Nested patterns of community assembly in the colonisation of artificial canopy habitats by oribatid mites

An observed species–area relationship (SAR) in assemblages of oribatid mites inhabiting natural canopy habitats (suspended soils) led to an experimental investigation of how patch size, height in canopy and moisture influence the species richness, abundance and community composition of arboreal oribatid mites. Colonisation by oribatid mites on 90 artificial canopy habitats (ACHs) of three sizes placed at each of three heights on the trunks of ten western redcedar trees was recorded over a 1‐year period. Fifty‐nine oribatid mite species colonised the ACHs, and richness increased with the moisture content and size of the habitat patch. Oribatid mite species richness and abundance, and ACH moisture content decreased with increasing ACH height in the canopy. Patterns in the species richness and community composition of ACHs were non‐random and demonstrated a significant nested pattern. Correlations of patch size, canopy height and moisture content with community nestedness suggest that species‐specific environmental tolerances combined with the differential dispersal abilities of species contributed to the non‐random patterns of composition in these habitats. In line with the prediction that niche‐selection filters out species from the regional pool that cannot tolerate environmental harshness, moisture‐stressed ACHs in the high canopy had lower community variability than ACHs in the lower canopy. Colonising source pools to ACHs were almost exclusively naturally‐occurring canopy sources, but low levels of colonisation from the forest floor were apparent at low heights within the ACH system. We conclude that stochastic dispersal dynamics within the canopy are crucial to understanding oribatid mite community structure in suspended soils, but that the relative importance of stochastic dispersal assembly may be dependent on a strong deterministic element to the environmental tolerances of individual species which drives non‐random patterns of community assembly.     

The association of oribatid mites with lichens

Oribatei (Acari, Cryptostigmata) are found in a variety of terrestrial habitats, and many are associated with lichens; the relationship ranges from casual to highly dependent. Eighty-three species associated with lichens have been surveyed, and a tentative classification, based on their ecological requirements, is presented: Group A consists of species restricted to lichens as a biotope, though occasionally occurring as accidentals in other habitats; Group B consists of species which while preferring lichens as a habitat and feeding source are also adapted to existence on other plants (though in some cases their immatures may be lichen-restricted); Group C consists of species which, though frequently found on lichens, are equally common in other biotopes, particularly mosses, and must be regarded as much more generalized in their feeding habits. Certain aspects of oribatid-lichen specificity are discussed. The importance of oribatid-lichen associations from the point of view of soil fertility and energetics is emphasized.     

Comparative water relations of sub-Antarctic and continental Antarctic oribatid mites

 Water availability, in addition to cold, is important in limiting biotic distribution in the Antarctic regions. In general, inland continental Antarctic habitats are dry, relative to maritime and sub-Antarctic habitats. This investigation compares the water relations of an endemic continental Antarctic oribatid mite, Maudheimia petronia Wallwork, and two sub-Antarctic oribatid mites, Halozetes fulvus Engelbrecht and Podacarus auberti Grandjean. M. petronia showed enhanced survival of dehydrating conditions, which may be attributable to both its greater resistance to and tolerance of water loss. The estimated lethal exposure times (LT₅₀) for M. petronia, P. auberti and H. fulvus held at 15°C and 0–5% RH were 250, 135 and 51 h, respectively. M. petronia lost water significantly more slowly than the sub-Antarctic mites (P<0.05), which did not differ in their rates of water loss (P>0.05). The mean losses of initial body water content after 45 h were 18.9, 27.3 and 29.3% for M. petronia, P. auberti and H. fulvus, respectively, and lethal water losses causing 50% of the sample to die were 65, 52, and 28%, respectively. These data suggest physiological adaptation by M. petronia for existence in periodically dry “chalikosystem” habitats at Antarctic nunataks. Comparisons of tolerance of submersion in freshwater showed P. auberti to be superior to M. petronia; the LT₅₀ values for submersion were >146 h and 32 h, respectively. Tolerance of submersion by P. auberti may be important for its existence in wet sub-Antarctic habitats. Conversely, the poor tolerance shown by M. petronia suggests that this mite has not been associated with moist environments. Received: 13 April 1995/Accepted: 4 August 1995     

