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Pheromone communication is central to the life history of insect parasites. Determining how pheromones affect parasite behavior can provide insights into host-parasite interactions and suggest novel avenues for parasite control. Lice infest thousands of bird and mammal species and feed on the host's feathers or blood. Despite the pervasiveness of lice in wild populations and the costs they exact on livestock and poultry industries, little is known about pheromone communication in this diverse group. Here, we test for pheromone communication in the wing lice (Columbicola columbae) of Rock Doves (Columba livia). Wing lice spend the majority of their lives on bird flight feathers where they hide from host preening by inserting their bodies between coarse feather barbs. To feed, wing lice must migrate to bird body regions where they consume the insulating barbs of contour feathers. We first show that wing lice readily form aggregations on flight feathers. Next, using a Y-tube olfactometer, we demonstrate that wing lice use pheromone communication to move toward groups of nearby conspecifics. This pheromone is likely an aggregation pheromone, as wing lice only produce the pheromone when placed on flight feathers. Finally, we found that when forced to choose between groups of male and female lice, male lice move toward male groups and females toward female groups, suggesting the use of multiple pheromones. Ongoing work aims to determine the chemical identity and function of these pheromones.

Herein, this work aims to reveal the gamma irradiation-assisted the sol–gel method for the synthesis of silver (Ag) modified-nickel molybdate nanoparticles (NiMoO 4 ; NMO NPs) and tested for their antimicrobial and antibiofilm activities against some pathogenic bacteria and unicellular fungi. The prepared samples were characterized via XRD, HR-TEM, SEM, EDX, and elemental mapping analysis. The antimicrobial potential was tested as ZOI and MIC, while antibiofilm was estimated by tube method. The detected diffraction peaks of bare NMO NPs affirmed the successful synthesis of NMO NPs without any foreign phases. Also, three diffraction peaks were detected affirming the formation of Ag NPs on the surface of NMO NPs. The average crystallite size for the bare NMO NPs and Ag@NMO NPs was found to be 71.8 nm and 48.28 nm, respectively. Also, the SEM images have illustrated the decoration of Ag NPs on the NMO surface. Further, the TEM image illustrated that the particles of NMO possess a hexagonal shape in the nanoscale regime. Also, the elemental mapping images confirm the uniform distribution of these elements over the Ag@NMO sample. Antimicrobial results revealed that the synthesized Ag@NMO NPs recorded the most significant inhibition zone more than NMO NPs against Enterococcus columbae (33.3 ± 0.115 mm), and Candida albicans (30.8 ± 0.572 mm), and the lowest MIC (0.048 µg/ml) against E. columbae . Antibiofilm activity of Ag@NMO NPs recording 94.32% for E. columbae , 91.99% for S. vitulinus , and 90.98% for C. albicans . SEM imaging in the lack of Ag@NMO NPs exhibited normally grown bacterial cells with standard typical semi-formed biofilm. After Ag@NMO NPs treatment, remarkable morphological changes; including the total lysis of the outer surface attended by deformations with the reduction in the whole viable number.

This study investigated the safety and efficacy of two forms of D-limonene (DL) against Columbicola columbae (pigeon feather lice); pure and a nanoemulsion formulation (DLN). The cell cytotoxicity of the prepared forms of DL/DLN was investigated using skin cell lines. In vitro and ex vivo bioassays were applied on lice. The ex vivo bioassay was done on cut feathers containing lice eggs. The in vivo experiment was conducted on pigeons naturally infested by lice. The infested pigeons were treated with DL, DLN, or deltamethrin (D) as a positive control. Both forms of D-limonene were found to be safe when applied to the normal human skin fibroblast cell line, but DLN was toxic to skin cell carcinoma. The in vitro and ex vivo results of both DL and DLN forms were similar. All eggs treated with DL, DLN, and D failed to hatch (100%). The in vivo results showed complete elimination of lice 24 h post-treatment (PT), and biochemical analysis showed that the treated birds retained normal kidney and liver functions. Treated groups also showed improved productivity in the 4 months PT. In conclusion, DL and DLN are safe and effective in controlling feather lice infestation in pigeons and successful treatment encourages bird productivity. Graphical Abstract

