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The aim of the study was to conduct quantitative and qualitative analysis of epigeic arthropods (Carabidae, Staphylinidae, Arachnida) occurring in crops within "Norfolk" rotation in organic farming. Arthropods’ collecting was carried out in 2014 at the Experimental Research Station Swojec of the Wrocław University of Environmental and Life Sciences and at the organic farm located at Kamieniec Wrocławski. In both locations ground beetles, rove beetles and arachnids were the most numerous arthropods. The highest number of ground beetles was found within oat treatment, while rove beetles and arachnids within fodder peas. The greatest diversity of ground beetles species was calculated in Kamieniec Wrocławski, in case of pea crops. It may be assumed that these crops, provided by organic farming method, are optimal habitat for beneficial epigeal arthropods development.
Celem pracy była analiza ilościowa i jakościowa zgrupowań stawonogów epigeicznych (Carabidae, Staphylinidae, Arachnida) występujących w uprawach płodozmianu norfolskiego, prowadzonych metoda ekologiczna. Odłowy stawonogów do pułapek glebowych prowadzono w 2014 roku, w Rolniczym Zakładzie Doświadczalnym Swojec, należącym do Uniwersytetu Przyrodniczego we Wrocławiu oraz w gospodarstwie ekologicznym w Kamieńcu Wrocławskim. W obu miejscowościach najliczniejsza grupa stawonogów były chrząszcze z rodzin biegaczowatych i kusakowatych oraz pajęczaki. Liczebność biegaczy najwyższa była w uprawie owsa, natomiast kusaków i pajęczaków najwięcej odłowiono w uprawie grochu pastewnego. Najwieksze zróżnicowanie gatunkowe biegaczowatych odnotowano w Kamieńcu Wrocławskim w uprawie peluszki. Można przypuszczać, że wymienione uprawy prowadzone metodą ekologiczną stanowią optymalne siedlisko dla rozwoju pożytecznych stawonogów naziemnych.
The impact of grazing has been discussed in many organisms, and it has been shown that it has considerable influence on the structural variation of vegetation, resulting in its tussocky appearance. Such spatial heterogeneity results in plants formations that facilitate other species by providing safe sites against predation and physical stress. On the Trnovski gozd plateau in western Slovenia, a secondary habitat of the rare, monotypic endemic umbelliferous species, Hladnikia pastinacifolia, was colonized by a relatively isolated population of the wide spread opilionid species, Phalangium opilio. We hypothesized that in this stony pasture, the impact of the structurally heterogenous vegetation that results from low-intensity grazing benefits both species on hot summer days. For this purpose, we classified vegetation formation types (VFT) and measured temperature and relative humidity in places settled by Ph. opilio individuals during their daily rest. According to the predominant species, we recognized six VFTs: Carlina acaulis, Ruta divaricata, Koeleria pyramidata, Juniperus communis, understory vegetation and grazed turf. Only the spiny C. acaulis and unpalatable R. divaricata facilitated H. pastinacifolia, while also acting as nurse plants. On the other hand, Ph. opilio preferred the understory, but also settled on the other VFts, except Ruta. During the highest daily temperature of about 38[degrees]C, Ph. opilio avoided the grazed turf. Temperature preferences refer to frequencies of individuals rather than to absolute temperature values. The frequencies were independent of sex and the VFTs. Females were more frequently found in tussocks showing higher temperature profiles (Juniperus, Koeleria). During the hot daytime, Ph. opilio was most sensitive to relative humidity, and less so to temperature, whilst the height of settlement varied in adjusting these two environmental factors. The distribution of males significantly differed between the subsequent morning, midday and evening series, but not between the morning and evening ones, while in females it differed between all the three time series. In habitats, such as stony dry pastures, low grazing intensity can maintain persistent populations of H. pastinacifolia and Ph. opilio even in extremely hot weather. Such grazing is the most convenient measure for protecting both species, especially the highly endangered Hladnikia. The major threat to such habitats is afforestation by Pinus nigra, which deserves additional management. We found that in stony pastures, low grazing intensity assures the structural heterogeneity of vegetation required to maintain persistent populations, of both H. pastinacifolia and Ph. opilio.
Content available remote A second camel spider (Arachnida: Solifugae) from Baltic amber
Fossil camel spiders (Arachnida: Solifugae) are extremely rare and only the second example ever recovered from Baltic amber (Paleogene: Eocene) is described here.Although superficially well preserved and more than twice the size of the previously known Baltic amber specimen, key taxonomic characters allowing meaningful comparisons to the other fossil and living material cannot, unfortunately, be resolved. It is formally treated here as Solifugae gen. et sp. indet., although we concede that it could be an adult of the previously recorded Baltic amber species Palaeoblossia groehni Dunlop,Wunderlich and Poinar, 2004.
Artificial defoliation is often used in studies of induced defense reactions of plants to damage by arthropods. However, little is known about the role of various external factors that may determine the nature of inducible defenses. Here we tested whether light level under which plants grow could affect the natural invasion of two-spotted spider mite (Tetranychus urticae Koch) with a broad range of host plants. For this study we used two host species that differ widely in shade tolerance: shade-adapted Norway maple (Acer platanoides L.) and sun-adapted European mountain ash (Sorbus aucuparia L.). The purpose of this study was to explore mite invasion and to test whether prior simulated defoliation, light conditions and host species differences in secondary defense metabolites (soluble phenolics) play a role in the pattern of invasion. One-year-old maple and ash seedlings growing in pots were placed into two shade houses that produced a treatment with 5% light transmittance, and the second group of seedlings was placed in full sunlight. The experiment was carried out in a location chronically affected by spider mite presence. The defoliation was performed in mid-May by manual removal of 0 (control), 25, 50, 75 and 100% of leaves. Natural two-spotted spider mite invasion took place in mid-July and was observed only on seedlings growing in the shade. Mites were found on leaves of almost all seedlings. However, the intensity of feeding damage to leaves was related to the level of earlier defoliation. Control and slightly to moderately (25.50%) defoliated seedlings of both species were most affected by spider mites. Mite feeding behavior was directly linked to changes in concentration of leaf carbon and phenolic compounds. Carbon content was positively correlated with the percent of seedlings damaged by spider mites in both tree species (R[^2]> 0.80; P <0.05). The highest concentration of phenolic compounds was observed in leaves of seedlings subjected to 50 and 75% defoliation. Our results indicated that two-spotted spider mites preferred plants grown in a shade environment and within these plants favored leaves which are high in carbon and low in phenolic compounds. Both plant species were able to survive early season leaf damage inflicted by spider mites. Inducible phenolic compounds were among defensive secondary metabolites contributing to low spider mite success in plants recovering from artificial spring defoliation.
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