Mite Assemblages Research Articles

Parasite traits, host traits, and environment as determinants of dark diversity affinity in flea and gamasid mite assemblages from the Palearctic

A species set in a site comprises species that are present (realized diversity) and species that could inhabit this site but are absent (dark diversity; DD). DD can be both species-driven (a species’ traits preclude its presence, independently of site features) and site-driven (site features preclude the species’ presence, independently of its traits). DD affinity (DDA) is a measure of species’ tendencies to be absent from sites that they could inhabit or of sites’ tendencies to lack species that could be present. Decomposition of DDA into DDA for species (ddasp) and for sites (ddasite) allows (a) disentangling these two mechanisms and (b) detecting species traits and site features contributing to their DDA. The species-site unified model is a Bayesian statistical model aimed at simultaneously estimating ddasp and ddasite. We applied it to flea and mite assemblages (a) within a host species across regions (component metacommunities; CtM; ddasite = ddaregion) and (b) within a region across host species (compound metacommunities; CdM, ddasite = ddahost). In CtMs, ddasp and ddaregion equally contributed to DD, whereas the relative contributions of ddasp and ddahost to DD in CdMs varied from the former being higher than the latter and vice versa. In CtM and CdM, ddasp increased in low-abundance ectoparasites exploiting a restricted number of hosts. In CtMs, ddaregion was associated with the regional environment, but we failed to find host traits affecting ddahost in CdMs. We conclude that ectoparasite species and either regions in CtMs or host species in CdMs independently contribute to DD.

Phytoseiid Mites: Trees, Ecology and Conservation

The highly variable ’leafscapes’ of plants across the world represent billions of square metres of mite habitat. The phytoseiid mites (Acari: Phytoseiidae), an extremely species-rich group of mostly generalist predators, are providers of ecosystem services for humanity worth many hundreds of millions of dollars annually by helping suppress phytophagous mites and insects in forests, agro-ecosystems, shade-houses and home gardens. In this study, the phytoseiid mite assemblages on the leaves of four species of common tree species, namely oak (Quercus cerris var. cerris), poplar (Populus deltoides, P. nigra) and walnut (Juglans regia), were compared. The three data sets used were generated in three independent seasonal studies in Samsun Province, Türkiye, between 2018 and 2022. In total, mite species in 18 families, including 15 families on walnut, were recorded. Nineteen phytoseiid species in 13 genera, Amblydromalus, Amblyseius, Euseius, Kampimodromus, Neoseiulella, Neoseiulus, Paraseiulus, Phytoseius, Transeius, Typhlodromina, Typhlodromips, Typhlodromus and Typhloseiulus, were collected. Only Eusieus amissibilis was collected from all three tree genera, whereas 14 species were collected from only one tree genus. Shannon diversity and Jaccard similarity indexes were calculated for mite families and phytoseiid genera and species. Potential reasons for the observed differences in the phytoseiid assemblages on the different host trees are explored in depth. In the ‘big picture’, global biodiversity, likely including many undescribed phytoseiid species, is threatened by widespread habitat degradation and destruction, especially in the tropics, and accelerating climate change, and rapidly stopping them is imperative.

Intercropping outweighs straw incorporation driving community and functional diversity of microarthropods after 5 years of tillage practices

