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One of the most devastating threats to global honey bee health is the ectoparasitic mite and viral vector Varroa destructor, yet the transmission dynamics of viruses carried by mites are poorly understood. RNA interference (RNAi) is a major antiviral defence mechanism in invertebrates including Varroa, where actively replicating viruses are degraded into virus-derived small interfering RNAs (vsiRNAs). Insects typically produce 20-22 nt vsiRNAs with sense and antisense polarity, however established viral infections in V. destructor lead to the production of 24-nt antisense vsiRNA fragments, which could indicate the presence of secondary siRNA synthesis. To better understand viral infection and transmission dynamics in V. destructor, we conducted small RNA sequencing of male and female mites throughout development, from egg to reproductive stages. Viral community structure was largely driven by developmental stage, with younger and older life stages clustering separately. We identified five viruses that are consistently degraded into antisense 24-nt vsiRNA across all developmental stages, suggesting that these viruses are transmitted vertically and form part of Varroa's core virome. This includes the highly diverse Varroa destructor virus 2 (VDV-2), for which we observe eight distinct VDV-2 strains that simultaneously co-infect individual mites throughout development. In contrast, sense and antisense 23-nt vsiRNA fragments are generated in response to the honey bee pathogen, Iflavirus aladeformis (deformed wing virus A, DWV-A) in eggs, but the vsiRNA size profile transitions to 24-nt antisense fragments at later life stages. Our results suggest that once a virus is first acquired by Varroa, a primary 23-nt sense and antisense antiviral response precedes the production of secondary 24-nt antisense vsiRNAs as the infection progresses. We confirm this observation using synthetic dsRNA, which show both primary and secondary siRNA processing, revealing how exogenous dsRNA processing occurs in Varroa. These results show distinct primary and secondary antiviral RNAi responses across V. destructor life stages and demonstrate how vsiRNA profiles can be used to infer virus transmission routes and long term persistence within vector populations.

Aim: Elucidating the mechanisms shaping parasite diversity patterns is critical because parasites encompass about 40% of known species, and are crucial for ecosystem structure and function. In free-living species, diversity patterns in the Anthropocene are shaped by niche-breadth because specialists (narrow niche-breadth taxa) are more sensitive to environmental disturbance compared to generalists (broad niche-breadth taxa). Like free-living species, parasites too can be categorized as specialists or generalists according to their niche-breadth (i.e., diversity of hosts they can infect). However, unlike free-living species, the effects of niche-breadth on parasite diversity patterns remain unclear. Here, we used haemosporidian parasites as a model system to identify factors affecting parasite diversity patterns, and test if these patterns differ between specialist (Haemoproteus) and generalist (Plasmodium) parasites. Location: Southern India Taxon: Haemoproteus spp. and Plasmodium spp. (Haemosporida) Methods: Blood samples from wild birds were screened using molecular tools to identify haemosporidian parasite lineages. Statistical analyses, including random forest models and generalized dissimilarity models, were utilized to evaluate how environmental and host factors drive spatial patterns of parasite and {beta} diversity. Results: Our results reveal that phylogenetic diversity is primarily shaped by host-related variables in the specialist parasites, but by numerous host- and environment-related factors in the generalists. In keeping with ecological theory, the specialist parasites showed higher diversity and lower evenness compared to the generalists. Additionally, while {beta} diversity of the specialist parasites was primarily driven by spatial differences in richness (e.g., taxon nestedness) rather than replacement (e.g., taxon turnover), the opposite pattern was found in the generalist. Main conclusion: The differential patterns and drivers of diversity in specialist vs. generalist parasites demonstrates why specialists parasites are good indicators of ecosystem health and elucidates the mechanism by which anthropogenic disturbance increases the risk of emerging infectious diseases which are primarily caused by generalist parasites.

Garden ponds are important elements of urban landscapes and provide numerous ecosystem services, but they may also support mosquito populations that can act as vectors of pathogens. However, mosquito occurrence in garden ponds has so far received limited attention. We engaged citizen scientists to provide data on their garden ponds and collect water samples for eDNA analysis to assess mosquito occurrence in 319 garden ponds across Hungary, with special focus on Anopheles maculipennis, a potential malaria-vector species. We tested the effects of land cover, local pond management activities and environmental factors on the probability of An. maculipennis occurrence in garden ponds. Overall mosquito occurrence was relatively low, with mosquitoes detected in 59 ponds (18%) and An. maculipennis detected in 46 ponds (14%). Agricultural land cover and pond age were associated with the occurrence of An. maculipennis in garden ponds. A higher percentage of agricultural land cover within 1000 m of garden ponds increased the probability of An. maculipennis occurrence, while occurrence was higher in newly created ponds ([≤] 2 years). Our results suggest that landscape context is more important than local pond characteristics in determining the occurrence of An. maculipennis in garden ponds. This study contributes to a better understanding of the landscape context in which a potential malaria-vector species occurs in urban and peri-urban environments and highlights the value of citizen science for large-scale data collection from privately owned ponds that are otherwise inaccessible to researchers.

