Mites of the family Cheyletidae (Acari: Prostigmata): phylogeny, distribution, evolution and analysis of parasite-host relationship

A modern system, phylogeny, distribution and host parasite relationships of cheyletid mites (Acari: Prostigmatal Cheyletidae) is shortly discussed. According to the phylogenetic hypothesis proposed by Bochkov and Fain (2001), the family Cheyletidae includes now 15 tribes: Acaropsellini, Bakini, Cheletogenini, Cheletosomatini, Chelonotini, Cheyletiini, Cheyletiellini, Cheyletini, Cheletomorphini, Criokerontini, Metacheyletiini, Niheliini, Ornithocheyletiini, Teinocheylini and one unnamed tribe including the genera Caudacheles and Alliea. The parasitic Cheyletidae were primarily free-living predators, frequently associated with nests of vertebrates. These mites, being predators, have numerous preadaptations to the parasitic mode of life and they possess high ecological plasticity. Therefore it was quite easy for these mites to adapt to parasitism on the vertebrates. According to our phylogenetical hypothesis, the parasitism on vertebrates has arisen independently in several phylogenetic lines of the cheyletids associated with nests of vertebrates. Such transition from nest predation to true parasitism probably occurred repeatedly and at different times. The cheyletid mites are more widely represented on birds than on mammals. Possibly, it is in relation with a more early origin of parasitism in the cheyletids associated with bird nests than in the cheyletids associated with mammal nests. An independent origin of the parasitism in many different cheyletid phyletic lines, arisen significantly later than the origin of such a parasitic group as myobiid mites, is probably the main reason, which could explain the recent mosaic distribution of the Cheyletidae among the mammalian taxa. Parasitic associations between cheyletids and vertebrates are more common than the associations between these mites and the invertebrates. In the invertebrates, these associations are generally restricted to a phoresy. The zoogeographical analysis showed that this family as whole is characterised by the extremely low endemisms. The most part of the free-living cheyletid mites are associated with Holarctic region (87%) and, therefore, this family, probably, originated there.     

Types of parasitism of acarines and insects on terrestrial vertebrates

According to the recent taxonomic revisions, over 40000 species of insects and acarines are parasites or micropredatory blood-suckers of mammals and birds. The largest fraction of them are micropredators and temporary or permanent ectoparasites, the minority being endoparasitic. Some arthropods (blood-sucking dipterans) use the host primarily as a food resource, whereas for others (many astigmatic mites) the host constitutes the entire environment. A number of life forms, or types of parasitism, have arisen in the insects and acarines in the course of their adaptive evolution to parasitism on terrestrial vertebrates. The term “type of parasitism” designates a set of convergently arising morpho-physiological and ecological adaptations (adaptive complexes), demonstrated by different arthropod taxa. A classification of the types of parasitism in arthropods is proposed based on their temporal, spatial, and trophic associations with vertebrates. The following seven types of parasitism are distinguished: micropredatory blood-suckers, nest ectoparasites (nidicoles), temporary ectoparasites with prolonged feeding, permanent ectoparasites, intracutaneous endoparasites, cavity endoparasites, and tissue endoparasites.     

Harmfulness of parasitic insects and acarines to mammals and birds

The paper summarizes the results of investigations on the harmfulness of the blood-sucking arthropods and ectoparasites to terrestrial vertebrates. Pathogenicity of parasitic arthropods strongly depends on the type of parasitism. Harmfulness to the hosts is analyzed separately in blood-sucking dipterans, ixodid ticks, gadflies, and both temporary (fleas and bugs) and permanent (biting lice, lice, acariform mites) ectoparasites. The pathogenicity of parasitic arthropods for the host organism is conditioned by the direct loss of blood and tissues, toxic effect of the arthropod’s saliva, and allergic reactions. Indirect injury from parasites is associated with deterioration of the host’s nutrition and loss of weight and viability. Pathogenicity for the host not resulting in its death is typical of parasitic arthropods, except for heavy attacks by blood-sucking Diptera which may lead to death of domesticated and wild animals. Most data on the pathogenicity of arthropods for vertebrates refer to domesticated animals. Annual losses to the world livestock breeding attributed to insects and acarines amount to several billion dollars. Direct evidence of ectoparasite pathogenicity to wild animals and effect on the host’s vital functions, reproduction, and population numbers in particular, is limited and unconvincing.     

