6,877 research outputs found
FIGURES 3 in New and interesting species of sacculonotic Haplozetidae (Acari, Oribatida, Haplozetidae) from Indonesia
No full textFIGURES 3. Haplozetes bayartogtokhi sp. nov., adult: A—leg I, without trochanter, left, paraxial view; B—femur, genu and tibia of leg II, right, antiaxial view; C—trochanter, femur and genu of leg III, left, antiaxial view; D—leg IV, left, antiaxial view. Scale bar 20 μm.Published as part of Ermilov, Sergey G., Sandmann, Dorothee & Scheu, Stefan, 2019, New and interesting species of sacculonotic Haplozetidae (Acari, Oribatida, Haplozetidae) from Indonesia, pp. 459-474 in Zootaxa 4656 (3) on page 463, DOI: 10.11646/zootaxa.4656.3.4, http://zenodo.org/record/336900
Diversity and distribution of soil micro-invertebrates across an altitudinal gradient in a tropical montane rainforest of Ecuador, with focus on free-living nematodes
No full textTraunspurger W, Reiff N, Krashevska V, Majdi N, Scheu S. Diversity and distribution of soil micro-invertebrates across an altitudinal gradient in a tropical montane rainforest of Ecuador, with focus on free-living nematodes. Pedobiologia. 2017;62:28-35
Decomposers and root feeders interactively affect plant defence in *Sinapis alba*
Full text linkLohmann M, Scheu S, Müller C. Decomposers and root feeders interactively affect plant defence in *Sinapis alba*. OECOLOGIA. 2009;160(2):289-298.Aboveground herbivory is well known to change plant growth and defence. In contrast, effects of soil organisms, acting alone or in concert, on allocation patterns are less well understood. We investigated separate and combined effects of the endogeic earthworm species Aporrectodea caliginosa and the root feeding nematode species Pratylenchus penetrans and Meloidogyne incognita on plant responses including growth and defence metabolite concentrations in leaves of white mustard, Sinapis alba. Soil biota had a strong impact on plant traits, with the intensity varying due to species combinations. Nematode infestation reduced shoot biomass and nitrogen concentration but only in the absence of earthworms. Earthworms likely counteracted the negative effects of nematodes. Infestation with the migratory lesion-nematode P. penetrans combined with earthworms led to increased root length. Earthworm biomass increased in the presence of this species, indicating that these nematodes increased the food resources of earthworms-presumably dead and decaying roots. Nitrogen-based defence compounds, i.e. glucosinolates, did not correlate with nitrogen levels. In the presence of earthworms, concentrations of aromatic glucosinolates in leaves were significantly increased. In contrast, infection with P. penetrans strongly decreased concentrations of glucosinolates (up to 81%). Infestation with the sedentary nematode M. incognita induced aromatic glucosinolates by more than 50% but only when earthworms were also present. Myrosinase activities, glucosinolate-hydrolysing enzymes, were unaffected by nematodes but reduced in the presence of earthworms. Our results document that root-feeding nematodes elicit systemic plant responses in defence metabolites, with the responses varying drastically with nematode species of different functional groups. Furthermore, systemic plant responses are also altered by decomposer animals, such as earthworms, challenging the assumption that induction of plant responses including defence traits is restricted to herbivores. Soil animals even interact and modulate the individual effects on plant growth and plant defence, thereby likely also influencing shoot herbivore attack
Transformation tropischer Regenwälder in Sumatra, Indonesien: Einblicke in ein integriertes Forschungsprogramm und Perspektiven für ober- und unterirdische Nahrungsnetze
No full textDer Vortrag gibt einen Überblick über ein deutsch-indonesisches Forschungsprojekt (SFB 990/EFForTS), in dem ökologische und sozioökonomische Konsequenzen der Umwandlung tropischer Tieflandregenwälder in Kautschuk- und Ölpalmenplantagen in Sumatra, Indonesien, über einen Zeitraum von 12 Jahren untersucht werden. Vertiefend stellt der Vortrag Konsequenzen für die Struktur und Funktionsweise ober- und unterirdischen Nahrungsnetzes tropischer Ökosysteme vor
Fig. 8 in Uncovering cryptic diversity in the enigmatic ant genus Overbeckia and insights into the phylogeny of Camponotini (Hymenoptera:Formicidae:Formicinae)