The Orthoflavivirus genus (flaviviruses) includes globally significant arboviruses, which cycle between arthropod vectors (mosquitoes and ticks) and vertebrate hosts. In contrast, no-known-vector flaviviruses (NKVFVs) have been isolated from rodents and bats, but not arthropods, so are thought to spread by vector-independent routes. However, little is known about the host range and pathogenic mechanisms of these viruses. To evaluate NKVFV pathogenesis, we infected wild-type, Ifnar1-/-, and Ifnar1-/- Ifngr1-/- mice by footpad inoculation with 12 NKVFVs: Entebbe bat virus (ENTV), Sokuluk virus (SOKV), Yokose virus (YOKV), Modoc virus (MODV), Apoi virus (APOIV), Jutiapa virus (JUTV), Sal Vieja virus (SVV), Dakar bat virus (DBV), Rio Bravo virus (RBV), Montana myotis leukoencephalitis virus (MMLV), Phnom Penh bat virus (PPBV), and Tamana bat virus (TABV). We compared these NKVFVs to the mosquito-borne Zika virus and Kedougou virus and to the tick-borne Langat virus and Kadam virus. We monitored disease signs and measured viremia. 7 NKVFVs (ENTV, SOKV, YOKV, MODV, APOIV, DBV, RBV) were virulent in Ifnar1-/- mice, causing 100% lethality within 9 dpi, accompanied by viremia. All viruses tested were virulent in Ifnar1-/- Ifngr1-/- mice and produced greater viremia compared to Ifnar1-/- mice. No viremia or disease signs were detected in wild-type mice. We further evaluated RBV, MMLV, and PPBV replication in mouse primary fibroblasts and bone marrow-derived macrophages, as well as in cell lines from three bat species. Altogether, our results provide new information about the virulence and replication phenotypes of NKVFVs, supporting future studies investigating NKVFV-specific and pan-flavivirus pathogenic mechanisms.

The parasitic unicellular microswimmer Trypanosoma brucei is the causative agent for severe diseases in humans and cattle. Trypanosomes have a complex life cycle with the best characterized stages being the bloodstream form (BSF) in the vascular system of the mammalian host and the procyclic form (PCF) in the gut of the tsetse fly vector. Morphologically, PCF and BSF trypanosomes appear very similar, being propelled by a single flagellum that is wrapped around the spindle-shaped cell body....

Tacaribe virus (TCRV) was the first arenavirus discovered in the New World and was isolated from Artibeus bats in Trinidad and Tobago in the 1950s. One isolate, TRVL-11573, remains but it was passaged by intracranial inoculation of newborn mice 22 times that likely changed its biology. This isolate has been extensively used for arenavirus research, including our previous work that showed it can cause fatal neurological disease in Jamaican fruit bats (Artibeus jamaicensis). Another divergent TCRV, DOM2014, was recently identified from a Jamaican fruit bat captured in the Dominican Republic that contained TCRV genome. A kidney fragment homogenate from this bat was inoculated into Jamaican fruit bats and all became infected with signs of mild liver disease. Experimental challenge of Jamaican fruit bats with DOM2014 led to nonfatal infection that persisted through the end of the study on day 21 and with contact transmission to naive bats. Histopathology, immunohistochemistry and serum chemistry confirmed infection and mild liver disease, but none of the bats produced neutralizing antibodies. B cell receptor transcripts suggested limited somatic hypermutation that could explain the lack of detectable neutralizing antibodies. Transcriptome profiling of livers and spleens showed signatures of a typical innate antiviral response; however, evidence of adaptive immune suppression was also present. Similarly, liver transcriptome analysis showed signatures of an expected innate antiviral response and metabolic dysfunction. The isolation of TCRV-DOM2014 provides a relevant model for the study of a bat reservoir host, and which may challenge the extensive work previously conducted with TRVL-11573.

In summer 2025, several Eurasian Blackbird (Turdus merula) deaths were reported on the Isle of Arran in Scotland. Initial investigation included post-mortem examination, where no diagnosis was achieved. Following Orthoflavivirus and avian paramyxovirus testing, Usutu virus RNA was detected in two Blackbirds by reverse transcription-PCR. Phylogenetic analysis identified Usutu virus Africa 3.2 lineage which clustered closely with existing UK detections, indicating geographic expansion rather than a new incursion. Subsequent surveillance confirmed the presence of several potential mosquito vector species.

