A new species of sucking louse (Psocodea: Phthiraptera: Anoplura: Hoplopleuridae) from the pale field rat, Rattus tunneyi (Rodentia: Muridae), in Australia

We describe and illustrate a new species of sucking louse, Hoplopleura tunneya new species, from the Australian pale field rat, Rattus tunneyi Thomas (Rodentia: Muridae). Currently, 22 species of the genus Hoplopleura Enderlein, 1904 (Phthiraptera: Anoplura: Hoplopleuridae) are known from Australian endemic rodents. Among the seven “new endemic” rodent species of the genus Rattus in Australia, R. tunneyi is one of five hosts to Hoplopleura lice. In addition, we give a list of all the species of Hoplopleura known from Australian endemic rodents. Including the introduced species Polyplax spinulosa, the total number of sucking louse species known from Australian endemic rodents is now 24.

Chewing Louse Species (Phthiraptera: Amblycera, Ischnocera) on Roadkill Wild Birds in Van Province: Five New Species in Turkey

Background: The present study was conducted to identify the lice species in birds that were struck and injured or killed by motor vehicles along the highway surrounding Lake Van, which is located between Van and Bitlis provinces in Turkey. Methods: The bird feathers were inspected using a macroscope. The isolated lice were placed in tubes containing 70% alcohol and were made translucent by 10% KOH. They were then glued using Canadian balsam and identified under light microscopy. Result: Of the 102 birds collected, 40 (40.8%) birds were infested with at least one louse species. In infested birds, 14 individual lice from 11 species were identified. Of these, Coloceras damicorne (Nitzsch, 1866), Columbicola claviformis (Denny, 1842), Ricinus serratus (Uchida, 1926), Philopterus coarctatus (Scopoli, 1763), Upupicola upupae (Schrank, 1803) were identified in birds for the first time in Turkey.

Highly rearranged mitochondrial genome in Falcolipeurus lice (Phthiraptera: Philopteridae) from endangered eagles

Background Fragmented mitochondrial (mt) genomes and extensive mt gene rearrangements have been frequently reported from parasitic lice (Insecta: Phthiraptera). However, relatively little is known about the mt genomes from the family Philopteridae, the most species-rich family within the suborder Ischnocera. Methods Herein, we use next-generation sequencing to decode the mt genome of Falcolipeurus suturalis and compare it with the mt genome of F. quadripustulatus. Phylogenetic relationships within the family Philopteridae were inferred from the concatenated 13 protein-coding genes of the two Falcolipeurus lice and members of the family Philopteridae using Bayesian inference (BI) and maximum likelihood (ML) methods. Results The complete mt genome of F. suturalis is a circular, double-stranded DNA molecule 16,659 bp in size that contains 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and three non-coding regions. The gene order of the F. suturalis mt genome is rearranged relative to that of F. quadripustulatus, and is radically different from both other louse species and the putative ancestral insect. Phylogenetic analyses revealed clear genetic distinctiveness between F. suturalis and F. quadripustulatus (Bayesian posterior probabilities = 1.0 and bootstrapping frequencies = 100), and that the genus Falcolipeurus is sister to the genus Ibidoecus (Bayesian posterior probabilities = 1.0 and bootstrapping frequencies = 100). Conclusions These datasets help to better understand gene rearrangements in lice and the phylogenetic position of Falcolipeurus and provide useful genetic markers for systematic studies of bird lice. Graphic abstract

The molecular targets of ivermectin and lotilaner in the human louse Pediculus humanus humanus: New prospects for the treatment of pediculosis

