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1. Bacterial communities of fungus-growing ant queens are species-specific and suggest vertical transmission

   https://doi.org/10.1371/journal.pone.0306011  

   Sadowski, Victoria A; Sapountzis, Panagiotis; Kooij, Pepijn W; Boomsma, Jacobus J; Adams, Rachelle_M M (October 2025, PLOS One)

   Chaline, Nicolas (Ed.)

   Multipartite symbioses are inherently complex, involving dynamic ecological interactions between organisms with intertwined yet distinct evolutionary histories. The fungus-growing (attine) ants facilitate maintenance of a symbiotic species network through maternal vertical transmission of a fungal symbiont. While the gut microbiomes of fungus-growing ant species are remarkably simple, their fungus gardens support diverse microbial communities. Here, we focus on the garden pellet stored in the nest-founding queen’s infrabuccal pocket—a food filter in the head that allows ants to expel large particles. The pellet is an inoculate of the new fungal garden but also contains other microbes. We used 16S rRNA gene amplicon sequencing to reconstruct the extent of vertical transmission of bacteria to new gardens via queen pellets in four sympatric fungus-growing ant species from Central Panama (Atta sexdens,Atta cephalotes,Acromyrmex echinatior,andMycetomoellerius mikromelanos). We also characterized the bacterial communities associated with queen eggs and tissues (mesosomas, guts and ovaries) to assess whether queens are likely to transmit symbiotic bacteria, such as cuticular Actinomycetota and endosymbionts (Wolbachia,Mesoplasma, andSpiroplasma). We made within and between species comparisons, focusing on three hypotheses: (H1) Queens vertically transmit garden-associated bacteria in the garden pellet. (H2) Fungus-growing ant-associated bacteria are maintained through vertical transmission by queens. (H3) Vertically transmitted bacterial communities have host ant species-specificity. While we found mixed evidence for vertical transmission of garden bacteria, our results support maternal transmission as an important route for ant-associated symbionts. The ant species-specificity we see in queen bacterial microbiota mirrors patterns of known symbiont presence in workers from previous studies. Overall, our results suggest that vertical transmission of bacterial associates is mediated by the ant hosts, however the mechanism behind bacterial acquisition before a mating flight and dispersal is not yet understood. 

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2. Highly diverse and unknown viruses may enhance Antarctic endoliths’ adaptability

   https://doi.org/10.1186/s40168-023-01554-6  

   Ettinger, Cassandra L.; Saunders, Morgan; Selbmann, Laura; Delgado-Baquerizo, Manuel; Donati, Claudio; Albanese, Davide; Roux, Simon; Tringe, Susannah; Pennacchio, Christa; del Rio, Tijana G.; et al (December 2023, Microbiome)

   Abstract Background Rock-dwelling microorganisms are key players in ecosystem functioning of Antarctic ice free-areas. Yet, little is known about their diversity and ecology, and further still, viruses in these communities have been largely unexplored despite important roles related to host metabolism and nutrient cycling. To begin to address this, we present a large-scale viral catalog from Antarctic rock microbial communities. Results We performed metagenomic analyses on rocks from across Antarctica representing a broad range of environmental and spatial conditions, and which resulted in a predicted viral catalog comprising > 75,000 viral operational taxonomic units (vOTUS). We found largely undescribed, highly diverse and spatially structured virus communities which had predicted auxiliary metabolic genes (AMGs) with functions indicating that they may be potentially influencing bacterial adaptation and biogeochemistry. Conclusion This catalog lays the foundation for expanding knowledge of virosphere diversity, function, spatial ecology, and dynamics in extreme environments. This work serves as a step towards exploring adaptability of microbial communities in the face of a changing climate. 

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3. Interaction with refuse piles is associated with co-occurrence of core gut microbiota in workers of the ant Aphaenogaster picea

   https://doi.org/10.1099/acmi.0.000832.v4  

   Pagalilauan, Alison; Pavloudi, Christina; Ospina, Santiago Meneses; Smith, Adam; Saw, Jimmy H (January 2025, Access Microbiology)

   Comparing the diversity of gut microbiota between and within social insect colonies can illustrate interactions between bacterial community composition and host behaviour. In many eusocial insect species, different workers exhibit different task behaviours. Evidence of compositional differences between core microbiota in different worker types could suggest a microbial association with the division of labour among workers. Here, we present the core microbiota ofAphaenogaster piceaant workers with different task behaviours. The genusAphaenogasteris abundant worldwide, yet the associated microbiota of this group is unstudied. Bacterial communities fromAphaenogaster piceagut samples in this study consist of 19 phyla, dominated by Proteobacteria, Cyanobacteria and Firmicutes. Analysis of 16S rRNA gene sequences reveals distinct similarity clustering ofAphaenogaster piceagut bacterial communities in workers that have more interactions with the refuse piles. Though gut bacterial communities of nurse and foraging ants are similar in overall composition and structure, the worker groups differ in relative abundances of dominant taxa. Gut bacterial communities from ants that have more interactions with refuse piles are dominated by amplicon sequence variants associated with Entomoplasmataceae. Interaction with faecal matter via refuse piles seems to have the greatest impact on microbial taxa distribution, and this effect appears to be independent of worker type. This is the first report surveying the gut microbiome community composition ofAphaenogasterants. 

