Many species of yeast are integral to human society. They produce many of our foods, beverages and industrial chemicals, challenge us as pathogens, and provide models for the study of our own biology. However, few species are regularly studied and much of their ecology remains unclear, hindering the development of knowledge that is needed to improve the relationships between humans and yeasts. There is increasing evidence that insects are an essential component of ascomycetous yeast ecology. We propose a 'dispersal-encounter hypothesis' whereby yeasts are dispersed by insects between ephemeral, spatially disparate sugar resources, and insects, in turn, obtain the benefits of an honest signal from yeasts for the sugar resources. We review the relationship between yeasts and insects through three main examples: social wasps, social bees and beetles, with some additional examples from fruit flies. Ultimately, we suggest that over the next decades, consideration of these ecological and evolutionary relationships between insects and yeasts will allow prediction of where new yeast diversity is most likely to be discovered, particularly yeasts with traits of interest to human industry.

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.

The microbiome of built structures has considerable influence over an inhabitant's well-being, yet the vast majority of research has focused on human-built structures. Ants are well-known architects, capable of constructing elaborate dwellings, the microbiome of which is underexplored. Here, we explore the bacterial and fungal microbiomes in functionally distinct chambers within and outside the nests of Azteca alfari ants in Cecropia peltata trees. We predicted that A. alfari colonies (1) maintain distinct microbiomes within their nests compared to the surrounding environment, (2) maintain distinct microbiomes among nest chambers used for different functions, and (3) limit both ant and plant pathogens inside their nests. In support of these predictions, we found that internal and external nest sampling locations had distinct microbial communities, and A. alfari maintained lower bacterial richness in their ‘nurseries’. While putative animal pathogens were suppressed in chambers that ants actively inhabited, putative plant pathogens were not, which does not support our hypothesis that A. alfari defends its host trees against microbial antagonists. Our results show that ants influence microbial communities inside their nests similar to studies of human homes. Unlike humans, ants limit the bacteria in their nurseries and potentially prevent the build-up of insect-infecting pathogens. These results highlight the importance of documenting how indoor microbiomes differ among species, which might improve our understanding of how to promote indoor health in human dwellings.

We surveyed Lepidoptera found on 11 species of Inga (Fabaceae:Mimosoideae) co-existing on Barro Colorado Island, Panama, to evaluate factors influencing diet choice. Of the 47 species of caterpillars (747 individuals) recorded, each fed on a distinct set of Inga. In the field, 96% of the individuals were found on young leaves. Growth rates of caterpillars that were fed leaves in the laboratory were 60% higher on young leaves compared to mature leaves. When caterpillars were fed leaves of nonhost Inga, they grew more slowly. These data provide support for a link between preference and performance. However, among hosts on which larvae normally occurred, faster growth rates were not associated with greater host electivity (the proportion of larvae found on each host species in the field, corrected for host abundance). Growth rates on normal hosts were positively correlated with leaf expansion rates of the host, and fast expansion was associated with leaves with higher nutritional content. Detailed studies on a gelechiid leaf roller, the species with the largest diet breadth, allowed us to assess the importance of factors other than growth that could influence diet electivity. This species showed a 1.7-fold difference in growth rate among Inga hosts and faster growth on species with fast-expanding leaves. However, there was no correlation between caterpillar growth rate and abundance on different host species. Instead, abundance of the gelechiid on each Inga species was significantly correlated with the temporal predictability of food (synchrony of leaf flushing) and was negatively correlated with competition (amount of leaf area removed by species other than the gelechiid). Although rates of parasitism were high (23-43%), there were no differences among hosts. Parasitism was also not related to measures of escape, such as growth rates of caterpillars, leaf expansion rates, and synchrony of leaf production. Together, food availability, parasitism, and competition explained 84% of the variation in host preference by the gelechiid. We suggest that these ecological interactions may be particularly important in determining diet choice initially and that preferences may be reinforced by subsequent divergence in host chemistry and/or the herbivore's ability to tolerate the secondary metabolites.

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 acorn‐nesting 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 nest—colonies 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 pressures—in addition to microclimate—have a significant impact on how colonies use nest spaces. Social insects are known to invest heavily in antimicrobial compounds that kill or slow the growth of microbes, but avoidance may represent an additional line of defense to prevent pathogen exposure.