Control of infestation by cosmopolitan lice (Pediculus humanus) is increasingly difficult due to the transmission of parasites resistant to pediculicides. However, since the targets for pediculicides have no been identified in human lice so far, their mechanisms of action remain largely unknown. The macrocyclic lactone ivermectin is active against a broad range of insects including human lice. Isoxazolines are a new chemical class exhibiting a strong insecticidal potential. They preferentially act on the γ-aminobutyric acid (GABA) receptor made of the resistant to dieldrin (RDL) subunit and, to a lesser extent on glutamate-gated chloride channels (GluCls) in some species. Here, we addressed the pediculicidal potential of isoxazolines and deciphered the molecular targets of ivermectin and the ectoparasiticide lotilaner in the human body louse species Pediculus humanus humanus. Using toxicity bioassays, we showed that fipronil, ivermectin and lotilaner are efficient pediculicides on adult lice. The RDL (Phh-RDL) and GluCl (Phh-GluCl) subunits were cloned and characterized by two-electrode voltage clamp electrophysiology in Xenopus laevis oocytes. Phh-RDL and Phh-GluCl formed functional homomeric receptors respectively gated by GABA and L-glutamate with EC50 values of 16.0 μM and 9.3 μM. Importantly, ivermectin displayed a super agonist action on Phh-GluCl, whereas Phh-RDL receptors were weakly affected. Reversally, lotilaner strongly inhibited the GABA-evoked currents in Phh-RDL with an IC50 value of 40.7 nM, whereas it had no effect on Phh-GluCl. We report here for the first time the insecticidal activity of isoxazolines on human ectoparasites and reveal the mode of action of ivermectin and lotilaner on GluCl and RDL channels from human lice. These results emphasize an expected extension of the use of the isoxazoline drug class as new pediculicidal agents to tackle resistant-louse infestations in humans.

Two New Species of Sucking Lice (Psocodea: Phthiraptera: Hoplopleuridae) from Chestnut Mice, Pseudomys gracilicaudatus and Pseudomys nanus (Rodentia: Muridae), in Australia

We describe two new species of sucking lice in the genus Hoplopleura Enderlein, 1904 (Psocodea: Phthiraptera: Hoplopleuridae) from Australia: Hoplopleura gracilicaudatusa n. sp. from the eastern chestnut mouse Pseudomys gracilicaudatus (Gould) (Rodentia: Muridae), and Hoplopleura nanusa n. sp. from the western chestnut mouse Pseudomys nanus (Gould) (Rodentia: Muridae). Pseudomys Gray is the most speciose genus of rodents endemic to Australia with 24 species; however, only two Pseudomys species have been reported previously to be hosts of sucking lice. The description of the new species in the present study doubles the number of sucking louse species known to parasitize Pseudomys mice and increases the total number of sucking louse species known from endemic Australian rodents from 21 to 23. Pseudomys gracilicaudatus and P. nanus are closely related murines that diverged ~1 MYA with distinct and widely separated extant geographic distributions. The two new Hoplopleura species described in the present study share some morphological characters and likely co-evolved and co-speciated with their chestnut mouse hosts.

Population Dynamics of Chewing Lice (Phthiraptera) Infesting Birds (Aves)

In the past 25 years, studies on interactions between chewing lice and their bird hosts have increased notably. This body of work reveals that sampling of live avian hosts, collection of the lice, and the aggregated distributions of louse infestations pose challenges for assessing louse populations. The number of lice on a bird varies among host taxa, often with host size and social system. Host preening behavior limits louse abundance, depending on bill shape. The small communities of lice (typically one–four species) that live on individual birds show species-specific patterns of abundance, with consistently common and rare species, and lower year-to-year population variability than other groups of insects. Most species of lice appear to breed continuously on their hosts, with seasonal patterns of abundance sometimes related to host reproduction and molting. Competition may have led to spatial partitioning of the host by louse species, but seldom contributes to current patterns of abundance.

Differential infestation of juvenile Pacific salmon by parasitic sea lice in British Columbia, Canada

