Phylogeny of the hard ticks (Ixodidae) inferred from 18S rRNA indicates that the genus Aponomma is paraphyletic

We examined the phylogeny of ticks (Acari:Parasitiformes:Ixodida) and their closest known mite relatives (Acari:Parasitiformes:Mesostigmata and Holothyrida) using 18S rRNA sequences. In our analyses, we included sequences from 36 taxa. Sequences for 13 hard ticks (Family Ixodidae), 5 soft ticks (Family Argasidae), and 2 mesostigmatid mites were obtained from the GenBank database and we generated sequences for 15 hard ticks and 1 holothyrid mite. Ten of these tick species were endemic to Australia. Our analyses indicated that the suborder Holothyrida is more closely related to Ixodida than to Mesostigmata, the group used as outgroup in earlier molecular studies. This finding is consistent with Lehtinen's (1991) hypothesis that the Holothyrida rather than the Mesostigmata is the sister-group to the Ixodida. Within the hard ticks the genus Aponomma and thus the family Amblyomminae were paraphyletic. Taxonomic revision of these taxa is needed. The genus Amblyomma was paraphyletic without the inclusion of "typical" Aponomma species (Ap. latum and Ap. fimbriatum). There was a basal divergence between endemic Australian and other species in both the Metastriata and the Prostriata divisions of the hard ticks.     

Phylogeny of parasitiform mites (Acari) based on rRNA

Acari (mites and ticks) form one the most diverse lineages of arthropods, but basal relationships in the group are still poorly understood. The current study addresses this issue for one of its two main lineages, the order Parasitiformes. Relationships are examined at the subordinal and infraordinal level using complete 18S and partial 28S nuclear rRNA sequence data. Most currently recognized lineages are recovered with good support, suggesting that nuclear rRNA, and specifically 18S rRNA, is very well suited for analyzing relationships at this level in this lineage. These results were found despite quite variable rates of sequence evolution, with rates "ratcheting up" from relatively low in most non-mite arachnid lineages, to intermediate in Pseudoscorpiones, the mite order Acariformes, and the parasitiform suborders Opilioacarida, Holothyrida, and Ixodida, to high in the parasitiform suborder Mesostigmata. The most species rich mesostigmatid infraorder, Dermanyssina, shows huge distances to the outgroups, but remarkably low within-group divergence in nuclear rRNA. This suggests the possibility of a relatively recent origin of this lineage.     

Zonal types of host-parasite complexes of arthropods and small mammals in the west Siberian Plain

Comparative analysis of the composition, population structure, and landscape distribution of small mammals and associated parasitic arthropods was performed for the plain part of West Siberia. Four main zonal complexes were distinguished, corresponding to different landscape zones or subzones: tundra, forest, forest-steppe (the northern forest-steppe subzone), and steppe (the southern forest-steppe subzone and steppes). The parasite specificity of each complex is defined by different systematic and ecological groups of arthropods: the tundra complex is defined by epizoic gamasid mites (Acari: Parasitiformes: Mesostigmata), the forest and forest-steppe complexes are defined by ticks (Acari: Parasitiformes: Ixodides) and fleas (Insecta: Siphonaptera), and the steppe complex is defined by fleas and nidicolous gamasid mites.     

Mesostigmatid Mites (Acari: Mesostigmata) on Rainforest Tree Trunks: Arboreal Specialists, but Substrate Generalists?

Predatory mites (Acari: Mesostigmata) on tree trunks without significant epiphytic growth in a subtropical rainforest in Eastern Australia were assessed for habitat specificity (i.e. whether they are tree trunk specialists or occupying other habitats) and the influence of host tree and bark structure on their abundance, species richness and species composition. The trunks of nine tree species from eight plant families representing smooth, intermediate and rough bark textures were sampled using a knockdown insecticide spray. In total, 12 species or morphospecies of Mesostigmata (excluding Uropodina sensu stricto) were collected, most of which are undescribed. Comparison with collections from other habitats indicates that epicorticolous Mesostigmata are mainly represented by suspended soil dwellers (six species), secondarily by generalists (four species) and a bark specialist (one species). A typical ground-dwelling species was also found but was represented only by a single individual. In terms of abundance, 50.5% of individuals were suspended soil dwellers, 40.7% bark specialists, and 8.3% generalists. Host species and bark roughness had no significant effect on abundance or species richness. Furthermore, there was no clear effect on species composition. The distribution of the most frequently encountered species suggests that most mesostigmatid mites living on bark use many or most rainforest tree species, independent of bark roughness. These findings support the hypothesis that some epicorticolous Mesostigmata use tree trunks as ‘highways’ for dispersing between habitat patches, while others use it as a permanent habitat.     

