The mandibular gland secretion of the ant, Myrmica scabrinodis

ABSTRACT. The volatile secretion of the mandibular gland of the common elbowed red ant, Myrmica scabrinodis Nyl., is shown to consist of ethanal, ethanol, acetone, 3-hexanone, 3-hexanol, 3-heptanone, 3-heptanol, 3-octanone, 3-octanol, 6-methyl-3-octanone, 6-methyl-3-octanol, 3-nonanone, 3-nonanol, 3-decanone and 3-undecanone. The electroantennographic response to the major components was recorded and compared with some related compounds. Behavioural tests were carried out on the major constituents, showing that 3-octanol is an attractant for workers, that 3-octanone increases the effect of 3-octanol, and 3-nonanone augments the linear speed of the ants.     

Operant conditioning in the ant Myrmica sabuleti

Operant conditioning could be obtained in the ant Myrmica sabuleti by presenting to the workers, during a six-day period, an apparatus containing either sugared water or meat as a reward. The conditioning obtained using sugared water as a reward was short lasting. A reconditioning was more persistent and lasted four hours. The ants' response was very precise, since they exhibited it only in front of an apparatus identical to that used during the training phase. Operant conditioning obtained using meat as a reward was more pronounced than that obtained by using sugared water, probably because meat is more valuable as a reward than sugar for the species studied, which is essentially a carnivorous one. Such a conditioning was rather persistent. Indeed, a first operant conditioning obtained by using meat as a reward could still be detected after seven hours, and a reconditioning was still significant after eight hours. One day after this eight-hour period without rewarding the ants, the response was higher again and a further day later, it was still significant. Since the operant conditioning is easy to perform and quantify and since the ants' response is very precise, such a conditioning can be used for further studying M. sabuleti workers' visual perception.     

The growth and development of colonies of the ant Myrmica

Summary Colony growth and development is conveniently divided into stages: pre-worker, juvenile, adolescent and mature. The pre-worker stage is one in which small workers are produced by the queen from her body reserves. The juvenile stage is characterised by a gradual increase in the egg production of the queen, and in the size of the workers. No doubt this is partly due to an improvement in food capture but other factors also exist; of great importance is the influence that the queen exerts on the growth and, development of individuals, an influence which is independent of population tension The adolescent stage is transtional; in it males first appear. The mature stage is one of full-sized workers and male and female sexual production.Gynes are produced when the ratio workers/larvae is high. This varies randomly in most colonies about a mean value, and the size of the formant winter larvae is proportional to it; but the cause of the variation is unknown. A condition of gyne production is that the colony be in a favourable environment, for even in large colonies, poor insolation causes small individual size. Very large colonies, in which workers are greatly in excess of those needed to rear the brood are uncommon, and it is suggested that this may be due to the population instability which the production and dissemination of sexuals causes.A model of geometric recurrence type is constructed which agrees reasonably well with the facts culled in various ways from different sources.

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Resumen Convenientement, el desarrollo y crecimiento de la colonia puédese dividir en estados como ser: pre-trabajador, juvenil, adolescente y estado maduro. El estado pre-trabajador es aquel en que la reina produce de sus reservas, trabajadoras pequeñas.El estado juvenil se caracteriza por el aumento paulatino en la producción de huevos por parte de la reina como también en el tamaño de las trabajadoras.Sin duda, esto se debe en parte a la mejora en su approvisionamiento pero existen también otros factores; es de gran importancia la influencia ejercida por la reina sobre el crecimiento y desarrollo de individuales, influencia ésta independiente de la tensión de populación.El estado adolescente es transicional-en él aparecen por primera los machos. El estado maduro es uno de trabajadoras perfectas y de producción masculino y femenino.Los genes se producen cuando la proporción de trabajadoras y larva es alta. Por casualidad esto varía en la mayoría de las colonias con un valor reducido y el tamaño de la larva en estado adormecente en proporción, pero se desconoce por qué motivo occurre la variación.Una condición en la producción del gene es de encontrarse la colonia en un ambiente favorable puesto que aún en colonias grandes la insolación pobre produce tamaños pequeños.Es extraño encontrar colonias grandes en las cuales las trabajadoras exeden aquellas que se requieren para la cría y sugiérese que puede ser que esto se debe a la instabilidad de la populación causada por la producción y deseminación sexual.Prodúces pues, un ejemplo de recurrencia geométrica que conforma bastante bien con los datos escogidos en varias maneras y de distintas fuentes.

