Morphological variation of chewing lice (Insecta: Phthiraptera) from different skua taxa

The lice, Haffneria grandis and Saemundssonia were extracted from their hosts, skuas (Aves: Stercorariidae). Lice were extracted from dead birds by combing feathers, while lice from live birds were extracted using a delousing chamber containing chloroform vapour. Lice were measured and the data analysed by canonical discriminant analysis. Lice show variation in morphology that is useful in identifying some of these hosts. This variation is presumably due to micro-environmental pressure provided by each host. Our interpretation is that these chewing lice have evolved to be adapted to each skua taxon; different sizes and morphologies of skua taxa result in different sizes and morphologies of Haffneria grandis and Saemundssonia.     

Immunization of rabbits with a midgut extract of the human body louse Pediculus humanus humanus: the effect of induced resistance on the louse population

Abstract. Resistance to human body lice, Pediculus humanus humanus L, induced by feeding on rabbits immunized with an extract of louse gut was studied. The mortality of lice fed on immunized rabbits was 73%, significantly higher than that of lice fed on control rabbits (52%) ( P < 0.01). The proportion of dead nymphs and female lice with ruptured guts was significantly higher in lice fed on immunized rabbits (P<0.01). The size of the bloodmeal was 35% greater in female lice fed on control rabbits than on immunized rabbits. Lice fed on immunized rabbits laid 40% less eggs than those fed on the controls, they also demonstrated a significant decrease in the number of eggs per female over time ( P < 0.01). 86% of the eggs laid by lice fed on immunized animals hatched, compared with 92% hatching of eggs laid by the lice fed on control animals (P< 0.01). With the exception of the first bloodmeal the percentage of hatched eggs which were laid between any two bloodmeals was significantly smaller (p<0.01) in the lice fed on immunized rabbits than in the control group. The first nymphal stage of lice fed on immunized rabbits took an average of 5.2 days to moult to the second stage, compared with 4 days for those fed on control rabbits.     

Effects of blood type and blood handling on feeding success,longevity and egg production in the body louse,Pediculus humanus humanus

The effects of feeding different types of human blood to human body lice, Pediculus humanus humanus L. (Phthiraptera: Pediculidae), on feeding success, longevity and numbers of eggs laid were investigated using an artificial blood‐feeding system in the laboratory. No significant differences were found between lice fed on different human blood types for any of the parameters tested. However, when lice were fed on human blood of one blood type followed immediately by a different blood type, they took significantly smaller bloodmeals, their longevity was reduced and they laid fewer eggs per female than control lice that had been fed twice on the same human blood type. When lice were fed human blood that had been stored for 1–26 weeks, the quantity of blood taken, the proportion of lice that became fully engorged and lice longevity diminished gradually as the storage time of the blood increased, but there was no effect of storage time on the mean number of eggs laid per female. However, lice would not feed on 26‐week‐old blood. The type of anticoagulant used had a significant effect on the proportion fed, longevity and number of eggs laid per female. Generally, EDTA (ethylenediaminetetraacetic acid)‐treated blood reduced longevity and the number of eggs laid per female to a greater degree than heparinized or citrated blood. Lice fed on rabbit blood took significantly larger amounts of blood, lived longer and laid a higher mean number of eggs per female than lice fed on human blood.     

Body size and fecundity are correlated in feather lice (Phthiraptera: Ischnocera): implications for Harrison's rule

1. Harrison's rule, which predicts that large‐bodied species of hosts have large‐bodied species of parasites, has been documented in a wide diversity of parasites. 2. Harrison's rule has been most thoroughly studied in avian feather lice, which escape from host defence (preening) by hiding in the feathers. Lice that are unable to hide are selectively removed by preening. Preening selects for small lice on small hosts, which have small feathers in which to hide. 3. Preening should not, however, select for large lice on large hosts. Instead, the larger size of lice on large hosts is thought to result from a positive relationship between size and fecundity, as shown for many other insects. 4. This study tested for a size–fecundity correlation within Columbicola columbae, the host‐specific ‘wing louse’ of rock pigeons (Columba livia). 5. The results confirm a positive relationship between female body length and number of eggs laid. 6. The study thus supports a mechanism consistent with stabilising selection leading to the evolution of the Harrison's rule pattern among species of Columbicola and their hosts.     

