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2 results on '"Sebastian Micki Buss"'

1. Establishment Success of the Beetle Tapeworm Hymenolepis diminuta Depends on Dose and Host Body Condition

Author

Suraj Dhakal, Sebastian Micki Buss, Elizabeth Jane Cassidy, Nicolai Vitt Meyling, and Brian Lund Fredensborg

Subjects
Hymenolepis diminuta, Tenebrio molitor, invertebrate–parasite model, cysticercoid establishment, host immune competence, Science
Abstract

Parasite effects on host fitness and immunology are often intensity-dependent. Unfortunately, only few experimental studies on insect-parasite interactions attempt to control the level of infection, which may contribute substantial variation to the fitness or immunological parameters of interest. The tapeworm Hymenolepis diminuta—flour beetle Tenebrio molitor model—has been used extensively for ecological and evolutionary host–parasite studies. Successful establishment of H. diminuta cysticercoids in T. molitor relies on ingestion of viable eggs and penetration of the gut wall by the onchosphere. Like in other insect models, there is a lack of standardization of the infection load of cysticercoids in beetles. The aims of this study were to: (1) quantify the relationship between exposure dose and establishment success across several H. diminuta egg concentrations; and (2) test parasite establishment in beetles while experimentally manipulating host body condition and potential immune response to infection. Different egg concentrations of H. diminuta isolated from infected rat feces were fed to individual beetles 7–10 days after eclosion and beetles were exposed to starvation, wounding, or insertion of a nylon filament one hour prior to infection. We found that the establishment of cysticercoids in relation to exposure dose could be accurately predicted using a power function where establishment success was low at three lowest doses and higher at the two highest doses tested. Long-term starvation had a negative effect on cysticercoid establishment success, while insertion of a nylon filament and wounding the beetles did not have any effect compared to control treatment. Thus, our results show that parasite load may be predicted from the exposure dose within the observed range, and that the relationship between dose and parasite establishment success is able to withstand some changes in host body condition.

Published
2018
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2. The relative importance of the bacterial pathway and soil inorganic nitrogen increase across an extreme wood ash application gradient

Author

Toke Bang-Andreasen, Louise Hindborg Mortensen, Regin Rønn, Rasmus Kjøller, Flemming Ekelund, Sara Bentzon-Tilia, Carla Cruz-Paredes, Sebastian Micki Buss, and Mette Vestergård

Subjects
structural equation model (SEM), 0301 basic medicine, high-resolution melt curve (HRM) analysis, Renewable Energy, Sustainability and the Environment, Chemistry, bacterial community structure, technology, industry, and agriculture, Forestry, Wood ash, 04 agricultural and veterinary sciences, inorganic nitrogen, respiratory system, complex mixtures, 03 medical and health sciences, protozoa, 030104 developmental biology, Environmental chemistry, Norway spruce, nematodes, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, Waste Management and Disposal, Agronomy and Crop Science, Inorganic nitrogen
Abstract

Ash from combustion of biofuels, for example wood chips, is often deposited as waste, but due to its high content of essential plant nutrients and alkalinity, it has been proposed to recycle ash as a fertilizer and liming agent in biofuel production forest. However, current legislation sets rather strict limitations for wood-ash application in biofuel production systems. The soil microfood web, that is microorganisms and their microfaunal grazers, protozoa and nematodes, is pivotal for essential ecosystem processes such as decomposition and plant nutrient release. Therefore, a thorough assessment of the impacts on microfood web structure and functioning must precede actions towards raising the currently allowed application rates. In a Danish Norway spruce plantation, we evaluate the impact of wood ash applied at dosages from 0 to the extreme case of 90 t ash ha −1 on the microfood web, the bacterial community structure, soil content of inorganic nitrogen, organic matter, dissolved organic carbon and nitrogen. Using structural equation modelling (SEM), we disentangled the direct effect of the disturbance imposed by ash per se, the associated pH increase and changes in prey abundance on individual organism groups in the microfood web. The SEM showed that the pH rise was the main driver of increasing abundances of culturable heterotrophic bacteria with increasing ash doses, and via trophical transfer, this also manifested as higher abundances of bacterial grazers. Fungal-feeding nematodes were unaffected by ash, whereas carnivorous/omnivorous nematodes decreased due to the direct effect of ash. Increasing ash doses enhanced the difference between bacterial communities of control plots and ash-amended plots. The ash-induced stimulation of culturable heterotrophic bacteria and bacterial grazers increased inorganic nitrogen availability at ash doses of 9 t ha −1 and above. Hence, raised limits for ash application may potentially benefit tree growth via enhanced N mineralization activity of the soil food web.

Published
2018
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