Co-phylogeny of a hyper-symbiotic system: Endosymbiotic bacteria (Gammaproteobacteria), chewing lice (Insecta: Phthiraptera) and birds (Passeriformes).

Chewing lice are hosts to endosymbiotic bacteria as well as themselves being permanent parasites. This offers a unique opportunity to examine the cophylogenetic relationships between three ecologically interconnected organismal groups: birds, chewing lice, and bacteria. Here, we examine the cophylogenetic relationships between lice in the genus Guimaraesiella Eichler, 1949, their endosymbiotic Sodalis-allied bacteria, and a range of bird species from across South China. Both event and distance-based cophylogenetic analyses were explored to compare phylogenies of the three organismal groups. Pair-wise comparisons between lice-endosymbionts and bird-endosymbionts indicated that their evolutionary histories are not independent. However, comparisons between lice and birds, showed mixed results; the distance-based method of ParaFit indicated that their evolutionary histories are not independent, while the event-based method of Jane indicated that their phylogenies were no more congruent than expected by chance. Notably, louse host-switching does not seem to have affected bacterial strains, as conspecific lice sampled from distantly related hosts share bacteria belonging to the same clade.

Chewing lice of passerine birds in reed beds in Slovakia, with a special focus on Panurus biarmicus.

A total of 1185 passerine birds representing five species were examined for chewing lice in reed beds in southwestern Slovakia in spring (April) 2008, 2009 and 2016. Additional collecting focused only on chewing lice from Panurus biarmicus (Linnaeus, 1758) (Passeriformes: Panuridae) was carried out in spring (April), summer (July) and autumn (October) 2019. A total of 283 (24%) birds were parasitized by 10 species of chewing lice of four genera: Penenirmus, Menacanthus, Philopterus, and Brueelia. Most birds showed only very light (1-10 lice/host; 74%) to light infestations (11-20 lice/host; 16%). The authors found significantly higher prevalences and mean abundances of chewing lice on residents/short-distance migrants, that is, P. biarmicus, Acrocephalus melanopogon (Temminck, 1823) (Passeriformes: Acrocephalidae), than on long-distance migratory birds, that is, Acrocephalus scirpaceus (Hermann, 1804), Acrocephalus schoenobaenus (Linnaeus, 1758) (Passeriformes: Acrocephalidae), Locustella luscinioides (Savi, 1824) (Passeriformes: Locustellidae). No significant difference was found in the total mean intensity of chewing lice between these two groups of birds. Ischnoceran lice were more prevalent and abundant than amblyceran lice on residents and short-distance migrants, whereas the opposite was found on bird species that migrate long distances. A total of 146 (58%, n = 251) P. biarmicus were parasitized by 1490 chewing lice. Males of P. biarmicus showed higher prevalence and mean abundance than females with gradually descending values of prevalence, mean abundance and mean intensity from spring to autumn. The knowledge of the occurrence and population dynamics of lice on wild passerine birds can be useful in endangered species conservation programs and can also be applied to captive passerine birds, which may be analogous to resident birds in this sense.

The interplay between host biogeography and phylogeny in structuring diversification of the feather louse genus Penenirmus.

Parasite diversification is influenced by many of the same factors that affect speciation of free-living organisms, such as biogeographic barriers. However, the ecology and evolution of the host lineage also has a major impact on parasite speciation. Here we explore the interplay between biogeography and host-association on the pattern of diversification in a group of ectoparasitic lice (Insecta: Phthiraptera: Penenirmus) that feeds on the feathers of woodpeckers, barbets, and honeyguides (Piciformes) and some songbirds (Passeriformes). We use whole genome sequencing of 41 ingroup and 12 outgroup samples to develop a phylogenomic dataset of DNA sequences from a reference set of 2395 single copy ortholog genes, for a total of nearly four million aligned base positions. The phylogenetic trees resulting from both concatenated and gene-tree/species-tree coalescent analyses were nearly identical and highly supported. These trees recovered the genus Penenirmus as monophyletic and identified several major clades, which tended to be associated with one major host group. However, cophylogenetic analysis revealed that host-switching was a prominent process in the diversification of this group. This host-switching generally occurred within single major biogeographic regions. We did, however, find one case in which it appears that a rare dispersal event by a woodpecker lineage from North America to Africa allowed its associated louse to colonize a woodpecker in Africa, even though the woodpecker lineage from North America never became established there.

