Biology subjects

Harry, M.

Publications and source records attributed to Harry, M..

6 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↗

bioRxiv2022

Wolbachia genomics support a tripartite nutritional symbiosis in blood-sucking Triatomine bugs

The nutritional symbiosis promoted by bacteria is a key determinant for adaptation and evolution of many insect lineages. A complex form of nutritional mutualism that arose in blood-sucking insects critically depends on diverse bacterial symbionts that supplement the diet of their nutrient-poor hosts with B vitamins. For instance, the triatomine bug Rhodnius prolixus, one of the main vectors of the Chagas disease in humans, is known to maintain a nutritional symbiosis with the gut symbionts Rhodococcus rhodnii. In this study, we show that Wolbachia symbionts are also widely distributed in the Rhodnius genus. We have screened a large set of Rhodnius blood-sucking bugs samples belonging to 17 different species and to the three phylogenetic groups, prolixus, pallescens and pictipes. We assembled 13 genomes of Wolbachia infecting eight Rhodnius species from prolixus and pictipes groups. We demonstrate that these Wolbachia belong to supergroup F and are closely related to Wolbachia infecting the bedbug Cimex lectularius (wCle). Although bedbugs and triatomines are very distantly related hemipteran bugs, the genomes of their respective Wolbachia were highly similar, suggesting recent horizontal host switches. We also show that Rhodnius Wolbachia genomes infecting the prolixus group encode intact biotin operon, the hallmark of nutritional symbiosis in bedbugs. This operon is lacking from all the other Wolbachia infecting R. pictipes. Finally, host genome analyses provide evidence of massive Wolbachia-to-Rhodnius gene transfers in almost samples, providing footprints of past infections that support a widespread and probably ancient symbiotic association between Wolbachia and triatomine bugs. Our results suggest that both Wolbachia and R. rhodnii gut symbionts and their Rhodnius host maintain a highly prevalent symbiotic relationship, in which the vertically-inherited Wolbachia has the metabolic potantial to ensure or complement, the nutritional mutualism provided by the gut symbionts. Specific loss of the biotin operon in some symbiont genomes suggests that the boundaries between obligatory mutualism, facultative mutualism and parasitism in Wolbachia are transient and fluid, supporting a dynamic process of transition and reversion from one state to another.

evolutionary biology↗

bioRxiv2020

Large-scale geographic survey provides insights into the colonization history of a major aphid pest on its cultivated apple host in Europe, North America and North Africa

AO_SCPLOWBSTRACTC_SCPLOWWith frequent host shifts involving the colonization of new hosts across large geographical ranges, crop pests are good models for examining the mechanisms of rapid colonization. The microbial partners of pest insects may also be involved in or affected by colonization processes, which has been little studied so far. We investigated the demographic history of the rosy apple aphid, Dysaphis plantaginea, a major pest of the cultivated apple (Malus domestica) in Europe, North Africa and North America, as well as the diversity of its microbiota. We genotyped a comprehensive sample of 714 colonies from Europe, Morocco and the US using mitochondrial (CytB and CO1), bacterial (16s rRNA and TrnpB), and 30 microsatellite markers. We detected five populations spread across the US, Morocco, Western and Eastern Europe and Spain. Populations showed weak genetic differentiation and high genetic diversity, except the ones from Morocco and North America that are likely the result of recent colonization events. Coalescent-based inferences revealed high levels of gene flow among populations during the colonization but did not allow determining the sequence of colonization of Europe, North America and Morroco by D. plantaginea, likely because of the weak genetic differentiation and the occurrence of gene flow among populations. We found that D. plantaginea rarely hosts other endosymbiotic bacteria than its obligate nutritional symbiont Buchnera aphidicola. This suggests that secondary endosymbionts did not play an important role in the rapid spread of the rosy apple aphid. These findings have fundamental importance for understanding pest colonization processes and implications for sustainable pest control programs.

evolutionary biology↗

bioRxiv2020

Chromosomal resolution reveals symbiotic virus colonization of parasitic wasp genomes

Most endogenous viruses, an important proportion of eukaryote genomes, are doomed to slowly decay. Little is known, however, on how they evolve when they confer a benefit to their host. Bracoviruses are essential for the parasitism success of parasitoid wasps, whose genomes they integrated ~103 million years ago. Here we show, from the assembly of a parasitoid wasp genome, for the first time at a chromosomal scale, that symbiotic bracovirus genes spread to and colonized all the chromosomes. Moreover, large viral clusters are stably maintained suggesting strong evolutionary constraints. Genomic comparison with another wasps revealed that this organization was already established ~53 mya. Transcriptomic analyses highlight temporal synchronization of viral gene expression, leading to particle production. Immune genes are not induced, however, indicating the virus is not perceived as foreign by the wasp. This recognition suggests that no conflicts remain between symbiotic partners when benefits to them converge.

genomics↗