Competition for dietary fructose between Moniliformis (acanthocephala) and growing rats

Crompton D. W. T., Singhvi A., Nesheim M. C. and Walters D. E. 1981. Competition for dietary fructose between Moniliformis (Acanthocephala) and growing rats. International journal for Parasitology11: 457–461. The food intake, weight gain and blood sugar of young rats, fed on diets containing growth-limiting amounts of fructose and infected with Moniliformis dubius (Acanthocephala) for 6 weeks, were measured and compared with values obtained from similar uninfected rats which had been treated in the same manner. The growth of the rats was closely related to the fructose content of the diet. However, on average, the infected rats gained less weight than their uninfected counterparts. Significant differences between the values for blood sugar from infected and uninfected rats were not detected when the diet contained 2% fructose. The blood sugar of infected rats fed on a diet containing 4% fructose was found to be significantly less than that of similar uninfected rats. Information was also obtained about the numbers, sex, dry weight and location of the Moniliformis in the small intestines of their hosts. Male and female Moniliformis from rats fed on the 4% fructose diet were found to be heavier than those from rats fed on the 2% fructose diet. The results can be interpreted to suggest that the reduction in the growth rate of the infected rats is due to competition for fructose between Moniliformis and the rat.     

The distribution of mallophaga on the domestic pigeon (Columba livia)

The distribution of Hohorstiella lata, Colpocephalum turbinatum, Campanulotes bidentatus compar, and Comlumbicola columbae on domestic pigeons were determined. Each species laid its eggs on a different part of the body but all fed on the fluffy part of the body feathers. H. lata also fed on blood, and C. turbinatum on its own eggs and nymphs. Reduction of the efficiency of preening led to an increase in the number of lice and more widespread distribution of nymphs and adults but not to a rapid change in the distribution of eggs. It is suggested that preening has played a major selective role, and that the morphological and behavioural adaptions of the lice are to ensure that they and their eggs survive this type of predation.     

Susceptibility of rainbow trout Oncorhynchus mykiss,Atlantic salmon Salmo salar and coho salmon Oncorhynchus kisutch to experimental infection with sea lice Lepeophtheirus salmonis

Physiological, immunological and biochemical parameters of blood and mucus, as well as skin histology, were compared in 3 salmonid species (rainbow trout Oncorhynchus mykiss, Atlantic salmon Salmo salar and coho salmon O. kisutch) following experimental infection with sea lice Lepeophtheirus salmonis. The 3 salmonid species were cohabited in order to standardize initial infection conditions. Lice density was significantly reduced on coho salmon within 7 to 14 d, while lice persisted in higher numbers on rainbow trout and Atlantic salmon. Lice matured more slowly on coho salmon than on the other 2 species, and maturation was slightly slower on rainbow trout than on Atlantic salmon. Head kidney macrophages from infected Atlantic salmon had diminished respiratory burst and phagocytic capacity at 14 and 21 d post-infection (dpi), while infected rainbow trout macrophages had reduced respiratory burst and phagocytic capacities at 21 dpi, compared to controls. The slower development of lice, coupled with delayed suppression of immune parameters, suggests that rainbow trout are slightly more resistant to lice than Atlantic salmon. Infected rainbow trout and Atlantic salmon showed increases in mucus lysozyme activities at 1 dpi, which decreased over the rest of the study. Mucus lysozyme activities of infected rainbow trout, however, remained higher than controls over the entire period. Coho salmon lysozyme activities did not increase in infected fish until 21 dpi. Mucus alkaline phosphatase levels were also higher in infected Atlantic salmon compared to controls at 3 and 21 dpi. Low molecular weight (LMW) proteases increased in infected rainbow trout and Atlantic salmon between 14 and 21 dpi. Histological analysis of the outer epithelium revealed mucus cell hypertrophy in rainbow trout and Atlantic salmon following infection. Plasma cortisol, glucose, electrolyte and protein concentrations and hematocrit all remained within physiological limits for each species, with no differences occurring between infected and control fish. Our results demonstrate that significant differences in mucus biochemistry and numbers of L. salmonis occur between these species.     

