Host-Adapted Strains of Spodoptera frugiperda Hold and Share a Core Microbial Community Across the Western Hemisphere.

The fall armyworm Spodoptera frugiperda is an important polyphagous agricultural pest in the Western Hemisphere and currently invasive to countries of the Eastern Hemisphere. This species has two host-adapted strains named "rice" and "corn" strains. Our goal was to identify the occurrence of core members in the gut bacterial community of fall armyworm larvae from distinct geographical distribution and/or host strain. We used next-generation sequencing to identify the microbial communities of S. frugiperda from corn fields in Brazil, Colombia, Mexico, Panama, Paraguay, and Peru, and rice fields from Panama. The larval gut microbiota of S. frugiperda larvae did not differ between the host strains nor was it affected by the geographical distribution of the populations investigated. Our findings provide additional support for Enterococcus and Pseudomonas as core members of the bacterial community associated with the larval gut of S. frugiperda, regardless of the site of collection or strain. Further investigations are required for a deeper understanding of the nature of this relationship.

Diet-related gut bacterial dysbiosis correlates with impaired development, increased mortality and Nosema disease in the honeybee (Apis mellifera).

Dysbiosis, defined as unhealthy shifts in bacterial community composition, can lower the colonization resistance of the gut to intrinsic pathogens. Here, we determined the effect of diet age and type on the health and bacterial community composition of the honeybee (Apis mellifera). We fed newly emerged bees fresh or aged diets, and then recorded host development and bacterial community composition from four distinct regions of the hosts' digestive tract. Feeding fresh pollen or fresh substitute, we found no difference in host mortality, diet consumption, development or microbial community composition. In contrast, bees fed aged diets suffered impaired development, increased mortality and developed a significantly dysbiotic microbiome. The consumption of aged diets resulted in a significant reduction in the core ileum bacterium Snodgrassella alvi and a corresponding increase in intrinsic pathogen Frischella perrara. Moreover, the relative abundance of S. alvi in the ileum was positively correlated with host survival and development. The inverse was true for both F. perrara and Parasacharibacter apium. Collectively, our findings suggest that the early establishment of S. alvi is associated with healthy nurse development and potentially excludes F. perrara and P. apium from the ileum. Although at low abundance, establishment of the common midgut pathogen Nosema spp. was significantly associated with ileum dysbiosis and associated host deficiencies. Moreover, dysbiosis in the ileum was reflected in the rectum, mouthparts and hypopharyngeal glands, suggesting a systemic host effect. Our findings demonstrate that typically occurring alterations in diet quality play a significant role in colony health and the establishment of a dysbiotic gut microbiome.

Ecological Succession in the Honey Bee Gut: Shift in Lactobacillus Strain Dominance During Early Adult Development.

In many vertebrates, social interactions and nutrition can affect the colonization of gut symbionts across generations. In the highly social honey bee, it is unknown to what extent the hive environment and older worker individuals contribute to the generational transmission of core gut bacteria. We used high-throughput sequencing to investigate the effect of nest materials and social contact on the colonization and succession of core hindgut microbiota in workers. With only brief exposure to hive materials following natural eclosion, gut bacterial communities at 3 and 7 days contained phylotypes typically found in the guts of mature adults regardless of treatment. Continuous exposure to nest materials or direct social interactions with mature adults did not affect the diversity or abundance of gut bacterial communities at the scale examined. Similarly, a common pollen supplement fed by beekeepers during pollen dearth had no effect. A consideration of unique OTUs revealed extensive microbial succession independent of treatment. The dominant Lactobacillus strain at 3 days was largely replaced by a different strain at day 7, revealing the colonization signature of a pioneer species. Similar but less pronounced patterns were evident in less abundant OTU's, many of which may influence community succession via alteration of the gut environment. Our results indicate that the process of bacterial community colonization in the hindgut is resilient to changes in the nutritional, hive, and social environment. Greater taxonomic resolution is needed to accurately resolve questions of ecological succession and typical proportional variation within and between core members of the gut bacterial community.

Key Edaphic Properties Largely Explain Temporal and Geographic Variation in Soil Microbial Communities across Four Biomes.

Soil microbial communities play a critical role in nutrient transformation and storage in all ecosystems. Quantifying the seasonal and long-term temporal extent of genetic and functional variation of soil microorganisms in response to biotic and abiotic changes within and across ecosystems will inform our understanding of the effect of climate change on these processes. We examined spatial and seasonal variation in microbial communities based on 16S rRNA gene sequencing and phospholipid fatty acid (PLFA) composition across four biomes: a tropical broadleaf forest (Hawaii), taiga (Alaska), semiarid grassland-shrubland (Utah), and a subtropical coniferous forest (Florida). In this study, we used a team-based instructional approach leveraging the iPlant Collaborative to examine publicly available National Ecological Observatory Network (NEON) 16S gene and PLFA measurements that quantify microbial diversity, composition, and growth. Both profiling techniques revealed that microbial communities grouped strongly by ecosystem and were predominately influenced by three edaphic factors: pH, soil water content, and cation exchange capacity. Temporal variability of microbial communities differed by profiling technique; 16S-based community measurements showed significant temporal variability only in the subtropical coniferous forest communities, specifically through changes within subgroups of Acidobacteria. Conversely, PLFA-based community measurements showed seasonal shifts in taiga and tropical broadleaf forest systems. These differences may be due to the premise that 16S-based measurements are predominantly influenced by large shifts in the abiotic soil environment, while PLFA-based analyses reflect the metabolically active fraction of the microbial community, which is more sensitive to local disturbances and biotic interactions. To address the technical issue of the response of soil microbial communities to sample storage temperature, we compared 16S-based community structure in soils stored at -80°C and -20°C and found no significant differences in community composition based on storage temperature. Free, open access datasets and data sharing platforms are powerful tools for integrating research and teaching in undergraduate and graduate student classrooms. They are a valuable resource for fostering interdisciplinary collaborations, testing ecological theory, model development and validation, and generating novel hypotheses. Training in data analysis and interpretation of large datasets in university classrooms through project-based learning improves the learning experience for students and enables their use of these significant resources throughout their careers.

Visual navigation in the Neotropical ant Odontomachus hastatus (Formicidae, Ponerinae), a predominantly nocturnal, canopy-dwelling predator of the Atlantic rainforest.

The arboreal ant Odontomachus hastatus nests among roots of epiphytic bromeliads in the sandy forest at Cardoso Island (Brazil). Crepuscular and nocturnal foragers travel up to 8m to search for arthropod prey in the canopy, where silhouettes of leaves and branches potentially provide directional information. We investigated the relevance of visual cues (canopy, horizon patterns) during navigation in O. hastatus. Laboratory experiments using a captive ant colony and a round foraging arena revealed that an artificial canopy pattern above the ants and horizon visual marks are effective orientation cues for homing O. hastatus. On the other hand, foragers that were only given a tridimensional landmark (cylinder) or chemical marks were unable to home correctly. Navigation by visual cues in O. hastatus is in accordance with other diurnal arboreal ants. Nocturnal luminosity (moon, stars) is apparently sufficient to produce contrasting silhouettes from the canopy and surrounding vegetation, thus providing orientation cues. Contrary to the plain floor of the round arena, chemical cues may be important for marking bifurcated arboreal routes. This experimental demonstration of the use of visual cues by a predominantly nocturnal arboreal ant provides important information for comparative studies on the evolution of spatial orientation behavior in ants. "This article is part of a Special Issue entitled: Neotropical Behaviour".