Community science platforms like iNaturalist generate unprecedented volumes of biodiversity data, but their scientific utility depends critically on accurate species identification; a persistent challenge when contributors often lack taxonomic expertise. We developed LizardLens, a two-stage machine learning pipeline that decouples object detection from species classification to enable fine-grained identification of morphologically similar organisms in visually complex field photographs. Using 10,000 verified iNaturalist images of five Anolis lizard species in Florida, we trained specialized YOLO-based detection and Swin Transformer classification models and compared performance against state-of-the-art single-stage architectures. Our two-stage pipeline achieved 83.0% Top-1 accuracy and a macro-averaged F1-score of 89.0%, indicating strong precision-recall performance across species and outperforming single-stage YOLOv8 and YOLOv12 models across all evaluation metrics for all species, with relative improvements ranging from 10.5% to 13.2%. Gradient-weighted Class Activation Mapping (Grad-CAM) indicated that the models predictions were consistently associated with regions corresponding to diagnostic morphological (e.g., head shape, feet, and limb lengths) and pattern features (e.g., ocular rings and body patterning), providing evidence that LizardLens leverages biologically relevant visual cues consistent with those used by expert taxonomists. Error analysis identified partial occlusion and multiple proximate individuals as primary sources of missed detections, while spurious detections of lizard-like environmental features (e.g., sticks, bark) represented the dominant false positive error mode. We deployed LizardLens as an accessible web application featuring interactive bounding box correction, ranked species predictions with confidence scores, directly supporting the Lizards on the Loose middle school community science initiative. By combining technical advances in fine-grained visual classification with user-centered design, LizardLens demonstrates how machine learning can simultaneously enhance data quality for biodiversity monitoring and provide authentic scientific experiences for student participants. Our approach is generalizable to other small-bodied organisms in complex habitats and provides a framework for translating computer vision advances into practical tools for community science and conservation.

Lyme disease is a tick-borne illness caused by the spirochaete bacterium Borrelia (Borreliella) burgdorferi. The black-legged tick Ixodes scapularis, which transmits B. burgdorferi and several other human pathogens, is endemic to the eastern United States and, due to climate change, is rapidly expanding into central and eastern Canada. Amplification and sequencing of bacterial DNA from I. scapularis is increasingly used to monitor the presence and abundance of B. burgdorferi and associated bacteria. However, variation in the nature of molecular data collected across studies presents challenges for analysis and interpretation. Here we use full-length Oxford Nanopore 16S ribosomal RNA gene amplicon sequencing to characterize the microbiome of I. scapularis, with an explicit focus on distinguishing between tick-adapted bacteria (endosymbionts and pathogens) and environmentally acquired bacteria (external sources, including soil, vegetation or vertebrate hosts). We show that environmental dominance strength differs between these two ecological classes of bacteria, and that environmental dominance does not appear to represent stochastic background alone; environmentally derived bacterial taxa detected in tick microbiomes are not mere contaminants. Paired soil microbiome profiling from tick collection sites will be required to test whether environmental dominance and associated co-occurrence structure track with seasonal changes in exposure and environmental microbial populations.

Human African Trypanosomiasis (HAT) or sleeping sickness is a systemic parasitic infection caused by the protozoan parasite Trypanosoma brucei. HAT is associated with substantial immunological, metabolic, and neurological pathology. Although reproductive dysfunction has previously been recognised in both human and experimental T. brucei infection, whether parasites can directly infiltrate the female reproductive tract (FRT), and how infection may reshape the FRT immune landscape remains poorly understood. Using a murine model of T. brucei infection we reveal that parasites are localised in the uterine lining (endometrium) during both acute and chronic infection stages in mice. Chronic T. brucei infection was associated with progressive fat wasting, disruption of the reproductive (oestrous) cycle, uterine and ovarian atrophy, and extensive transcriptional dysregulation across the hypothalamic-pituitary-gonadal (HPG) axis. Acute and chronic infection induced remodelling of the uterine immune landscape, characterised by T cell infiltration, pro-inflammatory myeloid activation, alongside broader type 1 inflammatory changes across reproductive tissues and HPG components. Ovarian pathology was accompanied by follicular degeneration, a reduction in corpora lutea and alterations to steroidogenic pathways. Hormonal rescue with selective oestrogen receptor modulator, tamoxifen, restored uterine morphology and prevented oestrous cycle arrest, but did not reverse the infection-induced uterine immune remodelling, indicating that endocrine dysfunction and infection-driven inflammation are distinct processes. Taken together, these findings identify the FRT as a major target of T. brucei infection and demonstrate how chronic parasitic infection can disrupt reproductive physiology through a combination of immune, endocrine, and metabolic pathways. They also highlight the need to specifically assess the FRT in other models of systemic inflammation.