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4. Heritable Viruses as Hidden Drivers of Insect Phenotypes and Evolution

   https://doi.org/10.1146/annurev-ento-121423-013439  

   Parker, Benjamin J; Rozo-Lopez, Paula (January 2026, Annual Review of Entomology)

   Recent studies using metatranscriptome sequencing have revealed a diversity of viruses associated with insects. Researchers have used various approaches to establish patterns of transmission of insect-specific viruses and have shown that insects often harbor viruses that are inherited from parents to offspring. It remains unclear, however, whether heritable viral symbioses can be understood in the same ecological and evolutionary framework that has been established for bacterial symbiosis. We review studies showing beneficial and pathogenic effects of heritable viruses on their hosts, and we discuss additional ways that heritable viruses shape insect evolution. We also compare bacterial and viral symbiosis and review ways that this emerging field can be used for biocontrol of pests and insect-borne pathogens. Heritable viruses are a key part of the ecology and evolution of insects. A framework for studying symbiosis between insects and these microbes is important for a comprehensive understanding of insect biology. 

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5. Bacteria Contribute to Plant Secondary Compound Degradation in a Generalist Herbivore System

   https://doi.org/10.1128/mBio.02146-20  

   Francoeur, Charlotte B.; Khadempour, Lily; Moreira-Soto, Rolando D.; Gotting, Kirsten; Book, Adam J.; Pinto-Tomás, Adrián A.; Keefover-Ring, Ken; Currie, Cameron R. (October 2020, mBio)

   McFall-Ngai, Margaret J. (Ed.)

   ABSTRACT Herbivores must overcome a variety of plant defenses, including coping with plant secondary compounds (PSCs). To help detoxify these defensive chemicals, several insect herbivores are known to harbor gut microbiota with the metabolic capacity to degrade PSCs. Leaf-cutter ants are generalist herbivores, obtaining sustenance from specialized fungus gardens that act as external digestive systems and which degrade the diverse collection of plants foraged by the ants. There is in vitro evidence that certain PSCs harm Leucoagaricus gongylophorus , the fungal cultivar of leaf-cutter ants, suggesting a role for the Proteobacteria -dominant bacterial community present within fungus gardens. In this study, we investigated the ability of symbiotic bacteria present within fungus gardens of leaf-cutter ants to degrade PSCs. We cultured fungus garden bacteria, sequenced the genomes of 42 isolates, and identified genes involved in PSC degradation, including genes encoding cytochrome P450 enzymes and genes in geraniol, cumate, cinnamate, and α-pinene/limonene degradation pathways. Using metatranscriptomic analysis, we showed that some of these degradation genes are expressed in situ . Most of the bacterial isolates grew unhindered in the presence of PSCs and, using gas chromatography-mass spectrometry (GC-MS), we determined that isolates from the genera Bacillus , Burkholderia , Enterobacter , Klebsiella , and Pseudomonas degrade α-pinene, β-caryophyllene, or linalool. Using a headspace sampler, we show that subcolonies of fungus gardens reduced α-pinene and linalool over a 36-h period, while L. gongylophorus strains alone reduced only linalool. Overall, our results reveal that the bacterial communities in fungus gardens play a pivotal role in alleviating the effect of PSCs on the leaf-cutter ant system. IMPORTANCE Leaf-cutter ants are dominant neotropical herbivores capable of deriving energy from a wide range of plant substrates. The success of leaf-cutter ants is largely due to their external gut, composed of key microbial symbionts, specifically, the fungal mutualist L. gongylophorus and a consistent bacterial community. Both symbionts are known to have critical roles in extracting energy from plant material, yet comparatively little is known about their roles in the detoxification of plant secondary compounds. In this study, we assessed if the bacterial communities associated with leaf-cutter ant fungus gardens can degrade harmful plant chemicals. We identify plant secondary compound detoxification in leaf-cutter ant gardens as a process that depends on the degradative potential of both the bacterial community and L. gongylophorus . Our findings suggest that the fungus garden and its associated microbial community influence the generalist foraging abilities of the ants, underscoring the importance of microbial symbionts in plant substrate suitability for herbivores. 

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