Alkaloids are important metabolites found across a variety of organisms with diverse ecological functions. Of particular interest are alkaloids found in ants, organisms well known for dominating the ecosystems they dwell in. Within ants, alkaloids are found in venom and function as potent weapons against heterospecific species. However, research is often limited to pest species or species with parasitic lifestyles and thus fails to address the broader ecological function of ant venom alkaloids. Here we describe a new species of free-living Megalomyrmex ant: Megalomyrmex peetersi sp. n. In addition, we identify its singular venom alkaloid (trans-2-butyl-5-heptylpyrrolidine) and elucidate the antibiotic and insecticidal functions of its venom. Our results show that Megalomyrmex peetersi sp. n. venom is an effective antibiotic and insecticide. These results are comparable to venom alkaloids found in other ant species, such as Solenopsis invicta. This research provides great insight into venom alkaloid function, and it is the first study to explore these ideas in the Megalomyrmex system.

Phylogenetic and functional group analyses of the genomes of anaerobic bacteria isolated from Periplaneta americana digestive tracts suggest that they represent novel Lachnospiraceae genera. PAL113 and PAL227 isolate genomes encoded short-chain fatty acid biosynthetic pathways and plant fiber and chitin catabolism and other carbohydrate utilization genes common in related Lachnospiraceae species, yet the presence of operons containing flagellar assembly pathways was among several distinguishing features. In general, PAL113 and PAL227 isolates encode an array of gene products that will enable them to thrive in the insect gut environment and potentially play a role in host diet processing. We hypothesize that the cladogenesis of these isolates can be a result of their oxygen sensitivity and reliance upon the host for dispersal and genetic drift and not necessarily a result of an ongoing mutualism.

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, and Mycetomoellerius 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, and Spiroplasma). 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.

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 an obligate fungal symbiont. While the gut microbiomes of fungus-growing ant species are remarkably simple, their fungal gardens support diverse microbial communities. Here, we focus on an understudied transmission bottleneck: the fungal garden pellet that nest-founding queens transfer to inoculate a new fungal garden. We used 16S rRNA metagenomic sequencing to reconstruct the extent of vertical transmission of bacteria to new gardens via queen pellets in four sympatric fungus-growing ant species ( Atta sexdens , Atta cephalotes , Acromyrmex echinatior , and Mycetomoellerius mikromelanos ) from Central Panama. We also characterized the bacterial communities associated with queen eggs and somatic tissues (mesosomas, guts and ovaries) to assess whether queens are likely to transmit symbiotic bacteria of workers, such as cuticular Actinobacteria and endosymbionts ( Wolbachia , Mesoplasma , and Spiroplasma ). Our results suggest that garden-associated bacteria are mainly horizontally acquired as the bacterial communities of pellets shared few bacterial taxa with the mature gardens of the four ant species investigated. While the bacterial communities of garden pellets showed some species-specificity, a subset of prevalent bacterial taxa were shared across ant species. Further, our findings provide evidence for vertical transmission of species-specific endosymbiotic bacteria through a transovarial route and/or via fecal droplets. Overall, while we found mixed evidence for vertical transmission of garden bacteria, our results support maternal transmission as a primary route for gut-associated symbionts. While our results suggest that vertical transmission of fungus-growing ant bacterial associates is mediated by the ant hosts, the mechanism behind this host control is not yet understood.