Ant nest architecture is shaped by local adaptation and plastic response to temperature

Social insects are among the most abundant arthropods in terrestrial ecosystems, where they provide ecosystem services. The effect of subterranean activity of ants on soil is well-studied, yet little is known about nest architecture due to the difficulty of observing belowground patterns. Furthermore, many species’ ranges span environmental gradients, and their nest architecture is likely shaped by the climatic and landscape features of their specific habitats. We investigated the effects of two temperature treatments on the shape and size of nests built by Formica podzolica ants collected from high and low elevations in the Colorado Rocky Mountains in a full factorial experiment. Ants nested in experimental chambers with soil surface temperatures matching the local temperatures of sample sites. We observed a plastic response of nest architecture to conditions experienced during excavation; workers experiencing a high temperature excavated deeper nests than those experiencing a cooler temperature. Further, we found evidence of local adaptation to temperature, with a significant interaction effect of natal elevation and temperature treatment on nest size and complexity. Specifically, workers from high elevation sites built larger nests with more tunnels when placed in the cool surface temperature treatment, and workers from low elevation sites exhibited the opposite pattern. Our results suggest that subterranean ant nest architecture is shaped by a combination of plastic and locally adapted building behaviors; we suggest that the flexibility of this ‘extended phenotype’ likely contributes to the widespread success of ants.

Nesting Biology of the Solitary Ground-Nesting Bee Diadasina riparia (Apidae: Emphorini)

We described the nesting behavior and ecology of Diadasina riparia, from an urban dry forest fragment. The nests of D. riparia were shallow with circular entrance, closed by a mud plug, from which a straight vertical tunnel ending in one or more brood cells. Most females need one day for construction and provisioning the nest. The natural enemies were flies of Anthrax genus, the cleptoparasitic bees Leiopodus trochantericus, and Mutillidae wasp. The feature about the life history, nest architecture, materials used, pollen provisions behavior and associated organisms of this species allow the comparison with other emphorines species.

Description of the male, nest architecture and biology notes of Zethus plaumanni Bohart & Stange, 1965 (Hymenoptera, Vespidae) in southern Brazil

Although diverse and widespread, there is much to improve on the knowledge of Zethus Fabricius, 1804 wasps. This includes aspects of many areas, such as data on taxonomy, behavior and biology. In the present study, we investigated Zethus plaumanni Bohart & Stange, 1965, a species hitherto known only from the female type in the literature, and worked to fill gaps on the knowledge of this species by describing the male and its genitalia, the nest structure and giving notes on the biology of individuals collected in trap-nests in southern Brazil. The male is diagnosable by characters also used for female identification. The nest follows the pattern of typical pre-existing cavity users, with a remarkable multi-layered nest plug. Sex ratio follows the 1:1 rule and sampling indicates diapause in the adult phase.

Climate Change Influences Basidiome Emergence of Leaf-Cutting Ant Cultivars

Maintaining symbiosis homeostasis is essential for mutualistic partners. Leaf-cutting ants evolved a long-term symbiotic mutualism with fungal cultivars for nourishment while using vertical asexual transmission across generations. Despite the ants’ efforts to suppress fungal sexual reproduction, scattered occurrences of cultivar basidiomes have been reported. Here, we review the literature for basidiome occurrences and associated climate data. We hypothesized that more basidiome events could be expected in scenarios with an increase in temperature and precipitation. Our field observations and climate data analyses indeed suggest that Acromyrmex coronatus colonies are prone to basidiome occurrences in warmer and wetter seasons. Even though our study partly depended on historical records, occurrences have increased, correlating with climate change. A nest architecture with low (or even the lack of) insulation might be the cause of this phenomenon. The nature of basidiome occurrences in the A. coronatus–fungus mutualism can be useful to elucidate how resilient mutualistic symbioses are in light of climate change scenarios.

Nests of Eufriesea aff. auriceps (Hymenoptera, Apidae, Euglossini) in remnants of Atlantic Forest and reforested areas

In recent decades, the use of the trap-nest technique has helped to increase knowledge on the nest architecture of many orchid bee species. This study describes the nest architecture of Eufriesea aff. auriceps constructed in trap-nests made of dried bamboo internodes (canes). The nests were placed in remnants of Atlantic forest and in reforested areas next to forest remnants and monitored monthly from August 2015 to August 2016 and from August 2018 to August 2019 in southern Brazil. The bamboo internodes occupied by bees varied in internal diameter from 1.0cm to 2.0 cm (`X = 1.7; SD = 0.3; N = 12) and in length from 11.0 cm to 28.0 cm (`X = 19.5; SD = 4.8; N = 12). The total size of the nests inside the bamboo internodes ranged from 9.0 cm to 19.9 cm (`X = 14.3; SD= 3.9; N = 12). The number of brood cells constructed per nest varied from 1 to 10 (`X = 4.0; SD = 2.3; N = 15). The cells were built with small pieces of bark cemented with resin, linearly arranged along the bamboo tube. Internally, the cell wall was lined with resin. The cells measured 1.5-3.0 cm (`X = 2.3 ± 0.5; N = 48) in length and 1.4-1.7 (`X = 1.5 ± 0.1; N = 17) cm in width. The internal contour of the cells was elliptical. Females of Eufriesea aff. auriceps occupied trap-nests in both the forest remnants and in areas undergoing restoration.

Nest Architecture and Animals Associated with Neoponera verenae (Forel) (Formicidae, Ponerinae)

The nests of ants Neoponera have chambers that can also be occupied by other species of organisms that can be tenants, visitors or prey. However, few studies have considered the assemblage of the associated species and described their composition. This study aimed to describe the architecture and catalog the visitors and prey species found in Neoponera verenae nests. Talcum powder was pumped inside eight nests to mark the chambers and tunnels. The nests were then excavated to describe the architecture and obtain measurements of chambers. The associated species encountered in the nests were collected and identified allowing us to obtain new records of visiting (Linepithema sp., cryptodesmid millipedes and Neotropacarus sp.) and prey taxa (membracids, apid bees and springtails) of N. verenae. Generally, nests had a single entrance hole and a depth of up to 42 cm. Nest chambers were found with three basic forms, elliptical, hangers and boot. Although studies show that this species can occupy abandoned nests of leaf-cutting ants, we found that the nests of N. verenae were more similar to those of Ectatomma ants. Indeed, we found one of the N. verenae nests was attached to a Ectatomma edentatum nest, leading us to suggest that N. verenae may occupy abandoned nests or displace other ants to occupy them.

Nest architecture is linked with ecological success in songbirds

Bird nests are essential structures that directly determine the fitness of an organism. While there is theory and evidence predicting an association between species nest traits and their habitat, few studies have comprehensively examined the macroevolutionary patterns driving nest evolution, species niche and their interrelation. Using information on 3174 species of songbirds, we show that species that build domed nests (i.e. nests with a roof) have smaller ranges, narrower thermal niches, are less likely to colonise urban environments and have potentially higher extinction rates compared to species that build open nests. Moreover, we show that these macroevolutionary patterns could be driven by the higher energetic demands when building domed nests, which consumes more time and might restrict breeding opportunities. These diverse strands of evidence suggest that the transition from domed to open nests in passerines represents an important evolutionary innovation behind the success of the largest radiation of birds.