Specificity of host-parasite relations between arthropods and terrestrial vertebrates

Specificity of partners in host-parasite system is one of its main characteristics. Unfortunately this term has different senses in scientific literature. In everyday practice one judges an extent of host specificity of a parasite mainly by indices of its occurrence and abundance on different host species. An occurrence of parasites in nature reflects general result of complex eco-physiological interrelationships between partners in hostparasite system. Specificity of parasites in a choice of hosts may depend on a belonging of the latter to certain taxa (phylogenetic specificity), or on biotic and abiotic factors (ecological specificity). In arthropods, the phylogentic specificity and coevolution are characteristic to a greater extent for permanent hosts (lice, Mallophaga, cheyletoid and feather mites). A coevolutionaryphylogenesis is disturbed by transfers of parasites onto new hosts, by different rates of speciation in filial lines or by an extinction of several parasite taxa. In temporary parasites different forms of ecological specificity are prevalent. A host specificity is expressed to the lesser extent in mosquitoes, horseflies and in other blood-sucking Diptera. In temporary parasites with a long-term feeding (ticks) coevolutionary sequences are relatively rare, because this parasites had to adapt not only to a life on host, but also to a lesser stable environment. In some nest-burrow bloodsuckers (fleas, gamasid mites and argasid ticks) the ecological specificity is shown no by their relations with certain host species, but by an associations with habitats occupied by hosts (burrow, nests, caves). In relation with a high dynamics of host-parasite system, a specificity of its partners is comparative and it is kept up only under specific ecological conditions.     

Morphological adaptations of acariform mites (Acari: Acariformes) to permanent parasitism on mammals

