Biology subjects

Mikaelyan, A.

Publications and source records attributed to Mikaelyan, A..

5 recordsLinked to original sources

bioRxiv2024

Lethal Disruption of the Symbiotic Gut Community in Eastern Subterranean Termite Caused by Boric Acid

AbstractThe Eastern subterranean termite, Reticulitermes flavipes (Kollar), is a significant pest, causing extensive damage to structures that amount to substantial economic losses. Traditional termite control methods have utilized boric acid, known for its broad-spectrum insecticidal properties, yet its impact on termite gut microbiomes and the implications of such effects remain understudied. Our study evaluates the dose-dependent mortality of R. flavipes upon being provided boric acid treated filter papers and investigates the resulting dysbiosis within the termite gut microbiome. Consistent with reports from other insects, mortality increased in a dose-dependent manner, with the highest boric acid concentration (203.7 {micro}g/cm2 of filter paper) significantly reducing termite survival. 16S rRNA gene sequencing of the gut microbiome revealed notable shifts in composition, indicating boric acid-induced dysbiosis. Aside from an overall decrease in microbial diversity, the relative abundance of some symbionts essential for termite nutrition decreased in response to higher boric acid concentrations, while several putative pathogens increased. Our findings extend the understanding of boric acids mode of action in termites, emphasizing its effect beyond direct toxicity to include significant microbiome modulation that can have dire effects on termite biology. Considering its potential to induce dysbiosis and potentially augment the effectiveness of entomopathogens, our study supports the continued use of boric acid and related compounds for termite-resistant treatments for wood.

zoology↗

bioRxiv2024

Fight, Retreat, Repeat: Field observation of male-male agonistic behavior in the wood-feeding cockroach, Panesthia angustipennis spadica (Dictyoptera: Blattodea: Blaberidae)

Conflict is one of the most critical factors affecting the behavior of animals related to their reproduction and survival, with aggressive interactions being central to acquiring resources or mating partners. This phenomenon is more common among males than females, impacting reproduction strategy and beginning of biparental care. Investigating such interactions in species closely related to social species can be illuminating, offering valuable insights into the factors that influence the emergence and maintenance of more complex social behaviors. In this context, we present a field study of male-male agonistic behavior in the wood-feeding cockroach, Panesthia angustipennis. Panesthia is the closest genus to the subsocial genus Salganea, which is known for its biparental care. Our field observations reveal a characteristic behavior where one male pushes a rival away from a female. The victorious male repeatedly returns to a specific site near the female, suggesting a strategy to minimize unnecessary conflict or protect the female. This behavior provides insights into the potential evolutionary strategies that may have evolved in the common ancestor shared by Salganea and Panesthia. Notably, the displaced males persistently reengage, highlighting the high resource value attributed to females and the consequential intensity of male competition. This study not only sheds light on the aggressive and pacifist tendencies in P. angustipennis but also contributes to understanding the evolutionary development of social structures in Salganea. Further experimental investigations into the aggressive behaviors of P. angustipennis will enhance our comprehension of the factors shaping the evolution of sociality in these species.

animal behavior and cognition↗

bioRxiv2023

Chewing Through Challenges: Exploring the Evolutionary Pathways to Wood-Feeding in Insects

Decaying wood, while an abundant and stable resource, presents considerable nutritional challenges due to its structural rigidity, chemical recalcitrance, and low nitrogen content. Despite these challenges, certain insect lineages have successfully evolved saproxylophagy (consuming and deriving sustenance from decaying wood), impacting nutrient recycling in ecosystems and carbon sequestration dynamics. This study explores the uneven phylogenetic distribution of saproxylophagy across insects and delves into the evolutionary origins of this trait in disparate insect orders. Employing a comprehensive analysis of gut microbiome data, encompassing both previously published datasets and newly generated data, from both saproxylophagous insects and their non-saproxylophagous relatives, this Hypothesis paper discusses the broader phylogenetic context and potential morphological, physiological, and symbiotic adaptations necessary for this dietary specialization. The study proposes the "Detritivore-First Hypothesis," suggesting an evolutionary pathway to saproxylophagy through detritivory, and highlights the critical role of symbiotic gut microbiomes in the digestion of decaying wood. The article aims to provide a deeper understanding of the macroevolutionary landscape and mechanisms underpinning the multiple origins and distribution of saproxylophagy in insects.

