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opencc-by-4.0Aug 2020View details →

ATTA-Ar calibration data for GRL submission

ATTA-Ar calibration data for GRL submission

opencc-zeroNov 2019View details →

Data from: Rain shadow effects predict population differences in thermal tolerance of leaf-cutting ant workers (Atta cephalotes)

Tests of hypotheses for the evolution of thermal physiology often rely on mean temperatures, but mounting evidence suggests geographic variation in temperature extremes is also an important predictor of species' thermal tolerances. Although the tropics are less thermally variable than higher latitude regions, rain shadows on the leeward sides of mountains can experience greater diel and seasonal variation in temperature than windward sites. Rain shadows provide opportunities to test predictions about the relationships of extreme temperatures with thermal physiology while controlling for latitude. We tested the hypothesis that populations of leaf-cutting ants (Atta cephalotes) in leeward, montane, and windward sites in Costa Rica would differ in upper thermal tolerances (CTmax) of workers. As predicted from rain shadow effects via extreme high temperatures, the leeward rain-shadow site yielded the highest mean CTmax (rain shadow site 42.1±0.3 °C, Montane site 38.2±0.5 °C, windward site 38.2±0.3 °C). This suggests that high-temperature extremes in tropical rain shadow forests can select for higher thermal tolerances. CTmax increased with worker body size within sites, but CTmax increased with body size more gradually at the two lowland sites, as predicted if local high temperatures selected more strongly on the most thermally vulnerable society members (small workers). This suggests that warmer lowland climates selected for colonies with less variation in heat tolerance than cooler high elevation climates.

opencc-zeroDec 2017View details →

Data from: Do an ecosystem engineer and environmental gradient act independently or in concert to shape juvenile plant communities? Tests with the leaf-cutter ant Atta laevigata in a Neotropical savanna

Background. Ecosystem Engineers are species that transform habitats in ways that influence other species. While the impacts of many engineers have been well described, our understanding of how their impact varies along environmental gradients remains limited. Although disentangling the effects of gradients and engineers on biodiversity is complicated – the gradients themselves can be altered by engineers – doing so is necessary to advance conceptual and mathematical models of ecosystem engineering. We used leaf-cutter ants (Atta spp.) to investigate the relative influence of gradients and environmental engineers on the abundance and species richness of woody plants. Methods. We conducted our research in South America's Cerrado. With a survey of plant recruits along a canopy cover gradient, and data on environmental conditions that influence plant recruitment, we fit statistical models that addressed the following questions: (1) Does A. laevigata modify the gradient in canopy cover found in our Cerrado site? (2) Do environmental conditions that influence woody plant establishment in the Cerrado vary with canopy cover or proximity to A. laevigata nests? (3) Do A. laevigata and canopy cover act independently or in concert to influence recruit abundance and species richness? Results. We found that environmental conditions previously shown to influence plant establishment in the Cerrado varied in concert with canopy cover, but that ants are not modifying the cover gradient or cover over nests. However, ants are modifying other local environmental conditions, and the magnitude and spatial extent of these changes is consistent across the gradient. In contrast to prior studies, we found that ant-related factors (e.g., proximity to nests, ant changes in surface conditions), rather than canopy cover, had the strongest effect on the abundance of plant recruits. However, the diversity of plants was influenced by both the engineer and the canopy cover gradient. Discussion. Atta laevigata in the Cerrado modify local conditions in ways that have strong but spatially restricted consequences for plant communities. We hypothesize that ants indirectly reduce seedling establishment by clearing litter and reducing soil moisture, which leads to seed and seedling desiccation. Altering soil nutrients could also reduce juvenile growth and survivorship; if so these indirect negative effects of engineering could exacerbate their direct effects of harvesting plants. The effects of Atta appear restricted to nest mounds, but they could be long-lasting because mounds persist long after a colony has died or migrated. Our results support the hypothesis that leaf-cutter ants play a dominant role in Cerrado plant demography. We suggest the ecological and economic footprint of these engineers may increase dramatically in coming decades due to the transformation of the Cerrado by human activities.

opencc-zeroDec 2015View details →

Leaf processing behavior in Atta leafcutter ants: 90% of leaf cutting takes place inside the nest, and ants select pieces that require less cutting

Leafcutter ants cut trimmings from plants, carry them to their underground nests, and cut them into smaller pieces before inoculating them with a fungus that serves as a primary food source for the colony. Cutting is energetically costly, so the amount of cutting is important in understanding foraging energetics. Estimates of the cutting density, meters of cutting per square meter of leaf, were made from samples of transported leaf cuttings and of fungal substrate from field colonies of Atta cephalotes and Atta colombica. To investigate cutting inside the nest, we made leaf-processing observations of our laboratory colony, A. cephalotes. We did not observe the commonly reported reduction of the leaf fragments into a pulp, which would greatly increase the energy cost of processing. Video clips of processing behaviors, including behaviors that have not previously been described, are linked. An estimated 2.9 (+0.3) kilometers of cutting with mandibles was required to reduce a square meter of leaf to fungal substrate. Only about 12% (+ 1%) of this cutting took place outside of the nest. The cutting density and energy cost is lower for leaf material with higher ratios of perimeter to area, so we tested for, and found that the laboratory ants had a preference for leaves that were pre-cut into smaller pieces.  Estimates suggest that the energy required to transport and cut up the leaf material is comparable to the metabolic energy available from the fungus grown on the leaves, and so conservation of energy is likely a particularly strong selective pressure for leafcutter ants.

