Ants

Nosocomial infections bring a high risk to the health of hospital patients and employees. Ants are common organisms in Brazilian hospitals, where they can act as dispersers of opportunistic microorganisms in places they forage. The occurrence of multi-resistant bacteria carried by ants was analyzed in two public hospitals (HA and HB) in southeastern Bahia, Brazil. In these two hospitals 132 workers belonging to three ant species were collected. The bacteria associated to these ants were identified and their susceptibility to antibiotics was evaluated. More than half (57.3%) of ants collected in HA were associated with some kind of bacteria, with 26.7% of them being opportunist bacteria, while 84,2% of the ants from HB presented associated bacteria growth, with 61.4% of them being opportunist bacteria. Twenty four species of bacteria were isolated. The Gram-positive bacilli of the genus Bacillus were the most frequent, followed by the Gram-positive cocci, Gram-negative bacilli (family Enterobacteriaceae) and Gram-negative non-fermenters bacilli. The profile of sensitivity of the bacterial isolates to drugs pointed out the existence of multi-resistant isolates carried by ants. For the first time, are reported cases of the same bacterial resistant isolates taken form homospecific ant workers that point out the importance of ants to bacteria dissemination and proliferation in a hospital. Our results suggest that the risk of contamination presented by these ants is similar to the one of any other mechanical vector of bacterial dissemination.

Some species of the fungal genus Ophiocordyceps that parasitize ants have evolved some degree of behavioral manipulation to increase their own transmission. Carpenter ants (Camponotus spp.) infected by Ophiocordyceps unilateralis species climb vegetation and bite leaves or other plant parts before death, while other ants infected by other Ophiocordyceps species die buried within or on the leaf-litter, attached to stems and tree trunks. The microenvironment of the host's death location is important for fungal development and dispersal to new hosts, being an interesting example of an extended phenotype. This study investigated the effect of humidity variation in space (15 km 2) and time (14 months) on the occurrence and expression of the extended Ophiocordyceps phenotype parasitizing ants in Central Amazonia. We found O. unilateralis s.l., O. kniphofioides s.l. and O. australis s.l. parasitizing 30 ant species, but O. unilateralis s.l. was by far the most abundant fungus. Parasitized Camponotus atriceps and C. bispinosus were more abundant and died in higher places in periods with greater air humidity. Otherwise, the abundance and height of C. senex cadavers were higher in drier plots. These results provide insights on how the spatial and temporal variation in air humidity may shape the occurrence and behavioral manipulation of ants infected by entomopathogenic fungi at larger scales.

Abstract.  1. We analysed ant species richness-environment relationships across the Subantartic-Patagonian transition, in southern South America. We tested the predictions of the (i) thermal limitation hypothesis: temperature limits ant species richness, (ii) the productivity hypothesis: ant richness is driven by the indirect effect of climate (temperature and precipitation) mediated by changes in plant environment (plant cover and litter accumulation). We also evaluated the effects of (iii) plant species richness, and (iv) habitat use by cattle on richness.2. We collected ants using 450 pitfall traps within a ∼150 × 150 km area. We used path analysis to evaluate the associations of ant richness with environmental predictors. We evaluated the influence of local abundance variation on richness-environment relationships; we applied principal co-ordinates of neighbour matrices to model the spatial autocorrelation in the data and combined spatial and ecological descriptors of ant richness into partial regression.3. Ant richness responded positively to indirect effects of precipitation mediated by shrub cover and tree cover, towards the west, and by litter accumulation, towards the east of the transition. Direct climatic effects on richness were negative or weak throughout. The local increase in plant species richness and habitat disturbance by cattle promoted an increase in ant richness, mostly towards the east of the transition. These results were not seriously affected by variation in local abundance and the spatial autocorrelation in the data.4. We suggest that climate, either directly or indirectly, through its biological effect on plant environment interacts with micro-spatial variation in habitat heterogeneity and disturbance to account for ant species diversity across this transition.