Fraser River Pacific salmon have declined in recent decades, possibly from parasitism by sea lice (Caligus clemensi and Lepeophtheirus salmonis). We describe the abundance of both louse species infesting co-migrating juvenile pink (Oncorhynchus gorbuscha), chum (Oncorhynchus keta), and sockeye (Oncorhynchus nerka) salmon over 5 years in the Discovery Islands and Johnstone Strait, British Columbia. The generalist louse, C. clemensi, was 5, 7, and 39 times more abundant than the salmonid specialist, L. salmonis, on pink, chum, and sockeye salmon, respectively. Caligus clemensi abundance was higher on pink salmon (0.45, 95% CI: 0.38–0.55) and sockeye (0.39, 95% CI: 0.33–0.47) than on chum salmon. Lepeophtheirus salmonis abundance was highest on pink salmon (0.09, 95% CI = 0.06–0.15). Caligus clemensi had higher abundances in Johnstone Strait than in the Discovery Islands. These results suggest differences in host specialization and transmission dynamics between louse species. Because both lice infest farmed salmon, but only C. clemensi infests Pacific herring (Clupea pallasii), conservation science and management regarding lice and Fraser River salmon should further consider C. clemensi and transmission from farmed salmon and wild herring.

Comparative phylogeography between parasitic sucking lice and their host the Namaqua rock mouse, Micaelamys namaquensis (Rodentia: Muridae)

To gain a deeper understanding of the mechanisms affecting parasite gene dispersal and subsequent evolution, we investigated mitochondrial and nuclear DNA phylogeographic structures of two ectoparasitic louse species, Polyplax praomydis and Hoplopleura patersoni, and compared this to their host Micaelamys namaquensis. Analyses of mitochondrial and nuclear DNA sequence data derived from 13 geographic populations resulted in the detection of distinct phylogenetic clades within the parasite and host species. Strong support for host–parasite co-divergence was found over larger geographic scales but failed to show complete co-divergence over fine geographic scales. This finding led to the partial rejection of the hypothesis that the evolution of species-specific permanent parasites will mirror the phylogeographic pattern of their host. JANE co-phylogenetic reconstructions support the notion that host switching best explains the discrepancies in geographic patterns. We conclude that host specificity and permanency on the host only plays a partial role in maintaining co-divergences between parasites and their hosts.

Eight New Species of Sucking Lice (Psocodea: Phthiraptera) From Endemic Murine Rodents in Australia and an Updated Identification Key

Based on a comprehensive study of museum specimens, eight new species of sucking lice of the genus Hoplopleura Enderlein, 1904 (Psocodea: Phthiraptera: Hoplopleuridae), are described from six genera of Australian Old Endemic rodents: Conilurus Ogilby, 1838 (Rodentia: Muridae), Leggadina Thomas, 1910 (Rodentia: Muridae), Leporillus Thomas, 1906 (Rodentia: Muridae), Mesembriomys Palmer, 1906 (Rodentia: Muridae), Pogonomys Milne-Edwards, 1877 (Rodentia: Muridae), and Xeromys Thomas, 1889 (Rodentia: Muridae). The description of these new species increases the number of sucking louse species from endemic Australian rodents from 13 to 21 and extends the records of sucking lice to all of the 14 genera of endemic rodents in Australia. Our results show that sucking lice are much more diverse among rodents in Australia than previously known. Furthermore, the Australian Hoplopleura species are host specific—each Hoplopleura species, including the eight new species described in the present study, parasitizes only a single host species, except Hoplopleura irritans Kuhn and Ludwig, 1967 (Psocodea: Phthiraptera: Hoplopleuridae) and Hoplopleura melomydis Weaver, 2017 (Psocodea: Phthiraptera: Hoplopleuridae), each of which is found on two host species. An updated dichotomous key for identifying Australian Hoplopleura species is included.

Calidolipeurus, new genus for Lipeurus megalops Piaget, 1880 (Phthiraptera: Ischnocera: Oxylipeurus-complex), with a redescription of the type species and a preliminary key to the Oxylipeurus-complex

The chewing louse species Lipeurus megalops Piaget, 1880, is redescribed and illustrated. This species has previously been placed in the genus Oxylipeurus Mjöberg, 1910, but marked differences in preantennal structure, male and female genitalia, abdominal chaetotaxy, and structure of abdominal plates indicate that this species is not closely related to other species in this genus. We therefore erect a new genus, Calidolipeurus gen. nov. for this species. Calidolipeurus is presently monotypic, containing only Calidolipeurus megalops gen. et comb. nov. We also provide a preliminary key to the Oxylipeurus-complex.