Mate availability and male dispersal in the Argentine ant Linepithema humile (Mayr) (=Iridomyrmex humilis)

In the Argentine ant Linepithema humile (=Iridomyrmex humilis) only males disperse whereas female sexuals (unmated winged queens) stay in their mother nest where they mate. This study investigated (1) whether dispersing males are accepted into foreign colonies, (2) whether they can mate with resident female sexuals, and (3) whether the propensity of males to disperse is affected by the expectation of mating in their mother nest. Field experiments demonstrated that males were accepted into foreign colonies only when these colonies contained female sexuals or queen pupae. Before and after the time of (sic) female sexuals, workers attacked and killed most of the foreign males. Laboratory experiments snowed that males that successfully enter foreign colonies can mate with resident female sexuals. The propensity of males to disperse was significantly influenced by the presence of female sexuals in their nest. Males were more likely to fly out from colonies containing no female sexuals than from those with them. These results are consistent with males preferentially dispersing when there is little or no opportunity to mate in their mother nest. Thus there are two mating strategies available for males: staying in their mother nest when an opportunity to mate arises or dispersing and attempting to mate in a foreign nest when there are no female sexuals in their mother nest. This latter behaviour could mediate gene flow between colonies and account for the lack of significant inbreeding previously documented in this species.

Régulation du nombre de reines chez la fourmi d'Argentine Iridomyrmex humilis (Hymenoptera: Formicidae)

Chez la fourmi d'Argentine Iridomyrmex humilis (Mayr), les ouvrières exécutent environ 90% des reines durant la période précédant la production de nouveaux sexués. Un tel comportement n'avait jamais été décrit chez d'autres espèces de fourmis. Ces exécutions ne dépendent ni du poids, ni vraisemblablement de la fécondité des reines. De plus, comme presque toutes les reines sont âgées de moins d'un an au moment des exécutions, il est aussi peu probable que les exécutions soient liées à l'âge des reines. Ces exécutions de reines représentent une perte estimée à environ 8% de la biomasse des sociétés.

Efecto de la temperatura en la tasa de puesta de reinas de la hormiga argentina, Linepithema humile (Mayr, 1868), (Hymenoptera, Dolichoderine) bajo condiciones experimentales de monoginia y poliginia = Effect of temperature on the oviposition rate of the argentine ant queens, Linepithema humile (Mayr 1868), (Hymenoptera, Dolichoderine) under experimental conditions

Data concerning the effect of temperature on different physiological parameters of an invasive species can be a useful tool to predict its potential distribution range through the use of modelling approaches. In the case of the Argentine ant these data are too scarce and incomplete. The aim of the present study is to compile new data regarding the effect of temperature on the oviposition rate of the Argentine ant queens. We analysed the oviposition rate of queens at twelve controlled temperatures, ranging from 10ºC to 34ºC under different monogynous and polygynous conditions. The oviposition rate of the Argentine ant queens is affected by temperature in the same manner, independently of the number of queens in the nest. The optimal temperature for egg laying was 28ºC, and its upper and lower limits depended on the degree of polygyny

“That you too were the I”: Forms of polyphonic communication in John Ashbery’s poetry