Extensive in situ radiation of feather lice on tinamous.

Tinamous host the highest generic diversity of lice of any group of birds, as well as hosting representatives of all four avian feather louse ecomorphs. Although the generic diversity of tinamou feather lice is well documented, few attempts have been made to reconstruct the phylogenetic relationships among these lice. To test whether tinamou feather lice form a monophyletic group as a whole, we used whole-genome sequencing to estimate a higher-level phylogeny of tinamou feather lice, together with a broad diversity of other avian feather louse groups. In total, we analysed sequences from over 1000 genes for 48 genera of avian lice using both concatenated and coalescent approaches to estimate the phylogeny of this diverse group of avian feather lice. Although the body louse ecomorph of tinamou feather lice formed a monophyletic group, they did not strictly form a monophyletic group together with the other three ecomorphs of tinamou feather lice. In particular, a clade comprised of several feather louse genera, mainly from South America, is nested phylogenetically within tinamou lice, which also have their main centre of diversity in South America. These results suggest in situ radiation of these parasites in South America.

Sex interacts with age-dependent change in the abundance of lice-infesting Amur Falcons (Falco amurensis).

Sex-biassed and age-biassed parasite infections are common in nature, including ectoparasites-vertebrate host systems. We investigated the effect of Amur Falcons' sex, age and body size on the abundance of their lice at a migratory stopover site, where the falcons' habitat use and behaviour are more homogeneous across sex and age categories than during the breeding season. We sampled Amur Falcons in Nagaland, India at major roosting sites in 2016. We applied generalized linear models (with negative binomial distribution and log-link) to model the abundance of their two most numerous lice (Colpocephalum subzerafae and Degeeriella rufa) using the host age category (juvenile or adult) and wing length, both in interaction with sex, as explanatory variables. The abundance of C. subzerafae was only affected by host age, being nearly four times higher on juveniles than on adults. Juveniles were also more infested with D. rufa than the adults. Additionally, the abundance of the latter species was lower on adult male Falcons as compared to adult females. A juvenile bias in ectoparasite infestations is common in nature, probably due to juveniles being immunologically naïve, more resource-limited and may be inexperienced in body maintenance behaviours like preening and grooming. On the other hand, female-biassed infestations are much rarer than male-biassed infestations. We briefly discuss the possible causes of female-biassed infestations on Amur Falcons reported here, and in the closely related Red-footed Falcon and Lesser Kestrel as reported in the literature.

Sex-dependent changes in the louse abundance of red-footed falcons (Falco vespertinus).

Permanent ectoparasites live in stable environments; thus, their population dynamics are mostly adapted to changes in the host life cycle. We aimed to investigate how static and dynamic traits of red-footed falcons interplay with the dynamics of their louse subpopulations during breeding and how they affect the colonisation of new hosts by lice. We sampled red-footed falcon (Falco vespertinus) nestlings (two breeding seasons) and adults (one breeding season) in southern Hungary. The mean abundance of Colpocephalum subzerafae and Degeeriella rufa lice on the nestlings was modelled with generalized linear mixed models using clutch size and host sex in interaction with wing length. For adults, we used wing length and the number of days after laying the first egg, both in interaction with sex. D. rufa abundances increased with the nestlings' wing length. In one year, this trend was steeper on females. In adult birds, both louse species exhibited higher abundances on females at the beginning, but it decreased subsequently through the breeding season. Contrarily, abundances were constantly low on adult males. Apparently, D. rufa postpones transmission until nestlings develop juvenile plumage and choose the more feathered individual among siblings. The sexual difference in the observed abundance could either be caused by the different plumage, or by the females' preference for less parasitized males. Moreover, females likely have more time to preen during the incubation period, lowering their louse burdens. Thus, sex-biased infestation levels likely arise due to parasite preferences in the nestlings and host behavioural processes in the adult falcons.

Two lineages of kingfisher feather lice exhibit differing degrees of cospeciation with their hosts.