In urban areas, organisms are exposed to high pollutant levels, especially element trace metals that may impact host-parasite interactions. Indeed, parasites have been reported to reduce the negative effects of pollutants on their hosts. The fitness of parasitized organisms in polluted environments may therefore be greater than that of unparasitized organisms. In our study, we used an experimental approach to test this hypothesis on feral pigeons (Columba livia), which are endemically parasitized by nematodes and exposed to high levels of lead in urban areas. We tested the combined effects of lead exposure and helminth parasitism on different pigeon fitness components: preening, immunocompetence, abundance of lice (Columbicola columbae) and haemosporidian parasites (Heamoproteus spp., Plasmodium spp.), reproduction investment, and oxidative stress. Our results show that among pigeons exposed to lead treatment, individuals harboring nematode parasites exhibit more preening activity and have fewer ectoparasites lice than nematode-free individuals. Benefits for nematode-parasitized individuals exposed to lead were not detected for other fitness parameters. Further studies are required to confirm the “parasite detoxification hypothesis” in pigeons and to identify the mechanisms by which this detoxification occurs.

Wolbachia is an intracellular endosymbiont bacterium found in nematodes and arthopods. Regarding mites, the Wolbachia supergroup U has been described based on strains found in the genus Spinturnix . In this study, ten specimens of Periglischrus iheringi (Mesostigmata: Spinturnicidae), collected from Artibeus obscurus (Chiroptera: Phyllostomidae) in Santa Catarina State, were found to be infected with Wolbachia . Phylogenetic analysis based on the 16 S rRNA gene revealed that the detected Wolbachia strain belongs to Supergroup F, which has also been detected in other ectoparasitic arthropods, such as Columbicola columbae (slender pigeon lice) and Cimex lectularius (bed bug). This study presents the first molecular detection of Wolbachia in P. iheringi .

Background Proteus spp. have long been recognized for their role in urinary tract infections, while recent evidence disclosed their implications in gastrointestinal diseases. Despite this, the taxonomy of clinically-derived Proteus spp., particularly those from gastrointestinal samples, remains understudied and is frequently mis-assigned, which limits our understanding of infections caused by these species. Results Four Proteus strains (i.e., DFP240708, LHD240705, TSJ240517 and WDL240414) were isolated from the appendiceal pus of patients with acute appendicitis, whole-genome average nucleotide identity (ANI) analysis identified all of them as Proteus genomosp. 6, different from that identified using the automated bacterial identification instrument (VITEK ® -32). Based on ANI and the core-genomic phylogenetic tree, we found that 87.5% of clinically-related strains previously identified as P. columbae should be re-classified as Proteus genomosp. 6. Additionally, the Proteus genomosp. 6 genomes all carry one or more beta-lactam resistance genes, but none carry aminoglycoside resistance genes, and antibiotic susceptibility testing conducted on the four strains isolated in this study confirmed these findings. Among the genomes analyzed, only four (two from this study (TSJ240517 and WDL240414)) carried virulence genes, specifically the hlyA , hlyB , and hlyD genes encoding hemolysin. Conclusion Our study highlights inaccuracies in the taxa classification of Proteus species under clinical settings, underscoring the necessity of using genomic-based taxonomic assignment methods. We revealed that the prevalence of Proteus genomosp. 6 in clinical infections has likely been underestimated. Furthermore, given the resistance-gene absence and their sensitivity to aminoglycosides, aminoglycosides may serve as a promising first-line treatment option for infections caused by this species.

species are the most common nematodes infecting pigeons. The current study investigated specific identity of nematode parasites collected from domestic pigeons ( ) in Al-Qassim Region, Saudi Arabia. Out of 354 pigeons, 13.3 % were infected with nematode parasites. The morphological structure and genetic relationship of nematode worms were studied using conventional methods (Light and scanning electron microscopes) coupled with the newly introduced molecular method. Microscopical and ultrastructure observations showed that the present nematode worms belong to the genus and have all the characteristic features of . Moreover, Random Amplifier morphometric (RAPD) PCR analysis revealed that the present had a close identity of up to 98.3 % to JX624729 for Cox-1 gene regions, and up to 98.3 % to LC057210, and EF180058 for ITS1-5.8s- ITS2 rDNA gene regions. Phylogenetic analysis supported the placement of this species within Ascaridiidae family with close relationships to other nematode species obtained from GenBank. Finally, our study recommends using molecular analysis in helminths identification as the main methodology for correct identification especially in closely related species.