Chewing Lice of Swan Geese (Anser cygnoides): New Host-Parasite Associations

Chewing lice (Phthiraptera) that parasitize the globally threatened swan goose Anser cygnoides have been long recognized since the early 19th century, but those records were probably biased towards sampling of captive or domestic geese due to the small population size and limited distribution of its wild hosts. To better understand the lice species parasitizing swan geese that are endemic to East Asia, we collected chewing lice from 14 wild geese caught at 3 lakes in northeastern Mongolia. The lice were morphologically identified as 16 Trinoton anserinum (Fabricius, 1805), 11 Ornithobius domesticus Arnold, 2005, and 1 Anaticola anseris (Linnaeus, 1758). These species are known from other geese and swans, but all of them were new to the swan goose. This result also indicates no overlap in lice species between older records and our findings from wild birds. Thus, ectoparasites collected from domestic or captive animals may provide biased information on the occurrence, prevalence, host selection, and host-ectoparasite interactions from those on wild hosts.     

Phylogenetics and host associations of Fahrenholzia sucking lice (Phthiraptera: Anoplura)

Abstract.  Mitochondrial and nuclear DNA sequence data were used to reconstruct phylogenetic relationships for eleven of the twelve currently recognized species of Fahrenholzia , lice found only on rodents of the family Heteromyidae. Field collections included twenty of the thirty-three known host associations and resulted in the discovery of four new associations. Phylogenetic analyses of the mitochondrial and nuclear datasets were in general agreement, resulting in a well-resolved Fahrenholzia phylogeny. Analyses supported the monophyly of lice parasitizing the host subfamily Heteromyinae (spiny pocket mice). Lice parasitizing the genera Chaetodipus (pocket mice) and Perognathus (silky pocket mice) each represent monophyletic lineages. Phylogenetic patterns and levels of genetic differentiation suggest that the widespread Fahrenholzia pinnata may contain several cryptic species. Cryptic species may exist also within the less widely distributed species, Fahrenholzia microcephala and Fahrenholzia reducta .     

Prevalence of head lice (Pediculus humanus capitis) infestation among schools workers in the Eastern Region,Saudi Arabia

In a cross-sectional survey in February-May 2019, the prevalence of Pediculosis capitis with demographic data and the behavioral practices were investigated among 750 participants in the Eastern region of Saudi Arabia. Female participation was highly remarked with a percentage of 94.08% compared to that of male one about 5.91%. A deficiency of knowledge about lice infestation was noted especially among illiterate participants raised from their socio-economic levels (p-value = 0.001). Lice infestation reached higher rates in children aged less than 20 years with itching of the hair scalp. The obtained results revealed that 59.33% of the respondents believed that frequency of personal hygiene and washing of hair were the best methods for preventing the lice infestation. However, the treatment of lice infestation using anti-lice agents (p-value = 0.020) was preferred by 14.26% of participants. Although knowledge about the preventive tools for lice infestation (p-value 0.089) was not significantly associated with the experience of infestation but knowledge about the appropriate treatment to kill lice (p-value 0.020) and the wrong practices in the treatment of a head lice infestation were (p-value 0.005) significantly associated with the experience of infestation. Health programs and campaigns preventions are highly advised to increase the awareness of Pediculosis capitis with an effective strategic plan to control, manage, and prevent this disease.     

Extra-pair paternity does not result in differential sexual selection in the mutually ornamented black swan (Cygnus atratus)

We studied patterns of parentage in 85 broods (332 cygnets) of black swans during three breeding seasons, using a set of eight polymorphic microsatellite markers. We detected both intraspecific brood parasitism (IBP; < 5% of cygnets per year) and extra-pair paternity (EPP). In these years, 10-17% (mean = 15.1%) of cygnets resulted from EPP, and 27-40% (mean 37.6%) of broods contained at least one extra-pair cygnet. Compared with levels of EPP in closely related species with similar life histories, these values are unexpectedly high. EPP in black swans appears unrelated to ecological factors (breeding density and synchrony) or genetic factors (genetic similarity between pair members or genetic quality of the offspring). We found no evidence that a mutual sexual feather ornament known to play a role in social mate choice in black swans (curled wing feathers) is involved in extra-pair mate choice. EPP does not lead to greater variance in reproductive success in males, relative to females in this species. We therefore suggest that EPP does not result in differential sexual selection on males and females, explaining why they are ornamented to the same degree.     