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Résumé L'accroissement de la colonie et son développement se font en quatre stades: une période pré-ouvrière, suivie des stades de jeunesse, d'adolescence et de maturité. Le premier stade est celui où la reine engendre et nourrit des petites ouvrières à partir de ses propres réserves. Le stade de jeunesse est marqué par une augmentation progressive de la ponte de la reine et aussi de la taille des ouvrières. La cause en est, sans doute, dans l'amélioration du butin, mais pas exclusivement, et nous signalons notamment l'influence exercée par la reine sur la croissance et le développement des individus, cette influence étant indépendante de l'état de la population.Le state d'adolescence est un stade de transition; c'est à cette époque que les mâles font leur première apparition.Au stade de maturité des ouvrières ayant atteint une taille normale cohabitent avec des fourmis mâles et femelles.Il apparaît des reines, lorsque le rapport ouvrières-larves est considérable. Dans la plupart des colonies, ce rapport varie au hasard autour d'une moyenne et il conditionne la grosseur des larves hivernantes; nous ignorons la cause de cette variation.Une colonie, même forte, comporte des sujets de petite taille si elle n'est pas soumise à un ensoleillement suffisant; ceci prouve que les conditions extérieures sont essentielles dans la production des reines. Il est assez rare de trouver de fortes colonies où le nombre des ouvrières est de beaucoup supérieur au nombre d'individus nécessaire à l'élevage du couvain; l'auteur pense que ceci peut-être dû à l'instabilité causée au sein de la colonie par la production et l'essaimage des sexués.On peut établir une formule géométrique de renouvellement-type qui s'accorde assez bien avec les données collationnées de sources diverses.

     

Larval recognition by workers of the ant Myrmica

Larvae are indistinguishable from pharate pupae, and both arouse more worker response than either pupae, or flaccid or shaven larvae. Larval skins elicit a normal response, and masking shows that a surface signal is widely dispersed. The reactive substance is insoluble in hexane, water, methanol, and 70 per cent ethanol, but soluble in acetone, ether and chloroform. It resists 100 °C for 10 min or more. Workers can distinguish diapause-developed from worker-biased brood in spring, not because of their size, their growth rate, or their queen-potentiality, but because they emit a special signal from the ventral surface. This signal is not species specific though the basic larval recognition signal is, at least between Myrmica rubra and Myrmica scabrinodis.     

A morphological comparison of alates between monogynous and polygynous colonies of Myrmica kotokui in northernmost Japan

Summary: Social structure and sexual size of two populations of Myrmica kotokui were compared. Most of the colonies were polygynous in one population and monogynous in the other. Mean body size of the queens was larger in the monogynous population than in the polygynous population. Although the polygynous population contained many large queens, their wing length was significantly shorter than that of queens in the monogynous population. Some females in the polygynous population were intermorphic between typical workers and queens, while the females of the monogynous population were clearly divided into worker and queen castes without any intermorphic females. The body size of the males showed a large variation and the mean was not significantly different between the two populations.     

Social factors affecting queen fecundity in the ant Myrmica rubra

ABSTRACT. At the end of winter, normal populations of the polygyne ant Myrmica rubra L. consist of queens, workers and larvae; the latter are dormant and all in the third stadium. During experimental culture in artificial nests in the laboratory, the starting number of all three of these categories was varied and in some, food supply was restricted too. In a population of workers and larvae, queens do not interfere with each other sufficiently to reduce their fecundity; they avoid congestion by dispersing under the canopy of workers. Queens suffer if food is withheld; they probably feed themselves and are thus largely independent of the number of workers. Even in favourable conditions with full food, the distribution of egg-batch sizes is not normal but follows a hollow curve that is well described by the negative binomial series. A poor food supply accentuates the hollow shape by increasing the number of non-laying queens and reducing the number that are able to lay large batches. Larvae also suppress fecundity but only if they have sufficient food to grow actively; as their number increases, egg production by queens decreases exponentially.     

Isolation and characterization of microsatellite loci in the ant Myrmica scabrinodis

Five polymorphic microsatellite loci were developed for the ant Myrmica scabrinodis using a magnetic bead hybridization selection protocol. The number of alleles per locus varied between three and six. Cross‐species amplification of four of the loci yielded positive amplification products in four Myrmica species, suggesting their general suitability for microsatellite analysis within this taxonomic group.     

New fungal pathogens of the red ant, Myrmica rubra, from the UK and implications for ant invasions in the USA

The red ant, Myrmica rubra, is an increasingly invasive pest species in north-eastern USA, where it is known as the European fire ant. During surveys for natural enemies in part of its native range in the UK, three previously unreported fungal pathogens developed on ants when incubated in the laboratory. These are described and illustrated: Paraisaria myrmicarum sp. nov., Hirsutella stilbelliformis var. myrmicarum var. nov., and Hirsutella subramanianii var. myrmicarum var. nov. Based on analyses of the protein coding region EF-1α and LSU?rDNA, all three described taxa are shown to be affiliated with the hypocrealean family?Ophiocordycipitaceae. The implications for the management of M. rubra in its exotic North American range using classical biological control are discussed.     