Phoretic mites associated with animal and human decomposition

Phoretic mites are likely the most abundant arthropods found on carcases and corpses. They outnumber their scavenger carriers in both number and diversity. Many phoretic mites travel on scavenger insects and are highly specific; they will arrive on a particular species of host and no other. Because of this, they may be useful as trace indicators of their carriers even when their carriers are absent. Phoretic mites can be valuable markers of time. They are usually found in a specialised transitional transport or dispersal stage, often moulting and transforming to adults shortly after arrival on a carcase or corpse. Many are characterised by faster development and generation cycles than their carriers. Humans are normally unaware, but we too carry mites; they are skin mites that are present in our clothes. More than 212 phoretic mite species associated with carcases have been reported in the literature. Among these, mites belonging to the Mesostigmata form the dominant group, represented by 127 species with 25 phoretic mite species belonging to the family Parasitidae and 48 to the Macrochelidae. Most of these mesostigmatids are associated with particular species of flies or carrion beetles, though some are associated with small mammals arriving during the early stages of decomposition. During dry decay, members of the Astigmata are more frequently found; 52 species are phoretic on scavengers, and the majority of these travel on late-arriving scavengers such as hide beetles, skin beetles and moths. Several species of carrion beetles can visit a corpse simultaneously, and each may carry 1–10 species of phoretic mites. An informative diversity of phoretic mites may be found on a decaying carcass at any given time. The composition of the phoretic mite assemblage on a carcass might provide valuable information about the conditions of and time elapsed since death.     

A Preliminary Assessment of the Utility of Elongation Factor-1α in Elucidating Relationships Among Basal Mesostigmata

Phylogenetic relationships in the Mesostigmata are assessed using DNA sequence data for a segment of the elongation factor-1alpha gene. This is the first application of this nuclear protein coding gene to problems of higher relationships in Parasitiformes. Initial testing revealed extensive variability in nucleotide and corresponding amino acid sequences, both among and within mesostigmatid infraorders. However, accuracy, as assessed by the ability of these data to recover well-supported taxa, was inconsistent for all analyses using unweighted data. None of these analyses consistently recovered Mesostigmata, although less inclusive taxa, such as Uropodina and Trigynaspida, were often recovered. Accuracy was highest for an analysis using applied weighting on the nucleotide sequence data. The overall results provide support for monophyly of Uropodina, Trigynaspida, and a grouping of Zerconina, Parasitina, and Dermanyssina, and suggest close relationships between Heterozerconina and Sejina.     

The functional morphology of the respiratory system of the Holothyrida (= Tetrastigmata) Acari: Anactinotrichida

The respiratory system of Holothyrus coccinella Gervais (Holothyridae) and Allothyrus australasiae (Womersley) (Allothyridae) were examined. The stigma-peritreme complex is connected to tracheae and ventilated by indirect muscles. The peritreme provides an alternative route for the entry of air into the tracheal system, should a stigma be occluded by debris and retards water vapour transpiration, the mechanisms of which are compared in the two species.     

Coprophilous mite communities as affected by concentration of plastic and glass particles

The community and trophic structure of mites was examined in cattle manure and their response to treatment of manure with solid-waste particles was investigated. Mites were collected from artificial dung pats exposed to natural colonization in the field for 16 days. The pats were composed of manure alone or manure separately mixed with waste-material particles of four types and concentrations.Mites were the numerically dominant taxon among arthropods in manure. The Prostigmata was the most abundant suborder, mainly represented by the families Pygmephoridae and Ereynetidae. The common families of Mesostigmata were all cosmopolitan. Correlations with other arthropods suggest that Mesostigmata are opportunistic predators, preying upon dipteran larvae, Collembola and other mites, and preyed upon by larger predatory insect larvae. Cryptostigmata and Astigmata were a numerically minor community component.The species composition and abundance upon treatment of manure with polyethylene, polystyrene and glass particles was similar to that of the treatment control, i.e. natural and inert sand. Relatively low concentrations, 5 and 30% (v/v), of particles in manure did not alter the mite communities despite important differences with untreated manure in final moisture content. These findings may be relevant to proposed methods of solid-waste disposal. High particle concentrations of 60 and 90% had detrimental effects to the abundance of mites in manure and were caused by the very low final moisture content and probably nutrient deficiency of these treatments. The persistence of members of the prostigmatid families Tydeidae, Nanorchestidae and Tarsonemidae in the moisture-deficient 90%-concentration treatments supports previous evidence of adaptations to low-water-content habitats.     

