Life Inside an Acorn: How Microclimate and Microbes Influence Nest Organization in Temnothorax Ants

Nests provide a buffer against environmental variation, but conditions may also vary at different locations within a nest. Conditions can vary based on abiotic factors, such as moisture and temperature, as well as biotic factors, such as the presence of microbes and potential pathogens. Therefore, characterizing how animals adjust their position inside their nests to track microclimate preferences while at the same time preventing pathogen exposure is necessary to understand the benefits nests provide. Here we studied how colonies of the acornânesting ant Temnothorax curvispinosus responded to experimental manipulation of moisture, temperature, and microbial growth inside their nests. Colonies showed no response to differences in moisture and moved to the bottom of the acorn regardless of moisture treatment. When nests were heated from the top to simulate warming by the sun, workers preferentially moved brood to the warm, upper half of the acorn, which would stimulate brood development. Finally, the strongest factor that influenced colony position was the presence of microbes inside the nestâcolonies avoided the bottom of the nest when it was inoculated with microbes, and colonies in new acorns shifted to the top of the acorn over time as mold and other microbes had time to grow. The relatively strong response of T. curvispinosus to microbial growth inside their nests suggests that pathogen pressuresâin addition to microclimateâhave a significan

Public questions spur the discovery of new bacterial species associated with lignin bioconversion of industrial waste

A citizen science project found that the greenhouse camel cricket (Diestrammena asynamora) is common in North American homes. Public response was to wonder “what good are they anyway?” and ecology and evolution guided the search for potential benefit. We predicted that camel crickets and similar household species would likely host bacteria with the ability to degrade recalcitrant carbon compounds. Lignocellulose is particularly relevant as it is difficult to degrade yet is an important feedstock for pulp and paper, chemical, and biofuel industries. We screened gut bacteria of greenhouse camel crickets and another household insect, a hide beetle (Dermestes maculatus) for the ability to grow on and degrade lignocellulose components as well as the lignocellulose-derived industrial waste product black liquor. From three greenhouse camel crickets and three hide beetles, 14 bacterial strains were identified capable of growth on lignocellulosic components, including lignin. Cedecea lapagei was selected for further study due to growth on most lignocellulose components. The C. lapagei secretome was identified using LC/MS/MS analysis. This work demonstrates a novel source of lignocellulose-degrading bacteria and introduces an effective workflow to identify bacterial enzymes for transforming industrial waste into value-added products. More generally, our research suggests the value of ecologically-guided discovery of novel organisms

Community Structure and Interaction Breadth in Beetle-Macrofungus Associations

A major goal of ecology is to understand the factors that shape interactions among species. In this study, I explored the little-known associations between beetles and macrofungal fruiting bodies to characterize patterns of beetle-fungus association and to investigate sources of variation in the structure of these trophic interactions. First, I characterized the composition and diversity of beetle-sporocarp associations at two sites in the Appalachian Mountains and foothills, and evaluated the extent to which beetle community structure varied with fungal species, sporocarp age, and sporocarp dry mass. My results showed that beetle abundance and diversity differed among fungal species and were positively associated with sporocarp age and dry mass. I also found evidence of a nested structure in beetle-sporocarp interactions, wherein specialists on both sides of the association interact preferentially with more generalized species. Next, I performed a field study of beetle-sporocarp associations over two summers to evaluate the factors related to interaction breadth in trophic associations. I found evidence that interaction breadth varies with the palatability of the food organism (as indicated by sporocarp toughness and sporocarp age) and showed that beetle interaction breadth was negatively correlated with sporocarp persistence. I found strong intraseasonal variation in interaction breadth, but no evidence that this variation was structured by precipitation or differences in beetle community composition. In my third chapter, I conducted a field experiment to investigate (1) the importance of an individual food organism's physical properties in determining its relative importance in the beetle-sporocarp interaction network and (2) whether the structure of the beetle-sporocarp interaction network cycles predictably with the time of day. My results show that size and density of individual food organisms may be important factors in determining their relative importance in an interaction network, and offer the first evidence of diurnal cycling in the structure of interaction networks

2011 Matrices

Data represent abundance matrices with columns representing species or morphospecies of adult beetles found on baits of mature, fresh sporocarps of _Pleurotus ostreatus_ mushrooms. Each entry represents the number of individuals of that beetle species found on a particular bait type (see paper for experimental design of bait arrays). Rows represent individual mushroom baits, with letter codes corresponding to positions in experimental arrays as described in the manuscript. Each tab in the data file represents a different census. Adult beetles were censused mornings and evenings on consecutive days

Data from: Interaction networks of macrofungi and mycophagous beetles reflect diurnal variation and the size and spatial arrangement of resources

Ecological networks are useful for characterizing interspecific associations and predicting the resilience of ecological communities. We evaluated how such networks vary with the size, spatial distribution, and timing of availability of resources, with a focus on beetle-macrofungal associations. We used 2 y of field experiments to construct ecological networks based on manipulated sporocarp baits (resources; Pleurotus ostreatus) and natural communities of beetles (consumers) in a temperate forest. Centrality and interaction strength increased with resource size, but were associated weakly with resource density and isolation, and not at all with position within patches. Whole-network connectance was greater in mornings (when beetle richness and abundance were high) than evenings. Interannual differences in networks were consistent with differences in beetle communities between years. The capacity of networks to vary temporally, spatially, and as a function of resource traits is examined in light of understanding beetle-macrofungal associations, which are important components of fungal ecology