The external morphological adaptations to parasitism in acariform mites (Acari: Acariformes), permanently parasiting mammals, are briefly summated and analyzed. According to several external morphological criteria (structures of gnathosoma, idiosoma, setation, legs and life cycle), the following six morphoecotypes were established: skin mites (i)-- Cheyletidae, Chirorhynchobiidae, Lobalgidae, Myobiidae, Myocoptidae (the most part), Rhyncoptidae, Psoroptidae; fur mites (ii)--Atopomelidae, Clirodiscidae, Listrophoridae, Myocoptidae (Trichoecius only); skin burrowing mites (iii)--Sarcoptidae; intradermal mites (iv) - sorergatidae and Demodicidae; interstitial mites (v) - pimyodicidae; respiratory mites (vi) - reynetidae, Gastronyssidae, Lemurnyssidae, Pneumocoptidae. In the case of prostigmatic mites, the detailed reconstruction of the origin and evolution of "parasitic" morphoecotypes is possible due to the tentative phylogenetic hypotheses, which were proposed for the infraorder Eleutherengon, a, including the most part of the permanent mammalian parasites among prostigmatic mites (Kethley in Norton, 1993; Bochkov, 2002). The parasitism of Speleognathinae (Ereynetidae) in the mammalian respiratory tract arose independently of the other prostigmats. It is quite possible that these mites switched on mammals from birds, because they are more widely represented on these hosts than on mammals. The prostigmatic parasitism on mammalian skin seems to be originated independently in myobiids, in the five cheyletid tribes, Cheyletiellini, Niheliini, and Teinocheylini, Chelonotini, Cheyletini, and, probably, in a cheyletoid ansector of the sister families Psorergatidae-Demodicidae (Bochkov, Fain, 2001; Bochkov, 2002). Demodicids and psorergatids developed adaptations to parasitism in the skin gland ducts and directly in the epithelial level, respectively in the process of the subsequent specialization. Mites of the family Epimyodicidae belong to the phylogenetic line independent of other cheyletoids. These mites possess the separate chelicerae and, therefore, can not be included to the superfamily Cheyletoidea. It is not quite clear whether they were skin parasites initially or they directly switched to parasitism from the predation. The phylogeny of sarcoptoid mites (Psoroptidia: Sarcoptoidea) is not developed, however, some hypotheses about origin and the following evolution of their morphoecotypes can be proposed. We belive that astigmatic mites inhabiting the mammalian respiratory tract transferred to parasitism independently of other sarcoptoids. The idiosoma of these mites is not so much flattened dorso-ventrally and has proportions which are similar to hose of free-living astigmatids. Moreover, in the most archaic species, the legs are not shortened or thickened as in the most parasites. The disappearance of many morphological structures in these mites, probably, happened parallely with some other sarcoptoids due to their parasitic mode of life. The skin inhabiting sarcoptoids belong to the "basic" morphoecotype, and all other sarcoptoid morphoecotypes, excluding respiratory mites, are derived from it. Some mites of this morphoecotype live on the concave surfaces of the widened spine-like hairs of the rodents belonging to the family Echimyidae (mites of the subfamily Echimytricalginae), in the mammalian ears (some Psoroptidae) or partially sink into the hair follicles (Rhynocoptidae). Finally, mites of the family Chirorhynchobiidae live on the bat wing edges attaching to them by their "ixodid-like" gnathosoma. The fur-sarcoptoids, probably, originated from the skin mites. This morphoecotype is divided onto two subtypes: mites with the dorso-ventrally flattened idiosoma (subtype I) and mites with the teretial idiosoma (subtype II). Each "fur-mite" family includes mites of the both subtypes. All mites of the first subtype belong to the early derivative lineages in their families. Among listrophorids such early derivative lineage is represented by the subfamily Aplodontochirinae (Bochkov, OConnor, 2006), and among Chirodiscidae--by mites of the subfamilies Chirodiscinae, Schizocoptinae, and Lemuroeciinae. Among the "fur" astigmatid families, the family Atopomelidae. probably, is the most archaic, and the most part of atopomelids belongs to the first subtype. However there are several more specialized atopomelid genera belonging to the second subtype, Atopomelus, Dasyurochirus, Lemuroptes, Murichirus, Metachiroecius etc. We believe that mites of the first subtype are represented by the "intermediate" forms between skin mites and mites of the second subtype. Some skin sarcoptoids transferred from skin parasitism to burrowing of the host skin (Sarcoptidae). The established morphoecotypes are partially corresponding to some morphoecotypes established by Mironov (1987) for feather mites. Our morphoecotypes of skin and skin burrowing mites perfectly correspond to Mironov's epidermoptoid and knemidocoptoid morphoecotypes, respectively. The proctophylloid morphoecotype (mites living on the wing feathers), which is the most widely represented within feather mites, has an analogy among mammalian mites - the subfamily Echimytricalginae. The analgoid (mites living in the down feathers) and dermoglyphoid (mites living in the feather quills) morphoecotypes have no analogues among mammalian mites for the obvious reasons. It is interesting why some microhabitats on the host body are not still occupied by prostigmatic or astigmatic mites. We believe that the nutrition is the main limitative factor here. The parasitic prostigmates evolved from predators and, therefore, feed on content of the living cells. They need the direct contact with the live tissues of the host and they belong, therefore, to the morphoecotypes represented by the respiratory, skin, gland duct, intradermal, and interstitial mites. Whereas, the most part of the skin inhabiting astigmats feed on the dead epithelial scales. For this reason these mites, so easily colonized fur of their hosts and feed on the hair grease there. On the other hand, some sarcoptoids transferred to the true parasitism and feed on the cambial cells of the skin epithelium. More over we do not know exactly about nutrition of rhyncoptids yet.     

Candidate predators for biological control of the poultry red mite Dermanyssus gallinae

The poultry red mite, Dermanyssus gallinae, is currently a significant pest in the poultry industry in Europe. Biological control by the introduction of predatory mites is one of the various options for controlling poultry red mites. Here, we present the first results of an attempt to identify potential predators by surveying the mite fauna of European starling (Sturnus vulgaris) nests, by assessing their ability to feed on poultry red mites and by testing for their inability to extract blood from bird hosts, i.e., newly hatched, young starlings and chickens. Two genuine predators of poultry red mites are identified: Hypoaspis aculeifer and Androlaelaps casalis. A review of the literature shows that some authors suspected the latter species to parasitize on the blood of birds and mammals, but they did not provide experimental evidence for these feeding habits and/or overlooked published evidence showing the reverse. We advocate careful analysis of the trophic structure of arthropods inhabiting bird nests as a basis for identifying candidate predators for control of poultry red mites.     

