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PubMed2001

Polyplax guatemalensis sp. n. (Phthiraptera: Anoplura), a new sucking louse from Peromyscus grandis, a montane cloud forest rodent from Guatemala.

The adult male and female of Polyplax guatemalensis sp. n. are described from the sigmodontine murid rodent Peromyscus grandis Goodwin collected in the Reserva de Biosfera, Sierra de las Minas, Guatemala, at an elevation of 2,200 m. The new species extends the number of known native species of Polyplax in the New World to four with none of them recorded south of Panama. Polyplax guatemalensis is morphologically most closely related to Polyplax auricularis which parasitises a cluster of closely related New World sigmodontine rodents from Canada to Panama. These two species can be distinguished from all other known species of Polyplax by the presence of partially overlapping, subtriangular, anterior abdominal plates in both sexes. Polyplax guatemalensis can be separated from P. auricularis by the abundant tergal abdominal setae and longer pseudopenis in males, and by the presence of one fewer anterior abdominal, subtriangular tergite and sternite in females.

Animals↗
PubMed2002

Evidence from mitochondrial DNA that head lice and body lice of humans (Phthiraptera: Pediculidae) are conspecific.

The specific status of the head and body lice of humans has been debated for more than 200 yr. To clarify the specific status of head and body lice, we sequenced 524 base pairs (bp) of the cytochrome oxidase I (COI) gene of 28 head and 28 body lice from nine countries. Ten haplotypes that differed by 1-5 bp at 11 nucleotide positions were identified. A phylogeny of these sequences indicates that these head and body lice are not from reciprocally monophyletic lineages. Indeed, head and body lice share three of the 10 haplotypes we found. F(ST) values and exact tests of haplotype frequencies showed significant differences between head and body lice. However, the same tests also showed significant differences among lice from different countries. Indeed, more of the variation in haplotype frequencies was explained by differences among lice from different countries than by differences between head and body lice. Our results indicate the following: (1) head and body lice do not represent reciprocally monophyletic lineages and are conspecific; (2) gene flow among populations of lice from different countries is limited; and (3) frequencies of COI haplotypes can be used to study maternal gene flow among populations of head and body lice and thus transmission of lice among their human hosts.

Animals↗
PubMed2001

Fecundity of Hoplopleura scapteromydis (Phthiraptera: Anoplura, Hoplopleuridae), ectoparasite of Scapteromys aquaticus (Rodentia: Muridae) in Rio de La Plata marshlands, Argentina.

Density and age structure of lice collected from captured Scapteromys aquaticus rodents were studied to estimate the fecundity of Hoplopleura scapteromydis. The number of eggs with a visible embryo inside (E), nymphs (N), adult males (AM), and adult females (AF) were recorded for each rodent. For the ith rodent, the fecundity of H. scapteromydis, F(i), was estimated as F(i) = [[E(i) + N(i)]/2]/AF(i)/T, where T represents the period of preimaginal development (unknown and arbitrarily considered as T = 1), and the sex ratio of the preimaginal stages was supposed to be 1:1. In order to look for density-dependent effects, F(i) was plotted against AM(i), this being an independent estimation of infrapopulation density. The number of rodents suitable for AF and AM calculations was 38 (57% of the parasitized animals). Almost 95% had a low-to-moderate louse burden (1 < AM < 30) and were captured every season, whereas only 3% had a heavy (61 < AM < 70, captured in winter) or very heavy (AM > 80, captured in summer) louse burden. The extreme values of F were 0.63 and 18 (1.3 and 36 if both sexes were considered). High-to-moderate F-values (F > 5) were estimated in only 5 rodents that exhibited low louse density, whereas low F-values (F < 5) were found at all louse densities. Notwithstanding the tendency toward an inverse relationship between fecundity and infrapopulation density, the correlation was not significantly different from 0.

Animals↗
PubMed2001

Lipid and protein composition at different developmental stages of Pediculus capitis (Arthropoda, Phthiraptera).

