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Eight new species of lice in the genus Columbicola Ewing are described: C. harbisoni (type host: Phaps histrionica (Gould)), C. koopae (type host: Geophaps scripta (Temminck)), C. eowilsoni (type host: Geophaps smithii (Jardine and Selby), C. wombeyi (type host: Geophaps plumifera Gould), C. masoni (type host: Petrophassa rufipennis Collett), C. waiteae (type host: Columba leucomela Temminck), C. rodmani (type host: Geopelia humeralis (Temminck)), and C. smithae (type host: Turtur brehmeri (Hartlaub)). Also, we provide a comprehensive checklist for the 88 known species of Columbicola (Phthiraptera: Ischnocera) and their pigeon and dove hosts (Aves: Columbiformes).

Competition—colonization trade-off models explain the coexistence of competing species in terms of a trade-off between competitive ability and the ability to colonize competitor-free patches of habitat. A simple prediction of these models is that inferior competitors will be superior dispersers. This prediction has seldom been tested in natural populations because measuring dispersal is difficult. Host—parasite systems are promising in this regard, especially those involving \"permanent\" parasites that complete their entire life cycle on the body of the host. Because of this close association with the host, the dispersal, i.e., transmission, of these parasites can be monitored very accurately. We tested the dispersal prediction of the competition—colonization model by documenting the transmission dynamics of feather-feeding lice, which are permanent, relatively host-specific parasites of birds. We compared two groups known as \"wing\" lice and \"body\" lice that are common parasites of Rock Pigeons (Columba livia Gmelin). The two groups are ecologically similar, and they compete for resources on the host. Previous work shows that body lice are competitively superior to wing lice, leading us to predict that wing lice should be better than body lice at dispersing to new host individuals. We tested this prediction by comparing the ability of wing and body lice to disperse between hosts using vertical- and horizontal-transmission mechanisms, including phoretic hitchhiking on parasitic flies (Diptera: Hippoboscidae). A series of experiments with both captive and wild birds confirmed that wing lice are much better than body lice at colonizing new hosts. Wing lice showed significantly greater vertical transmission to nestlings, and they were quite capable of phoretic transmission to new hosts on flies. In contrast, body lice were not phoretic. These results provide the first rigorous demonstration of phoretic transmission in lice, and they underscore the importance of a community-level approach to understanding the ecology of parasite transmission dynamics.

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.

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

Parasitic “wing lice” (Phthiraptera: Columbicola) and their dove and pigeon hosts are a well-recognized model system for coevolutionary studies at the intersection of micro- and macroevolution. Selection on lice in microevolutionary time occurs as pigeons and doves defend themselves against lice by preening. In turn, behavioral and morphological adaptations of the lice improve their ability to evade host defense. Over macroevolutionary time wing lice tend to cospeciate with their hosts; yet, some species of Columbicola have switched to new host species. Understanding the ecological and evolutionary factors that influence coadaptation and codiversification in this system will substantially improve our understanding of coevolution in general. However, further work is hampered by the lack of a robust phylogenetic framework for Columbicola spp. and their hosts. Previous attempts to resolve the phylogeny of Columbicola based on sequences from a few genes provided limited support. Here, we apply a new approach, target restricted assembly, to assemble 977 orthologous gene sequences from whole-genome sequence data generated from very small, ethanol-preserved specimens, representing up to 61 species of wing lice. Both concatenation and coalescent methods were used to estimate the species tree. These two approaches yielded consistent and well-supported trees with 90% of all relationships receiving 100% support, which is a substantial improvement over previous studies. We used this new phylogeny to show that biogeographic ranges are generally conserved within clades of Columbicola wing lice. Limited inconsistencies are probably attributable to intercontinental dispersal of hosts, and host switching by some of the lice.

An ischnoceran louse, Columbicola bacillus infesting Ring dove, Streptopelia decaocto was subjected to in vitro experimentation. The data obtained through in vitro experimentation was utilized to construct the life table and to determine its intrinsic rate of natural increase (rm). The value of rm appeared to be 0.054. At this rate, the population of C. bacillus is supposed to be double after 12.95 days, indicating that it is moderate breeder.

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 .

A recent paper in this journal concerning parasites of rock pigeons (Columba livia) published by Ali and colleagues exemplifies a growing trend of misidentified parasites in the literature, despite increased online resources that should help facilitate accurate identification. In the Ali et al. paper, a pigeon louse in the genus Columbicola (Phthiraptera: Ischnocera) is misidentified as Menopon gallinae, which is a parasite of chickens (Gallus gallus) and their relatives; moreover, this louse is from an entirely different suborder of lice (Phthiraptera: Amblycera). Another louse is misidentified as Goniodes dissimilis, another parasite of chickens and junglefowl. In addition, photographs of cestodes from pigeons in the same paper are not sufficient to confirm identification. Misidentifications are fueled, in part, by increasing pressure to publish coupled with a decrease in taxonomic expertise. We consider the downstream consequences of misidentification and suggest guidelines for authors, reviewers, and editors that could help to improve the reliability of specimen-based research.

Chewing lice comprise a large group of ectoparasites that colonize and adversely affect several domestic and wild birds including pigeons. In Saudi Arabia, there is a lack of studies describing such ectoparasites and their infestation rates. Through this work, a new record, Columbicola, tschulyschman Eichler (C. tschulyschman Eichler) was collected from domestic pigeons (Columba livia domestica, Linnaeus). The collected C. tschulyschman Eichler was morphologically identified based on specific taxonomic keys. Mitochondrial (COI) and nuclear (EF-1α) gene fragments were used for molecular identification and phylogenetic reconstruction. In this study, the C. tschulyschman Eichler accounted for around 69.40%. To our knowledge, this is the first report of C. tschulyschman Eichler in Riyadh, Saudi Arabia. To improve the tree topology and differentiate between genera, further studies should utilize the 16s rRNA.