The characteristics of the relationships of arthropods of the refuge complex with the causative agents of transmissible viral infections in bird rookeries

The isolation of viruses of tick-borne encephalitis, West Nile fever, and Omsk hemorrhagic fever from arthropods of nests of colonial birds (rook, sand martin, tree sparrow, Laridae) in different zones of West Siberia (from tundra to steppe) has been analyzed. The role of gamasid mites, hematophages and saprophages, characteristic inhabitants of nests of colonial birds, and of the tick Ixodes lividus in connection with their biology, coadaptation with hosts, microclimatic nest conditions, etc. has been evaluated. It has been concluded that the whole nest community of arthropods in a nest rather than one infected individual has to be regarded as an infective unit in colonies.     

Parasite Infestation and Parental Care in the Barn Swallow Hirundo rustical a Test of the Resource-provisioning Model of Parasite-mediated Sexual Selection

Barn swallows, Hirundo rustica, are commonly infested by the haematophagous tropical fowl mite Omithonyssus bursa (Macronyssidae, Gamasida), which severely reduces various measures of reproductive success among the barn swallow hosts. Food provisioning rate by parent barn swallows, measured in terms of absolute feeding rate by males and females and relative feeding rate by males (percentage of food provided by the male parent), was not significantly related to natural levels of infestation of nests. Experimental manipulation of mite loads in nests during the egg-laying period of the first clutch, which also affected mite loads of parent barn swallows, significantly affected food-provisioning rates of single-brooded, but not of double-brooded barn swallows. These results suggest that effects of mites on the parenting ability of barn swallow hosts depend on host resistance towards parasites. This is consistent with the resource-provisioning hypothesis of parasite-mediated sexual selection, suggesting that females prefer parasite-free males because they are efficient parents, but also with the hypothesis that females prefer males with traits signalling genetic resistance to parasites.     

Feather mites (Acari: Astigmata) and body condition of their avian hosts: a large correlative study

Feather mites are arthropods that live on or in the feathers of birds, and are among the commonest avian ectosymbionts. However, the nature of the ecological interaction between feather mites and birds remains unclear, some studies reporting negative effects of feather mites on their hosts and others reporting positive or no effects. Here we use a large dataset comprising 20 189 measurements taken from 83 species of birds collected during 22 yr in 151 localities from seven countries in Europe and North Africa to explore the correlation between feather mite abundance and body condition of their hosts. We predicted that, if wing‐dwelling feather mites are parasites, a negative correlation with host body condition should be found, while a mutualistic interaction should yield positive correlation. Although negative relationships between feather mite abundance and host body condition were found in a few species of birds, the sign of the correlation was positive in most bird species (69%). The overall effect size was only slightly positive (r =0.066). The effect of feather mite abundance explained <10% of variance in body condition in most species (87%). Results suggest that feather mites are not parasites of birds, but rather that they hold a commensalistic relationship where feather mites may benefit from feeding on uropygial gland secretions of their hosts and birds do not seem to obtain a great benefit from the presence of feather mites.     

Morphology of Parasitengona mites (Acariformes: Parasitengona) and their possible evolutionary scenario

On the basis of the analysis of morphology and biology of representatives of the Parasitengona, mostly trombiculids, trombidiids and water mites, a new attempt is made to clarify probable evolutionary scenario in this group of the higher trombidiform mites (Actinedida). It is supposed that the very old ancestral group of terrestrial arachnids, having bite-sucking mouth-parts, poorly differentiated sac-like midgut and capability to extra-oral digestion, fed predatory on different small soil arthropods at all phases of the life cycle. They were small segmented orthotrichous homeomorphic arachnids at the rank of genus or family. The favorable feeding conditions of the adult phase have led to the small eggs rich in yolk and the small larva. The latter have led in turn to the necessity of intensive feeding at the larval stage to complete the ontogenesis. Further in evolution, this group gave rise at once to two or even more large paraphyletic branches. Most of them retained feeding on arthropods with transition of larvae to much more effective parasitic feeding provided with the additional specialization of the larval stage. This branch comprise divergently radiated paraphyletic terrestrial and secondary-water water mites each having long course of evolution resulted in the recent groups of Calyptostomatoidea, Erythraeoidea, Trombidioidea and several superfamilies of water mites. Another branch of the ancestral Parasitengona has followed the way of adaptation of larvae to feeding on vertebrates, which were being attacked by the larvae in the environment of pasture. The parasitism on vertebrates has lead to several radical specializations of these mites and their significant evolutionary progress. At the same time, the similar ontogenetic dynamics, as well as synchronous reduction of particular developmental stages in all parasitengones, inevitably indicate the monophyletic origin of the whole branch of Parasitengona with Pterygosomatidae as the most probable sister group.     