Revision of Dennyus (Collodennyus) lice (Phthiraptera: Menoponidae) from swiftlets, with descriptions of new taxa and a comparison of host–parasite relationships

Lice of the subgenus Dennyus ( Collodennyus ) are host specific, permanent parasites of swiftlets (Aves: Apodidae). As a prelude to a test of the hypothesis that these lice have cospeciated with their hosts, we revise the taxonomy of the subgenus, redescribing the seven previously recognized species, and adding thirteen new species and three new subspecies. All twenty-three of these louse taxa are found on swiftlets (Apodiformes: Apodidae), with four from hosts of the genus Collocalia , eighteen from Aerodramus , and one from Hydrochous . Successful identification is associated in most cases with females; males are only tenuously separable. A complete host–parasite list for the subgenus Collodennyus is provided, as well as a key for the identification of these taxa. Limited morphological variation within the subgenus has prevented ready extraction of discrete characters for cladistic analysis. In the absence of such characters, a cluster analysis of female and male lice is presented. Comparison of a dendrogram for Dennyus ( Collodennyus ) with a molecular phylogeny for the swiftlet hosts suggests that the history of the swiftlet–louse association has been complex, including episodes of host switching and independent speciation by the lice.     

Louse infestations of tree shrews (Tupaia glis)

Nine adult tree shrews, Tupaia glis, recently imported from West Malaysia were visually examined for ectoparasites while under general anesthesia. Three shrews were infested by the sucking louse, Sathrax durus , and six shrews had louse ova belonging to this species; two shrews had neither lice nor ova. A total of 20 adult female, 10 adult male, and three third instar nymphal lice was collected. Lice were located on the head, flanks, and dorsal body of shrews while ova were recorded mainly from the anterior flanks but also from some adjacent host sites. The tree shrews appeared to tolerate the lice well although louse vector capacity was not assessed. The last date that lice were recorded from shrews was 22 days after colony set-up, and the last date on which seemingly viable ova were recorded was 64 days after set-up showing that the infestations were ultimately lost.     

Managing plague on prairie dog colonies: insecticides as ectoparasiticides

Human health practitioners and wildlife biologists use insecticides to manage plague by suppressing fleas (Siphonaptera), but insecticides can also kill other ectoparasites. We investigated effects of deltamethrin and fipronil on ectoparasites from black‐tailed prairie dogs (Cynomys ludovicianus, BTPDs). In late July, 2018, we treated three sites with 0.05% deltamethrin dust and 5 sites with host‐fed 0.005% fipronil grain. Three non‐treated sites functioned as experimental baselines. We collected ectoparasites before treatments (June‐July, 2018) and after treatments (August‐October, 2018, June‐July, 2019). Both deltamethrin and fipronil suppressed fleas for at least 12 months. Deltamethrin had no detectable effect on mites (Arachnida). Fipronil suppressed mites for at least 12 months. Lice (Phthiraptera) were scarce on non‐treated sites throughout the study, complicating interpretation. Concentrating on eight sites where all three ectoparasites where found in June‐July, 2018 (before treatments), flea intensity was greatest on BTPDs carrying many lice and mites. These three ectoparasites co‐occurred at high numbers, which might facilitate plague transmission in some cases. Lethal effects of insecticides on ectoparasite communities are potentially advantageous in the context of plague management.     