Host specificity among Maculinea butterflies in Myrmica ant nests

Summary Ecological studies have been made of all 5 European species of Maculinea. These confirm that M. nausithous and M. rebeli live underground in Myrmica ant nests for 10 months of the year, as has long been known for the other 3 species. The main discovery was that each Maculinea species depends on a single, and different, host species of Myrmica. This specificity contradicts previous papers and scientific reviews of the relationship between Maculinea and ants. Therefore, early records are re-examined and 3 reasons are given to explain why most are misleading when applied to wild populations. Dependence on a single, rather than any, species of Myrmica explains why Maculinea populations exist in only a small minority of biotopes where their foodplants and Myrmica ants abound. It also explains the puzzling disappearance of Maculinea populations from apparently suitable sites. The discovery that M. alcon and M. rebeli depend on separate species of Myrmica that are not even closely related strengthens the argument that these butterflies are good species.     

The visual perception of the ant Myrmica ruginodis (Hymenoptera: Formicidae)

Myrmica ruginodis workers are able to distinguish black or white circles from black or white squares, black or white ellipses from black or white rectangles as well as hollow circles or ellipses from hollow squares or rectangles. They can also distinguish differently oriented elements as well as objects containing a various number of elements. These workers are also able to perceive and discriminate transparent cues on a black background and even small luminous spots on a black ceiling. Such visual abilities are in agreement with the species?? eye morphology and system of navigation: the eyes are rather large with a well-developed posterio-dorsal part, and the foragers rely exclusively on cues located above them, neglecting odorous elements as long as visual perception is possible. Probably, they might use cues located in the canopy and the sky to travel in certain circumstances.     

Reproductive allocation within a polygyne, polydomous colony of the ant Myrmica rubra

1. Ant colonies commonly have multiple egg‐laying queens (secondary polygyny). Polygyny is frequently associated with polydomy (single colonies occupy multiple nest sites) and restricted dispersal of females. The production dynamics and reproductive allocation patterns within a population comprising one polygyne, polydomous colony of the red ant Myrmica rubra were studied. 2. Queen number per nest increased with nest density and the number of adult workers increased with the number of resident queens and with nest density. This suggests that nest site limitation promotes polygyny and that workers accumulate in nest units incapable of budding. 3. Nest productivity increased with the number of adult workers and production per queen was independent of queen number. Productivity increased with nest density, suggesting local resource enhancement. This shows that productivity can be a linear function of queen numbers and that the limiting factor is not the egg‐laying capacity of queens. 4. The total and per capita production of reproductives decreased towards the periphery of the colony, suggesting that the spatial location of nest units affects sexual production. Thus nests at the periphery of the colony invested more heavily in new workers. This is consistent with earlier observations in plants and could either represent investment in future budding or increased defence. 5. The colony produced only five new queens and 2071 males, hence the sex ratio was extremely male biased.     

Queen recognition by brood-rearing workers of the ant Myrmica rubra L

The means by which queens communicate their presence to workers and so influence broodrearing, in particular caste determination, have been analysed; both chemical and topographical stimuli are used. This follows from the fact that though dead inseminated queens are effective, the following are not: dead virgins (same shape but different smell), lipid extracted mature queens (same shape but no smell), parts of inseminated queens alone or together (same smell but different shape). This also rules out a drug-like influence on workers or larvae. The chemicals are not produced in the two main head glands, the mandibular and the pharyngeal, as no loss of potency follows their excision. The abdomen is the most likely source of a substance, the emission of which must vary seasonally.     

Phylogeography of the ant Myrmica rubra and its inquiline social parasite

Widely distributed Palearctic insects are ideal to study phylogeographic patterns owing to their high potential to survive in many Pleistocene refugia and-after the glaciation-to recolonize vast, continuous areas. Nevertheless, such species have received little phylogeographic attention. Here, we investigated the Pleistocene refugia and subsequent postglacial colonization of the common, abundant, and widely distributed ant Myrmica rubra over most of its Palearctic area, using mitochondrial DNA (mtDNA). The western and eastern populations of M. rubra belonged predominantly to separate haplogroups, which formed a broad secondary contact zone in Central Europe. The distribution of genetic diversity and haplogroups implied that M. rubra survived the last glaciation in multiple refugia located over an extensive area from Iberia in the west to Siberia in the east, and colonized its present areas of distribution along several routes. The matrilineal genetic structure of M. rubra was probably formed during the last glaciation and subsequent postglacial expansion. Additionally, because M. rubra has two queen morphs, the obligately socially parasitic microgyne and its macrogyne host, we tested the suggested speciation of the parasite. Locally, the parasite and host usually belonged to the same haplogroup but differed in haplotype frequencies. This indicates that genetic differentiation between the morphs is a universal pattern and thus incipient, sympatric speciation of the parasite from its host is possible. If speciation is taking place, however, it is not yet visible as lineage sorting of the mtDNA between the morphs.     