Crop-leguminous intercropping and straw incorporation are considerable approaches to sustainable agriculture and have been widely used as a coping strategy to mitigate the negative effects caused by intensive agriculture. Yet, as a sustainable agriculture requires a deeper understanding of the impacts of conservation tillage practices on soil fauna, such as collembolans and acarid mites. These organisms are considered the most abundant and functionally critical soil fauna in many terrestrial natural, agricultural, and urban systems. In the present study, we assessed the responses of the community and functional diversity of collembolan and acarid mite assemblages to long-term intercropping and straw incorporation practices in a temperate farming land, in China. The experimental site was established with a full-factorial design of conservation managements (maize monocropping, maize-peanut intercropping, without maize straw addition, and with maize straw addition) over five consecutive years. Results showed that intercropping doubled collembolan and acarid density. Most of the enriched species in the intercropping field were euedaphic collembolans and cleptoparasitic mites. Nonetheless, the density of most phoretic species decreased, resulting in a negative effect of intercropping on acarid diversity. Despite straw incorporation additionally boosting the intercropping-induced increases in biomass, richness, and density of the collembolan community, the effects of straw incorporation on the community structure of collembolans and acarid mites were negligible. Similarly, intercropping affected the functional composition of collembolans and mites differently. Intercropping favored euedaphic collembolans characterized by less-developed furca, ocelli and sexual reproduction, but fungivorous, and benefited the cleptoparasitic mites that might be transported by their provisional hosts during pollinating peanut flowers. Moreover, intercropping decreased the functional dispersion of acarid mites, resulting in an acarid community with a homogenized ecological niche of acarid mites. In contrast, the ecological niche was more differentiated. Similar to intercropping, the ecological niche of collembolans in the field with straw was relatively higher, as well as the functional divergence, suggesting more intense resource competition between collembolans. In conclusion, intercropping has species-specific effects on the community and functional diversity of collembolans and mites and is relatively beneficial to collembolans, whereas straw incorporation has a marginal advantage on collembolans and acarid mites.

Long-term post-fire recovery of an oribatid mite assemblage: A case study from a temperate coniferous forest

Wildfire represents a significant natural disturbance factor in forest ecosystems expected to further increase in importance due to global climate change. It has a detrimental short-term impact on soil biota, but much less is known about its long-term effects, especially on soil mesofauna. Our study compared oribatid assemblages of the forest floor in moderately-burned forest sites along a post-fire chronosequence (8 fire history classes covering 0–110 years since fire) with near-by reference sites without fire history. All sites were situated on acidic soils in the Central European Elbe Sandstone Mountains (Bohemian Switzerland National Park, NW Czechia), mostly covered by pine and spruce forests. Data were analysed using linear mixed-effect models. We found a substantial impact of fire on oribatid assemblages. Whereas lower densities were observed for the first few years after a fire only, changes in assemblage feeding guilds persisted over at least four decades. Shifts towards smaller body size, parthenogenesis and fungivory at burned sites compared to larger body size, sexual reproduction and detritivory in unburned controls implied changes in assemblage functioning. The changes in functional traits, which correspond to previous research findings on the recovery of oribatid mites after clear-cutting, underscore a more universal pattern of post-disturbance development.

Environmental role of different‐aged pine and oak stands growing on post‐agricultural and forest lands in forming the Mesostigmata mites communities

AbstractReclamation of agricultural soil and forest succession after afforestation proceeds slowly and at many levels. Therefore, the history of land use is recorded in the soil's physical, chemical and ecological parameters for many decades. This process depends on time and the form of afforestation, which primarily includes tree species. In our study, we analyzed differences in the physical and chemical characteristics of pine and oak stands on forest and post‐agricultural land at 22, 42 and 62 y/o. Our study revealed that 14 of 24 examined parameters (litter pH, soil pH, litter thickness, soil organic matter, Corg, bulk density, C/N ratio, soil moisture, soil K, Mg and Mn content, N and Ca litter content, Mg litter content) differed significantly among examined habitats (land use, stand age and tree species). We calculated the abundance, species richness and diversity of the mite communities (Acari, Mesostigmata) for each habitat type. In total, 6730 mites were classified into 72 taxa (60 species, 11 genera and one taxon as family). The highest abundance was recorded in 42 y/o. oak stands on post‐agricultural land, while the lowest is in 22 y/o. pine and oak stands on post‐agricultural land. The highest species richness and diversity were recorded in the oldest oak stand on post‐agricultural land. In contrast, the lowest diversity was recorded in the youngest oak and pine stands on post‐agricultural land. Our results demonstrate that the negative impact of the agricultural history of land use weakens over time and provides a better understanding of land use history on the relations between the soil environment and soil fauna, including mesostigmatid mite assemblages.