Tarkastelen tutkimuksessani amerikkalaisen John Ashberyn (1927–) runoudessa lmenevää moniäänisyyttä. Runoutta pidetään yleensä yksiäänisenä puheena, kun taas omaanin ajatellaan erityisesti Mihail Bahtinin vaikutuksesta olevan luonnostaan oniääninen kirjallisuudenlaji. Ashberyn postmoderni runous haastaa tämän äsityksen. Ashbery tunnetaan vakiintuneita runouskäsityksiä vastaan kirjoittavana avantgarde-runoilijana. Pääasiallisina tutkimuskohteinani ovat Ashberyn pitkä runoelma nimeltä ”Litany” (1979) sekä lyhyiden runojen valikoima Your Name Here (2000). Vertailukohtana tarkastelen Ashberyn yhdessä James Schuylerin kanssa kirjoittamaa romaania A Nest of Ninnies (1969). Teoreettisena pohjana on käytetty Ashberyä käsittelevän muun tutkimuksen lisäksi muun muassa jälkistrukturalistisiin teorioihin liittyviä ajatuksia pronominien vaikutuksesta siihen miten lukija muodostaa käsityksen subjektiivisesta läsnäolosta runossa. Ashbery käyttää persoonapronomineja ilman selkeitä viittaussuhteita. Viittaussuhteiden hämärtymisen ja fragmentaarisuuden vuoksi Ashberyn runoja pidetään usein vaikeina, eikä niistä ole helppo löytää yhtä selkeää aihetta. Hajanaisuus on kuitenkin motivoitua, koska juuri se mahdollistaa moniäänisyyden ja avoimen tekstin, joka voi sisältää monia merkityksiä. Kun runossa ei ole yhden puhujan hallitsevaa ääntä, lukijan rooli merkitysten muodostajana nousee keskeiseksi. ”Litany” on selkeästi metatekstuaalinen runo, jossa fiktiivinen taso sekoittuu runouden, taiteen ja kritiikin mahdollisuuksien pohdintaan. Runo hahmottelee uudenlaista, moniäänistä teorian ja runouden rajoja purkavaa kommunikaation muotoa. Toisen persoonan pronominien voidaan runossa usein ajatella puhuttelevan lukijaa. Your Name Here -kokoelmassa puolestaan toisen persoonan pronominipositiot määrittyvät usein tietyiksi henkilöhahmoiksi runojen maailmassa, ja pronominipositioiden kautta runoissa rakentuu moniäänisiä dialogeja määrittymättömien henkilöhahmojen välille. Näin lukijan huomio suunnataan ensisijaisesti kommunikaation ja arkipäivän kielenkäytön kliseiden sävyihin ja asiayhteyksiin pikemminkin kuin yksittäisten lausumien sisältöön. A Nest of Ninnies -romaani toimii näennäisestä dialogisuudestaan huolimatta ennen kaikkea yksiäänisesti, sillä romaanin yksiulotteisten henkilöhahmojen esittämiä ajatuksia hallitsee parodioimaan pyrkivä kertojanääni. Ashberyn runojen ja romaanin tarkasteleminen osoittaa, että käsitys runoudesta väistämättä yksiäänisenä ja romaanista moniäänisenä ei ole kaikilta osin ongelmaton. Moniääninen, monimerkityksinen runo voi tarjota toiselle itsenäisen aseman.

Niche Differentiation and Fine-Scale Projections for Argentine Ants Based on Remotely Sensed Data

Modeling ecological niches of species is a promising approach for predicting the geographic potential of invasive species in new environments. Argentine ants (Linepithema humile) rank among the most successful invasive species: native to South America, they have invaded broad areas worldwide. Despite their widespread success, little is known about what makes an area susceptible - or not - to invasion. Here, we use a genetic algorithm approach to ecological niche modeling based on high-resolution remote-sensing data to examine the roles of niche similarity and difference in predicting invasions by this species. Our comparisons support a picture of general conservatism of the species' ecological characteristics, in spite of distinct geographic and community contexts

Ascertaining Key Factors Behind the Coexistence of the Native Ant Species Plagiolepis pygmaea with the Invasive Argentine Ant Linepithema humile (Hymenoptera: Formicidae)

The Argentine ant, Linepithema humile, is a world-wide invasive ant species. Its presence has a strong negative impact on ant diversity. The present study attempts to highlight the reasons for the coexistence of this highly dominant species with Plagiolepis pygmaea, the only native ant species that has proved able to resist the invasion in a natural ecosystem in the north-east of the Iberian Peninsula. To quantify the aggressiveness level of both species we performed aggressiveness tests on workers in different areas: a) Argentine ant workers from areas with P. pygmaea, b) Argentine ant workers from areas without P. pygmaea, c) P. pygmaea from a non-invaded area and d) P. pygmaea from an invaded area. We also confronted Argentine ant workers with P. pallidula and T. nigerrimum. These aggressiveness tests showed that the coexistence of these two species of ants was not due to a habituation process, since the aggressiveness level observed between the four kinds of confrontations were fairly similar. We also found a lack of aggressiveness between Argentine ant workers and P. pygmaea, and highly submissive behavior in the latter when confronted with the invader. The peaceful character of P. pygmaea together with its markedly submissive behavior may be the main factors behind the coexistence of these species in the study area