No full textFig. 8. Variation in Overbeckia species occurrence across four vegetation types and two seasons in the EFForTS project (dry season, bars in red; wet season, bars in blue). Values on the y-axis show the number of cases in which the species occurred at least once in a subplot. In total, 19 individuals and 14 occurrences were found across 192 subplots sampled during dry and wet seasons (0.07% occupancy). At the level of different sites (forest plots), only 9 of 32 sampled here by canopy fogging were occupied by the genus.Published as part of Klimeš, Petr, Drescher, Jochen, Buchori, Damayanti, Hidayat, Purnama, Nazarreta, Rizky, Potocký, Pavel, Rimandai, Maling, Scheu, Stefan & Matos-Maraví, Pável, 2022, Uncovering cryptic diversity in the enigmatic ant genus Overbeckia and insights into the phylogeny of Camponotini (Hymenoptera:Formicidae:Formicinae), pp. 277-288 in Invertebrate Systematics 36 (6) on page 572, DOI: 10.1071/is21067, http://zenodo.org/record/698729
Climate change triggers effects of fungal pathogens and insect herbivores on litter decomposition
No full textIncreasing infestation by insect herbivores and pathogenic fungi in response to climate change will inevitably impact the amount and quality of leaf litter inputs into the soil. However, little is known on the interactive effect of infestation severity and climate change on litter decomposition, and no such study has been published for deciduous forests in Central Europe. We assessed changes in initial chemical quality of beech (Fagus sylvatica L.) and maple litter (Acer platanoides L) in response to infestation by the gall midge Mikiola fagi Hart. and the pathogenic fungus Sawadaea tulasnei Fuckel, respectively, and investigated interactive effects of infestation severity, changes in temperature and soil moisture on carbon mineralization in a short-term laboratory study. We found that infestation by the gall midge M. fagi and the pathogenic fungus S. tulasnei significantly changed the chemical quality of beech and maple litter. Changes in element concentrations were generally positive and more pronounced, and if negative less pronounced for maple than beech litter most likely due to high quality fungal tissue remaining on litter after abscission. More importantly, alterations in litter chemical quality did not translate to distinct patterns of carbon mineralization at ambient conditions, but even low amounts of infested litter accelerated carbon mineralization at moderately increased soil moisture and in particular at higher temperature. Our results indicate that insect herbivores and fungal pathogens can markedly alter initial litter chemical quality, but that afterlife effects on carbon mineralization depend on soil moisture and temperature, suggesting that increased infestation severity under projected climate change potentially increases soil carbon release in deciduous forests in Central Europe. (C) 2014 Elsevier Masson SAS. All rights reserved
Fertilizer addition lessens the flux of microbial carbon to higher trophic levels in soil food webs of grassland
No full textRoots and root-derived C compounds are increasingly recognised as important resources for soil animal food webs. We used C-13-labelled glucose as a model C compound representing root exudates to follow the incorporation of root-derived C into the soil animal food web of a temperate grassland over a period of 52 weeks. We investigated variations in glucose C incorporation with fertilizer addition and sward composition, i.e. variations in plant functional groups. The approach allowed the differentiation of trophic chains based on primary decomposers feeding on litter and phytophagous species feeding on roots (i.e. not incorporating glucose C) from those based on secondary decomposers feeding on microorganisms (thereby assimilating glucose C). Each of the studied soil animal species incorporated glucose C, indicating that the majority of grassland soil animal species rely on microorganisms as food resources with microorganisms being fuelled by root exudates. However, incorporation of glucose C into soil animal species varied markedly with species identity, suggesting that detritivorous microarthropods complement each other in channelling microbial C through soil food webs. Fertilizer addition markedly reduced the concentration of glucose C in most soil animal species as well as the absolute transfer of glucose C into oribatid mites as major secondary decomposers. The results suggest that fertilizer addition shifts the basis of the decomposer food web towards the use of unlabelled resources, presumably roots, i.e. towards a herbivore system, thereby lessening the link between microorganisms and microbial grazers and hampering the propagation of microbial C to higher trophic levels.Ministry of Science and Culture of Lower Saxony; Niedersachsisches Vora
Control of aphids on wheat by generalist predators: effects of predator density and the presence of alternative prey