Consequences of Spiraea tomentosa invasion in Uropodina mite (Acari: Mesostigmata) communities in wet meadows

Vegetation cover has been consistently reported to be a factor influencing soil biota. Massive spreading of invasive plants may transform native plant communities, changing the quality of habitats as a result of modification of soil properties, most often having a directional effect on soil microorganisms and soil fauna. One of the most numerous microarthropods in the litter and soil is Acari. It has been shown that invasive plants usually have a negative effect on mites. We hypothesized that invasive Spiraea tomentosa affects the structure of the Uropodina community and that the abundance and species richness of Uropodina are lower in stands monodominated by S. tomentosa than in wet meadows free of this alien species. The research was carried out in wet meadows, where permanent plots were established in an invaded and uninvaded area of each meadow, soil samples were collected, soil moisture was determined and the mites were extracted. We found that Uropodina mite communities differed in the abundance of individual species but that the abundance and richness of species in their communities were similar. S. tomentosa invasion led primarily to changes in the quality of Uropodina communities, due to an increase in the shares of species from forest and hygrophilous habitats. Our results suggest that alien plant invasion does not always induce directional changes in mite assemblages, and conclude that the impact of an alien species on Uropodina may cause significant changes in the abundance and richness of individual species without causing significant changes in the abundance and diversity of their community.

Long-term post-fire recovery of oribatid mites depends on the recovery of soil properties in a fire-adapted pine forest

Fire is a highly important factor affecting the forest structure as well as its functions. The understanding of the post-fire recovery mechanisms could be especially useful in the face of globally increasing fire frequencies. Fire-adapted forests in Minnesota provide a unique opportunity to study these recovery mechanisms due to their long and well-documented history of prescribed burnings and wildfires. We investigated oribatid mite (Acari: Oribatida) assemblages along a 126-year post-fire chronosequence, together with soil physical, chemical and microbial properties (e.g. bulk density, organic matter content, C, N and P content, microbial biomass). Whereas the effect of prescribed burning was negligible, the wildfire decreased oribatid density (–86 %) and diversity (–38 %) for at least 13 years. The recovery of oribatid mites corresponded to the changes in soil properties, being correlated negatively to bulk density and positively to organic matter content, water holding capacity and microbial activity and biomass. The recovery did not depend simply on the time elapsed since fire, but it was rather a complex response to long-term (15–20 years), fire-induced changes in the soil environment.

An exploratory analysis of the structure of tetranychid and phytoseiid assemblages in walnut orchards in California.

Spider mites were considered secondary pests of walnut production in California, under the control of phytoseiid predators. Due to increased importance as walnut pests in recent decades there is renewed interest in the structure and function of the associated phytoseiid assemblage. In this study we report the results from a 3 year survey of the tetranychid and phytoseiid assemblages in walnut orchards in the Central Valley of California. The survey was conducted to determine the range and dominance of web-spinning Tetranychus species present, to investigate the species richness and dominance of the phytoseiid species present, and to explore whether patterns of variation in the relative abundance of phytoseiid species could be explained by one or more explanatory variables. Tetranychus urticae was the dominant spider mite in all growing regions and years with T. pacificus and T. turkestani also present in orchards in the southern San Joaquin Valley. Phytoseiid species richness declined with latitude among the three walnut growing regions and of the 13 species found Amblyseius similoides, Euseius stipulatus, Galendromus occidentalis and Typhlodromus caudiglans were the most abundant and widespread species present. Mean proportional abundance significantly increased from early (mid May-July) to late (August-mid October) season and from southern to northern growing regions for Type II and IV predators, but significantly decreased from early to late season and from southern to northern growing regions for Type III predators. The mean proportional abundance of Type II predators, particularly G. occidentalis, significantly increased and that of Type III predators significantly decreased with mean Tetranychus density in individual orchards. The current survey provides a more in-depth analysis of mite assemblages in walnut orchards in California and can be used to better inform adaptive management strategies for integrated mite management in the future.