Dispersal patterns of pest earth mites (Acari: Penthaleidae) in pastures and crops

Control methods in pest earth mites and other mites often depend on low dispersal rates, yet there are no experimental estimates of these rates. To rectify this, adult movement rates were estimated in the earth mite Halotydeus destructor Tucker and the winter grain mite, Penthaleus major (Duges), using mark-release-recapture techniques. Mean square dispersal distances were used to estimate diffusion coefficients. In pasture, coefficients were in the range 0.3-1.3 for these species. This suggests that 90% of the population moves < 5-11 m in a 10-d period, or 7-16 m within their adult lifetime. Releases of mites in adjacent pea/wheat crops indicated directional movement toward the more favored pea host. However, there was no directional movement when adjacent plots of peas and lupins were compared, even though lupins are poor hosts. These results indicate that broad border sprays or border culturing will be needed to prevent mite movement from adjacent paddocks.     

An efficient and non-destructive DNA extraction method for oribatid mites

Molecular methods play an important role in systematic acarology and DNA extraction is the first step in this ground. Nowadays, the varieties of methods are being used for extraction of DNA, but most of them destroy the important external characters that are essential for morphological identification. In order to overcome the problem of associating molecular and morphological information, we have developed a simple, efficient and non-destructive DNA extraction method for oribatid mites. The non-destructive method was tested on three different species [Oppia nitens C.L. Koch, 1836 (Oppiidae), Acrotritia ardua C.L. Koch, 1841 (Euphthiracaridae), and Amerus polonicus Kulczynski, 1902 (Ameridae)] and exoskeleton of specimens were preserved in Hoyer’s medium on glass microscopic slides for further identification via morphological studies. This method is more time consuming than commercial kits, but is easier and cheaper, meanwhile, allows systematic analysis with linking the morphological and genetic traits from a single mite. The most important advantage of TNES method is that after using this non-destructive method, specimens preserve all of their morphological features.     

Dispersal patterns, social structure and mortality of wolves living in agricultural habitats in Spain

Wolf Canis lupus dispersal, social structure and mortality have been extensively studied in natural and semi-natural areas of North America and northern Europe but have never been assessed in agricultural areas. From 1997 to 2004, 14 wolves (11 in a wolf-saturated area and three in a low-density area) were radio-collared with long-lasting transmitters in a Spanish agricultural area containing a high-human-population density, a dense network of roads and a shortage of wild ungulates. The wolves mainly feed on an overabundance of livestock carrion. Nine wolves (one of them, three times) dispersed during the study period. The mean age and distance of natal dispersal were 24.8 months and 32 km. The natal dispersal period was much longer in wolves radio-collared in the saturated area (mean >14.6 months) than in the low-density area (<1 month). All three of the dispersers living in the low-density area, and two of the six dispersers in the saturated area settled and bred during the study. The average tenure of six breeders was 4.5 years. The radio-collared wolves spent 72% of the monitoring time living in packs and the rest living in pairs, as dispersers or as peripheral wolves, but the percentage of loners was much higher in the saturated (33.5%) than in the low density (1.6%) areas. The overall annual mortality was 18% (lower than in most populations studied in less modified habitats), but lone wolves had a significantly higher mortality than members of packs and pairs. Nine wolves died during the study, none of them due to natural causes. In general, our results are very similar to those obtained in less modified habitats, except for the dispersal distance, which was much shorter than in other studies. We suggest that barriers and habitat constraints may reduce dispersal distances in our study area.     

Temperature effects on locomotor activity rates of sub-Antarctic oribatid mites

The influence of temperature on locomotor activity was determined for the sub-Antarctic mites, Halozetes fulvus Engelbrecht and Podacarus auberti Grandjean. In both species walking was severely impaired at below-freezing temperatures. Above zero, locomotor activity rates increased with a rise in temperature over a wide temperature range (for example, this was 2–30°C for H. fulvus), and they showed a biologically normal level of sensitivity to change in temperature. All the calculated Q₁₀ values for mean rates over 5° intervals varied between 1.3 and 2.9. The present data are compared with some rate functions of maritime and continental Antarctic micro-arthropods, and they confirm the relative enhancement of the physiological rate by a continental Antarctic mite. One explanation for the less temperature-sensitive rates in H. fulvus and P. auberti may be that they have relatively more time available for normal biological activity.     