Unlike most bird species, individual kingfisher species (Aves: Alcedinidae) are typically parasitized by only a single genus of louse (Alcedoffula, Alcedoecus, or Emersoniella). These louse genera are typically specific to a particular kingfisher subfamily. Specifically, Alcedoecus and Emersoniella parasitize Halcyoninae, whereas Alcedoffula parasitizes Alcedininae and Cerylinae. Although Emersoniella is geographically restricted to the Indo-Pacific region, Alcedoecus and Alcedoffula are geographically widespread. We used DNA sequences from two genes, the mitochondrial COI and nuclear EF-1α genes, to infer phylogenies for the two geographically widespread genera of kingfisher lice, Alcedoffula and Alcedoecus. These phylogenies included 47 kingfisher lice sampled from 11 of the 19 currently recognized genera of kingfishers. We compared louse phylogenies to host phylogenies to reconstruct their cophylogenetic history. Two distinct clades occur within Alcedoffula, one that infests Alcedininae and a second that infests Cerylinae. All species of Alcedoecus were found only on host species of the subfamily Halcyoninae. Cophylogenetic analysis indicated that Alcedoecus, as well as the clade of Alcedoffula occurring on Alcedininae, do not show evidence of cospeciation. In contrast, the clade of Alcedoffula occurring on Cerylinae showed strong evidence of cospeciation.

Using human head lice to unravel neglect and cause of death.

Despite the common association of human lice with abandoned or neglected people, no procedure to assess pediculosis, aimed to detect signs of neglect, exists. Investigating the two most common forms of head louse infestation, regular and severe, we define lice-markers of neglect and develop a protocol and survey form to record and assess pediculosis. The study of head lice from a deceased victim of neglect helped unravel time-length since death, frequency of exposure to neglect and the cause and circumstances related to the death. Nit-clusters are markers of neglect, indicating length and frequency of neglect episodes. In the case study used here that culminated in the death of the victim, sustained abandonment started circa 2 years before discovery. The lice suggested that death was caused by overconsumption of a powerful calcium channel blocker, an antihypertensive, an excess of which in lice food supply (blood) stops oogenesis. Despite hosting thousands of adult females on the hair, lice reproduction stopped and nits were no longer developed or deposited on the hairs at the root end. This short distance of the shaft with no nits provided a time estimation of overdosing of almost 2 months before death.

Chewing lice from high-altitude and migrating birds in Yunnan, China, with descriptions of two new species of Guimaraesiella.

In total, 366 birds representing 55 species in 24 families and eight orders, were examined for chewing lice (Phthiraptera: Amblycera, Ischnocera) in two high-altitude localities in Yunnan Province, China. In Ailaoshan, almost all of the birds examined were resident passeriforms, of which 36% were parasitized by chewing lice. In Jinshanyakou, most birds were on migration, and included both passerine and non-passerine birds. Of the passerine birds caught in Jinshanyakou, only one bird (0.7%) was parasitized by chewing lice. The prevalence of Myrsidea and Brueelia-complex lice on birds caught in Ailaoshan was higher than in previous reports. Of the chewing lice identifiable to species level, three represent new records for China: Actornithophilus hoplopteri (Mjöberg, 1910), Maculinirmus ljosalfar Gustafsson & Bush, 2017 and Quadraceps sinensis Timmermann, 1954. In total, 17 new host records are included, of which we describe two as new species in the Brueelia-complex: Guimaraesiella (Cicchinella) ailaoshanensis sp. nov. ex Schoeniparus dubius dubius (Hume, 1874) and G. (C.) montisodalis sp. nov. ex Fulvetta manipurensis tonkinensis Delacour & Jabouille, 1930. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:9FC3D8EE-2CED-4DBE-A1DB-471B71260D27.

Simultaneous radiation of bird and mammal lice following the K-Pg boundary.

The diversification of parasite groups often occurs at the same time as the diversification of their hosts. However, most studies demonstrating this concordance only examine single host-parasite groups. Multiple diverse lineages of ectoparasitic lice occur across both birds and mammals. Here, we describe the evolutionary history of lice based on analyses of 1107 single-copy orthologous genes from sequenced genomes of 46 species of lice. We identify three major diverse groups of lice: one exclusively on mammals, one almost exclusively on birds and one on both birds and mammals. Each of these groups radiated just after the Cretaceous-Paleogene (K-Pg) boundary, the time of the mass extinction event of the dinosaurs and rapid diversification of most of the modern lineages of birds and mammals.