Temporal and spatial patterns of sea lice levels on sea trout in western Scotland in relation to fish farm production cycles

The relationship between aquaculture and infestations of sea lice on wild sea trout (Salmo trutta) populations is controversial. Although some authors have concluded that there is a link between aquaculture and lice burdens on wild fish, others have questioned this interpretation. Lice levels have been shown to be generally higher on Atlantic salmon farms during the second years of two-year production cycles. Here we investigate whether this pattern relates to lice burdens on wild fish across broad temporal and spatial axes. Within Loch Shieldaig across five successive farm cycles from 2000 to 2009, the percentage of sea trout with lice, and those above a critical level, were significantly higher in the second year of a two-year production cycle. These patterns were mirrored in 2002–2003 across the Scottish west coast. The results suggest a link between Atlantic salmon farms and sea lice burdens on sea trout in the west of Scotland.     

Host sympatry and body size influence parasite straggling rate in a highly connected multihost,multiparasite system

Parasite lineages commonly diverge when host lineages diverge. However, when large clades of hosts and parasites are analyzed, some cases suggest host switching as another major diversification mechanism. The first step in host switching is the appearance of a parasite on an atypical host, or “straggling.” We analyze the conditions associated with straggling events. We use five species of colonially nesting seabirds from the Galapagos Archipelago and two genera of highly specific ectoparasitic lice to examine host switching. We use both genetic and morphological identification of lice, together with measurements of spatial distribution of hosts in mixed breeding colonies, to test: (1) effects of local host community composition on straggling parasite identity; (2) effects of relative host density within a mixed colony on straggling frequency and parasite species identity; and (3) how straggling rates are influenced by the specifics of louse attachment. Finally, we determine whether there is evidence of breeding in cases where straggling adult lice were found, which may indicate a shift from straggling to the initial stages of host switching. We analyzed more than 5,000 parasite individuals and found that only ~1% of lice could be considered stragglers, with ~5% of 436 host individuals having straggling parasites. We found that the presence of the typical host and recipient host in the same locality influenced straggling. Additionally, parasites most likely to be found on alternate hosts are those that are smaller than the typical parasite of that host, implying that the ability of lice to attach to the host might limit host switching. Given that lice generally follow Harrison's rule, with larger parasites on larger hosts, parasites infecting the larger host species are less likely to successfully colonize smaller host species. Moreover, our study supports the general perception that successful colonization of a novel host is extremely rare, as we found only one nymph of a straggling species, which may indicate successful reproduction.     

Field trials in Norway with SLICE (0.2% emamectin benzoate) for the oral treatment of sea lice infestation in farmed Atlantic salmon Salmo salar

Four commercial salmon farms on the West coast of Norway were recruited to a programme of field trials in which the efficacy of SLICE (0.2% emamectin benzoate; Schering-Plough Animal Health) was compared with a commercially available product, EKTOBANN (teflubenzuron 2 g kg(-1); Skretting A/S) in treating natural sea lice Lepeophtheirus salmonis infections in Atlantic salmon Salmo salmar L. At each test site, 3 fish pens were treated with each product. In total, nearly 1.2 million first-year-class fish were included in the trial, of which approximately 561,000 received emamectin benzoate at a dosage of 50 microg kg(-1) body wt d(-1), while approximately 610,000 received teflubenzuron at a dosage of 10 mg kg(-1) body wt d(-1). Medicated feed was provided at 0.5% body wt d(-1) over 7 consecutive days. Feed containing emamectin benzoate was generally well accepted by the fish and no problems were encountered in feeding the medicated diet at the desired dose. Lice numbers were counted 2 d before and 1, 7, 14 and 21 d after commencement of treatment. While treatment with both substances rapidly reduced lice numbers, pens treated with emamectin benzoate were found to harbour significantly fewer lice 14 and 21 d post-treatment. Twenty-one days following treatment with emamectin benzoate the lice abundance was reduced on average by 94%. Limited sampling outside the main study period indicated that emamectin benzoate protects against sea-lice infestation over longer periods.     