An ant-associated mesostigmatid mite in Baltic amber

Fossil mesostigmatid mites (Acari: Parasitiformes: Mesostigmata) are extremely rare, and specimens from only nine families, including four named species, have been described so far. A new record of Myrmozercon sp. described here from Eocene (ca 44–49 Myr) Baltic amber represents the first—and so far only—fossil example of the derived, extant family Laelapidae. Significantly, modern species of this genus are habitually myrmecophilous and the fossil mite described here is preserved attached to the head of the dolichoderine ant Ctenobethylus goepperti (Mayr, 1868). It thus offers the oldest unequivocal evidence for an ecological association between mesostigmatid mites and social insects in the order Hymenoptera.     

Effects of a mulch layer on the assemblage and abundance of mesostigmatan mites and other arthropods in the soil of a sugarcane agro-ecosystem in Australia

Sugarcane farmers can utilise a soil conservation technique called green cane trash blanketing, a form of mulching that can increase plant productivity through a number of channels, e.g., via altering soil physical, chemical and biological characteristics, and influence soil arthropod assemblages. Predatory mites (Mesostigmata) are important components of soil communities because they can control populations of other soil-dwelling pest species. Our aim was to characterise mulch-influenced predatory Mesostigmata community assemblages in sugarcane soils in Queensland, Australia. We found that application of a mulch layer significantly increased the abundance of Mesostigmata, and oribatid mites and collembolans, in soils. Furthermore, we observed that the assemblages of Mesostigmata in soil covered by mulch were significantly different to those in bare soil; and the assemblages of Mesostigmata changed over time. The assemblages of Mesostigmata, but not Oribatida or collembolans, were significantly different in soil under mulch depending on whether the mulch was freshly laid, or decomposing. Our results show that the use of mulch, specifically the green cane trash blanket, can increase overall microarthropod abundance including Mesostigmata. This is likely due to increased habitat complexity and changing resource availability.     

Characteristics of zonal distribution of the gamasid mites connected with small mammals and their nests in Western Siberia

Analysis of long-term data on the fauna, landscape distribution, and structure of communities of the gamasid mites (Acari:Parasitiformes:Mesostigmata) connected with small mammals and their nests in the plain part of Western Siberia is carried out. By now, presence of 249 gamasid mite species is established in the territory under study, including 193 free-living and 56 parasitic species. Gamasid mites are represented by the maximal number of species on small mammals and in thers nests in northern forest-steppe (102 and 105 species respectively). Nine parasitic species from two ecological groups (epizoic and nidicolous) were found in all landscape zones of the West Siberian Plain, namely: 1) epizoic species Laelaps clethrionomydis Lange, 1955, Laelaps hilaris C. L. Koch, 1836, and Hyperlaelaps arvalis Zachvatkin, 1948 (obligatory non-exclusive hematophagous); 2) nidicolous species Androlaelaps casalis Berlese, 1887 (obligatory non-exclusive hematophagous), Eulaelaps stabularis C. L. Koch, 1836, Haemogamasus nidiformnes Bregetova, 1955 (facultative hematophagous), Haemnogamnasus ambulans Thorell, 1872 (obligatory non-exclusive hematophagous), Hirstionyssus isabellinus Oudemans, 1913, and Hirstionyssus eusoricis Bregetova, 1956 (obligatory exclusive hematophagous). Last three species demonstrate the mixed type of parasitism. The population of gamasid mites on small mammals is most specific in tundra, southern forest-steppe and steppe; the fauna of gamasid mites in nests is most specific in southern forest-steppe and steppe.     

Landscape aspects of host-parasite relationships between parasitic arthropods and the narrow-skulled vole Microtus gregalis (Rodentia) in Western Siberia

Comparative zoogeographic analysis of outcomes accumulated in the course of long-term investigation the parasitic and free-living arthropods (Acarina: Parasitiformes; Insecta: Siphonaptera) associated with three subspecies of the narrow-skulled vole (Microtus gregalis gregalis, M. g. major, M. g. eversmanni) in various landscape zones and subzones in a flat part of Western Siberia, foothills of the Altai-Sayan mountain system and mountains of Southwest Altai. The obtained data, on the one hand, recover specific features of certain parasite communities that reflect ecological peculiarity of a host species living in conditions of concrete landscapes, on the other hand, a high degree of similarity between species set of some ectoparasitic and nidicolous arthropod groups from different subspecies of M. gregalis. The systematic list of ectoparasitic and nidicolous arthropods associated with M. gregalis and representing Gamasoidea mites, ticks and fleas is provided.     

