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Rezumat

In Romania, phytoseiid mites was notified sporadically with the occasion of some ecological works referring to the whole Mesostigmata. Seven years of investigations carried out in Danube Delta Biosphere Reserve led to the identification of 12 species belonging to the family Phytoseiidae (Acari: Mesostigmata) namely Amblyseius merid-ionalis Berlese, A.obtusus (Koch) sensu Karg, A. terreus Kolodochka, Graminaseius graminis (Chant), Neoseiulus alpinus (Schweizer), N. cinctutus (Livshitz & Kuznetsov), N. extricatus (Kolodochka), N. tervus Meshkov, Proprioseiopsis messor (Wainstein), P. scurra (Wainstein & Beglyarov), Transeius macrospermathecus Papadoulis, Emmanouel & Kapaxidi, Typhlodromus (Anthoseius) kerkirae Swirski & Ragusa. With the exception of A. meridionalis and A. obtusus the rest of the species are reported for the first time from Romania.

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Mites belonging to the order Mesostigmata have different types of life, those which populate soil habitats and litter being generally free living predators. Predatory mites play a leading role in biological control, but they are considered useful in bioindication, also. This study explored in a comparative way the edaphic gamasid communities from a series of forest ecosystems, meadows and agroecosystems in order to evaluate the impact of natural and anthropic factors and to highlight the bioindicator value of these mites. Both a quantitative and a qualitative analysis were performed. The degree of anthropization could be evidenced at the level of all analyzed ecosystems. A reduction of the number of species and individuals in the ecosystems marked by human interventions was observed. Generally, the phenomenon was more pronounced in forest ecosystems than in the praticolous ones. From the point of view of the ecological peculiarities of the species, a differentiation was noticed that in natural forests the silvicolous species are dominating while in plantations, meadows and agroecosystems the praticolous ones are the majority. In the case of natural forests the best represented family is Zerconidae with 2 genera and 8 species. In the rest of the studied ecosystems on the first place is Hypoaspididae with 1, 2 or 3 genera and 5 species or even more.

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Rezumat

The aim of our proposals for soil sampling regarding mesofauna study in soils from greenhouses or polytunnels is motivated by the high soil heterogeneity and large variability of easy exchangeable soil properties such as water content, soluble salts distribution especially under drip irrigation and local fertilization. The intensive technology for growing vegetables or flowers, high irrigation requirements and the high soil moisture favors, in short time the degradation of morphological, physical, chemical properties and especially biological activity of the greenhouses soils. The large variability of the mesofauna species with different requirements to environmental conditions (e. g., hygrophilous to xerophilous species as regards soil humidity, salt tolerant or sensitive species to soil salinity etc.) has lead us to adapt soil sampling methods to particular conditions of every location. One of particular situation was in greenhouse where practice drip irrigation and local fertilizations of tomato plants. Using the adapted sampling methods, the identified mesofauna species confirmed the large variability of soil properties from plant rows, on the border of wetting strip, at middle distances of the plant rows and on the horticultural substrata used for seedling obtaining. After processing of field and laboratory obtained data we consider that proposed diagram for design location is useful for practical application in order to detect initiation processes of soil degradation and establish the proper measures to prevent decreasing soil quality. © SGEM 2018.

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Free-living predatory mesostigmatid soil mites from five different forests from the Danube Delta Biosphere Reserve (DDBR) were analyzed in order to get information for defining the conservation status of the investigated sites. On the whole, in the five studied sites 32 species of Mesostigmata belonging to 22 genera and 11 families were recorded. The analyzed material includes new species of Romanian fauna as well as rare and less cited species from Romania. A quarter of the identified species were formerly found in the Danube Delta, two species being identified only within DDBR territory. The particular conditions of each stand (vegetation, type of soil etc.) as well as climatic conditions influence both the quantitative and qualitative aspects of the structure of the mesostigmatid mites communities. Horizontal and vertical distributions and the aspects of demographic structure are discussed and the degree of similarity of the gamasid mite communities from the five sites were analyzed on the basis of specific composition and quantitative parameters. © Călugăr A.

