New microsporidia parasitizing bark lice (Insecta: Psocoptera)

Two species of bark lice, Xanthocaecilius sommermanae Mockford and Polypsocus corruptus Hagen, collected in a canopy Malaise trap placed in Great Smoky Mountains National Park as part of a survey of the park’s fauna, were found to be infected with microsporidia. Diagnosis was originally based on light microscopy, and was confirmed by PCR amplification and electron microscopy. This is the first record of microsporidia infection in the insect order Psocoptera. Four morphological spore types corresponded to four original SSUrDNA sequences (Genbank accession no. FJ865221-24), suggesting infection with four microsporidia species. Two of those species were examined by electron microscopy. We describe here one new genus and two new species based on morphological and sequence data: Antonospora psocopterae sp. n. with elongated diplokaryotic spores, 4.4 ± 0.05 × 1.9 ± 0.03 μm and Mockfordia xanthocaeciliae gen. n. sp. n. with ovocylindrical monokaryotic spores, 2.5 ± 0.10 × 1.4 ± 0.02 μm. A. psocopterae displayed high sequence (95%) and structural similarity with Antonospora scoticae, fell within a well supported dichotomy with A. scoticae inside the Antonospora-Paranosema clade in phylogenetic analyses by NJ, PS and ML. M. xanthocaeciliae did not exhibit much sequence or structural similarity with any of known microsporidia species, except Encephalitozoon spp. M. xanthocaeciliae fell within one clade with Encephalitozoon spp. in phylogenies and shared with encephalitozoons structural resemblance and about 80% of SSUrDNA sequence identity. The other two species were not described and provisionally were placed to the collective genus Microsporidium as Microsporidium sp. 1 and Microsporidium sp. 4 from bark lice because of insufficient morphological data. The finding that samples fixed and stored for months in propylene glycol (“antifreeze”) are good enough for DNA sequence analysis and can be used for morphological analyses (if no better fixation alternatives are available), is promising for future surveys for microsporidia.     

Elevated genetic diversity of mitochondrial genes in asexual populations of Bark Lice ('Psocoptera': Echmepteryx hageni)

Asexual reproduction is commonly thought to be associated with low genetic diversity in animals. Echmepteryx hageni (Insecta: 'Psocoptera') is one of several psocopteran species that are primarily parthenogenetic, but also exists in small, isolated sexual populations. We used mitochondrial DNA sequences to investigate the population history and genealogical relationships between the sexual and asexual forms of this species. The asexual population of E. hageni exhibits extremely high mitochondrial haplotype diversity (H=0.98), whereas the sexual forms had significantly lower haplotypic diversity (H=0.25, after correcting for sample size). This diversity in asexuals represents one the greatest genetic diversities reported for asexual animals in the literature. Nucleotide diversities were also higher in asexual compared to sexual populations (π=0.0071 vs. 0.00027). Compared to other reported estimates of π in insects, asexual nucleotide diversity is high, but not remarkably elevated. Three hypotheses might explain the elevated genetic diversity of asexual populations: (i) larger effective population size, (ii) greater mutation rate or (iii) possible recent origin of sexuals. In addition, phylogeographic analysis revealed little geographic structure among asexual E. hageni, although specimens from the upper Midwest form a single clade and are genetically differentiated. The mismatch distribution and neutrality tests indicate a historical population size increase, possibly associated with expansion from glacial refugia.     

Parthenogenesis in Psocids (Insecta: Psocoptera)

SYNOPSIS. Obligate thelytokous parthenogenesis and, more rarely,facultative thelytoky are known to occur in psocids. The formerphenomenon is known in 28 species. The latter is known onlyin two species, both of which have obligatorily thelytokousforms as well as bisexual ones. Attempts to force thelytokousfemales to mate have been carried out for four nominal species.All have failed. Differences in color or color pattern betweenthe bisexual and thelytokous forms of a nominal species havebeen observed in two instances. In Echmepteryx hageni this seemsto involve divergence where the two forms occur sympatricallybut on different habitats. Investigations of geographic distributionof bisexual and thelytokous forms of a nominal species showin several cases that the thelytokous forms are much more widespreadthan the bisexual ones. In eastern United States, bisexual formstend to occur peripherally and in ecologically unusual areas.The areas of occurrence of bisexual populations may be relictual,and some of them may have been Pleistocene refugia. Most ofthese areas correspond to areas where coniferous trees now forman important part of the forest.     