Protein and lipid compositions were studied at different developmental stages of Pediculus capitis De Geer 1778. Phosphatidylcholine was found to be the predominant lipid at all stages and in both sexes. Palmitic and oleic acids were the main fatty acids throughout the 3 stages studied. A marked decline was observed in the total lipid content and triacylglyceride concentration during development, suggesting that their consumption is an energy source. The electrophoretic mobility revealed the predominance of a 320-kDa protein in eggs and adult females, whereas 2 major proteins of 514 and 439 kDa were found in nymphs, as well as in male and female adults. Two very high density lipoprotein fractions were isolated by ultracentrifugation of egg cytosol in a density gradient of NaBr. Both reserve lipoproteins contained phospholipids and triacylglycerols as the predominant lipids and a protein band of around 320 kDa. The structure of this band is likely to be similar to that found in females in a vitellogenic state.

Animals↗
PubMed2004

Linognathus weisseri n. sp. (Phthiraptera: Linognathidae) of impalas, Aepyceros melampus: description and biology.

The adult male and female and first instar nymph of the sucking louse Linognathus weisseri n. sp. are described. This louse was collected from impalas, Aepyceros melampus, at three localities in Limpopo Province, and at three in Mpumalanga Province, South Africa. Although it usually accounted for only a small proportion of the total louse burden, its overall prevalence exceeded 27%. Its prevalence on adult male impalas (9%) was significantly lower (P = 0.004) than that on adult females (39%), but did not differ among age classes. However, the intensity of L. weisseri infestation was higher on lambs than on yearlings and adults, and peaked on impalas in late winter to early summer. Five species of lice are now known to parasitize impalas and a key for distinguishing adults of these species is included.

Age Factors↗
PubMed2004

Multiple origins of parasitism in lice.

A major fraction of the diversity of insects is parasitic, as herbivores, parasitoids or vertebrate ectopara sites. Understanding this diversity requires information on the origin of parasitism in various insect groups. Parasitic lice (Phthiraptera) are the only major group of insects in which all members are permanent parasites of birds or mammals. Lice are classified into a single order but are thought to be closely related to, or derived from, book lice and bark lice (Psocoptera). Here, we use sequences of the nuclear 18S rDNA gene to investigate the relationships among Phthiraptera and Psocoptera and to identify the origins of parasitism in this group (termed Psocodea). Maximum-likelihood (ML), Bayesian ML and parsimony analyses of these data indicate that lice are embedded within the psocopteran infraorder Nanopsocetae, making the order Psocoptera paraphyletic (i.e. does not contain all descendants of a single common ancestor). Furthermore, one family of Psocoptera, Liposcelididae, is identified as the sister taxon to the louse suborder Amblycera, making parasitic lice (Phthiraptera) a polyphyletic order (i.e. descended from two separate ancestors). We infer from these results that parasitism of vertebrates arose twice independently within Psocodea, once in the common ancestor of Amblycera and once in the common ancestor of all other parasitic lice.

Animals↗
PubMed2004

Infestation of people with lice in Kathmandu and Pokhara, Nepal.

The prevalence of infestation with head lice and body lice, Pediculus spp. (Phthiraptera: Pediculidae) and pubic (crab) lice Pthirus pubis (L.) (Phthiraptera: Pthiridae), was recorded from 484 people in Nepal. The prevalence of head lice varied from 16% in a sample of people aged 10-39 years of age, to 59% in street children. Simultaneous infestations with head and body lice (double infestations) varied from 18% in slum children to 59% in street children.

Adolescent↗
PubMed1998

A different tempo of mitochondrial DNA evolution in birds and their parasitic lice.

A phylogeny for the lice (Insecta: Phthiraptera: genus Dennyus) parasitic on swiftlets (Aves: Collocalliinae) was constructed based on mitochondrial cytochrome b DNA sequences. This phylogeny is congruent with previous phenetic analyses of morphometric data for the lice. Comparison with a previously obtained phylogeny for the hosts indicates some degree of cospeciation. These cospeciation events are used to compare relative rates of evolution in the birds and their lice for the same segment of the cytochrome b gene. Cytochrome b is evolving two to three times more rapidly in lice than in birds, and louse cytochrome b is highly divergent compared to that of most other insects. Although generation time has been suggested as an explanation for the disparity in evolutionary rates between lice and their hosts, we suggest that the small effective population sizes of lice coupled with founder events occurring during transmission to new host individuals may be an important factor.