No full textThere is evidence for both positive and negative effects of generalist predators on pest populations and the various reasons for these contrasting observations are under debate. We studied the influence of a generalist predator, Pardosa lugubris (Walckenaer) (Araneae: Lycosidae), on an aphid pest species, Rhopalosiphum padi (L.) (Hemiptera: Aphididae; low food quality for the spider), and its host plant wheat, Triticum spec. (Poaceae). We focused on the role of spider density and the availability of alternative prey, Drosophila melanogaster Meigen (Diptera: Drosophilidae; high food quality). The presence of spiders significantly affected plant performance and aphid biomass. Alternative prey and spider density strongly interacted in affecting aphids and plants. High spider density significantly improved plant performance but also at low spider density plants benefited from spiders especially in the presence of alternative prey. The results suggest that generalist arthropod predators may successfully reduce plant damage by herbivores. However, their ability to control prey populations varies with predator nutrition, the control of low-quality prey being enhanced if alternative higher-quality prey is available.DFG (Deutsche Forschungsgemeinschaft
Shifts in trophic interactions with forest type in soil generalist predators as indicated by complementary analyses of fatty acids and stable isotopes
No full textHuman impact on structure and functioning of ecosystems is rapidly increasing. Virtually all European forests are managed with major implications for diversity and structure of food webs. Centipedes (Chilopoda: Lithobiidae) are abundant arthropod predators in European temperate forest soils with a generalistic feeding behaviour. However, little is known on the variability in the prey spectrum of centipedes with land use and the responsible factors. Combining fatty acid (FA) analysis, which allows determination of the relative contribution of different prey to predator nutrition, and stable isotope analysis, providing insight into the trophic structure of decomposer food webs, we investigated variations in trophic niches of two dominant centipede species, Lithobius mutabilis and Lithobius crassipes, in differently aged beech and spruce forests. FA composition of the two centipede species differed significantly with bacterial marker FAs being more abundant in L. crassipes as compared to L. mutabilis. Differences were most pronounced in spruce as compared to beech forests. The results suggest that dense needle litter in coniferous forests may restrict prey availability to the larger L. mutabilis and confine foraging to the litter surface whereas the smaller L. crassipes is able to also exploit prey of deeper litter layers. Lithobius crassipes was significantly more enriched in N-15 and C-13 compared to L. mutabilis suggesting that, compared to L. mutabilis, the smaller L. crassipes occupies higher trophic levels and relies more on root derived carbon. The results indicate that trophic niches of centipedes vary in a species specific way between forest types with body size and habitat structure being major determinants of the variations in the prey spectrum. Combining techniques for delineating predator-prey interactions allowed insights into variations in trophic interrelationships and their driving forces in temperate forest soil food webs.DFG [1374
Reliability of isotopic fractionation (Delta N-15, Delta C-13) for the delimitation of trophic levels of oribatid mites: Diet strongly affects Delta C-13 but not Delta N-15
No full textStable isotope analysis has become an analytical tool of central importance in trophic ecology. The actual degree of isotopic fractionation, however, remains a black-box in most studies. Hence, mean values for trophic enrichment from other taxa are commonly used to delimitate trophic levels. On the other hand, resource composition as well as consumer physiology both influence fractionation patterns. Especially in soil food webs, high variability of isotopic fractionation has been found for both N-15 and C-13. Here, we investigate effects of diet on trophic enrichment in a no-choice feeding, experiment with the oribatid mite model species Archegozetes longisetosus and a set of fungal, animal, algal and plant resources (seeds and vegetative tissues). We found consistent trophic enrichment for nitrogen irrespective of diet (Delta N-15 = 3.9 parts per thousand), but no reliable fractionation for carbon being negative for fungi (Delta C-13 = 1.8 parts per thousand), neutral for algae, and positive for the remaining plant and animal resources (Delta C-13 = 2.3 parts per thousand). The results suggest that delta N-15 is a reliable marker for delimiting the trophic level of oribatid mites and presumably other soil detritivores, while understanding delta C-13 signals needs a priori knowledge about isotopic fractionation with respect to consumed resources. (C) 2016 Published by Elsevier Ltd
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