Experimental treatment of dog lice infestation in interior Alaska wolf packs

Biting dog lice (Trichodectes canis) were first detected on wolves (Canis lupus) in Southcentral Alaska (USA) in 1981 introduced via domestic dogs. Lice infestation expanded north via wolf dispersal to the Tanana Flats of Interior Alaska in December 2003. Effects of this ectoparasite on wolves were persistent with moderate to severe clinical signs of pediculosis lasting multiple generations. Our objectives were to evaluate the extent of lice infestation on wolves within the Tanana Flats and develop a management program that limited further transmission. We implemented a treatment method that consisted of multiple applications of oral antiparasitic ivermectin-injected baits aerially distributed at den and rendezvous sites during mid-May through August. During 2005–2010, we evaluated 12–19 packs annually as part of a treatment group and 3 infested packs as a control. Infestation rates of treatment packs prior to treatment varied from 15% in 2005 (2 of 13), 50% in 2006 (7 of 14), 24% in 2007 (4 of 17), 5% in 2008 (1 of 19), and 0% in 2009–2010 (0 of 19). We treated 50%, 71%, and 75% of the infested treatment packs during 2005–2007, respectively. All treated packs were lice-free the winter following treatment, whereas all 3 control packs remained infested. The combination of treatment and harvest successfully eliminated the local source population of lice within 3 years and we found no evidence of lice infestation within the treatment area during the last 3 years of the study. By using this treatment method, managers can eliminate dog lice infestations of wolves in areas ≤13,000 km². By initiating treatment promptly after detection, transmission to unexposed nearby packs can be postponed and the local source population of lice on wolves eradicated. © 2013 The Wildlife Society.     

Identification of Different Bartonella Species in the Cattle Tail Louse (Haematopinus quadripertusus) and in Cattle Blood

Bartonella spp. are worldwide-distributed facultative intracellular bacteria that exhibit an immense genomic diversity across mammal and arthropod hosts. The occurrence of cattle-associated Bartonella species was investigated in the cattle tail louse Haematopinus quadripertusus and in dairy cattle blood from Israel. Lice were collected from cattle from two dairy farms during summer 2011, and both lice and cow blood samples were collected from additional seven farms during the successive winter. The lice were identified morphologically and molecularly using 18S rRNA sequencing. Thereafter, they were screened for Bartonella DNA by conventional and real-time PCR assays using four partial genetic loci (gltA, rpoB, ssrA, and internal transcribed spacer [ITS]). A potentially novel Bartonella variant, closely related to other ruminant bartonellae, was identified in 11 of 13 louse pools collected in summer. In the cattle blood, the prevalence of Bartonella infection was 38%, identified as B. bovis and B. henselae (24 and 12%, respectively). A third genotype, closely related to Bartonella melophagi and Bartonella chomelii (based on the ssrA gene) and to B. bovis (based on the ITS sequence) was identified in a single cow. The relatively high prevalence of these Bartonella species in cattle and the occurrence of phylogenetically diverse Bartonella variants in both cattle and their lice suggest the potential role of this animal system in the generation of Bartonella species diversity.     

Evidence That Head and Body Lice on Homeless Persons Have the Same Genotype

Human head lice and body lice are morphologically and biologically similar but have distinct ecologies. They were shown to have almost the same basic genetic content (one gene is absent in head lice), but differentially express certain genes, presumably responsible for the vector competence. They are now believed to be ecotypes of the same species (Pediculus humanus) and based on mitochondrial studies, body lice have been included with head lice in one of three clades of human head lice (Clade A). Here, we tested whether head and body lice collected from the same host belong to the same population by examining highly polymorphic intergenic spacers. This study was performed on lice collected from five homeless persons living in the same shelter in which Clade A lice are prevalent. Lice were individually genotyped at four spacer loci. The genetic identity and diversity of lice from head and body populations were compared for each homeless person. Population genetic structure was tested between lice from the two body regions and between the lice from different host individuals.We found two pairs of head and body lice on the same homeless person with identical multi locus genotypes. No difference in genetic diversity was found between head and body louse populations and no evidence of significant structure between the louse populations was found, even after controlling for a possible effect of the host individual. More surprisingly, no structure was obvious between lice of different homeless persons.We believe that the head and body lice collected from our five subjects belong to the same population and are shared between people living in the same shelter. These findings confirm that head and body lice are two ecotypes of the same species and show the importance of implementing measures to prevent lice transmission between homeless people in shelters.