A review of available methods and description of a new method for eliminating ectoparasites from bird nests

Bird nests offer an ideal situation to manipulate ectoparasites and study how they impact hosts. Several methods are available to eliminate parasites from nests and each has its own suite of advantages and disadvantages. For example, recent toxicity research has revealed that some commonly used insecticides may not be suitable for use in experiments with nestlings. This highlights the need for investigators to control for the effects of methods used to eliminate nest parasites within experimental designs. Methods that can be used across treatment groups are also often needed to study the effects of variation in parasite intensity. To aid investigators in deciding which method(s) to use, we provide a comprehensive review of available methods for eliminating nest ectoparasites and also describe a new heat gun method. We tested the effectiveness of the heat‐gun method with nests of Barn Swallows (Hirundo rustica) to which 100 nest mites were added and then quantified the number of surviving mites and other naturally occurring arthropods. We found that fully heated nests had significantly fewer mites and other arthropods than partially heated or control nests. Use of the heat gun had no negative effects on nestling growth or mortality rates. In studies of avian nest ectoparasites, investigators need to consider methods that can be used across treatment groups to ensure that unaccounted for toxicity effects are not influencing results and leading to underestimation of the often subtle effects of ectoparasites on birds.     

Ecological correlates of body size in gamasid mites parasitic on small mammals: abundance and niche breadth

We studied ecological correlates of body size (abundance and niche breadth) in gamasid mites parasitic on small mammals in 28 regions of the Palearctic. We predicted that smaller species would be characterized by higher abundance than larger species, all else (e.g. host species) being equal. We also predicted that host specificity of mites would decrease (that is, number of host species they use would increase) with an increase in their body size. We focused on mites collected from host bodies that include a) species that feed solely on host’s blood (obligate exclusive haematophages), b) species that feed on both host’s blood and small arthropods (obligate non‐exclusive haematophages), and c) facultative haematophages. We expected that the relationship between body size and abundance and/or host specificity would be more pronounced in obligate exclusively haematophagous mites than for obligate non‐exclusively and facultative haematophagous mites. Across all mite species across regions, mean abundance correlated negatively with body size. The same was true for obligate haematophagous species, but not for facultative haematophages. When mite communities on the same host in a location were considered, the negative body mass–abundance relationship was found in only 3 of 44 communities. Nevertheless, a meta‐analytic (across host species) estimate of the slope of this relationship appeared to be significantly negative. No significant relationship between mite body size and host specificity was found in the analyses across all mite species as well as in obligate exclusive or obligate non‐exclusive haematophages. However, the number of hosts used by facultative haematophagous mites decreased significantly with an increase in their body size. We explain the relationships between morphological (body size) and ecological (abundance and niche breadth) properties of ectoparasites by their interactions with hosts or physical environment.     

Blood-feeding in mosquitoes: probing time and salivary gland anti-haemostatic activities in representatives of three genera (Aedes, Anopheles, Culex)

Mosquitoes (Diptera: Culicidae) face their hosts' haemostatic mechanisms when attempting to feed on blood. Accordingly, they antagonize haemostasis by salivary agents that include anti-clotting, anti-platelet and vasodilatory compounds. Because haemostasis is a complex and redundant physiological response that varies between vertebrates, it is to be expected that haematophagous animals have a salivary armoury that most efficiently counteracts their preferred hosts. The mosquito Culex quinquefasciatus Say, which has a strong tendency to ornithophagy, appears to have only recently adapted to mammals and may not have evolved efficient mechanisms to counteract mammalian platelet responses, while birds only have relatively inefficient thrombocytes. Accordingly, we compared the probing behaviour of Cx. quinquefasciatus with two other mosquito species from different backgrounds: Aedes aegypti (L.) and Anopheles albimanus Weidemann, that have apparently had a longer evolutionary association with mammals. Culex takes much more time to find blood on a mammalian host (human or mouse) when compared to the two other mosquito species, but does not differ in probing behaviour when feeding on a chicken. Salivary anti-haemostatic components were also measured in those three species of mosquito and results are discussed in context with the probing behaviour.     

