flowering Plants.

Simple SummaryMyrmecochory is seed dispersal of numerous plant species mediated by ants. We investigate ant–plant interactions under field conditions across two study sites in Central Europe. Three obligatory myrmecocohrous plants are chosen for the experiments: snowdrop Galanthus nivalis, hollow root Corydalis cava and European wild ginger Asarum europaeum. We experimentally alter diaspore morphology and record seed removal rates across five treatments: elaiosomes without seeds, diaspore without elaiosome, 1/2 elaiosome + diaspore, 1/2 diaspore + elaiosome and control. Elaiosomes of European wild ginger constitute about 30% of diaspore weight, elaiosomes of snowdrop constitute 13% and elaiosomes of hollow root constitute only 7.5%. Diaspore/elaiosome removal rates are highest in European wild ginger (34%), followed by hollow root (26%) and snowdrop (10%). Only two ants interact with diaspores, the acorn ant Temnothorax crassispinus and the red ant Myrmica ruginodis. Ants respond to elaiosome/seed ratio by removing elaiosomes without diaspores most frequently, followed by 1/2 diaspore + elaiosome, control, diaspores without elaiosomes and 1/2 elaiosome with diaspore. Plants do not effectively manipulate ant behavior and no dispersal benefits from interactions with ants are observed.Interactions between ants and plants vary from being occasionally beneficial to neutral and negative. Ant-mediated dispersal of obligatory myrmecochorous plants is considered mutualistic interaction, providing benefits to plants in terms of seed dispersal. Ants are rewarded by providing elaiosome, sugar, lipid and protein-rich appendages attached to seeds (diaspores). We experimentally examine rates of diaspore removal rates among three species of plants (snowdrop Galanthus nivalis, hollow root Corydalis cava and European wild ginger Asarum europaeum) under field conditions in two study sites in Central Europe. Diaspore morphology is altered by manipulating both elaiosome and seed size. The small-sized acorn ant Temnothorax crassispinus interacts with the snowdrop and hollow root and the moderately-sized red ant Myrmica ruginodis interacts with European wild ginger. Experimental manipulation with elaiosomes yields largely non-significant results. Diaspore removal rates are generally low (snowdrop 10%, hollow root 26%, European wild ginger 34%) probably due to the small size of ants relative to heavy diaspores. Many ants are observed to consume elaiosomes in situ (cheating). We conclude that ant–plant relationships in this case are not mutualistic but rather neutral/slightly negative, because the plants do not obtain any apparent benefits from their interactions with ants.

Spatial distancing by fungus-exposed Myrmica ants is prompted by sickness rather than contagiousness

The ecological success of ants relies on their high level of sociality and cooperation between genetically related nestmates. However, these group-living insects suffer from elevated risks of disease outbreak in the whole nest. To face this sanitary challenge, social and spatial distancing of pathogen-exposed individuals from susceptible nestmates appear to be simple, although efficient, ways to limit the propagation of contact-transmitted pathogens. Here we question whether spatial distancing in Myrmica rubra ants is an active response of diseased individuals that correlates with their level of infectiousness. We contaminated foragers with spores of Metarhizium brunneum entomopathogenic fungus. We daily tracked the location of these pathogen-exposed individuals and we analyzed their movement patterns until their death on the 5th day post-contamination. Quite unexpectedly, we found that contagious individuals, whose body was covered with infectious spores, did not reduce their mobility nor stayed far away from larvae in order to limit pathogen transmission to healthy nestmates. Spatial distancing occurred later when diseased individuals were no longer contagious because spores had penetrated their body. These sick ants mainly stayed outside the nest, were less mobile and showed a shift from a superdiffusive to subdiffusive walking pattern. Furthermore, these diseased ants did not actively head towards directions that were opposite to the nest entrance. This study found no evidence for early spatial distancing by contaminated M.rubra workers that would fit to the actual risk of colony-wide contagion. Coupled to a lower mobility and area-reduced walking patterns, the late distancing of moribund individuals appears to be a symptom of sickness resulting from fungus-induced physical and physiological dysfunctions. Besides questioning the truly altruistic nature of death in isolation in this system (and potentially others), we discuss about the ecological and physiological constraints that explain the absence of early distancing when some ant species are exposed to pathogens.

A Synthesis of Six Recent Studies on Numerosity Abilities in an Ant

AbstractWorking on the numerosity ability of the ant Myrmica sabuleti, we have already summarized for the readers’ convenience our previous papers in two successive publications. Since that time, we have produced six more papers on the subject, and we thought it was time to present a summary of them. These studies deal with the ants’ ability in expecting the following element in an arithmetic or a geometric sequence, as well as with the required similarity between visual cues and the maximum horizontal and vertical distance between such cues enabling the ants to mentally add them up. The experimental methods that were used in these studies are here only briefly reported and their most important results are concisely related, as the extended information can be found in these six papers here summarized. We present novel tables and figures for illustrating this synthesis.

Ectoparasitic fungi of Myrmica ants alter the success of parasitic butterflies

Exploitation of organisms by multiple parasite species is common in nature, but interactions among parasites have rarely been studied. Myrmica ants are rich in parasites. Among others, the ectoparasitic Rickia wasmannii fungus and the parasitic caterpillars of myrmecophilous Phengaris butterflies often infect the same Myrmica colonies. In this study, we examined the effects of R. wasmannii on the adoption, long-term development, and survival of P. alcon. In laboratory conditions, caterpillars introduced into nests of Myrmica scabrinodis uninfected with R. wasmannii survived significantly longer compared to caterpillars introduced into infected nests. In the field, joint infection was less common than expected if both parasites exploited M. scabrinodis colonies independently. Pre-pupal caterpillars of P. alcon were somewhat larger in nests infected with R. wasmannii than those found in uninfected nests. Based on these results it seems that R. wasmannii infection of M. scabrinodis affects the survival and development of P. alcon caterpillars, suggesting competition between these two ant parasites.