Type of Material, Not Tree Hole Characteristics Shapes Uropodina Mites’ Species Composition in Excavated Tree Holes

Uropodina mites are organisms regularly found in the breeding sites of vertebrates. However, studies devoted to the nest dwellers of hole-nesting birds have been performed nearly exclusively in artificial places, i.e., nest boxes. Here, we describe an assemblage of mites from the Uropodina group living in excavated tree holes. We performed this study in western Poland, sampling material from 49 tree holes excavated by great spotted and black woodpeckers. We divided the material extracted from the tree holes into three categories: wood debris, remnants of bird nests, and remnants of insects. In total, we found 12 species from the Uropodina group. The two most numerous species, Leiodinychus orbicularis and Chiropturopoda nidiphila, constituted ca. 93% of the assemblage. Two other species, Apionoseius infirmus and Uroobovella obovata, were also relatively frequent. Among the assessed factors (woodpecker species, tree hole characteristics, and type of material), only the presence of insect remains, predominantly bat guano, affected species diversity and mite abundance the most. Our study is the first to describe an assemblage of Uropodina species in excavated tree holes and discover two extremely rare mite species, Ch. nidiphila and Nanteria banatica, related to the presence of bat guano in these cavities.

Water mites and their use as bioindicators of water quality conditions: a Pennsylvania case study

Water mites (Acariformes: Hydrachnidia) are one of the planet's most diverse and abundant groups of aquatic arthropods. With more than 7,500 described species, water mites have been documented in nearly every known freshwater environment. In lotic systems, water mites are commonly found in fast-flowing, riffle-run stream habitats, where one square meter of substrate can contain as many as 5,000 individual mites representing more than 50 species, 30 genera, and all 8 superfamilies. Despite their widespread distribution, relative diversity, and abundance, water mites have been widely neglected in freshwater biomonitoring efforts. However, several studies across the globe have found that water mites can be used as successful bioindicators of water quality conditions. Thus, the following study provides one of the first detailed examinations of lotic water mites and their bioindicator potential in North America. We sampled water mites from sites along 'attaining' (unpolluted) and agriculturally 'impaired' (polluted) riffle-run stream habitats and compared their assemblages to other physicochemical and benthic macroinvertebrate metrics used to quantify water quality in Pennsylvania. In total, we collected 9,139 individual water mites representing 5 superfamilies, 9 families, and 14 genera from both attaining (n = 13) and impaired (n = 13) streams. Similar to other global studies, we found significant differences between the water mite assemblages of attaining and impaired streams, with attaining streams having greater richness and diversity of water mites. Our data shows that several mite taxa are associated with biological and physicochemical conditions of water quality, where some known sensitive taxa are increasingly dominant in attaining streams and less dominant in impaired streams. Conversely, some pollution-tolerant taxa dominance increases in impaired streams while sensitive taxa abundance declines. These findings illustrate that water mites vary in their sensitivity to pollution and are suitable bioindicator species whose inclusion in biomonitoring assessments will increase assessment accuracy.

The phoretic mite (Arachnida: Acari) assemblage of the Douglas-fir beetle (Coleoptera: Curculionidae) in central British Columbia, Canada

Abstract The phoretic mite assemblage of the Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins (Coleoptera: Curculionidae), has not been thoroughly documented. Phoretic mites can impact fitness and population dynamics of hosts; documenting a mite assemblage may provide information on their ecological roles. We caught Douglas-fir beetles in central British Columbia, Canada, and sorted associated mites into morphospecies. Representatives of the morphospecies were DNA barcoded (CO1 barcode region), indicating at least nine operational taxonomic units (OTUs). Representatives of all OTUs were slide-mounted and morphologically identified. There was a mean of 50.5 ± 4.7 mites per beetle, with both females and males carrying similar numbers of most mite species, except for OTU B1, which was found in higher numbers on females. OTU B1, Parawinterschmidtia furnissi (Woodring) (Astigmata: Winterschmidtiidae), was found in substantially higher numbers than all other OTUs and was always clustered in large aggregations in an anterior pocket on the beetles’ subelytral surface. When this OTU was removed from the calculation, the mean number dropped to 1.3 ± 0.2 mites per beetle. The consistent high numbers of OTU B1 in conjunction with its consistent anatomical aggregation suggests an important interaction between this particular mite species and the Douglas-fir beetle.

River Habitat Survey: Does This Help to Explain the Nature of Water Mite (Acari and Hydrachnidia) Assemblages?