Automictic and apomictic parthenogenesis in psocids (Insecta: Psocoptera)

Karyotypes and meiosis patterns in three obligatory thelytokous Psocoptera species have been studied for the first time. Females of Aaroniella badonneli (Danks) display 9 chiasmatic bivalents in oocyte metaphase I (2n = 18), hence meiosis is of the automictic type. Females of Ectopsocus meridionalis Ribaga and Valenzuela sp. display 3n = 27, and 27 univalent chromosomes are present in oocyte metaphase I. Thus, meiosis in these species is of the apomictic type.     

Ultrastructure and cluster formation in ovaries of bark lice,Peripsocus phaeopterus (Stephens) and Stenopsocus stigmaticus (Imhof and Labram) (Insecta : Psocoptera)

Ultrastructure and previtellogenic growth of ovaries of Peripsocus phaeopterus (Stephens) and Stenopsocus stigmaticus (Imhof and Labram) (Insecta : Psocoptera) are described. The germ cell cluster formation was analyzed in an ovariole of a nymph using ultrathin serial sectioning. Fifteen germ cell clusters were found; 13 contained 4 cystocytes each, while 2 clusters, situated in the very tip, were composed of 2 cystocytes each. A fully developed cluster rises by 2 synchronized mitotic divisions, each followed by incomplete cytokinesis. Microtubules derived from the preceding mitoses form a transient midbody within the intercellular bridge. Later on, a fusome fills each bridge, while at fusomal rims parallel oriented microtubules are tightly associated. Some of these microtubules stretch to cell membranes nearby. The fusomes fuse into a polyfusome and a rosette is thus formed by which all intercellular bridges are drawn together. All cystocytes enter the prophase of meiosis up to pachynema. One of the 2 inner cells continues meiosis and develops as an oocyte, whereas all others transform into nurse cells. After rosette formation, the polyfusome-associated microtubules vanish and some time later, when the nurse cell-oocyte differentiation becomes apparent, the polyfusome itself becomes destroyed. The intercellular bridge, joining the first nurse cell with the 3rd moves away from the other 2. During previtellogenesis, 5 phases can be distinguished, 2 of which are interpreted as logarithmical growth phases with different slopes. The whole set of characters elaborated here for the polytrophic meroistic ovary of psocopterans is fully consistent with the characters of polytrophic meroistic ovaries of Holometabola, indicating a monophyletic origin.     

Four new Psocoptera from Lebanese amber (Insecta: Psocomorpha: Trogiomorpha)

Four new trogiomorphan Psocoptera are described from the Lower Cretaceous Lebanese amber, viz. Bcharreglaris amunobi n. gen., n. sp., Setoglaris reemae n.gen., n. sp., Libanoglaris chehabi n.sp., and Libanoglaris randatae n. sp. These discoveries show that the Lower Cretaceous biodiversity of the Trogiomorpha was very high.     

Sense organs on the antennal flagellum of psocids (Insecta,Psocoptera)

The sense organs on the antennal flagella of five species of winged psocids belonging to two families of Psocoptera, Psocidae and Leptopsocidae, have been examined. All agree in possessing tactile hairs, thick-walled chemoreceptors and long, porous chemoreceptors. Thin-walled chemoreceptors were identified in all species except Metylophorous novaescotiae. Coeloconic chemoreceptors were present in all species except Echmepteryx hageni. Campaniform sense organs were found only in Metylophorus novaescotiae and Psocus leidyi.     