Leaf-cutting ants (Atta spp.) are known for their extensive defoliation in neo-tropical forests and savannahs. Debate about the costs and benefits of their activities has been largely dominated by their detrimental effects on agriculture and agroforestry. However, the large accumulation of nutrients and changes in soil properties near their nests might benefit plants growing near them. Here, we test whether trees use nutrients that accumulate in debris piles near, or refuse chambers within, leaf-cutting ant nests. At two tropical sites (a moist tropical forest site in Panama and a savannah site in Brazil), we fed leaves labelled with the stable isotope 15N to two species of leaf-cutting ants (Atta colombica and Atta laevigata) and traced the stable isotope label in plants surrounding the two nests. Thus, we show that plants in both sites access resources associated with Atta nests. In addition, leaf tissue of trees near the nests labelled with 15N had significantly higher calcium co...

We determined the size characteristics of foragers of the leaf-cutting ant Atta sexdens in a mature eucalyptus forest in Campos dos Goytacazes, Rio de Janeiro State, Brazil, at daytime (7: 30 to 10: 00 hr) and nighttime (19: 00 to 23: 00 hr). There were no significant differences between daytime and nighttime ant mass (Ma), but leaf fragment mass (Ml) and burden (B = [Ma + Ml]/Ma), which indicates relative load capacity, were significantly greater at daytime. There was a positive linear relationship between Ma and Ml for the combined daytime and nighttime data, and increases in Ma resulted in lower B. We compared A. sexdens characteristics with published results for Atta cephalotes, a closely related species. A. sexdens is larger and therefore able to carry heavier loads, but its burden is about 72% of the average value for A. cephalotes. We suggest that the lower load capacity of A. sexdens in comparison to A. cephalotes is related to its relatively larger size.<br>Nós determ...

En este trabajo se ha comparado la organización de los lóbulos antenales (LAs) y su representación topográfica en los cuerpos fungiformes (CFs) en soldados de dos especies de hormigas, Atta mexicana y Camponotus ocreatus. La comparación morfológica sugiere que los LAs de A. mexicana podrían ser más especializados que los de C. ocreatus a expensas de capacidades más generales. En ambas especies, el LA está organizado en seis grupos de glomérulos, cada uno inervado por su propio tracto. La inervación de las neuronas de proyección (NP), las cuales conectan los LAs con los CFs a través de los tractos antenoprotocerebrales (TAP), divide el LA en dos regiones, anterior y posterior. Los cálices de los CFs tienen varias capas que reciben información olfativa segregada: NP que inervan los grupos anteriores de glomérulos envían axones a través del TAP-lateral hacia el cuerno lateral (CL) y después hacia la capa interna del cáliz, mientras que las NP que inervan los grupos posteriores de glomérulos envían axones a través del TAP-medial a la capa externa del cáliz y después al CL. Estos resultados muestran que la organización del LA está representada topográficamente en los CFs formando un mapa odotópico. Las dos vías que conectan los LAs con los CFs podrían representar dos canales para el procesamiento de diferentes clases de olores o diferentes propiedades de los estímulos olfativos. Los resultados neuroanatómicos sugieren una organización funcional conservada en los himenópteros sociales.

A previous report of the discovery of exocrine glands in the antennal club of queens and workers of Solenopsis invicta Buren, 1972 left open the question of the extent to which similar glands occur in the Formicidae family. We wanted to know if these antennal glands are unique to Solenopsis, or they are found in a wider taxonomic group. Using scanning electron microscopy, we examined the antennae of 41 ant species. Presence of the antennal glands was indicated by a characteristic circumferential ring of pores in a distal antennal segment of workers. Pores were found in the 9th antennal segment of all 26 species of Solenopsis examined. Pores were absent in the following: Monomorium minimum, M. pharaonis, Pheidole sp., Crematogaster sp., Linepithema humile, Forelius sp., Dorymyrmex sp., Paratrechina sp., Oecophylla smaragdina, Campanotus sp., Ectatomma ruidum, E. tuberlatum, and Pseudomyrmex ferruginea. However, pores were found in the antennal club of Tetramorium bicarinatum workers and queens. After KOH digestion of T. bicarinatum antennae, internal canals were observed in both workers and queens, and the canals are connected to spherical reservoirs in queens. T. bicarinatum was the only non-Solenopsis species examined, which showed evidence for antennal glands in the distal funiculus. Microsc. Res. Tech., 2008. © 2008 Wiley-Liss, Inc.

