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.     

Population biology of swift (Apus apus) ectoparasites in relation to host reproductive success

Abstract.

• 1 We censused ectoparasite populations of adult and nestling swifts over the course of the host's breeding season. Nearly all of the birds were infested with chewing lice and two-thirds of the nests were infested with louse flies. Feather mites were observed but not quantified.
• 2 Lice and louse flies both showed aggregated distributions among hosts. Louse eggs, hatched lice and adult louse flies had negative binomial distributions, whereas the aggregated distribution of louse fly pupae was not adequately described by negative binomial or Poisson models.
• 3 Transmission of lice from parents to offspring was documented. A comparison of the age structure of lice on parents and offspring indicated that most transmission was by nymphal lice.
• 4 Host reproductive success and survival appeared to be independent of the number of lice or louse flies. Neither parasite correlated with the number, body mass, or date of fledging of young birds, nor with the overwinter survival of adults. We caution, however, that experimental manipulations of parasite load are required for a definitive test of the impact of ectoparasites on evolutionary fitness components.

     

On the ubiquity and phylogeny of Wolbachia in lice

Wolbachia are intracellular bacteria that occur in an estimated 20% of arthropod species. They are of broad interest because they profoundly affect the reproductive fitness of diverse host taxa. Here we document the apparent ubiquity and diversity of Wolbachia in the insect orders Anoplura (sucking lice) and Mallophaga (chewing lice), by detecting single or multiple infections in each of 25 tested populations of lice, representing 19 species from 15 genera spanning eight taxonomic families. Phylogenetic analyses indicate a high diversity of Wolbachia in lice, as evidenced by the identification of 39 unique strains. Some of these strains are apparently unique to lice, whereas others are similar to strains that infect other insect taxa. Wolbachia are transmitted from infected females to their offspring via egg cytoplasm, such that similar species of lice are predicted to have similar strains of Wolbachia. This predicted pattern is not supported in the current study and may reflect multiple events of recent horizontal transmission between host species. At present, there is no known mechanism that would allow for this latter mode of transmission to and within species of lice.     

Intrinsic rate of natural increase of Brueelia amandavae (Ischnocera, Phthiraptera) populations infesting Indian red avadavat

The incubation period of eggs, duration of three nymphal instars, adult longevity and the daily egg-deposition rate of the ischnoceran Phthiraptera, Brueelia amandavae, were determined by rearing the louse in vitro (35 ± 1°C, 75–82% RH, feather diet). The data obtained were utilized for life table construction and determination of the intrinsic rate of natural increase (0.031 per day) and the doubling time (23.45 days) of the louse population. The doubling time of the louse in in vivo experiments was 21.5 days.     

Molecular identification of Campanulotes bidentatus Scopoli, 1763 (Phthiraptera,Philopteridae) infecting the domestic pigeon Columba livia from Saudi Arabia

The taxonomy of the order Phthiraptera is unstable and still problematic to researchers. Most of the current taxon classifications are mainly based on morphological features. Campanulotes bidentatus belongs to the chewing lice of the Philopteridae family that mostly parasitic on birds. There is a lack of sequence data and phylogenetic analyses on the family Philopteridae. In the current study, C. bidentatus was collected from the domestic pigeon Columba livia and identified morphologically and molecularly based on the mitochondrial cytochrome c oxidase subunit 1 gene (COI). The infection rate of the Campanulotes genus was approximately 58.82% in this study. Phylogenetic analysis based on the mt COI gene was informative for members of Philopteridae and the group taxon genera formed distinct clades. Future studies were recommended using the 16s rRNA to enhance the tree topology and obtain clear differentiation between genera.     