Novel Primers From Informative Nuclear Loci for Louse Molecular Phylogenetics (Insecta: Phthiraptera).

While parasitic lice (Insecta: Phthiraptera) have historically been an important model taxon for understanding host-parasite coevolution, very few molecular markers have been developed for phylogenetic analysis. The current markers are insufficient to resolve many of the deeper nodes in this group; therefore, sequences from additional genetic loci are necessary. Here, we design primers targeting several nuclear protein coding genes based on a complete genome and transcriptome of Pediculus humanus L. plus transcriptomes and modest coverage genomic data from five genera of avian feather lice. These primers were tested on 32 genera of avian feather lice (Ischnocera), including multiple species within some genera. All of the new primer combinations produced sequences for the majority of the genera and had similar or higher divergences than the most widely used nuclear protein-coding gene in lice, EF-1α. These results indicate that these new loci will be useful in resolving phylogenetic relationships among parasitic lice.

How many threatened lice are there? An approximation to the red list of the Spanish Phthiraptera.

Although the idea of conserving parasites as part of biodiversity is not new, these in general and lice in particular, are not included in the threatened list of invertebrate fauna. Assuming that the conservation status of a lice species is similar to that of its host, the number of threatened lice within the Spanish entomofauna was estimated based on the known host-lice assemblages. The lice parasitizing many of the Spanish birds and mammals are unknown. Overall, I found 6 extinct (EX) species; 4 critically endangered (CR); 15 endangered (EN), 7 vulnerable (VU) and 1 species near threatened (NT), at regional level. Since the status of hosts varies through time and space, it, (together with those of their lice, must be periodically updated. In addition to a number of reasons that justify the conservation of parasites, lice deserve being conserved, particularly, because of their scientific value.

Distribution of phoretic mites and lice in Pseudolynchia canariensis living on pigeons and the relationship with seasonality, carrier sex, plumage coloration and age of definitive hosts.

Among the parasites, some groups that have a limited capacity for locomotion, such as mites and lice, the transmission is challenging to win. These ectoparasites disperse through direct contact between hosts or, in some cases, through phoresy. However, these processes are not well-documented in detail because they are difficult to observe and quantify. In the present study, the patterns of distribution of skin mites and phoretic lice on hippoboscid louse fly Pseudolynchia canariensis sampled from Columba livia were evaluated. The analyzed pigeons were juveniles and adults, with three distinct plumage colors: blue checker, spread, or wild type, and were caught over 24 months. A total of 1,381 hippoboscid flies were collected on 377 hosts. The plumage color did not influence the infestation patterns of louse flies on juvenile and adult pigeons, nor did it influence the infestation patterns of skin mites and phoretic lice on the hippoboscid flies. However, the environmental temperature was directly related to higher prevalence, mean infestation intensity, and phoretic species richness on P. canariensis during the hottest seasons. Furthermore, a higher abundance of phoretic mite eggs, including embryonated eggs, was observed in females of P. canariensis in all seasons.

Control of the chewing louse Bovicola (Werneckiella) ocellatus in donkeys, using essential oils.

Infestations by lice can be a significant clinical and welfare issue in the management of large animals. The limited range of commercial pediculicides available and the development of resistance have led to the need to explore alternative louse management approaches. The results of in vitro and in vivo trials undertaken to control populations of the donkey chewing louse, Bovicola ocellatus (Piaget) (Phthiraptera: Trichodectidae) using the essential oils of tea tree (Melaleuca alternifolia) and lavender (Lavandula angustifolia) are reported here. Results of contact and vapour bioassays showed that 5% (v/v) tea tree and lavender oils resulted in > 80% louse mortality after 2 h of exposure. On farms, separate groups of 10 donkeys sprayed with 5% (v/v) tea tree and lavender oil as part of their usual grooming regime showed significant reductions in louse numbers compared with a control group (0.2% polysorbate 80 in water). These findings indicate that tea tree and lavender essential oils can provide clinically useful levels of control of B. ocellatus when used as part of a grooming routine and suggest that with further development could form the basis of an easy to apply and valuable component of a louse management programme for donkeys.

Evaluation of two methods for quantifying passeriform lice.