A B S T R A C T Changes in land-use and climate increase the flammability of forests across southeast Amazonia, potentially driving abrupt fire-mediated transitions to derived savannas – grass-dominated degraded forests with scattered trees. However, the extent to which the forest fauna undergoes a parallel process remains poorly understood. Here we test the hypothesis that the process of fire-driven forest shifts towards derived savannas has congruent cascading effects on ant communities by causing declines in forest specialists and an influx of open-habitat taxa. In 2013 we collected ants using subterranean, epigaeic and arboreal pitfall traps in three adjacent 50-ha plots: an unburnt control and two treatment plots that were burnt either triennially or annually from 2004 to 2010. Frequent fire was associated with a marked decline of specialist forest species (almost 50%), and an influx of open-habitat taxa that were absent from the unburnt plot. The effects were particularly pronounced for epigaeic ants: their abundance, biomass, species richness and species composition were impacted by fires, and this was the main stratum occupied by the open-habitat species. Previous studies have shown that a similar conversion is not triggered by single fires, and they therefore require recurrent fires. Our results provide experimental evidence that the process of tropical forest conversion towards derived savannas caused by repeated burning is a broad one that affects not only plants, but involves parallel compositional shifts of animal communities. The prevention of recurrent fires is a priority challenge for avoiding widespread biotic conversion of tropical forests to derived savannas.

Understanding how anthropogenic disturbance influences patterns of community composition and the reinforcing interactive processes that structure communities is important to mitigate threats to biodiversity. Competition is considered a primary reinforcing process, yet little is known concerning disturbance effects on competitive interaction networks. We examined how differences in ant community composition between undisturbed and disturbed Bornean rainforest, is potentially reflected by changes in competitive interactions over a food resource. Comparing 10 primary forest sites to 10 in selectively-logged forest, we found higher genus richness and diversity in the primary forest, with 18.5% and 13.0% of genera endemic to primary and logged respectively. From 180 hours of filming bait cards, we assessed ant-ant interactions, finding that despite considered aggression over food sources, the majority of ant interactions were neutral. Proportion of competitive interactions at bait cards did not differ between forest type, however, the rate and per capita number of competitive interactions was significantly lower in logged forest. Furthermore, the majority of genera showed large changes in aggression-score with often inverse relationships to their occupancy rank. This provides evidence of a shuffled competitive network, and these unexpected changes in aggressive relationships could be considered a type of competitive network re-wiring after disturbance.

We compared the ant assemblages from four very heterogeneous habitats over a short-distance elevational gradient of vegetation (due to the presence of an inselberg) at the Nouragues Research Station, French Guiana. We focused on litter-dwelling ants, combining the use of pitfall traps and the Winkler method according to the Ants of the Leaf Litter Protocol. This permitted us to note (1) a high leaf-litter ant diversity overall, (2) a decreasing diversity gradient from the lowland rainforest to the top of the inselberg, and (3) changes in species density, composition and functional structure. While the ant assemblages on the plateau and inselberg can be considered functionally similar and typical of an Amazonian rainforest, that of the transition forest, relatively homogenous, rather corresponded to an ant fauna typical of open areas. By contrast, the liana forest assemblage was unexpectedly rich and dense, sheltering a litter-dwelling ant fauna dominated by numerous and abundant cryptic species. These taxonomical and functional dissimilarities point out the great influence of the environmental heterogeneity, which, through variable abiotic conditions, contributes to maintaining an exceptionally rich ant biodiversity in these Neotropical habitats.