Amino Acid Sequence↗
PubMed2004

Parasite biodiversity and host defenses: chewing lice and immune response of their avian hosts.

Antagonistic host-parasite interactions lead to coevolution of host defenses and parasite virulence. Such adaptation by parasites to host defenses may occur to the detriment of the ability of parasites to exploit alternative hosts, causing parasite specialization and speciation. We investigated the relationship between level of anti-parasite defense in hosts and taxonomic richness of two chewing louse suborders (Phthiraptera: Amblycera, Ischnocera) on birds. While Amblyceran lice tend to occur in contact with host skin, feed on host skin and chew emerging tips of developing feathers to obtain blood, Ischnoceran lice live on feathers and feed on the non-living keratin of feather barbules. We hypothesized that Amblyceran abundance and richness would have evolved in response to interaction with the immune system of the host, while Ischnoceran taxonomic richness would have evolved independently of immunological constraints. In an interspecific comparison, the abundance of Ischnocerans was positively related to host body size, while host body mass and Ischnoceran taxonomic richness accounted for the abundance of Amblycerans. Amblyceran taxonomic richness was predicted by the intensity of T-cell mediated immune response of nestling hosts, while the T-cell response of adults had no significant effect. In contrast, Ischnoceran taxonomic richness was not predicted by host T-cell responses. These results suggest that the taxonomic richness of different parasite taxa is influenced by different host defenses, and they are consistent with the hypothesis that increasing host allocation to immune defense increases Amblyceran biodiversity.

Animals↗
PubMed2006

Impact of the botanical insecticide Neem Azal on survival and reproduction of the biting louse Damalinia limbata on angora goats.

Secondary metabolites present in the neem tree (Azadirachta indica A. Juss, Meliaceae), exhibit a wide range of biological activities in insects. However, few studies have been undertaken to assess the potential of neem products as insecticides for the control of ectoparasites of domestic animals. This study was undertaken to estimate the efficacy of Neem Azal, an azadirachtin-rich extract of neem seeds, in controlling Damalinia limbata (Phthiraptera) louse infestation of angora goats. The study was conducted on a fibre animal farm situated in Central Italy. Groups of 11-12 goats were treated with Neem Azal at an azadirachtin concentration of 650ppm or 125ppm, with Neguvon or were left untreated. Their louse burden was assessed fortnightly to monthly for 22 weeks. A reduction in louse densities of 76-96% was observed from week 2 to week 18 after treatment with the neem solution containing azadirachtin at a concentration of 650ppm. At the lower test concentration (125ppm) a reduction of 60-92% could be recorded from week 2 to week 14. Neem Azal was found to reduce the survival of both adult and nymph stages of D. limbata and to interfere with oviposition and oogenesis of female lice. A decrease in oviposition was observed in neem exposed female lice and the examination of their ovaries revealed morphological alterations in both vitellogenic and previtellogenic ovarioles at the follicular and germinal level. Since neem compounds target different life stages and physiological processes of D. limbata, the development of insecticide resistance by biting lice exposed to neem-based insecticides appears unlikely. For this reason and for its prolonged activity, which in principle allows angora goats to be protected for a large part of the mohair production cycle, neem-based insecticides may have a potential interest for mohair producing breeders.

Animals↗
PubMed2002

The perils of using host relationships in parasite taxonomy: phylogeny of the Degeeriella complex.