Coexistence of bisexual and unisexual populations of Nysius groenlandicus in the Zackenberg Valley,Northeast Greenland

The seed‐feeding true bug Nysius groenlandicus (Zetterstedt) (Heteroptera: Lygaeidae) has temperature and humidity preferences similar to many desert‐inhabiting insects. Nevertheless, it is widely distributed in Greenland and occurs even in high arctic areas. This seeming paradox implies that the species has developed physiological, ecological, and behavioral mechanisms that enable it to cope with the extreme arctic environment. One of these adaptations is its ability to reproduce both sexually and asexually. Sexual reproduction is most common in coastal populations, whereas asexual reproduction (parthenogenesis) occurs mainly in inland populations. Preliminary data from the Zackenberg Valley in Northeast Greenland indicated that both reproductive strategies occurred within the same area. We therefore decided to focus on this area to find evidence of (1) coexistence of unisexual and bisexual populations, (2) factors that correlate with the distribution of the two reproductive types, and (3) morphological differences between females from sexual and asexual populations. We sampled N. groenlandicus at 51 sites within the Zackenberg area. Males and females were found in almost equal numbers in only four of the samples, and only in samples taken close to the coast line, whereas samples from the inner part of the valley consisted almost entirely of females. Thus, the distribution of uni‐ and bisexual populations at the local scale agreed with the pattern previously found for Greenland as a whole. Using data obtained from two climate stations operated in the area, we showed that average summer temperatures tend to be more favorable for N. groenlandicus in the inner part of the valley than at the coast. The inland populations inhabited small isolated patches, whereas the sexual populations were found in the more homogeneous areas along the coast. Data support the hypothesis that coexistence of the two reproductive types is maintained by a combination of environmental variability, which gives sexual reproduction an advantage, and metapopulation dynamics characterized by frequent extinctions and re‐colonizations, which favors asexual reproduction. Head width of females from unisexual populations was on average 7% larger than that of females from bisexual populations. The mechanism behind this morphological difference needs further investigation.     

Remarkable levels of avian louse (Insecta: Phthiraptera) diversity in the Congo Basin

Although the Democratic Republic of the Congo is considered a megadiverse country, the Congo Basin is not recognized as a conservation priority because of gross underestimates of species diversity and endemism, especially for invertebrate taxa. Examining ectoparasitic chewing lice parasitizing birds in this region could provide valuable information pertaining to the diversity of invertebrate taxa as well as host–parasite interactions within the Congo Basin. In this study, we used molecular and morphological data to examine avian louse diversity. From 60 parasitized birds, we documented 39 new host associations, and at least 12 and 17 species of amblyceran and ischnoceran chewing lice, respectively. Morphologically, we identified a minimum of 13 new species. Due to a lack of available reference material, we were unable to identify some specimens and it is likely many, if not all of these, represent new species. Our sampling efforts, morphological examinations and molecular analyses reveal an astounding amount of louse diversity in the Congo Basin.     

Molecular systematics of the bark lice infraorder Caeciliusetae (Insecta: Psocodea)

The phylogenetic relationships of bark lice and parasitic lice (Insecta: Psocodea) have been studied in a number of recent molecular phylogenetic analyses based on DNA sequences. Many of these studies have focused on the position of parasitic lice within the free‐living bark lice. However, fewer such studies have examined the relationships among major groups of free‐living bark lice and their implications for classification. In this study we focus on the infraorder Caeciliusetae, a large group of bark lice (?1000 species) within the suborder Psocomorpha. Using sequences of two mitochondrial and two nuclear genes, we estimated the phylogeny for relationships among the five recognized families within the infraorder Caeciliusetae. Based on the results, the sister‐group relationship and respective monophyly of Stenopsocidae and Dasydemellidae is strongly supported. Monophyly of the larger families Amphipsocidae and Caeciliusidae was not supported, although the causes of this were the placement of two distinct subfamilies (Paracaeciliinae and Calocaeciliinae). The monophyly of Asiopsocidae could not be tested because it was sampled only by one species. Based on these results and consideration of morphological characters, we propose a new classification for Caeciliusetae, recognizing six families: Amphipsocidae, Stenopsocidae, Dasydemellidae, Asiopsocidae, Paracaeciliidae and Caeciliusidae. We expect that this new classification will stabilize the higher‐level taxonomy of this group and help to identify groups in need of further work among these insects.     