Quantifying beetle-macrofungal associations in a temperate biodiversity hot spot

<p>Beetles (Coleoptera) are often among the most abundant and diverse insects that feed on sporocarps of macrofungi, but little is known regarding their relative specialism or generalism in most communities. We surveyed >9000 sporocarps in montane hardwood forest in the Appalachian Mountains (USA) to characterize associations of mycophagous beetles and macrofungi. We used traditional metrics and network analyses to quantify relationships between sporocarp traits (mass, age, persistence, and toughness) and assemblages of adult beetles, drawing from >50 000 beetles collected over two survey years. Strict-sense specificity was rare in these associations: most beetle species were found on multiple fungal genera, and most fungi hosted multiple beetle species. Sporocarp age and fresh mass were positively associated with beetle diversity in fungi with ephemeral sporocarps (here including 12 genera of Agaricales and Russulales), but sporocarp persistence was not. In Polyporales, beetle diversity was greater in softer sporocarps than in tough or woody sporocarps. The increase of beetle diversity in aging sporocarps could not be attributed to increases in sporocarp mass or sampling point in the growing season, suggesting that age-related changes in chemistry or structure may support increasingly diverse beetle communities. Interaction networks differed as a function of sporocarp age, revealing that community-wide measures of generalism (i.e., network connectance) and evenness (i.e., variance in normalized degree) change as sporocarps mature and senesce. Beetles observed on Agaricales and Russulales with more persistent sporocarps had narrower interaction breadth (i.e., were more host-specific) than those on less persistent sporocarps, and beetles on Polyporales with tougher sporocarps had narrower interaction breadth than those on soft sporocarps. In addition to providing a large-scale evaluation of sporocarp use by adult beetles in this temperate biodiversity hot spot, this study shows that characteristics of food organisms are associated with specialism and generalism in interactions relevant to fungal and forest ecology.</p

Data from: Reproduction in flame azalea (Rhododendron calendulaceum, Ericaceae): a rare case of insect wing pollination

Although many angiosperms are serviced by flying pollinators, reports of wings as pollen vectors are rare. Flame azalea (Rhododendron calendulaceum) is visited by diverse insects, yet previous observations suggested that only butterfly wings may transfer pollen to stigmas. We used an experimental approach to determine whether butterfly wings are the primary vehicle of pollination in flame azalea. Over two seasons of observations, only butterflies (Papilio glaucus and Speyeria cybele) contacted both anthers and stigmas, yet because of differences in wing-flapping behavior, P. glaucus transferred pollen most efficiently. In contrast, bee species specialized either on pollen or nectar but did not contact both anthers and stigmas. A field experiment revealed that flowers excluding butterflies experienced almost complete fruit failure, whereas fruit set in open flowers did not differ from those that were hand pollinated. Additionally, butterflies had 56-fold more azalea pollen on their wings than bodies, while azalea stigmas bore both pollen and wing scales. These results suggest that plants with many visitors contacting reproductive organs may still specialize on a single guild of visitors for pollination and that wing-borne pollen transfer is a key mode of flame azalea pollination

Too big to be noticed: cryptic invasion of Asian camel crickets in North American houses

Despite the rapid expansion of the built environment, we know little about the biology of species living in human-constructed habitats. Camel crickets (Rhaphidophoridae) are commonly observed in North American houses and include a range of native taxa as well as the Asian Diestrammena asynamora (Adelung), a species occasionally reported from houses though considered to be established only in greenhouses. We launched a continental-scale citizen science campaign to better understand the relative distributions and frequency of native and nonnative camel crickets in human homes across North America. Participants contributed survey data about the presence or absence of camel crickets in homes, as well as photographs and specimens of camel crickets allowing us to identify the major genera and/or species in and around houses. Together, these data offer insight into the geographical distribution of camel crickets as a presence in homes, as well as the relative frequency and distribution of native and nonnative camel crickets encountered in houses. In so doing, we show that the exotic Diestrammena asynamora not only has become a common presence in eastern houses, but is found in these environments far more frequently than native camel crickets. Supplemental pitfall trapping along transects in 10 urban yards in Raleigh, NC revealed that D. asynamora can be extremely abundant locally around some homes, with as many as 52 individuals collected from pitfalls in a single yard over two days of sampling. The number of D. asynamora individuals present in a trap was negatively correlated with the trap’s distance from a house, suggesting that these insects may be preferentially associated with houses but also are present outside. In addition, we report the establishment in the northeastern United States of a second exotic species, putatively Diestrammena japanica Blatchley, which was previously undocumented in the literature. Our results offer new insight into the relative frequency and distribution of camel crickets living in human homes, and emphasize the importance of the built environment as habitat for two little-known invading species of Orthoptera

Pollen & wing scale load on stigmas from naturally visited flowers

After observing a visit by a butterfly in the field, stigmas from R. calendulaceum flowers were clipped and attached to a microscope slide in the field. Data show presence/absence (=Y/N) of pollen and butterfly wing scales on stigmas as scored after examining stigmas under the microscope