The taxonomy of lice (Insecta: Phthiraptera) is often heavily influenced by host taxonomy. The use of host information to define genera of avian lice in the widespread Degeeriella complex has been prevalent but has created problems. Several workers have suggested that genera defined on the basis of host association are not monophyletic. We used sequences of nuclear (elongation factor-1alpha) and mitochondrial (cytochrome oxidase I) genes to test the monophyly of several genera in the Degeeriella complex. Parsimony and likelihood analyses of these data indicated that many genera in the Degeeriella complex are not monophyletic, such that species occurring on the same host groups do not form monophyletic groups. Biological features of hosts (including predaceous habits, brood parasitism, and hole nesting) for species in the Degeeriella complex likely provide opportunities for switching of lice between host groups. In addition, dispersal of lice via phoresy on hippoboscid flies also likely provides opportunities for host switching in the Degeeriella complex. This study indicates that the overuse of host taxonomy in louse taxonomy can result in classifications that do not reflect phylogenetic history.

Animals↗
PubMed2003

When do parasites fail to speciate in response to host speciation?

Cospeciation generally increases the similarity between host and parasite phylogenies. Incongruence between host and parasite phylogenies has previously been explained in terms of host switching, sorting, and duplication events. Here, we describe an additional process, failure of the parasite to speciate in response to host speciation, that may be important in some host-parasite systems. Failure to speciate is likely to occur when gene flow among parasite populations is much higher than that of their hosts. We reconstructed trees from mitochondrial and nuclear DNA sequences for pigeons and doves (Aves: Columbiformes) and their feather lice in the genus Columbicola (Insecta: Phthiraptera). Although comparisons of the trees from each group revealed a significant amount of cospeciation, there was also a significant degree of incongruence. Cophylogenetic analyses generally indicated that host switching may be an important process in the history of this host-parasite association. Using terminal sister taxon comparisons, we also identified three apparent cases where the host has speciated but the associated parasite has not. In two of these cases of failure to speciate, these comparisons involve allopatric sister taxa of hosts whose lice also occur on hosts sympatric with both of the allopatric sisters. These additional hosts for generalist lice may promote gene flow with lice on the allopatric sister species. Relative rate comparisons for the mitochondrial cytochrome oxidase I gene indicate that molecular substitution occurs about 11 times faster in lice than in their avian hosts.

Animals↗
PubMed2004

Ecology of congruence: past meets present.

Phylogenetic congruence is governed by various macroevolutionary events, including cospeciation, host switching, sorting, duplication, and failure to speciate. The relative frequency of these events may be influenced by factors that govern the distribution and abundance of the interacting groups; i.e., ecological factors. If so, it may be possible to predict the degree of phylogenetic congruence between two groups from information about their ecology. Unfortunately, adequate comparative ecological data are not available for many of the systems that have been subjected to cophylogenetic analysis. An exception is provided by chewing lice (Insecta: Phthiraptera), which parasitize birds and mammals. For a few genera of these lice, enough data have now been published to begin exploring the relationship between ecology and congruence. In general, there is a correspondence between important ecological factors and the degree of phylogenetic congruence. Careful comparison of these genera suggests that dispersal is a more fundamental barrier to host switching among related hosts than is establishment. Transfer experiments show that host-specific lice can survive and reproduce on novel hosts that are similar in size to the native host as long as the lice can disperse to these hosts. To date, studies of parasite dispersal have been mainly inferential. A better understanding of the role of dispersal will require more direct data on dispersal frequency and distances.

Animals↗
PubMed2000

Seabird and louse coevolution: complex histories revealed by 12S rRNA sequences and reconciliation analyses.

We investigated the coevolutionary history of seabirds (orders Procellariiformes and Sphenisciformes) and their lice (order Phthiraptera). Independent trees were produced for the seabirds (tree derived from 12S ribosomal RNA, isoenzyme, and behavioral data) and their lice (trees derived from 12S rRNA data). Brook's parsimony analysis (BPA) supported a general history of cospeciation (consistency index = 0.84, retention index = 0.81). We inferred that the homoplasy in the BPA was caused by one intrahost speciation, one potential host-switching, and eight or nine sorting events. Using reconciliation analysis, we quantified the cost of fitting the louse tree onto the seabird tree. The reconciled trees postulated one host-switching, nine cospeciation, three or four intrahost speciation, and 11 to 14 sorting events. The number of cospeciation events was significantly more than would be expected from chance alone (P < 0.01). The sequence data were used to test for rate heterogeneity for both seabirds and lice. Neither data set displayed significant rate heterogeneity. An examination of the codivergent nodes revealed that seabirds and lice have cospeciated synchronously and that lice have evolved at approximately 5.5 times the rate of seabirds. The degree of sequence divergence supported some of the postulated intrahost speciation events (e.g., Halipeurus predated the evolution of their present hosts). The sequence data also supported some of the postulated host-switching events. These results demonstrate the value of sequence data and reconciliation analyses in unraveling complex histories between hosts and their parasites.