Population genetics of Himalayan balsam (Impatiens glandulifera): comparison of native and introduced populations

Background: Invasive species can interfere in the structure and functioning of ecosystems. Better understanding of the evolution of such species will be useful when planning their management and eradication.

Aims: We aimed to compare patterns of genetic variability in Impatiens glandulifera in native and introduced regions.

Methods: We used native samples from India and Pakistan, and non-native samples from Canada, Finland and the UK. Genetic analyses included genotyping using 10 microsatellite markers and sequencing of the nuclear ITS region.

Results: Mean allele numbers from native and introduced samples were even, 8.8 and 8.5, respectively, while expected heterozygosities were higher in native samples (mean 0.738) than in non-native samples (mean 0.477). Hardy–Weinberg equilibrium testing indicated significant heterozygote deficiencies at 70% of the loci. Inbreeding coefficients were high in both native and introduced regions (range 0.201–0.726). STRUCTURE analyses showed that native samples from India and Pakistan possessed similar clustering patterns while non-native samples from the UK and Canada resembled each other. One of the four Finnish populations had a similar pattern with the UK and Canadian populations, while the rest showed similarly unique genetic compositions. ITS sequencing indicated in Pakistani samples two polymorphic sites not found in Indian samples but present in some samples from Canada, Finland and the UK.

Conclusions: Distinct population genetic patterns indicate that human-mediated dispersal is important in I. glandulifera.     

Transmission ratio distortion in the human body louse, Pediculus humanus (Insecta: Phthiraptera)

We studied inheritance at three microsatellite loci in eight F, and two F2 families of the body (clothes) louse of humans, Pediculus humanus. The alleles of heterozygous female-parents were always inherited in a Mendelian fashion in these families. Alleles from heterozygous male-parents, however, were inherited in two different ways: (i) in a Mendelian fashion and (ii) in a non-Mendelian fashion, where males passed to their offspring only one of their two alleles, that is, 100% nonrandom transmission. In male body lice, where there was non-Mendelian inheritance, the paternally inherited set of alleles was eliminated. We interpret this pattern of inheritance as evidence for extreme transmission ratio distortion of paternal alleles in this species.     

New species of bark beetles from the Rovno amber (Insecta: Coleoptera: Scolytidae)

Two new species of bark beetles are described from the Late Eocene Rovno amber. Xylechinus mozolevskae sp. nov. (Hylesininae: Tomicini) is the first fossil representative of this genus, differing from recent species in having large triangular scales along the suture. Taphramites rovnoensis sp. nov. (Scolytinae: Dryocoetini) differs from the closest species, T. gnathotrichus from Baltic amber, in the presence of short thin hairs on the elytra.     

Studies on populations of Folsomia candida (Insecta: Collembola)

Summary Experiments are described that were designed to investigate the effects of food availability and rate of exploitation on the growth and production of populations of Folsomia candida (Willem). In an initial experiment in which there was excess food it was found that increasing the rate of exploitation resulted in increases in both the numerical and biomass productivity of the populations. In a second experiment it was shown that, when there is severe competition for food, the rate of exploitation does not affect either the biomass or the numerical production. It is concluded that the effect of overcrowding, in the form of competition for space, does contribute to the growth in numbers of populations, but that the supply of food plays a more important role in regulating the population. Anomalous results, showing that exploitation has a lesser effect when there is severe competition for food, are discussed.     

Reinterpretations of clypeus and maxilla in Psocoptera, and their significance in phylogeny of Paraneoptera (Insecta: Neoptera)

Morphology of the head and mouthparts in Psocoptera was investigated, and revised interpretations for clypeus and maxilla were proposed. The convex plate in the frontal region of the head capsule is the postclypeus, rather than the frons; the galea is clearly differentiated from the stipes and the origin of the stipito-lacinial muscle is partly shifted from the stipes to the base of the galea; the cardo is completely fused with the stipes without any suture or sulcus. Brief discussions on the evolution of piercing and sucking mouthparts and on the phylogeny of Paraneoptera were provided, based on these revised interpretations.