The effect of queen ants on the survival of Maculinea arion larvae in Myrmica ant nests

Summary The mortality of Maculinea arion caterpillars was measured in both laboratory and wild Myrmica nests, and found to be nearly 3 times higher in nests that had queen ants present. This is attributed to queen effect, which causes worker ants in nests with queens to attack large ant larvae (gynes) that would otherwise develop into new queens. Maculinea arion caterpillars mimic Myrmica larvae, and are usually attacked during the first 10 days after adoption, when they pass through the size range of ant gyne larvae. Caterpillars are also likely to be attacked during this period because their nethod of feeding brings them into close contact with the skins of large ant larvae, which contain gyne larval pheromones; older caterpillars are large enough to eat larvae without their exposed surfaces contacting the larval skin. In the wild, many caterpillars of Maculinea arion die in ant nests, and this has been shown in previous work to be the key factor that determines changes in their abundance from year to year. It is suggested that queen effect can be an important cause of these deaths, and one that particularly affects populations of butterflies that breed on sites with long-established plagioclimaxes of short turf rather than short-lived grass-land successions.     

Homopterans and an invasive red ant, Myrmica rubra (L.), in Maine

Myrmica rubra (L.), is an invasive ant that is spreading across eastern North America. It is presently found in over 40 communities in Maine and areas in Vermont, New Hampshire, Massachusetts, New York, and several provinces in the Canadian Maritimes and Ontario. In addition to disrupting native ant faunas, invasive ants also have been shown to influence homopteran abundance and species composition. We conducted surveys of Homoptera in infested and noninfested sites and conducted manipulative experiments to quantify the effects of M. rubra on homopteran abundance and composition in the summers of 2003, 2006, and 2007 on Mount Desert Island, ME. In 2003, Homoptera family-level richness was higher in infested sites compared with noninfested sites with two out of three sampling methods. Homopteran abundance in infested compared with noninfested sites depended upon the site. The sites with the highest population of M. rubra were associated with significant differences in Homoptera population abundance. In 2006 and 2007, two out of three host plants sampled had significantly higher abundances of the aphids, Aphis spiraephila Patch and Prociphilus tessellatus Fitch. An ant exclusion field experiment on the native plant, meadowsweet (Spiraea alba Du Roi), resulted in higher abundances of A. spiraephila with M. rubra tending compared with native ant tending. A predator exclusion field experiment was conducted on meadowsweet using adult ladybeetles, Hippodamia convergens Guérin-Méneville, larval green lacewings, Chyrsoperla carnea Stephens, and no predators. Predator impacts on aphid populations were reduced in the presence of M. rubra with C. carnea and moderately reduced with H. convergens.     

Distribution of an invasive ant, Myrmica rubra (Hymenoptera: Formicidae), in Maine

Introduced populations of the north temperate ant species, Myrmica rubra (L.), have become pestiferous in various locations in the northeastern United States, particularly in coastal communities in Maine. Native populations of this ant are widely distributed throughout northern Europe and western Asia; however, nest densities in its native range do not usually reach the high levels observed for many introduced populations. This aggressive ant readily stings, and because of its high densities, homeowners continually encounter nests at a frequency that interferes with use of their properties. Surveys were conducted in Maine from 2001 through 2004 to determine the statewide extent of current infestations. Nests in established populations in coastal Maine were sampled from April through September to assess seasonal changes in the density and composition of colonies. Similarities and differences between introduced populations of M. rubra in Maine and published reports of this species in Europe are discussed. Museum records of this species in North America were also researched and are presented.     

Effect of habitat saturation on the number and turnover of queens in the polygynous ant,Myrmica sulcinodis

In polygynous social insects more than one queen reproduces in a colony. In such populations ecological factors affecting survival and reproduction of queens are likely to be of prime importance for social organization. In particular, habitat saturation leading to severe limitations in the availability of nest sites has been suggested to promote high queen number. In this study we examine the social and genetic structure of colonies in the polygynous ant Myrmica sulcinodis. We investigated a single breeding population in two adjacent habitats which differed markedly in the availability of nest sites. In the main habitat M. sulcinodis occupied almost all suitable nest sites, whereas in the other (marginal) habitat most sites were unoccupied by ants, due to a recent fire. In support of the habitat saturation hypothesis, the number of queens per colony which could explain the estimated relatedness among workers was almost five times higher for the main habitat than for the marginal habitat. This is the first demonstration that the kin structure of a social insect population is plastic and responds adaptively to short-term changes in ecological constraints such as nest site availability. Based on combined genetic and demographic data we discuss queen reproductive strategies and suggest that a special class of queen ‘floaters’ only stays ephemerally in the colonies, thus causing a substantial turnover of reproducing queens across years.