Two methods commonly used to quantify ectoparasites on live birds are visual examination and dust-ruffling. Visual examination provides an estimate of ectoparasite abundance based on an observer's timed inspection of various body regions on a bird. Dust-ruffling involves application of insecticidal powder to feathers that are then ruffled to dislodge ectoparasites onto a collection surface where they can then be counted. Despite the common use of these methods in the field, the proportion of actual ectoparasites they account for has only been tested with Rock Pigeons (Columba livia), a relatively large-bodied species (238-302 g) with dense plumage. We tested the accuracy of the two methods using European Starlings (Sturnus vulgaris; ~75 g). We first quantified the number of lice (Brueelia nebulosa) on starlings using visual examination, followed immediately by dust-ruffling. Birds were then euthanized and the proportion of lice accounted for by each method was compared to the total number of lice on each bird as determined with a body-washing method. Visual examination and dust-ruffling each accounted for a relatively small proportion of total lice (14% and 16%, respectively), but both were still significant predictors of abundance. The number of lice observed by visual examination accounted for 68% of the variation in total abundance. Similarly, the number of lice recovered by dust-ruffling accounted for 72% of the variation in total abundance. Our results show that both methods can be used to reliably quantify the abundance of lice on European Starlings and other similar-sized passerines.

Host body size, not host population size, predicts genome-wide effective population size of parasites.

The effective population size (Ne) of an organism is expected to be generally proportional to the total number of individuals in a population. In parasites, we might expect the effective population size to be proportional to host population size and host body size, because both are expected to increase the number of parasite individuals. However, among other factors, parasite populations are sometimes so extremely subdivided that high levels of inbreeding may distort these predicted relationships. Here, we used whole-genome sequence data from dove parasites (71 feather louse species of the genus Columbicola) and phylogenetic comparative methods to study the relationship between parasite effective population size and host population size and body size. We found that parasite effective population size is largely explained by host body size but not host population size. These results suggest the potential local population size (infrapopulation or deme size) is more predictive of the long-term effective population size of parasites than is the total number of potential parasite infrapopulations (i.e., host individuals).

Prevalence and diversity of parasitic bird lice (Insecta: Psocodea) in northeast Arkansas.

Many groups of parasites lack basic information on biodiversity and host associations, which poses challenges for conservation and understanding the ecological relationships between hosts and their parasites. This gap in knowledge is particularly relevant for parasitic species with obscure lifestyles. Ectoparasitc bird lice (Insecta: Psocodea: Phthiraptera) are a group of parasites that has received a relatively substantial research focus, yet patterns of bird-louse relationships and louse diversity remain understudied in many geographic regions, including in parts of the southeastern United States. In this study, we assessed the diversity, prevalence, abundance, and intensity of lice from live and salvaged birds in northeastern Arkansas. We also focused on the frequency of co-occurrence of lice and symbiotic feather mites. Finally, we used nuclear and mitochondrial genes to assess the phylogenic relationships among the most common genera of lice in our sample. We found a total louse prevalence of 10.57% with the highest prevalence on the Passeriformes families Turdidae, Passerellidae, and Parulidae. We also found the louse genera Myrsidea and Brueelia to be the most prevalent and abundant in our sample. Additionally, we reported several novel associations among well-studied bird species. We also found that louse phylogenic patterns tend to reflect host taxonomy and/or ecology. Overall, our results provide important insight into the biodiversity, community structure, and host interactions of parasitic lice from North American birds.

Chewing lice of wild birds in Iran: new data and a checklist of avian louse species reported in Iran.