evolutionary biology↗

bioRxiv2021

Genomes of gut bacteria from Nasonia wasps shed light on phylosymbiosis and microbe-assisted hybrid breakdown

Phylosymbiosis is a cross-system trend whereby microbial community relationships recapitulate the host phylogeny. In Nasonia parasitoid wasps, phylosymbiosis occurs throughout development, is distinguishable between sexes, and benefits host development and survival. Moreover, the microbiome shifts in hybrids as a rare Proteus bacteria in the microbiome becomes dominant. The larval hybrids then catastrophically succumb to bacterial-assisted lethality and reproductive isolation between the species. Two important questions for understanding phylosymbiosis and bacterial-assisted lethality in hybrids are: (i) Do the Nasonia bacterial genomes differ from other animal isolates and (ii) Are the hybrid bacterial genomes the same as those in the parental species? Here we report the cultivation, whole genome sequencing, and comparative analyses of the most abundant gut bacteria in Nasonia larvae, Providencia rettgeri and Proteus mirabilis. Characterization of new isolates shows Proteus mirabilis forms a more robust biofilm than Providencia rettgeri and when grown in co-culture, Proteus mirabilis significantly outcompetes Providencia rettgeri. Providencia rettgeri genomes from Nasonia are similar to each other and more divergent to pathogenic, human-associates strains. Proteus mirabilis from N. vitripennis, N. giraulti, and their hybrid offspring are nearly identical and relatively distinct from human isolates. These results indicate that members of the larval gut microbiome within Nasonia are most similar to each other, and the strain of the dominant Proteus mirabilis in hybrids is resident in parental species. Holobiont interactions between shared, resident members of the wasp microbiome and the host underpin phylosymbiosis and hybrid breakdown. IMPORTANCEAnimal and plant hosts often establish intimate relationships with their microbiomes. In varied environments, closely-related host species share more similar microbiomes, a pattern termed phylosymbiosis. When phylosymbiosis is functionally significant and beneficial, microbial transplants between host species or host hybridization can have detrimental consequences on host biology. In the Nasonia parasitoid wasp genus that contains a phylosymbiotic gut community, both effects occur and provide evidence for selective pressures on the holobiont. Here, we show that bacterial genomes in Nasonia differ from other environments and harbor genes with unique functions that may regulate phylosymbiotic relationships. Furthermore, the bacteria in hybrids are identical to parental species, thus supporting a hologenomic tenet that the same members of the microbiome and the host genome impact phylosymbiosis, hybrid breakdown, and speciation.

microbiology↗

bioRxiv2018

Gut microbial compositions mirror caste-specific diets in a major lineage of eusocial insects

Eusocial insects owe their ecological success to the division of labour and processes within colonies often rely on the presence of specific microbial symbionts, but associations between microbial community compositions and castes with different tasks and diets within colonies remain largely unexplored. Fungus-growing termites evolved to use fungi to externally degrade plant material, complemented by specific and complex gut microbiotas. Here we explore to which extent division of labour and dietary differences within fungus-growing termite castes are linked to gut bacterial community structure. Using amplicon sequencing, we characterise community compositions in sterile (worker and soldier) and reproductive (queen and king) termites and combine this with gut enzyme, microscopy, and in situ analyses to further elucidate sterile caste-specific microbiota compositions. Gut bacterial communities are structured primarily according to termite caste and genus. In contrast to the observed rich and diverse sterile caste microbiotas, royal pair microbiotas are extremely skewed and dominated by few bacterial taxa, reflecting the specialised dietary intake and unique, reproduction-centred lifestyle of the queen and king.

microbiology↗