Effect of Seasonal Dynamics on Queen Densities of the Argentine Ant (Linepithema Humile) in an Invaded Natural Area of the NE Iberian Peninsula

The annual elimination of large numbers of Argentine ant queens near the advance front of an invasion could be a useful tool for weakening the species’ dispersion and, therefore, limiting its establishment in non-invaded areas. However, before carrying out trials to test the effectiveness of this method it would be essential to have sufficient knowledge of the effect of seasonal dynamics acting on the queens’ densities of the species in order to determine the most favourable period of the year to act. We analyzed the seasonal densities and nest dynamics of Argentine ant queens in an invaded Mediterranean natural ecosystem. We observed that the queens’ density varied depending on the season of the year and that this variation was mainly due to the seasonal dynamics of nest aggregations in winter and ant dispersions in summer. The greatest densities per litre of nest soil were observed in winter (December to March, approximately) and the lowest densities were observed in summer ( June to July). This information is essential for improving current knowledge of the Argentine ant’s biology and developing control methods based on the elimination of queens in invaded natural areas

Comparing Methods of Evaluating the Spread of Argentine Ants in Natural Habitats: Pitfall Traps vs. Baiting

Two methods of trapping Argentine ants in natural habitats are compared. both methods are used on the boundaries of an invaded area with the goal of assessing the spread of the invasion front. Pitfall surveys take longer to obtain results than bait surveys, but bait surveys are only a “snapshot” of the moment, with less chance of detecting Argentine ant workers. significant differences are found between the methods in terms of the number of traps occupied by Argentine ants, native ants or a combination of both. Differences in the richness of native ant species are found as well, showing that pitfall surveys are necessary to assess such richness. Despite this, no differences in the assessment of spread are found between the methods. bait surveys are an easier and faster method to assess the spread of Argentine ants, spread being one of the most important characteristics of biological invasions

Numerical Dominance of the Argentine Ant vs Native Ants and Consequences on Soil Resource Searching in Mediterranean Cork-Oak Forests (Hymenoptera: Formicidae)

This study is focused on the dominance exerted by the invasive Argentine ant over native ants in a coastal Mediterranean area. Theimpact of this invasive ant on native ant assemblages and its consequences on total ant biomass and on the intensity of habitat explorationwere evaluated. Foraging ants were observed and their trajectories recorded during 5-minute periods in two study zones, one invaded andthe other non-invaded. Ant species detected, ant worker abundance, ant biomass and the intensity of soil surface searching done by antswere compared between the two zones. The Argentine ant invasion provoked a drastic reduction of the ant species richness. Apparentlyonly one native ant species is able to coexist with the Argentine ant, the cryptic Plagiolepis pygmaea. Ant worker abundance was also modified after the invasion: the number of Argentine ant workers detected, which represented 92% of the invaded zone, was two times higher than the number of native ant workers detected in the non-invaded zone. The total ant biomass was inversely affected, becoming four times lower in the invaded zone highly dominated by Linepithema humile. The higher number of Argentine ant workers and their fast tempo of activity implied an alteration of the intensity of soil surface searching: scanning by the Argentine ants in the invaded zone was higher than that done by the native ants in the non-invaded zone, and the estimated time for a complete soil surface scan was 64 minutes in the invaded zone and 108 minutes in the non-invaded zone. Consequently, resources will be discovered faster by ants in the invaded zone than in the non-invaded zone. The increase of the mean temperature and the decrease of the relative humidity from May to August reduced the ant activity in the two study zones but this reduction was greater in the invaded zone

Re-evaluating oral poetry : research on the composers ́ field

Lectio praecursoria University of Helsinki 5.2.2011.