Natural enemies of the gall maker Eugeniamyia dispar (Diptera: Cecidomyiidae) were studied on the urban area of Porto Alegre, RS, Brazil from October 1993 to March 1996. Galls and associated arthropods were followed weekly in the field on individual host plants (Eugenia uniflora, Myrtaceae) and also in the laboratory. Three species of ants attacked the galls, the most common being Pseudomyrmex sp. A proportion of galls was parasitised by Rileya sp. (Eurytomidae). The adults of this solitary ectoparasitoid were also attacked by the ants and fell prey to spider webs.

The rapid growth of the human population, as well as an increase in urbanism, have resulted in the existence of new cities quickly and not adequately studied to be compatible with nature, which led to severe damage to the environment at all levels. The objective of this research is to discuss solutions to reduce the ongoing problems of urban expansion using bio-imitation and reach a vision of a sustainable city by classifying the roles played by biomimetics and their reflections on the performance of the built environment. Indeed, nature was and still is the first teacher of man and the main inspiration. Nature is as much an inspiration to architects as it is to scientists; this paper illustrates the relationship between science and biomimicry in planning new sustainable cities. The research follows the comparative approach that analyzes and compares methodologies for the physical life concepts of some insect colonies like ant colonies and bee settlements in the living world that are similar in their lives to human life, how they are integrated into the framework of physical planning and engaged that with the principles of the sustainable built environment, by showing great ingenuity in the manner they build their dwellings in a way that considers the surrounding environmental and climatic factors such as good Ventilation, control of various temperature and humidity inside the shelter. Concerning that, the case study is a kind of exploration and attempt to reach design guidelines for detailed planning for the built environment in new sustainable cities.

Las hormigas cortadoras de hojas (Atta laevigata) son una plaga económicamente importante en las plantaciones forestales de Pinus sp. y Eucalyptus sp. en la empresa Refocosta S.A.S., cuyo control se fundamenta en el uso de insecticidas orgánicos de síntesis. Con el objeto de evaluar la efectividad de métodos alternativos de control, como insecticidas de origen vegetal, biológico y productos inorgánicos, se seleccionaron 35 nidos activos de la hormiga y se trataron con los hongos entomopatógenos Metarhizium anisopliae, y Beauveria bassiana, el hongo antagónico Trichoderma viride, el macerado de semillas de Canavalia ensiformis, el compuesto fósil tierras diatomeas y el producto químico Attakill (Cuyo ingrediente activo es Sulfluramida) como control. Se evaluó la actividad de los nidos previo al tratamiento y a los 20, 40 y 65 días después de la aplicación. Al final de la tercera revisión no se observó mortalidad en las colonias tratadas con hongos y con C. ensiformis, mientras que las tierras diatomeas disminuyeron la actividad de los nidos solamente las 2 primeras semanas. El producto Attakill produjo un 100% de mortalidad. Se concluye que la efectividad de los métodos alternativos en el control evaluados contra A. laevigata, es inferior a la mortalidad generada por el insecticida orgánico Attakill.

The successful life of insect societies has evolved from the division of labor among more or less specialized individuals, who carry out all necessary tasks for the maintenance and growth of the colony. The extreme division of labor has produced workers specialized in the removal of dead members of the colony, an evident and highly stereotyped behavior called undertaking which consists of the ability to recognize and dispose of the dead members of the colony using specific chemical cues. Although living in enclosed nests has contributed to the ecological success of social insects due to environmental control, it also poses disadvantages. Nests of social insects, containing dense groups of genetically close individuals with frequent physical contact, present ideal conditions for the incidence and dispersion of infectious diseases. To maintain strict microbiological control inside the nest, these insects have evolved hygienic behavioral strategies to avoid and control the proliferation of pathogens. Undertaking behavior is one of the fundamental strategies to exert microbiological control inside the nest by means of suitable management and removal of dead members of the colony, to prevent the emergence of epidemics that may lead the insect society to extinction. Therefore, undertaking behavior has been fundamental to the evolution of social insects. This stereotyped behavior constitutes an excellent model for the understanding of both social evolution and the neurobiological basis of social behavior. In this paper, we review the present knowledge on undertaking behavior, and outline some perspectives of the study of such far-reaching behavior of social organization.