Overwintering ecology of alpine Collembola and oribatid mites from the Austrian Alps

Abstract. 1. Collembola and oribatid mites from windswept mountain ridges at about 2700 m a.s.l. in the Austrian Alps were all killed by freezing, and depend on supercooling to survive low winter temperatures. The Collembola Tetracanthella afurcata Handschin, Xenylla acauda Gisin and Isotoma spp. collected in January had average supercooling points between -25 and -29°C, and the oribatid mites Fuscozetes fuscipes (Koch) and Lepidozetes singularis Berlese of about -28 and -31°C respectively. The ability to supercool was not increased during storage at -5°C, and was generally lower in species collected in March.
2. The oribatid mites Fuscozetes intermedius Caroli and Maffia, F. fuscipes, Damaeus diversipilis (Willmann) and L.singularis contained from 9 to 16 μg glycerol per mg fresh weight after storage at -5°C, while no glycerol could be detected in the Collembola Isotoma spp., T.afurcata and Onychiurus vontoernei Gisin.
3. Activity below 0°C was observed in T.afurcata and O.vontoernei , which had chill-coma temperatures of -7.7 and -4.9°C respectively.
4. Some specimens of F.intermedius survived more than 90 days of anoxia at 0°C, T.afurcata up to 60 days and O.vontoernei up to 24 days.
5. The overwintering biology of Collembola and oribatid mites from the Austrian Alps appears similar to that of Norwegian species, except that those from Austria have slightly lower supercooling points and higher contents of glycerol.     

Spatial and environmental factors contributing to patterns in arboreal and terrestrial oribatid mite diversity across spatial scales

Recruitment is a crucial event in the plant life cycle that is very sensitive to interaction with established vegetation. Based on a large comparative experiment, we tested the hypothesis that the components of recruitment––emergence time and rate, seedling survival and biomass––differ in response to plant–plant interactions during recruitment. The consequences for the population are predicted with a simple demographic model assessing the response of seed production. In a common garden experiment, we recorded the recruitment of four target species in an individual-based survey protocol. A total of 7,680 seeds were sown within 20 neighbourhoods, consisting of 19 mono-specific herbaceous stands and a control treatment without vegetation. We measured transmitted light, temperature and moisture at soil surface to characterise the environmental conditions within neighbourhoods. The mean height of neighbours controlled temperature buffering and light interception and thus depicted the interaction gradient. Emergence rate and time increased with neighbour height in two of the four target species, while seedling survival and biomass significantly decreased with neighbour height in three and all four target species, respectively. We recorded a shift in seedling neighbour interactions under the tallest neighbours that largely favoured emergence but strongly depressed seedling survival and biomass. The components of recruitment were predicted to differ in their impact on later adult performance. Biomass strongly contributed to predicted seed production in three target species, and emergence had an equal or greater impact on a fourth species. These results confirm the fundamental role of plant–plant interactions in the recruitment of herbaceous species through a complex combination of habitat amelioration, which facilitates emergence and light competition, which in turn limits seedling survival and biomass.     

Chemical ecology of oribatid mites III. Chemical composition of oil gland exudates from two oribatid mites, Trhypochthoniellus sp. and Trhypochthonius japonicus (Acari: Trhypochthoniidae)

The composition of oil gland exudates from two oribatid mites, Trhypochthoniellus sp. and Trhypochthonius japonicus, was studied with reference to the related species Trhypochthoniellus crassus. Trhypochthoniellus sp. contained a mixture of seven compounds; (Z,Z)-6,9-heptadecadiene, geranial, 3-hydroxybenzene-1,2-dicarbaldehyde (γ-acaridial), neryl formate, neral, (Z)-8-heptadecene and geranyl formate in decreasing order of abundance. The profile of the components from T. japonicus consisted of two types depending on the locality of sampling with unknown reason; one possessing a mixture of eight compounds [(Z,E)-farnesal, γ-acaridial, (Z,Z)-6,9-heptadecadiene, (E,E)-farnesal, (Z)-8-heptadecene and geranial in decreasing order] together with two unknown compounds, and the other composed of the same set of compounds together with 2-hydroxy-6-methylbenzaldehyde as the most abundant component. Relative abundance among common components was consistent between the two types of T. japonicus. Profiles of components differed among three species including T. crasus. The phylogenetic relationship between Oribatida and Astigmata was discussed based on secretory compounds commonly distributed between these two suborders. This revised version was published online in July 2006 with corrections to the Cover Date.     