In the European Union, assessments of the quality of the aquatic environment based on aquatic invertebrates are mandatory. Biological methods are supplemented with hydromorphological assessments of watercourses. There are many studies analysing the relationships between aquatic invertebrates and the hydromorphological assessment of the environment by the River Habitat Survey (RHS) method, but thus far, there has been no detailed study including water mites (Acari, Hydrachnidia) and the application of this method. In the present study, the following research hypothesis was put forth: a hydromorphological characterization of habitats is a significant element explaining the nature of water mite communities, and the RHS method can be used to predict the characteristics of Hydrachnidia populations in a river. The research was carried out in a small lowland river, the River Krąpiel (north-western Poland). Six locations were selected as representative of some state of habitat modification for the assessment of the hydromorphological conditions of the river and the collection of biological samples. The following conclusions can be drawn from the research: (1) the biology and ecology of water mites make them suitable as bioindicators of the environment, including hydromorphological modifications, and (2) the hydromorphological characteristics of habitats explain the nature of water mite communities in the river at the level of general population parameters (number of specimens and species), while at the species level, general regularities in water mite fauna distribution in river ecosystems, the continuity of the river ecosystem, and characteristics at a smaller spatial scale (habitat scale) better explain water mite community structure than the hydromorphological indices determined for a given site or section of the river.

Diversity and structure of feather mite communities on seabirds from the north–east Atlantic and Mediterranean Sea

The richness and structure of symbiont assemblages are shaped by many factors acting at different spatial and temporal scales. Among them, host phylogeny and geographic distance play essential roles. To explore drivers of richness and structure of symbiont assemblages, feather mites and seabirds are an attractive model due to their peculiar traits. Feather mites are permanent ectosymbionts and considered highly host-specific with limited dispersal abilities. Seabirds harbour species-rich feather mite communities and their colonial breeding provides opportunities for symbionts to exploit several host species. To unravel the richness and test the influence of host phylogeny and geographic distance on mite communities, we collected feather mites from 11 seabird species breeding across the Atlantic Ocean and Mediterranean Sea. Using morphological criteria, we identified 33 mite species, of which 17 were new or recently described species. Based on community similarity analyses, mite communities were clearly structured by host genera, while the effect of geography within host genera or species was weak and sometimes negligible. We found a weak but significant effect of geographic distance on similarity patterns in mite communities for Cory’s shearwaters Calonectris borealis. Feather mite specificity mainly occurred at the host-genus rather than at host-species level, suggesting that previously inferred host species-specificity may have resulted from poorly sampling closely related host species. Overall, our results show that host phylogeny plays a greater role than geography in determining the composition and structure of mite assemblages and pinpoints the importance of sampling mites from closely-related host species before describing mite specificity patterns.

Strong variations and shifting mechanisms of altitudal diversity and abundance patterns in soil oribatid mites (Acari: Oribatida) on the Changbai Mountain, China

Biological composition and structure vary strongly with elevation, however, the vertical distribution of soil fauna and its drivers have been rarely investigated. Oribatid mites play an essential role in soil faunal composition, where they can occur at high densities and mediate soil ecological processes and functions. Here, we comprehensively investigated the composition and diversity of soil oribatid mites, at nine altitudes (from 600 to 2200 m asl) and four vegetation types from forest to alpine tundra on the Changbai Mountain in July 2021. In total, 67 species were identified among 37,224 oribatid mite individuals. Oribatid mite species varied strongly with altitude and vegetation type, and only a few species overlapped between elevations. Species abundance and diversity declined significantly as altitude increased, while abundance exhibited a hump-shaped distribution along an elevational gradient, peaking at 1200 m. Beta diversity decomposition analyses revealed that species replacement processes dominated community compositional differences across all study sites (both between vegetation types and elevations). Meanwhile, soil oribatid mite community composition is greatly affected by elevation and vegetation type. Specifically, oribatid mite community varies with elevation across vegetation types. Twelve and twenty indicator species were found at different elevations and vegetation types, respectively. Our study shows that soil moisture content, total phosphorus, available phosphorus, ammonium nitrogen, and nitrate nitrogen are the most dominant drivers of oribatid mite composition patterns. These findings indicate oribatid mite assemblages have a distinct vertical distribution pattern and are coupled with different aboveground vegetation types, implying that changes in aboveground vegetation will cause shifts in soil fauna under future climate change.