Animals↗
PubMed2004

Scratching an ancient itch: an Eocene bird louse fossil.

Out of the 30 extant orders of insects, all but one, the parasitic lice (Insecta: Phthiraptera), have a confirmed fossil record. Here, we report the discovery of what appears to be the first bird louse fossil: an exceptionally well-preserved specimen collected from the crater of the Eckfeld maar near Manderscheid, Germany. The 44-million-year-old specimen shows close phylogenetic affinities with modern feather louse ectoparasites of aquatic birds. Preservation of feather remnants in the specimen's foregut confirms its association as a bird ectoparasite. Based on a phylogenetic analysis of the specimen and palaeoecological data, we suggest that this louse was the parasite of a large ancestor to modern Anseriformes (swans, geese and ducks) or Charadriiformes (shorebirds). The crown group position of this fossil in the phylogeny of lice confirms the group's long coevolutionary history with birds and points to an early origin for lice, perhaps inherited from early-feathered theropod dinosaurs.

Animals↗
PubMed2006

Fossil Liposcelididae and the lice ages (Insecta: Psocodea).

Fossilized, winged adults belonging to the psocopteran family Liposcelididae are reported in amber from the mid-Cretaceous (ca 100 Myr) of Myanmar (described as Cretoscelis burmitica, gen. et sp. n.) and the Miocene (ca 20 Myr) of the Dominican Republic (Belaphopsocus dominicus sp. n.). Cretoscelis is an extinct sister group to all other Liposcelididae and the family is the free-living sister group to the true lice (order Phthiraptera, all of which are ectoparasites of birds and mammals). A phylogenetic hypothesis of relationships among genera of Liposcelididae, including fossils, reveals perfect correspondence between the chronology of fossils and cladistic rank of taxa. Lice and Liposcelididae minimally diverged 100 Myr, perhaps even in the earliest Cretaceous 145 Myr or earlier, in which case the hosts of lice would have been early mammals, early birds and possibly other feathered theropod dinosaurs, as well as haired pterosaurs.

Animals↗
PubMed2003

Linking coevolutionary history to ecological process: doves and lice.

Many host-specific parasites are restricted to a limited range of host species by ecological barriers that impede dispersal and successful establishment. In some cases, microevolutionary differentiation is apparent on top of host specificity, as evidenced by significant parasite population genetic structure among host populations. Ecological barriers responsible for specificity and genetic structure can, in principle, reinforce macroevolutionary processes that generate congruent host-parasite phylogenies. However, few studies have explored both the micro- and macroevolutionary ramifications of close association in a single host-parasite system. Here we compare the macroevolutionary histories of two genera of feather lice (Phthiraptera: Ischnocera) that both parasitize New World pigeons and doves (Aves: Columbiformes). Earlier work has shown that dove body lice (genus Physconelloides) are more host specific and have greater population genetic structure than dove wing lice (Columbicola). We reconstructed phylogenies for representatives of the two genera of lice and their hosts, using nuclear and mitochondrial DNA sequences. The phylogenies were well resolved and generally well supported. We compared the phylogenies of body lice and wing lice to the host phylogeny using reconciliation analyses. We found that dove body lice show strong evidence of cospeciation whereas dove wing lice do not. Although the ecology of body and wing lice is very similar, differences in their dispersal ability may underlie these joint differences in host specificity, population genetic structure, and coevolutionary history.

Animals↗