opencc-zeroNov 2015View details →

Foraging Networks of the Leaf-Cutting Ant Atta bisphaerica

This dataset describes the foraging network of four nests of the leaf-cutting ant Atta bisphaerica over an 8-month period covering the whole humid season and part of the dry season. All nests were in a pasture located in the southern part of the Brazilian state of Minas Gerais, near the municipality of Coronel Pacheco( 21° 39'S, 43° 21'W, altitude: 800m). The networks consist of underground tunnels connecting the nests to distant foraging holes from which one or several foraging trails depart to reach resource patches. The dataset gives the positions and status (active, inactive, close) of the foraging holes as well as the number, length and terminal position of each trail departing from these holes.

opennotspecifiedMar 2019View details →

Leafcutter ants of the genus Atta in the Insects Collection at the Field Museum of Natural History. The field data on the attached tags are transcribed for entry into databases such as AntWeb and the Global Biodiversity Information Facility. Photograph: Matthew Nelsen. in The Evolution of Natural History Collections

Leafcutter ants of the genus Atta in the Insects Collection at the Field Museum of Natural History. The field data on the attached tags are transcribed for entry into databases such as AntWeb and the Global Biodiversity Information Facility. Photograph: Matthew Nelsen.

Figure 4 in Biological attributes of Argentinian phorid parasitoids (Insecta: Diptera: Phoridae) of leaf-cutting ants, Acromyrmex and Atta

Figure 4. Natural parasitism rate by phorid species reared from ants collected from foraging trails at San Cristóbal for Acromyrmex phorids and discriminated by seasons. Numbers represent nest codes. Ant species names are abbreviated in the upper-left corner with the three first letters of the species epithet (lob: Acromyrmex lobicornis, lun: Acromyrmex lundii, hey: Acromyrmex heyeri, cra: Acromyrmex crassispinus, his: Acromyrmex hispidus, fra: Acromyrmex fracticornis, str: Acromyrmex striatus). Note that the y and x axes differ across plots, and the bottom plot from the right shows results for two ant species (Ac. fracticornis parasitized by "other phorids" in grey and Ac. striatus parasitized by Ap. exstriatus in white).

Figure 1 in Biological attributes of Argentinian phorid parasitoids (Insecta: Diptera: Phoridae) of leaf-cutting ants, Acromyrmex and Atta

Figure 1. Ant size (head width in mm) distributions from foragers or waste removers from all nests pooled (in dark grey) discriminating those selected by different species of phorids (in white); light grey represents the intersection of both distributions). Left column, parasitoids of Acromyrmex: Myrmosicarius catharinensis selecting Acromyrmex heyeri foragers, Myrmosicarius cristobalensis selecting Acromyrmex lobicornis foragers, and Myrmosicarius crudelis selecting Acromyrmex crassispinus waste removers; right column, parasitoids of Atta vollenweideri: Myrmosicarius brandaoi, Myrmosicarius gonzalezae and Eibesfeldtphora trilobata. Asterisk denotes median values and black arrows indicate range of

Figure 5 in Biological attributes of Argentinian phorid parasitoids (Insecta: Diptera: Phoridae) of leaf-cutting ants, Acromyrmex and Atta

Figure 5. Natural parasitism rate by phorid species reared from Atta vollenweideri foragers, discriminated by seasons. The contribution of the two Myrmosicarius species was estimated together, as males were not possible to be identified. Numbers represent nest codes to follow parasitism through time.

Figure 3 in Biological attributes of Argentinian phorid parasitoids (Insecta: Diptera: Phoridae) of leaf-cutting ants, Acromyrmex and Atta

Figure 3. Seasonal parasitism rates by phorid parasitoids from of Atta and Acromyrmex ants. Boxes represent median and quartiles; circles are outliers.

Figure 2 in Biological attributes of Argentinian phorid parasitoids (Insecta: Diptera: Phoridae) of leaf-cutting ants, Acromyrmex and Atta

Figure 2. Adjusted least square regression lines for ant head sizes selected by phorids and the thorax width of the adult parasitoids that emerged from them. Above, parasitoids of Acromyrmex; below, Atta's phorids; note different scales in both axes.

opennotspecifiedDec 2012View details →

FIGURES 1–3. Female phorid fly oviscapes, lateral. 1 in Parasitoid phorid flies (Diptera: Phoridae) from the threatened leafcutter ant Atta robusta Borgmeier (Hymenoptera: Formicidae)

FIGURES 1–3. Female phorid fly oviscapes, lateral. 1. Eibesfeldtphora breviloba; 2. Eibesfeldtphora digitalis; 3. Myrmosicarius exrobustus.

publicSep 2025View details →

Mechanical properties and cuticle organisation in mandibles are related to the task specialisation in leafcutter ants (Atta laevigata, Attini, Formicidae)

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publicNov 2019View details →

Data from: Rain shadow effects predict population differences in thermal tolerance of leaf-cutting ant workers (Atta cephalotes)

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