Longitudinal Changes in Diverse Assemblages of Water Mites (Hydrachnidia) along a Lowland River in Croatia

Water mites are the most diverse freshwater group of Acari and despite growing research interest in the ecology of this group, the environmental influences along longitudinal river gradients on their assemblages are still not fully understood. The objective of this study was to determine how physico-chemical water properties and hydromorphological alterations affect the composition and distribution of water mite assemblages along a longitudinal river gradient. Macroinvertebrate samples were collected from 20 study sites distributed longitudinally along the entire 106 km course of a lowland river (Bednja River) in the Pannonian Lowlands ecoregion of Croatia. At each site, 20 samples were collected with regard to microhabitat composition (+400 samples in total). In parallel with the sampling of macroinvertebrates at each site, the physico-chemical water properties were measured and the degree of hydromorphological alteration was assessed (European Standard EN 15843:2010). Both the number of taxa and water mite abundance were found to increase significantly with increasing distance from the source. However, the assemblages from the upper reaches and those from the lower reaches shared very few species, emphasizing the importance of species-level identification. Water mite species richness and diversity were not reduced with increased levels of variables associated with organic enrichment and eutrophication pressures. Similarly, hydromorphological alteration did not reduce either water mite abundance or species richness and was positively correlated with both. Furthermore, a correspondence analysis on water mite microhabitat preferences revealed that 32% of all species were positively associated with artificial microhabitats (technolithal). These positive associations may be the result of reduced competitive pressure from other larger invertebrates, as well as a possible preference for higher velocity, which usually occurs on smooth technolithal surfaces. A total of 22 different species of water mites were found during this study, 8 of which (or 36% of all species found) were recorded for the first time in Croatia.

Exploring the diversity and host association of tarsonemid mites in West Bengal, a highly biodiverse state of Eastern India

The family Tarsonemidae is an extremely diverse assemblage of heterostigmatid mites which include phytophagous, fungivorous, detriphagous, algivorous and insect parasitic species living in various terrestrial, arboreal, subcortical or nidicolous habitats. Many of these mites pose a serious threat to global agriculture due to their direct feeding on crop plants or indirect transmission of disease-causing bacterial or fungal spores to healthy plants. For instance, Polyphagotarsonemus latus may reproduce year-round in all tropical and subtropical habitats and feed on more than 60 different plant families. Steneotarsonemus species, such as S. spinki and S. subfurcatus, attack rice and can significantly reduce the harvest, S. ananas attacks pineapple, and S. laticeps targets lilies. In temperate forests of the Northern Hemisphere, several Tarsonemus species phoretic on curculionid beetles transfer lethal fungal spores on healthy pine trees, while some other species pose a real hazard to cultivated mushrooms and stored products.

Water mites (Acariformes, Hydrachnidia) of Siberia: DNA-based species identification for global climate change monitoring programs

Water mites (Hydrachnidia) are good model organisms for the assessment and long-term monitoring of the biological impacts of natural and human-induced environmental changes in freshwater ecosystems, including those related to global climate change. There are approximately 7,500 species, 485 genera and 56 families. Water mite communities can be affected by pollution and variations in temperature, dissolved oxygen level, conductivity and carbonate concentrations. Due to the complex interactions of water mites with other members of the macroinvertebrate fauna and their habitats, water mite assemblages can rapidly respond to perturbances in the interconnected ecological networks of aquatic communities, and therefore are particularly suitable for early warning systems that monitor water quality. However, monitoring programs using water mites as bioindicators may be impeded by difficulties associated with species identification. Siberia is a crucial region for biodiversity conservation and climatic research by being a major carbon sink due to the large amounts of carbon preserved in permafrost and sequestered by vast boreal forests and peatbogs, and is also a key region for climate change research. There are several reference sites in the Arctic tundra, forest and grassland areas allocated for long-term monitoring of climatically active gases, as well as assessment of the impact of climate change on animal and plant communities.