Review of oribatid mites as intermediate hosts of tapeworms of the Anoplocephalidae

A list of oribatid mites acting as intermediate hosts of tapeworms of the Anoplocephaldae is provided. to date, 127 species of oribatids included in 27 families, are implicated as intermediate hosts of the 14 genera and 27 species of anoplocephalid tapeworms. The most cited mites families are Oribatulidae with 35 species, Galumnidae with 22 species and Ceratozetidae with 15 species. Scheloribates laevigatus (Oribatulidae) is the species that demonstrated most susceptibility, both natural and experimental, to develop larval forms of anoplocephalid tapeworms. A theoretical-methodological model for parasitology based on the trophic characteristics of the intermediate and definitive mammalian hosts is reviewed.     

A list of oribatid mites (Acari,Oribatida) of Vietnam

A species list of identified oribatid mite taxa (Acari, Oribatida) in the fauna of Vietnam is provided. During 1967–2015, a total of 535 species/subspecies from 222 genera and 81 families was registered. Of these, 194 species/subspecies were described as new for science from Vietnam.     

Informing conservation by identifying range shift patterns across breeding habitats and migration strategies

A species distribution combines the resources and climatic tolerances that allow an individual or population to persist. As these conditions change, one mechanism to maintain favorable resources is for an organism to shift its range. Much of the research examining range shifts has focused on dynamic distribution boundaries wheras the role of species breeding habitat or migration strategies on shift tendencies has received less attention. We expand on previous research by using a large suite of avian species (i.e., 277), analyzing observed abundance-weighted average latitudes, and categorizing species by breeding environment and migration strategy. We used the North American Breeding Bird Survey dataset to address two questions: (1) Has the center of observed abundance for individual species shifted latitudinally? (2) Is there a relationship between migration strategy or breeding habitat and range shifts? Results indicate the majority of species have experienced poleward range shifts over the last 43 years, and birds breeding in all habitat showed trends of poleward shift but only those species breeding in scrub-shrub and grassland environments were different from zero. Additionally, species that are short distance migrants are experiencing significant poleward shifts while Neotropical and permanent residents had shifts that were not different from zero. Our findings do support the general trend expected from climate driven changes (i.e., > 52 % shifting poleward), however, the proportion of species exhibiting equatorial shifts (24 %) or no significant shifts (23 %) illustrates the complex interplay between land cover, climate, species interactions, and other forces that can interact to influence breeding ranges over time. Regardless of the mechanisms driving range shifts, our findings emphasize the need for connecting and expanding habitats for those species experiencing range shifts. This research describes the patterns of breeding birds through central North America and we encourage future research to focus on the mechanisms driving these patterns.     

Successions of oribatid mites (Acariformes: Oribatida) on disturbed areas

During recovery succession, structural and functional changes in oribatid mite communities occur: the number of species increases, the structure becomes more complex, the proportion of surface-living and nonspecialized forms increases, and the role of parthenogenetic species decreases. The direction of succession is to form a community characteristic of the zonal type of vegetation. Four stages are selected. The colonization-accumulation stage involves the initial accumulation of organic matter due to activity of microorganisms. Oribatids are not numerous at this stage. The unstructured stage is characterized by unstable monodominant communities of parthenogenetic oribatids with short life cycles. The next stage is structuring, when the proportion of parthenogenetic forms decreases, and that of nonspecialized forms increases. Communities are monodominant. The final stage is stabilization. The proportion of parthenogenetic species decreases noticeably. The generic and species composition of the communities stabilizes. The community achieves zonal features.