Biology subjects

Almeida, C. E.

Publications and source records attributed to Almeida, C. E..

3 recordsLinked to original sources

bioRxiv2026

Evolutionary Dynamics of the Complete Chemosensory Repertoire in Kissing Bugs of the Genus Rhodnius: Divergent Odorant Receptors Contrast with Conserved Gene Families

Chemosensory systems play a central role in host detection, feeding behavior, and habitat selection in hematophagous insects. Here, we performed a comparative evolutionary analysis of chemosensory gene repertoires across 13 species of the Chagas disease vector genus Rhodnius. While gustatory receptors (GRs), ionotropic receptors (IRs), odorant-binding proteins (OBPs), and chemosensory proteins (CSPs) remained globally conserved, odorant receptors (ORs) displayed extensive lineage-specific expansions, tandem duplications, dynamic transcriptomic regulation, and recurrent signatures of positive selection. Major OR expansions were observed in Rhodnius robustus and Rhodnius colombiensis, suggesting increased sensory diversification in ecologically heterogeneous lineages. In contrast, conserved GR1 expression supports the maintenance of ancestral sugar-detection pathways despite hematophagy lifestyle. We further found no evidence of the canonical insect CO2-associated GRs, suggesting alternative molecular mechanisms for CO2 perception in Triatominae. Several receptors, including Orco, also displayed shifts in selective constraints between sylvatic and domiciliary species, consistent with sensory remodeling associated with adaptation to domestic habitats. Together, our results identify ORs as the most evolutionarily dynamic component of the Rhodnius chemosensory repertoire and highlight contrasting evolutionary trajectories among chemosensory gene families during ecological diversification and vector adaptation.

evolutionary biology↗

bioRxiv2026

Metagenomic Analyses Reveal a Constrained Network of Nutritional Symbionts in Kissing Bugs

Triatominae bugs are the main vectors of Chagas disease in Latin America and rely on microbial nutritional symbiosis to complement their haematophagous diet with B-vitamins. While Rhodococcus bacteria have been identified as key symbionts, diverse metabarcoding analyses have suggested additional candidates. However, symbiont genomic data and metabolic capabilities remain largely uncharacterized. To address this gap, we generated metagenomic assemblies for 14 Triatominae and captured 15 bacterial genomes belonging to 4 genera (Rhodococcus, Wolbachia, Symbiopectobacterium and Arsenophonus) across 9 triatominae species. We identified five co-infection cases, including one involving two distinct Arsenophonus symbionts, one exhibiting hallmarks of massive genome degradation. Phylogenetic analyses revealed that Triatominae-associated symbionts form monophyletic groups within each genus, suggesting common origins followed by co-evolution with their hosts. Annotation of vitamin B metabolic genes indicates that most symbionts harbour incomplete pathways, with evidence of metabolic complementation between co-infecting symbionts. Additionally, we identified bacterial genes laterally transferred into host insect genomes, interpreted as footprints of present or past symbiotic associations. Nearly all Triatominae genomes displayed transferred genes from all four bacterial genera, including hosts with no detectable symbiont in genome assemblies. Taken together with these discoveries support the existence of a stable and limited network of four possible nutritional symbiont lineages with rare evidence of symbiont turn-overs. Significance statementTriatominae bugs, vectors of Chagas disease, are known to harbor a diverse community of nutritional bacterial symbionts whose genomic and metabolic roles have remained largely unexplored. By reconstructing 15 symbiont genomes that segregate as four bacterial genera, we provide important insight into the origins, the evolution and the metabolic structure of the nutritional symbiosis in triatominae. These findings support a stable, evolutionary conserved network of nutritional symbionts with limited turnover.

evolutionary biology↗

bioRxiv2023

Hematophagous triatomine bugs feed also on plants and express functional amylase

BACKGROUNDBlood feeding is a secondary adaptation in hematophagous bugs that ancestrally feed on plants. Many vector proteins are devoted to cope with the hosts defenses and to process the blood meal. In contrast, one can expect that some digestive enzymes devoted to phytophagous diet were lost during or after this peculiar adaptation. And yet, in many strictly hematophagous arthropods, alpha-amylases genes, coding the enzymes that digest starch from plants, are still present and transcribed, including in the blood-sucking bug Rhodnius prolixus and its related species R. robustus (Hemiptera, Reduviidae, Triatominae). Triatominae bugs are vectors of Trypanosoma cruzi, the causal agent of Chagasdisease. Besides the parasitic human infection by the vector-borne route via an exposition to infected feces, an oral route is documented by the ingestion of contaminated food or juices made from palm fruit trees. METHODOLOGY/PRINCIPAL FINDINGSWe hypothesized that retaining alpha-amylase could be advantageous if the bugs happen to consume occasionally plant tissues. To this end, we surveyed hundreds of gut DNA extracts from the sylvatic species R. robustus caught on palm trees to detect traces of plant meals. We found plant DNA in over 8 % of the R. robustus samples, mostly the palm tree Attalea speciosa. Moreover, we showed that the R. robustus alpha-amylase retained normal amylolytic activity. CONCLUSIONSPreserving alpha-amylase function could be an important way of optimally harness plant substrates, and plant feeding could be a way for bridging the gap between two blood meals. Our data indicate that plants are a common and yet underestimated food source in the wild for Triatomine. Author SummaryAdaptation to a specific diet is often accompanied by metabolic, behavioral, physiological changes and hence by genetic changes like gene family expansion, gene losses or gains. In blood-sucking insects some adaptive features such as salivary components acting against blood clotting are known. However, it is intriguing that a digestive enzyme, alpha-amylase, which digests starch, is conserved in those animals, because blood does not contain starch nor related glucose polymers. This is the case in the blood-sucking bugs of the Rhodnius genus (Hemiptera, Reduviidae), which are vectors of the Chagasdisease, an important health issue in Latin America. In this study, we evidence for the first time that sylvatic bugs R. robustus also consume plant tissues in the wild. We detected by PCR performed on DNA from digestive tract that a significant number of wild-caught individuals harbored plant DNA, especially from Attalea palm trees, on which they used to nest. We showed that the amylase enzyme is normally active on starch. We suggest plant feeding could be a way for bridging the gap between two blood meals but might not be linked to nutritional distress.

ecology↗