Integrating phylogenomic and population genomic patterns in avian lice provides a more complete picture of parasite evolution

Parasite diversity accounts for most of the biodiversity on earth, and is shaped by many processes (e.g., cospeciation, host switching). To identify the effects of the processes that shape parasite diversity, it is ideal to incorporate both deep (phylogenetic) and shallow (population) perspectives. To this end, we developed a novel workflow to obtain phylogenetic and population genetic data from whole genome sequences of body lice parasitizing New World ground‐doves. Phylogenies from these data showed consistent, highly resolved species‐level relationships for the lice. By comparing the louse and ground‐dove phylogenies, we found that over long‐term evolutionary scales their phylogenies were largely congruent. Many louse lineages (both species and populations) also demonstrated high host‐specificity, suggesting ground‐dove divergence is a primary driver of their parasites’ diversity. However, the few louse taxa that are generalists are structured according to biogeography at the population level. This suggests dispersal among sympatric hosts has some effect on body louse diversity, but over deeper time scales the parasites eventually sort according to host species. Overall, our results demonstrate that multiple factors explain the patterns of diversity in this group of parasites, and that the effects of these factors can vary over different evolutionary scales. The integrative approach we employed was crucial for uncovering these patterns, and should be broadly applicable to other studies.     

A hitchhiker’s guide to parasite transmission: The phoretic behaviour of feather lice

Transmission to new hosts is a fundamental challenge for parasites. Some species meet this challenge by hitchhiking on other, more mobile parasite species, a behaviour known as phoresis. For example, feather-feeding lice that parasitise birds disperse to new hosts by hitchhiking on parasitic louse flies, which fly between individual birds. Oddly, however, some species of feather lice do not engage in phoresis. For example, although Rock Pigeon (Columba livia) “wing” lice (Columbicola columbae) frequently move to new hosts phoretically on louse flies (Pseudolynchia canariensis), Rock Pigeon “body” lice (Campanulotes compar) do not. This difference in phoretic behaviour is puzzling because the two species of lice have very similar life cycles and are equally dependent on transmission to new hosts. We conducted a series of experiments designed to compare the orientation, locomotion and attachment capabilities of these two species of lice, in relation to louse flies. We show that wing lice use fly activity as a cue in orientation and locomotion, whereas body lice do not. We also show that wing lice are more capable of remaining attached to active flies that are walking, grooming or flying. The superior phoretic ability of wing lice may be related to morphological adaptations for life on wing feathers, compared to body feathers.     

Human lice show photopositive behaviour to white light

We studied the behavioural response of body lice and head lice to white light. We also evaluated the influence of starvation and the presence of other individuals on this response. Experiments were performed in a rectangular arena, half of which was illuminated and the other half kept in the dark. Two experiments were performed: in the first, a single louse was released into the arena for 60 min and the percentage of time spent in the illuminated half was recorded; in the second experiment, a group of lice was released and the number of insects in the illuminated half was recorded. The results showed that the average number of lice and time spent in the illuminated side of the arena was statistically higher than for the controls. Starvation did not influence the reaction of lice, but the number of insects in the illuminated area did increase with the size of the group. This study shows that human lice are photopositive towards white light and that this behaviour is not affected by the nutritional state of the insects. Moreover, it is enhanced by the presence of other lice.     

Three new species of the genus Philopteroides Mey, 2004 (Phthiraptera,Ischnocera, Philopteridae) from?New?Zealand

We describe and illustrate three new species of chewing lice in the genus Philopteroides parasitic on passerines (Order Passeriformes, families Acanthizidae, Rhipiduridae and Petroicidae) from New Zealand. They are: Philopteroides pilgrimisp. n. from Gerygone igata igata; Philopteroides fuliginosussp. n. from Rhipidura fuliginosa placabilis and Rhipidura fuliginosa fuliginosa; and Philopteroides macrocephalussp. n. from Petroica macrocephala macrocephala and Petroica macrocephala dannefaerdi. The identity of Docophorus lineatus Giebel, 1874 is discussed based on its morphology and host association. We also transfer Tyranniphilopterus beckeri to the genus Philopteroides, and provide a key to identify adults of 12 of the 13 species now included in Philopteroides.