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Our investigation has been focused on establishing the slowing down plant growth at the border of polytunnels. In order to determine the limiting factors of plant growth, we have conducted studies on soil properties, entomofauna and soil mesofauna. The research has been carried out in several polytunnels located in North Eastern Romania (Bacău, Iaşi, Bârlad, Fălticeni, Hârlău, Târgu Frumos, Matca-Tecuci) In the field were developed and characterized soil profiles and samples were taken to determine the states of compactness and humidity. The results of researches revealed a strong growth stagnation of tomatoes, cucumbers, eggplants and peppers. The areas where plants have recorded the lowest growth are found in the lateral parts and at the entrance to the polytunnels, as a result of the larger amounts of rainfall, recorded during the vegetation season. Following the analysis, we found that there is a direct correlation between the width of the over wetted soil strip in the lateral parts of the polytunnel and its constructive parameters (width, height, plastic or glass walls), the distance between the polytunnels and the characteristics of the ploughed and under ploughed soil layers. As a result of a pluvial front, the amount of water fallen on the soil unit between the polytunnels, is 6 to 20 times higher than the land in the vicinity of the polytunnels, due to the water flowing from both sides of the solarium. Compaction of the plough layer between the polytunnels, the presence of the hardpan layer, are the additional factors on which the water infiltration rate depends. In addition to the growing stagnation of cultivated plants, a more pronounced incidence of diseases and a more intense attack of the pests, represented by Thysanoptera (Thrips tabaci) and Homoptera, especially aphids – Myzus persicae and Hemiptera – greenhouse whitefly (Trialeurodes vaporariorum). Mesofauna is known as indicator of edaphic conditions, such as water excess. Our investigation revealed very large differences, both quantitative and qualitative, between samples with excess moisture and dry soil between rows. Thus, the average global density was about 35 times higher in the excessively wet soil, and some groups missing in the dry soil are present here (Astigmata and Trombidiformes among mites), whereas. © SGEM 2018.

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Genus Veigaia Oudemans, 1905 of the Veigaiidae family (Acari: Mesostigmata: Veigaiidae) is one of the most ubiquitous genera from Holarctic Region. In Romania 10 species were recorded as being distributed across the entire country. In the frame of this study we present the distribution data of all recorded Romanian Veigaia species: Veigaia cerva (Kramer, 1876); Veigaia exigua (Berlese, 1917); Veigaia kochi (Tragaardh, 1901); Veigaia nemorensis (C.L. Koch, 1839); Veigaia paradoxa Willmann, 1951; Veigaia planicola Berlese, 1892; Veigaia propinqua Willmann, 1936; Veigaia transisalae (Oudemans, 1902), Veigaia transylvanica Kontschan & Ujvari, 2008 and Veigaia uncata Farrier, 1957. At the same time, new characteristic ecological requirements for the Veigaia species were described (type of ecosystem, habitat, altitude and soil).

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The main objective of this study was to compare soil mesofauna communities in natural and anthropogenic forests from Danube Delta Biosphere Reserve and establish a baseline data in monitoring the disturbed sites. The abundance and diversity of edaphic microarthropods were analyzed in five plots, three of them being natural forests and two plantations (Canada poplar, and respectively willow). The mites from Trombidiformes and Oribatida were closely investigated being identified at family level. Qualitative analysis of edaphic microarthropods evidences numerical dominance of mites, excepting only one stand (Canada poplar plantation). Among mites Oribatida owns the biggest weight (76.6 - 94.1% of the total mites), followed by Trombidiformes or Mesostigmata. Among insects the collembolans hold higher density in the poplar plantation, and the lowest one in the willow plantation. Structure of mites communities differs between the investigated ecosystems both in quantitative and qualitative aspects depending on particular conditions of each plot. © 2016 Vasile Goldis University Press.

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