The origin of parasitism in trombiculid mites (Acariformes: Trombiculidae)]

On the basis of literary data and original investigations some phylogenetic, ecological and morphological aspects of the origin of parasitism in trombiculid mites are carefully considered for the first time. It is shown that parasitism in this group of trombidiform mites is a relatively young historical phenomenon and was formed after their ontogenesis had differentiated into active and quiescent stages. Therefore, in the life pattern of trombiculid mites the character of individual development, that defines their biotopical restriction, is much more important than the phase parasitism. Primitive organization of the digestive system and extraintestinal digestion, so characteristic of this group, are one of the main reasons of the origin of their parasitism. Under pasture conditions trombiculid mites, that initially were predators-entomophages with bite-sucking mouth parts, pass easily to parasitism on vertebrate animals and become primary lymphophages. They use the vertebrate host's organism exclusively as a source of food and by the extent of polyphagia are very close to free-living blood-sucking insects. Stylostome, that develops during feeding of trombiculid larvae and some other closely related groups of trombidiform mites, is a universal structure for achieving a large amount of food on a wide range of animals during a relatively short period of time and reflects wide host-parasite specificity of these parasitic mites. From the historical view the larvae of trombiculid mites did not pass from one group of hosts to the others, but owing to morphological preadaptation to parasitism passed in a definite historical period, not earlier than Paleogene, to parasitism on all classes of terrestrial vertebrates, especially on mammals, their primary hosts.     

Are hippoboscid flies a major mode of transmission of feather mites?

Feather mites (Astigmata) are distributed around the world, living on the feathers of birds, but their mechanisms for transmission among hosts are not fully understood. There is anecdotal evidence of feather mites attached to louseflies (Diptera: Hippoboscidae), suggesting that feather mites may use these flies as a mode of phoretic transmission among birds. Two bird-lousefly associations (alpine swift Apus melba-Crataerina melbae and feral pigeon Columba livia-Pseudolynchia canariensis) were inspected to test the hypothesis that feather mites use hippoboscid flies as major mode of transmission. Both bird species showed a high prevalence and abundance of feather mites and louseflies. However, no feather mites were found attached to the 405 louseflies inspected, although skin mites (Epidermoptidae and Cheyletiellidae) were found on louseflies collected from feral pigeons. This study suggests that feather mites do not use hippoboscid flies as a major mode of transmission among birds.     

Potential role of parasitism in the evolution of mutualism in astigmatid mites: Hemisarcoptes cooremani as a model

Phoresy is a symbiotic interaction that results in dispersal, benefiting the relocated organism without negatively impacting the phoretic host. It has long been considered that phoresy among astigmatid mites is somehow an intermediate precursor to the evolution of parasitism within the group. In astigmatid mites, only the heteromorphic deutonymph (hypopode) participates in phoretic dispersal, and the plesiomorphic hypopode may be the key to understanding the dynamics of the evolution of that parasitism. Hypopodes of Hemisarcoptes cooremani (Acari: Acariformes) and their phoretic beetle host Chilocorus cacti (Coleoptera: Coccinellidae) have become the experimental focus for studies concerned with the potential forces that influence the transition of a free-living life style into various coevolved relationships. Previous radiolabeling studies applied to H. cooremani and C. cacti determined that hypopodes of H. cooremani acquired resources from adults of C. cacti while in transit, negating the paradigm that the heteromorphy was purely phoretic. To further probe this relationship, we tested whether materials could be passed from the mites to their hosts. We report here a study using a tritium radiolabel, which indicated that beetles also acquire resources from the hypopodes. These results have implications for understanding the complex relationship between H. cooremani and C. cacti. We propose that this relationship should now correctly be defined as mutualistic (not phoretic) and develop a general model for the potential role of parasitism in the evolution of mutualism among the Astigmata.     