Vegetation structure define mite assemblage on plants: a case study in Cerrado biome

We compared abundance and richness of mites on Miconia albicans (Sw.) Steud. (Melastomataceae) found in Cerrado grassland (CGR) and in Cerrado sensu stricto (CSS), in order to evaluate the effect of plant physiognomy on mite assemblage structure, in the Parque Nacional das Emas, Goiás State, Brazil, a biological reserve of Cerrado biome. In total, 453 mites of 45 species belonging to 14 families were collected. Stigmaeidae was the most abundant predatory mite family, represented by a single unidentified Agistemus species. Among phytophagous mites, species of Lorryia (Tydeidae) were the most common. Lorryia turrialbensis Baker, 1968 is reported for the first time on a Cerrado plant species. We concluded that the Cerrado phytophysiognomy can determine the organization of mite assemblages since CSS sheltered higher species richness and abundance of mites on M. albicans due to has more habitat complexity, species richness and abundance of plants than CGR. Therefore, CSS can provide more food resources, microhabitats for shelter and oviposition favoring the occurrence and populational development of plant mites.

First data on water mite (Acari, Hydrachnidia) assemblages of Point Rosa Marsh, Harrison Township, Michigan, USA,and their use as environmental bioindicators of aquatic health

Water mites are aquatic arachnids that have been used in Europe and Central America as bioindicators of ecological health in various freshwater ecosystems (including bogs). Water mites can be found in high densities in the Laurentian Great Lakes and adjacent habitats. Although they are abundant, water mites are generally not used in the assessment of aquatic habitats in the Great Lakes and are usually assigned to the “other” category in macroinvertebrate assessments. This is despite evidence of their utility as aquatic bioindicators. In the present study we consider water mites as bioindicators of the environmental health of Point Rosa marsh, a threatened marsh found on the US side of transboundary Lake St. Clair. The abundance of water mites in Point Rosa Marsh increased from 2017 to 2019 as lake water levels increased. Although increasing water levels in Lake St. Clair can be considered a negative event due to loss of irreplaceable coastal habitat by erosion with potential economic impacts, this present study indicates that water mite populations in Point Rosa Marsh increased during the same period (2017 to 2019). As a result of our study we: update the biodiversity of water mites from Lake St. Clair with new records compared to the last report from the lake over 45 years ago, first report on water mite assemblages at Point Rosa marsh at the Lake St. Clair Metropark on Lake St. Clair and the first demonstration of water mites used as bioindicators in the habitats of the Laurentian Great Lakes.

Crop species and year affect soil-dwelling Collembola and Acari more strongly than fertilisation regime in an arable field

Drivers of soil-dwelling microarthropods represent one of the most addressed topics in soil ecology, and diverse results have been reported in the literature. In the present study, an extremely long-term fertilised monoculture system provided a special opportunity to investigate the drivers of soil-dwelling springtail and mite assemblages. The cropping system included wheat and maize monoculture and biculture and was managed with mineral and organic fertilisers for over 50 years. Soil samples were collected two times a year for two years from four blocks. Soil-dwelling mite groups and springtail orders were identified and analysed based on soil characteristics and compared amongst different treatments to reveal the drivers. In addition, oribatid mites and springtails were identified at the species level and analysed. The most important parameters were ‘crop species’ and ‘study year’. Most Collembola and Acari groups were more abundant in wheat plantations, and there were yearly variations within different mite and collembolan groups. Fertilisation appeared to produce no effect on microarthropod assemblages; however, soil pH and phosphate concentration differed according to fertilisation treatment. Overall, the four blocks at the study site effectively reflected the spatial patterns of oribatid species. Specifically, the dominant collembolan species exhibited similar patterns to the major collembolan orders, whereas oribatid species presented different patterns within Oribatida. The studied special agricultural system helped reveal important drivers of soil-dwelling Collembola and Acari, and these soil-dwelling microarthropod assemblages are affected more strongly by ‘crop species’ and ‘study year’ than by long-term fertilisation regime.