Mitochondrial genome reorganization characterizes various lineages of mesostigmatid mites (Acari: Parasitiformes)

Mesostigmata is an extremely diverse group of mites with more than 11,000 described species in 109 families. The complete mitochondrial (mt) genomes of five species of mesostigmatid mites from three families (Varroidae, Ologamasidae, Phytoseiidae) have been reported previously; all of them are rearranged or highly rearranged in gene order. However, it is unclear when mt genome reorganization occurred and how common it is in mesostigmatid mites. We sequenced the mt genomes of ten species of mesostigmatid mites from five more families (Blattisociidae, Diplogyniidae, Laelapidae, Macrochelidae, Parasitidae). We found that species in the families Diplogyniidae and Parasitidae have retained the ancestral mt genome organization of arthropods, which is in stark contrast to the highly rearranged mt genomes in the Phytoseiidae species. As in the Varroidae and Ologamasidae species, the mt genomes of the Blattisociidae, Macrochelidae and Laelapidae species are also rearranged but are less rearranged than in the Phytoseiidae species. Each of the six mesostigmatid families that have rearranged mt genomes is characterized by unique gene order not seen in other mesostigmatid families. Furthermore, the mt genome organization also differs among three genera of the Phytoseiidae, between two genera of the Laelapidae, and among three Macrocheles species of the Macrochelidae. Our results indicate that: (a) the most recent common ancestor of mesostigmatid mites likely retained the ancestral mt genome organization of arthropods; and (b) mt genome organization characterizes various lineages of mesostigmatid mites and provides a valuable source of information for understanding their phylogeny and evolution.     

Predatory Mites in Tropical Australia: Local Species Richness complementarity1

Although little supporting data is available, mites (Acari) are often considered to be one of the ‘hyperdiverse’ taxa in tropical ecosystems. To test this assumption, we sampled single guilds of predatory mites (Hydracarina and Mesostigmata) in three different habitats (fresh water, rotting fungi, and forest foliage) across a range of sites in monsoonal, wet-tropical, and subtropical Australia. Most species (61%) were collected at a single site; as a result, all seven collector's curves rose steeply with little indication of reaching asymptotes. Regional faunas ranged from 87–94 percent distinct and of the 247 species identified, 114 (46%) were previously unknown in Australia and appear to be new. Even within taxonomically well-studied groups, such as the Hydracarina and Phytoseiidae, we found many new species (32% and 60%, respectively). Our results suggest that the diversity of tropical mites is very high and comparable to that of many insect taxa. We propose a simple model to explain our results, i.e. that in the tropics, high levels of complementarity between sites amplify local mite species richness. We tested this model by additional sampling, comparing within-site to between-site complementarity, and contrasting temperate with tropical foliar Mesostigmata. As predicted by the model, collecting at new sites continued to accumulate new species, complementarity was significantly greater between-sites than within-sites (72 vs. 25%), and temperate collections were more homogeneous and less diverse than tropical collections.     

Arthropods in biodiversity hotspots: the case of the Phytoseiidae (Acari: Mesostigmata)

The biodiversity hotspot concept was defined by Myers in 1988 to determine priority areas for conservation. They have high endemism levels and have lost more than 70% of their original vegetated area. To date, there is little information on arthropod diversity in these zones. This work focuses on the biodiversity of the Phytoseiidae (Acari), one of the best known among the order Mesostigmata, in these threatened areas. These mites are usually predators and they are worldwide spread. Geographic distribution of phytoseiids in 27 biodiversity hostspots was assessed from data of the last world catalogue published in 2004. One thousand two hundred and thirty species are reported from at least one hotspot (62% of the total species number) and 604 species (30% of the total species number) are endemic to the 27 hotspots considered. The number of reports/publication in hotspot areas (2.6) is higher than in non-hotspot zones (1.5). Hotspots areas could be thus considered as a great reservoir of the Phytoseiidae diversity, just as they are for vertebrates and plants. Correlations between plant, vertebrate, mite diversity and endemism, as well as congruence rates between endemism levels of these three organisms suggest that the biodiversity patterns of plants and vertebrates mirror well those of the Phytoseiidae (both for endemicity and species richness). More intense conservation efforts in biodiversity hotspots would thus be assumed to affect plant and vertebrate biodiversity, as already known, but also arthropod biodiversity, as it was assumed. These results further support thus the importance of these zones in biodiversity conservation, even for organisms like mites, very small and poorly studied in this regards. More data on arthropods are, however, required to confirm these preliminary observations.     

