Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2018
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Authors
Johannes BreidenbachAbstract
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The apple fruit moth Argyresthia conjugella (Lepidoptera, Yponomeutidae) is a seed predator of rowan (Sorbus aucuparia) and is distributed in Europe and Asia. In Fennoscandia (Finland, Norway and Sweden), rowan fruit production is low every 2–4 years, and apple (Malus domestica) functions as an alternative host, resulting in economic loss in apple crops in inter-mast years. We have used Illumina MiSeq sequencing to identify a set of 19 novel tetra-nucleotide short tandem repeats (STRs) in Argyresthia conjugella. Such motifs are recommended for genetic monitoring, which may help to determine the eco-evolutionary processes acting on this pest insect. The 19 STRs were optimized and amplified into five multiplex PCR reactions. We tested individuals collected from Norway and Sweden (n = 64), and detected very high genetic variation (average 13.6 alleles, He = 0.75) compared to most other Lepidoptera species studied so far. Spatial genetic differentiation was low and gene flow was high in the test populations, although two non-spatial clusters could be detected. We conclude that this set of genetic markers may be a useful resource for population genetic monitoring of this economical important insect species.
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Although pasture is low-cost feed, many farmers find it difficult to maintain high milk yield when using pasturefor high-yielding dairy cows in automatically milked herds. Therefore, a seven-week experiment with 40 cows inearly to mid-lactation was performed to evaluate a management model for including pasture in the diet withoutjeopardizing milk production. Within a part-time grazing system with morning and evening outdoor access, wecompared a group with ad libitum grass silage indoors combined with access to a small grass-covered permanentpaddock for exercise and recreation (group EX) with a group offered production pasture at a high allowance percow and day combined with restricted grass silage allowance at night (group PROD). Both groups had the sameoutdoor access times and the same concentrate allowance based on pre-experimental milk yield. Milk yield andmilking frequency were recorded daily in the automatic milking unit. Milk recordings and samplings for de-termination of milk composition took place weekly and outdoor behaviour of cows was recorded during pastureaccess hours on six observation days, evenly distributed over the experimental period. During the experiment,average metabolisable energy concentration was higher in the grass silage offered both groups than in pastureherbage. However, our results showed no significant difference in daily milk yield between treatments.Furthermore, no signifi cant differences between treatments were found in energy-corrected milk, milk fatproduction, or body weight change. Milk protein production was, however, significantly higher in group PROD.In early lactation, no difference in milking frequency was observed between treatments while for cows in mid- tolate lactation, milking frequency was significantly higher in group EX than group PROD. Over the entire ex-periment, group EX cows spent significantly less time outdoors than group PROD. In conclusion, offering highyielding dairy cows in automatic milking systems high-quality pasture at a high allowance for a few hours inmorning and afternoon appears to be an interesting alternative to exercise paddock with full indoor feeding, as itcan reduce costs for supplementary silage, facilitate natural behaviour, and encourage cows to spend more timeoutdoors, while maintaining milk production at a level comparable to that of full indoor feeding.
Authors
Fernanda de Cássia Neves Esteca Luis Rodolfo Rodrigues Gilberto José de Moraes Italo, Júnior Delalibera Ingeborg KlingenAbstract
Mulching of soil beds of strawberry fields is usually done with polyethylene film in southern Minas Gerais state, Brazil. This material is relatively expensive and difficult to discard after use. In some countries, mulching is done with the use of organic material that could have an advantage over the use of plastic for its easier degradation after use, and for favoring edaphic beneficial organisms. Predatory mites (especially Gamasina, Mesostigmata) may be abundant in the soil and could conceivably move to the soil surface and onto the short-growing strawberry plants at night, helping in the control or pest arthropods. The two-spotted spider mite, Tetranychus urticae Koch, is considered an important strawberry pest in that region, where the fungus Neozygites floridana (Weiser and Muma) has been found to infect it. Different mulching types could affect the incidence of this pathogen. Dehydrated coffee husk and pulp (DCHP) is a byproduct readily available in southern Minas Gerais, where could be used as organic mulching in strawberry beds. The temporary contact of that material with the soil of a patch of natural vegetation could facilitate its colonization by edaphic predatory mites helpful in the control of strawberry pests. The objective of this work was to study the effect of mulching type on the population dynamics of the two-spotted spider mite, associate mites and N. floridana, in a greenhouse and in the field. The use of DCHP increased the number of edaphic Gamasina on strawberry plants—Proctolaelaps pygmaeus (Müller) (Melicharidae) and Blattisocius dentriticus (Berlese) (Blattisociidae) were observed on strawberry leaflets, mainly in nocturnal samplings, indicating their possible daily migration from soil to plants. Lower levels of two-spotted spider mite occurred on plants from pots or soil beds mulched with DCHP instead of polyethylene film, possibly because of the slightly higher levels of mites of the family Phytoseiidae and infection by N. floridana. Adding DCHP onto the floor of natural vegetation did not result in higher diversity or levels of gamasine mites on DCHP. Complementary studies should be conducted to find ways to increase diversity and density of those organisms in strawberry beds, in an attempt to improve biological control of strawberry pests. The decision to use DCHP for mulching should also take into account other factors such as strawberry yield, costs and efficiency of weed management, to be evaluated in subsequent studies.
Abstract
1. Large-scale pattern-oriented approaches are useful to understand the multi-level processes that shape the genetic structure of a population. Matching the scales of patterns and putative processes is both a key to success and a challenge. 2. We have developed a simple statistical approach, based on variogram analysis, that identifies multiple spatial scales where the population pattern, in this case genetic structure, have highest expression (i.e. the spatial scales at which the strength of patterning of isolation-by-distance (IBD) residual variance reached maximum) from empirical data and, thus, at which scales it should be studied relative to the underlying processes. The approach is applicable to any spatially explicit pairwise data, including genetic, morphological or ecological distance or similarity of individuals, populations and ecosystems. To exemplify possible applications of this approach, we analysed microsatellite genotypes of 1,530 brown bears from Sweden and Norway. 3. The variogram approach identified two scales at which population structure was strongest, thus indicating two different scale-dependent processes: home-rangerelated processes at scales <35 km, and subpopulation division at scales >98 km. On the basis of this, we performed a scale-explicit analysis of genetic structure using DResD analysis and compared the results with those obtained by the Bayesian clustering implemented in structure. 4. We found that the genetic cluster identified in central Scandinavia by Structure is caused by IBD, with distinct gene flow barriers to the south and north. We discuss possible applications and research perspectives to further develop the approach.
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Authors
Bjørn Egil FløAbstract
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