Between September 2019 and December 2023, a total of 612 wild birds representing 16 orders, 33 families, 60 genera, and 78 species from nine provinces of Iran with different climates namely Hamedan (n = 54), Sistan-va-Baluchestan (n = 372), Kerman (n = 73), South Khorasan (n = 52), Mazandaran (n = 7), Chaharmahal-va-Bakhtiari (n = 2), Gilan (n = 2), Golestan (n = 18), North Khorasan (n = 9), and Razavi Khorasan (n = 23) were examined for chewing lice infestation. Naked eye examination revealed that 58 birds (9.5%) were infested with at least one chewing louse species. Collected lice specimens belonged to 28 species from the families Philopteridae, Menoponidae and Laemobothriidae including Strigiphilus strigis (n = 55, 15.6%), Falcolipeurus quadripustulatus (n = 41, 11.6%), Craspedorrhynchus platystomus (n = 40, 11.3%), Colpocephalum turbinatum (n = 36, 10.2%), Laemobothrion maximum (n = 25, 7.1%), Nosopon lucidum (n = 20, 5.6%), Degeeriella fulva (n = 18, 5.1%), Colpocephalum eucarenum (n = 16, 4.5%), Laemobothrion vulturis (n = 15, 4.2%), Anaticola crassicornis (n = 13, 3.7%), Craspedorrhynchus aquilinus (n = 9, 2.5%), Degeeriella fusca (n = 7, 2.0%), Aegypoecus trigonoceps (n = 7, 2.0%), Quadraceps obscurus (n = 6, 1.7%), Colpocephalum impressum (n = 6, 1.7%), Trinoton querquedulae (n = 6, 1.7%), Colpocephalum heterosoma (n = 5, 1.4%), Colpocephalum nanum (n = 5, 1.4%), Lunaceps holophaeus (n = 4, 1.1%), Quadraceps spp. (n = 4, 1.1%), Actornithophilus uniseriatus (n = 2, 0.6%), Nosopon chanabense (n = 2, 0.6%), Actornithophilus cornutus (n = 1, 0.3%), Cuclotogaster heterographus (n = 1, 0.3%), Falcolipeurus suturalis (n = 1, 0.3%), Laemobothrion atrum (n = 1, 0.3%), Colpocephalum gypsi (n = 1, 0.3%), and Rallicola cuspidatus (n = 1, 0.3%). All of these species except six, i.e., Trinoton spp., C. aquilinus, L. vulturis, L. maximum, C. impressum, C. turbinatum, and C. heterographus are recorded for the first time from Iran. This study is the largest epidemiological study to date performed in the country. Data reported herein contribute to our knowledge about diversity of avian chewing lice from wild birds in Iran. In this paper, an updated checklist of louse species reported from Iran according to their avian hosts is presented.

PHYLOGENETIC RELATIONSHIPS OF GUIMARAESIELLA AND PRICEIELLA (PHTHIRAPTERA: ISCHNOCERA) FROM BABBLERS AND NON-BABBLERS (PASSERIFORMES).

Babblers (Passeriformes: Leiothrichidae, Pellorneidae, Timaliidae) are parasitized by more genera of lice of the Brueelia complex than any other group of songbirds. However, the relationships of these louse groups are poorly known. We here try to resolve the relationships between Guimaraesiella (Guimaraesiella), Guimaraesiella (Cicchinella), and their putative sister group Priceiella by using mitochondrial cytochrome c subunit 1 (COI), 12S, and 16S sequences. Our data indicate that G. (Cicchinella) forms a monophyletic group of lice from babblers, but the relationship between G. (Guimaraesiella), G. (Cicchinella), and Priceiella could not be resolved. Moreover, the position of the third lineage of babbler-specific lice, containing only the aberrant species Guimaraesiella montisodalis, is unresolved. Morphologically, this species is different from all other Guimaraesiella in several characters and may represent a distinct lineage. We present some data indicating that (1) the Nanling Mountain range may be a biogeographical barrier to chewing lice and (2) host participation in mixed-species feeding flocks may influence host associations in Brueelia-complex chewing lice.

Genomic Approaches to Uncovering the Coevolutionary History of Parasitic Lice.

Next-generation sequencing technologies are revolutionizing the fields of genomics, phylogenetics, and population genetics. These new genomic approaches have been extensively applied to a major group of parasites, the lice (Insecta: Phthiraptera) of birds and mammals. Two louse genomes have been assembled and annotated to date, and these have opened up new resources for the study of louse biology. Whole genome sequencing has been used to assemble large phylogenomic datasets for lice, incorporating sequences of thousands of genes. These datasets have provided highly supported trees at all taxonomic levels, ranging from relationships among the major groups of lice to those among closely related species. Such approaches have also been applied at the population scale in lice, revealing patterns of population subdivision and inbreeding. Finally, whole genome sequence datasets can also be used for additional study beyond that of the louse nuclear genome, such as in the study of mitochondrial genome fragmentation or endosymbiont function.