Study of present day folk poetry

Kirja-arvio

k-Casein gene frequencies support subdivision and historical origin of Argentine Creole cattle

Gene frequencies at the k-casein locus were estimated in six different herds (N = 180) of Argentinean Creole cattle. The results showed a strong influence of subdivision and independent evolution on the divergence of the observed gene frequencies. These results suggest that the population structure of these herds favor the maintenance of polymorphism, which is of crucial importance for the long-time survival of populations.

Collective Memory Embodied in Poetry as Poison. The Mnemonic Role of Romantic Poets Discussed on the Basis of Adam Mickiewicz’ Konrad Wallenrod and Forefathers (Part III)

This thesis constitutes an interdisciplinary approach to the Polish Romanticism combining literature studies with memory studies, nationalism research and psychoanalysis. This phenomenon-based study attempts to answer the question, how the Polish national poet Adam Mickiewicz (1798–1855) – or more exactly the implied authors in his works – perceived the role of poetry in mnemonic terms and how it changes in course of time. Consequently, ‘memory in literature’ (Astrin Erll and Ansger Nünning) is discussed here. Two pieces of writing by Mickiewicz – Konrad Wallenrod [1828] and the third part of Forefathers [1832], where a bard respectively a poetic genius appears – are seen as meta-texts defining goals of poets in time of the political non-existence of a state. Poetry is supposed to keep memory of the glorious past alive, kindle the love for the motherland, support the collective identity of a group and initiate a liberation movement. Poets function as memory guards, leaders of the nation and prophets. Thus, literature is a medium of collective memory – it stores crucial contents, transmits them and acts as a cue. Nevertheless, shifting the focus from the community towards well-being of individuals, which is consistent with the postmodern thinking, the impact that poetry has on members of a given memory culture (Jan Assmann) can be described in ‘vampiric’ terms (Maria Janion). Poetry embodying collective memory may be compared to ‘poison’, ‘infecting’ people with a nationalistic way of thinking to their disadvantage as far as their personal lives are concerned.

Inhibition of cyclooxygenase activity by standardized hydroalcoholic extracts of four Asteraceae species from the Argentine Puna

We determined the anti-inflammatory activity of standardized extracts of four medicinal plant species (Baccharis incarum, B. boliviensis, Chuquiraga atacamensis, Parastrephia lucida) that grow in the Argentine Puna (3800 m above sea level) and that are used to reduce oxidative stress and alleviate gout and arthritic pain. The extracts of plant aerial parts were standardized in terms of total phenolic compounds and flavone/flavanone content and free radical scavenging activity. All extracts showed high phenolic compound concentration (0.5-1.6 mg/mL), mainly flavones and flavonols (0.1-0.8 mg/mL). The extracts showed hydrogen donating ability (DPPH and ABTS) and reactive oxygen species scavenging activity (O2●-, OH-, H2O2). The ability of the extracts to inhibit cyclooxygenase enzymes (COX-1 and COX-2) was determined by calculating percent inhibition of PGE2 production measured by enzyme immunoassay. All extracts inhibited both enzymes with IC50 values of 2.0 to 16.7 µg/mL. The anti-inflammatory activity of B. incarum and C. atacamensis extracts was higher than that of B. boliviensis and P. lucida. The IC50 values obtained for indomethacin were 0.11 and 0.78 µM for COX-1 and COX-2, respectively. The present results are consistent with the anecdotal use of these species in phytotherapic preparations.

Institutions, credibility and crisis: the inconsistencies of Argentine exchange rate policy (1991-2006)

The purpose of this article is twofold. The first is to explain the time inconsistencies of the convertibility regime that led to the 2001 crisis. The argument suggests that the credibility requirements for convertibility induced a dynamic of legal, fiscal, financial and external commitments that increased exit costs and time inconsistencies. The second objective is to explain the tensions of the floating regime that replaced convertibility in 2002. We describe the effects of a floating exchange rate on macroeconomic imbalance and the growing tension between competitiveness and inflation.