Transmission of antimicrobial resistance in the gut microbiome of gregarious cockroaches: the importance of interaction between antibiotic exposed and non-exposed populations.

Antimicrobial resistance (AMR) is a major global health concern, further complicated by its spread via the microbiome bacterial members. While mathematical models discuss AMR transmission through the symbiotic microbiome, experimental studies are scarce. Herein, we used a gregarious cockroach, Pycnoscelus surinamensis, as an in vivo animal model for AMR transmission investigations. We explored whether the effect of antimicrobial treatment is detectable with metagenomic sequencing, and whether AMR genes can be spread and established in unchallenged (not treated with antibiotics) individuals following contact with treated donors, and under various frequencies of interaction. Gut and soil substrate microbiomes were investigated by metagenomic sequencing for bacterial community composition and resistome profiling. We found that tetracycline treatment altered the treated gut microbiome by decreasing bacterial diversity and increasing the abundance of tetracycline resistance genes. Untreated cockroaches that interacted with treated donors also had elevated tetracycline resistance. The levels of resistance differed depending on the magnitude and frequency of donor transfer. Additionally, treated donors showed signs of microbiome recovery due to their interaction with the untreated ones. Similar patterns were also recorded in the soil substrate microbiomes. Our results shed light on how interacting microbiomes facilitate AMR gene transmission to previously unchallenged hosts, a dynamic influenced by the interaction frequencies, using an in vivo model to validate theoretical AMR transmission models.IMPORTANCEAntimicrobial resistance is a rising threat to human and animal health. The spread of resistance through the transmission of the symbiotic gut microbiome is of concern and has been explored in theoretical modeling studies. In this study, we employ gregarious insect populations to examine the emergence and transmission of antimicrobial resistance in vivo and validate modeling hypotheses. We find that antimicrobial treatment increases the levels of resistance in treated populations. Most importantly, we show that resistance increased in untreated populations after interacting with the treated ones. The level of resistance transmission was affected by the magnitude and frequency of population mixing. Our results highlight the importance of microbial transmission in the spread of antimicrobial resistance.

A New Termitophilous Genus of Paederinae Rove Beetles (Coleoptera, Staphylinidae) from the Neotropics and Its Phylogenetic Position.

We describe a new genus and species of Paederinae rove beetles, Ruptor cordatus gen. et sp. nov., which lives in the arboreal nests of the termite Labiotermes labralis (Holmgren, 1906) in the Amazon lowlands of Peru. The morphology of Ruptor gen. nov. is highly derived, apparently due to its close association with the termite host, and thus, morphologically, the genus cannot be classified further than Lathrobiini incertae sedis. In order to address the sister-group relationships of Ruptor gen. nov., we conducted a molecular phylogenetic analysis based on seven gene fragments. The analysis indeed resolved the genus as a member of the tribe Lathrobiini and placed it nested within the informal clade of 'Medonina and allied taxa'. We provide a morphological comparison of the new genus with all known myrmeco- and termitophilous representatives of the subfamily, and to the extent possible, we illustrate other relevant and poorly known Neotropical Paederinae inquilines.

Total-evidence analysis resolves the phylogenetic position of an enigmatic group of Paederinae rove beetles (Coleoptera: Staphylinidae).

Paederinae is one of the most diverse subfamilies among rove beetles, yet their evolutionary history remains poorly understood. This is attributed to the limited number of phylogenetic studies, which either sought answers at a shallower taxonomic level or included limited taxon sampling. Especially problematic is the position of the rare Neotropical tribe Cylindroxystini, morphologically one of the most puzzling groups of Paederinae. The phylogenetic position of this group within Paederinae was never understood, though its rank in the classification has already been shifted twice. We assembled molecular and morphological data matrices sampled from all currently recognized Paederinae subtribes, including both genera of Cylindroxystini, and used these data to estimate phylogenetic relationships using Bayesian inference. A total of 123 morphological characters and 4,631 bp of nuclear (28S, TP, Wg, CADA, CADC, ArgK) and mitochondrial (COI) sequences were analyzed for 76 taxa. The current tribe Cylindroxystini was resolved as a monophylum within the tribe Lathrobiini as sister to the genus Pseudolathra, and together they are sister to the so-called 'Medonina and allied taxa' clade. Based on these results, we downgraded Cylindroxystini back to the subtribal level, Cylindroxystina status reinstated, now with a known sister group. The resulting phylogeny is the largest of the subfamily Paederinae to date and lays the foundation for establishing a natural classification of the group.

Taxonomic notes on the genus Quwatanabius in Taiwan (Coleoptera: Staphylinidae).

The description of the male of the species Quwatanabius chiaw (Smetana, 1995) is provided for the first time, including a habitus photo and illustrations of the aedeagus. A brief discussion of the endemic status of Q. chiaw on the island of Taiwan, as well as additional Taiwanese material of the wide-spread Q. flavicornis (Sharp, 1889) are also provided.