is a common haemosporidian worldwide blood parasite affecting domestic pigeons ( ). Therefore, this study aimed to detect the incidence of infection in domestic pigeons with morpho-molecular identification. In the current study, blood samples were collected from 125 domestic pigeons between 2023 and 2024 and analyzed using both microscopic and molecular techniques. positive birds underwent postmortem (PM) and histopathological examinations, as well as cytokine immunological reaction assessments. It was found that around 8% (10/125) of pigeons were positive for infection, and their morphological characteristics were reported. induces observable macroscopic and microscopic alterations in the infected tissues, which increases the cytokine immunological reaction in the infected birds. The infected birds suffered from severe histopathological changes in most haemopoietic and parenchymatous organs. The transcript levels of inflammatory markers such as IL-6, IFN-γ, and IL-1β were significantly upregulated in -infected birds. Additionally, the samples' mRNA level of the apoptotic Cas-3 indicated apoptotic activity. Hematic parasites can pose a serious health threat to pigeons as they invade red blood cells and internal organs, leading to anemia, weakness, weight loss, and even death in severe cases. Epidemiological studies and surveys are essential for monitoring these hematologic parasites. Furthermore, additional research is recommended to evaluate the efficacy of various herbal extracts in comparison to the most frequently used drugs for managing this issue in affected pigeons.

1. Interspecific competition influences which, how many and where species coexist in biological communities. Interactions between species in different trophic levels can mediate interspecific competition; e.g. predators are known to reduce competition between prey species by suppressing their population sizes. A parallel phenomenon may take place in host-parasite systems, with host defence mediating competition between parasite species. 2. We experimentally investigated the impact of host defence (preening) on competitive interactions between two species of feather-feeding lice: 'wing' lice Columbicola columbae and 'body' lice Campanulotes compar. Both species are host-specific parasites that co-occur on rock pigeons Columba livia. 3. We show that wing lice and body lice compete and that host defence mediates the magnitude of this competitive interaction. 4. Competition is asymmetrical; wing louse populations are negatively impacted by body lice, but not vice versa. This competitive asymmetry is consistent with the fact that body lice predominate in microhabitats on the host's body that offer the most food and the most space. 5. Our results indicate that host-defence-mediated competition can influence the structure of parasite communities and may play a part in the evolution of parasite diversity.

Domestic pigeons are a significant protein source in Egypt, and are also used for racing, ornamentation, and exhibition. They are susceptible to various intestinal parasites, resulting in economic losses from disease and mortality, delayed growth, and reduced productivity. There is limited information available on intestinal parasitic infections in domestic pigeons in Egypt, and reports from some governorates, e.g., Dakahlia, are lacking. In the present study, intestines and faecal contents of 782 adult domestic pigeons ( Columba livia domestica ) were examined. These pigeons were clinically ill, i.e., had signs of emaciation, ruffled feathers, and general weakness, and were collected, over one year, from veterinary clinics as well as local bird markets in two Egyptian Nile Delta governorates; Dakahlia ( n  = 348) and Gharbia ( n  = 434). Overall, 23.53% of the tested pigeons were infected. Pigeons in Gharbia (28.57%) had a higher statistically significant ( p -value < 0.001) prevalence than those in Dakahlia (17.24%). Four parasites were detected with statistically significant ( p -value < 0.001) prevalence variations. Eimeria species was the most frequently detected ( n  = 136; 17.39%), and three species were identified; Eimeria labbeana -like (types A and B), Eimeria columbarum -like, and Eimeria kapotei -like oocysts. The roundworm Ascaridia columbae was detected in 85 (10.87%) pigeons, whereas the tapeworm Raillietina echinobothrida was detected in 24 (3.07%) pigeons. Eggs of Capillaria spp. were only detected in five pigeons (0.64%). Earlier reports on parasitic infections in pigeons from Egypt were reviewed. A brief taxonomic revision on oocysts of various Eimeria species was provided. Oocysts of several Eimeria species from pigeons display minimal differences, and have overlapping morphometrics, causing considerable confusion. Therefore, the classification of Eimeria species of Columbiformes should be thoroughly revised using both morphological and molecular data. This study emphasizes the importance of addressing pigeon parasites from a veterinary perspective in terms of proper diagnosis and control by providing essential data on intestinal parasitic infections in pigeons in Egypt based on current and published data aiming for decreased economic losses.