Contrasting diversity dynamics of phoretic mites and beetles associated with vertebrate carrion

Carrion is an ephemeral and nutrient-rich resource that attracts a diverse array of arthropods as it decomposes. Carrion-associated mites often disperse between animal carcasses using phoresy, the transport of one species by another. Yet few studies have contrasted the dynamics of mite assemblages with other insect taxa present at carrion. We examined and compared the changes in abundance, species richness and composition of mite and beetle assemblages sampled at kangaroo carcasses in a grassy eucalypt woodland at four different times over a 6-month period. We found that the majority of mites were phoretic, with the mesostigmatid genera Uroseius (Uropodidae), Macrocheles (Macrochelidae) and Parasitus (Parasitidae) the most abundant taxa (excluding astigmatid mites). Abundance and richness patterns of mites and beetles were very different, with mites reaching peak abundance and richness at weeks 6 and 12, and beetles at weeks 1 and 6. Both mites and beetles showed clear successional patterns via changes in species presence and relative abundance. Our study shows that mesostigmatid mite assemblages have a delay in peak abundance and richness relative to beetle assemblages. This suggests that differences in dispersal and reproductive traits of arthropods may contribute to the contrasting diversity dynamics of carrion arthropod communities, and further highlights the role of carrion as a driver of diversity and heterogeneity in ecosystems.     

Origin and higher-level relationships of psoroptidian mites (Acari: Astigmata: Psoroptidia): evidence from three nuclear genes

Phylogenic relationships of the Psoroptidia, a group of primarily parasitic mites of vertebrates, were investigated based on sequences from three nuclear genes (4.2 kb aligned) sampled from 126 taxa. Several morphological classification schemes and a recent molecular analysis, suggesting that the group may not be monophyletic were statistically rejected by newly generated molecular data, and the results are robust under a range of analytical and partition strategies. Six families Psoroptidae, Lobalgidae (mammalian parasites), Pyroglyphidae (house dust mites and parasites inside feather calamus), Turbinoptidae (upper respiratory track parasites of birds), Psoroptoididae (downy feather mites), and Epidermoptidae (skin parasites of birds) form a well-supported monophyletic group (the epidermoptid-psoroptid complex). These relationships, recovered by combined and separate analyses of all gene partitions, were previously suspected based on some morphological evidence, but evidence has been dismissed as resulting from convergence based on similar parasitic ecologies. The existence of the epidermoptid-psoroptid complex and the statistical rejection of Sarcoptoidea (the morphology-based group joining all mammal-associated mites) indicate that current classification criteria, influenced as they are by host preferences, need to be reassessed for non-pterolichoid superfamilies. However, two of our findings remain sensitive to analytical methods and assumptions: (i) the families Heterocoptidae and Hypoderatidae as the first and second closest outgroups of Psoroptidia, respectively, and (ii) the superfamily Pterolichoidea (including Freyanoidea) forming a sister clade to the remaining psoroptidian superfamilies. Our findings suggest that (i) house dust mites (Pyroglyphidae: Dermatophagoidinae) originated from a parasitic ancestor within the core of Psoroptidia, violating a basic principle of evolution that it is virtually impossible for a permanent parasite to become free-living, and (ii) there were at least two shifts from presumably avian to mammalian hosts.     

Larval parasitism of spring-dwelling alpine water mites (Hydrachnidia,Acari): a study with particular reference to chironomid hosts

During faunistic investigations on spring habitats in the alpine National Park Berchtesgaden (Bavaria, Germany), water mites were found to be the group with the highest share of species strongly adapted to springs. At four sample sites at two spring complexes, insect emergence was screened for parasitism by larval water mites. A total of at least 36 host species were recorded as being parasitized by 19 water mite species. As in many other habitats, the most important host taxon was shown to be the nematoceran family Chironomidae, both in the number of species and individuals parasitized. Likewise, the number of water mite species attached to chironomids was high. Further host species were found among the Plecoptera, Trichoptera, Coleoptera, Limoniidae and Empididae (Diptera). These taxa were only parasitized by a single water mite species in each case. For 13 mite species, new hosts were recorded for the first time. For another six species, the known host spectrum could be confirmed and/or supplemented. The parasitological data presented (e.g., prevalences, selected attachment sites on the host, larval phenology, intensity of parasitism) provide, in most cases, basic information concerning previously unknown parasite–host associations. At this time, the reason for the strong crenobiosis in water mites cannot be explained by their parasitism.