Natural enemies of natural enemies: the potential top‐down impact of predators on entomopathogenic nematode populations

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Parasite in peril? A new species of mite in the genus Ophiomegistus Banks (Parasitiformes: Paramegistidae) on an endangered host,the pygmy bluetongue lizard Tiliqua adelaidensis (Peters) (Squamata: Scincidae)

Host‐parasite relationships are generally understudied in wild populations but have a potential to influence host population dynamics and the broader ecosystem, which becomes particularly important when the host is endangered. Herein we describe a new species of parasitic mite from the genus Ophiomegistus (Parasitiformes: Mesostigmata: Paramegistidae) of an endangered South Australian skink; the pygmy bluetongue lizard (Tiliqua adelaidensis). Adult mites were observed on lizard hosts in three different host populations, among which prevalence varied. No temporal trend in prevalence was evident over two spring‐summer seasons of monitoring. We hypothesise that the reliance on burrows as refuges by T. adelaidensis may be essential for the completion of the mite life cycle and also for horizontal transmission. The conservation implications of not only its effect on the host, but also its potential status as an endangered species itself, are considered.     

Carcases and mites

Mites are involved in the decomposition of animal carcases and human corpses at every stage. From initial decay at the fresh stage until dry decomposition at the skeletal stage, a huge diversity of Acari, including members of the Mesostigmata, Prostigmata, Astigmata, Endeostigmata, Oribatida and Ixodida, are an integral part of the constantly changing food webs on, in and beneath the carrion. During the desiccation stage in wave 6 of Mégnin’s system, mites can become the dominant fauna on the decomposing body. Under conditions unfavourable for the colonisation of insects, such as concealment, low temperature or mummification, mites might become the most important or even the only arthropods on a dead body. Some mite species will be represented by a few specimens, whereas others might build up in numbers to several million individuals. Astigmata are most prominent in numbers and Mesostigmata in diversity. More than 100 mite species and over 60 mite families were collected from animal carcases, and around 75 species and over 20 families from human corpses.     

Adults of European ant‐like stone beetles (Coleoptera: Staphylinidae: Scydmaeninae) Scydmaenus tarsatus Müller & Kunze and Scydmaenus hellwigii (Herbst) prey on soft‐bodied arthropods

Scydmaenine beetles are commonly described as predators specialized in capturing and feeding on armored mites of the order Oribatida, and documented cases of feeding on other live arthropods have not been known. Based on laboratory observations and a broad choice of Acari (armored and soft‐bodied) and other soil arthropods, food preferences and associated behavior of two scydmaenine species are clarified and described. Adults of Scydmaenus tarsatus ignored oribatid and mesostigmatan mites, but readily attacked and fed on a soft‐bodied Rhizoglyphus sp. (Acaridae), and on small springtails, especially on Ceratophysella denticulata (Hypogastruridae). A water drinking behavior was observed for this species, not reported previously in any Staphylinidae. Scydmaenus hellwigii ignored all tested Acari (including Rhizoglyphus) and scavenged on dead neanurine collembolans or freshly cut pieces of large springtails; a long term culture was maintained by feeding beetles with isotomid springtails. Previously reported strict specialization of Scydmaenus as a predator on Oribatida was not confirmed and it is concluded that the studied species feed on live soft‐bodied organisms and scavenge on dead arthropods.     

Mesostigmata diversity by manure type: a reference study and new datasets from southwestern Iran

Manure-inhabiting Mesostigmata mites are important biological control agents of pest flies. However, the biodiversity of this mite community is mainly known from Europe and America, and especially from cattle manure. This study examined the diversity and abundance of Mesostigmata mites associated with various types of manure in an (intensive) agricultural region of the Middle East, i.e., the city Ahvaz and its suburbs, in southwest Iran. Mite samples were extracted from manure of cattle, buffalo, sheep, horse, poultry and quail in 30 livestock and poultry farms. In total, 40 species belonging to 24 genera and 16 families were identified. The most diverse families were Laelapidae with eight species, Macrochelidae with seven and Parasitidae with six. Macrocheles muscaedomesticae and Uroobovella marginata were the most widespread species, recorded in 28 and 27 out of 30 collection sites, respectively. Two species, M. sumbaensis and U. marginata, were found in all studied manures. Simpson’s diversity index recorded the highest diversity in buffalo and sheep manure. Real and theoretical species richness (rarefaction curves) were congruent in number of individuals. The presence of seven species of Macrochelidae in the manure confirms that these are important predators of the house fly for the region of Ahvaz and its suburbs. Members of the Parasitidae were highly prevalent, with one species known as a specialized predator of house fly eggs. This work aims to encourage further studies on the diversity of Mesostigmata in these agricultural settings, and further continue assessing the feasibility of these mites as effective biocontrol agents of filth flies in different types of manure and from different corners of the world.