Jørgen Axelsen

Jørgen Axelsen
Aarhus University | AU · Department of Bioscience

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32
Publications
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976
Citations

Publications

Publications (32)
Article
Full-text available
Caesalpinia bonduc is overexploited and threatened due to its importance in medicine. This study aims at assessing on farm seedling productivity of C. bonduc by aid of simulation modelling in order to design its appropriate plantation techniques, harvesting intervals, and soil conditions. Data were collected from nursery and field experiments by me...
Article
Weaver ants (Oecophylla spp.) are managed in plantations to control insect pests and are sometimes harvested as a protein-rich food source. In both cases, the amount of insect prey caught by the ants is imperative for returns, as more prey leads to more effective biocontrol and to a higher production of ants. Malaise-like traps placed in trees may...
Article
The population development of Dasyneura brassicae was investigated by water traps, plant samples, funnel traps, soil samples and emergence traps in unsprayed plots of winter rape and spring rape. The resulting census data were used to estimate the mortality during life stages and between life stages. High mortality rates were found throughout the l...
Article
Taylor's power law was used to analyse the spatial distribution of the pollen beetle Meligethes aeneus F. in spring sown rape. Sampling was carried out on small plots (5 × 10 m) and the coefficients of the power law were estimated. Their spatial distribution may not be distinct from a random one at low densities. At higher densities the beetles agg...
Article
Full-text available
We present a simulation study of the role of birds and egg pod predators in the population dynamics of the Senegalese grasshopper. The model was an energetics-driven ecosystem model that included a natural Sahelian grass, millet, grasshoppers, the egg pod predators bombyliidae and Tenebrionidae, and 24 species of birds that prey on grasshopper nymp...
Article
Preference studies of many different collembolan species have categorised collembolans being selective in their food choice. To clarify whether collembolan food selectivity is related to fitness parameters, three species, Folsomia fimetaria, Protaphorura armata and Heteromurus nitidus, were fed three fungal species, Alternaria infectoria, Mucor hie...
Article
Between 1986 and 2003 the Danish government introduced three Pesticide Action Plans to reduce the pesticide usage. In order to simulate the expected effects of the third Pesticide Action Plan a large quantity of field data was collected to calibrate and validate the simulations of the growth of a number of weed species and crops in a simulation mod...
Article
The aim of this study was to assess, whether organic dairy farming has increased the biological diversity of field boundary vegetation when compared to conventional dairy farming, and if increasing organic farming duration affected diversity.The diversity of plant species in field boundaries was found to be higher under organic than under conventio...
Article
Full-text available
Vegetation data including plant cover, biomass, species richness, and vegetation height was sampled on a copper-contaminated field with total copper contents varying from 50 to almost 3,000 mg/kg soil. The field was covered by early succession grassland dominated by Agrostis stolonifera. Plant cover, biomass, species richness, and vegetation height...
Article
In agricultural soil, a suite of anthropogenic events shape the ecosystem processes and populations. However, the impact from anthropogenic sources on the soil environment is almost exclusively assessed for chemicals, although other factors like crop and tillage practices have an important impact as well. Thus, the farming system as a whole should...
Article
Short-range predator–prey interactions among small soil-dwelling arthropods are poorly understood. In this study, we measured the behavioural interactions between the predacious mite Hypoaspis aculeifer Canestrini (Gamasida: Laelapidae) and its collembolan prey Folsomia fimetaria L. (Collembola: Isotomidae) and the influence of sex, size, starvatio...
Article
Full-text available
Patterns in spring-active carabid beetle assemblages were described in relation to four organic soil management regimes (no soil nutrient addition, undersowing, animal manure, undersowing + manure) in two areas of Denmark by means of pitfall trapping. On the island of Zealand, the Flakkebjerg study area had 22 species, 3-10 species/trap, and the sp...
Article
Tillage operations and field traffic may cause soil compaction and alter the pore characteristics in soil. These practices often lead to a reduction in habitable pore space for the soil mesofauna. In the present study the abundance of some euedaphic species of Collembola was investigated under a range of soil bulk densities normally found in agricu...
Article
Full-text available
A new and simplified method for extraction of ergosterol (ergosta-5,7,22-trien-3beta-ol) from fungi in soil and litter was developed using pre-soaking extraction and paraffin oil for recovery. Recoveries of ergosterol were in the range of 94-100% depending on the solvent to oil ratio. Extraction efficiencies equal to heat-assisted extraction treatm...
Article
The spring and summer abundance of soil living mites and Collembola was investigated in organically grown field plots which had been covered with either the nitrogen catch crops winter rye, hairy vetch, fodder radish and a control (stubble). The catch crops were incorporated in the soil shortly before sowing of spring barley with under sown clover...
Article
1. The Collembola is one of the important prey groups for generalist arthropod predators in agro-ecosystems. Differences in the quality of available species may play a significant role in the build-up of a community of natural enemies. The value of some common epigeic and hemi-edaphic Collembola as prey for adults and larvae of the carabid beetle B...
Article
Full-text available
In order to evaluate the power of laboratory toxicity tests to predict the situation in the field, soil microarthropods were studied at the population and community levels in a copper contaminated field, and data were compared to the outcome of single species laboratory tests in the same soil type from a companion study. In addition to copper, the...
Article
Egg production by the cereal spider Erigone atra was used as a fitness parameter for evaluating the food quality of two species of Collembola: Folsomia fimetaria and Isotoma anglicana. Drosophila melanogaster was used as reference prey. We tested the hypothesis that due to differences in food quality, the two Collembola species would affect the rep...
Article
The relationship between crop architecture and spray interception was investigated in spring barley at two developmental stages. Height and outer surface area were determined for stems, leaves and ears, when present. To trace the droplet interception by the crop a fluorescent dye was used. To avoid difficulties in measuring spray deposition on plan...
Article
Direct topical impact of an insecticide spray on a population of a non-target leaf-eating beetle, Gastrophysa polygoni, was studied, and the relative importance of phenology, instar susceptibility and instar specific exposure was evaluated. Two insecticides, cypermethrin and dimethoate, were investigated. In the laboratory, topical toxicity to eggs...
Article
Simulation models must be clear in their concepts and design to be useful tools for ecological research. To facilitate clear and efficient model development, we present a modelling framework (OOMP) based on the concepts of the metabolic pool model and on object-oriented programming techniques. Modellers can use OOMP: (1) to increase productivity th...
Article
Full-text available
A mathematical simulation model (Gutierrez type) has been developed to investigate the predator-prey interactions in a two species ecotoxicological test system. The test system consists of the predacious mite (Hypoaspis aculeifer Canestrini) and, as prey, the collembolan Folsomia fimetaria L. in a microcosm (5.5 cm high × 6.0 cm in diameter) with 3...
Article
In this paper we examine the hypothesis that diapause induction in the polyvoltine pod midge Dasyneura brassicae Winn. (Diptera: Cecidomyiidae) is controlled by cumulative global solar radiation during the larval stage. The correlation between field observations of relative diapause for 3 years and four environmental factors (daylength, temperature...
Article
The interaction between the pod gall midge (Dasyneura brassicae Winn.) and its most important parasitoid (Platygaster oebalus Walk.) in rape fields was investigated by aid of a computer model. The model is driven by temperature and the population dynamics is modelled by a distributed delay procedure. A relatively large program procedure was used to...
Article
The population development of the pod gall midge (Dasyneura brassicae Winn.) in winter rape and spring rape (Brassica napus L.) is described by a computer model. The model is temperature driven and the population dynamics is described by a distributed delay procedure.Simulation by the model was found to be a useful tool to gain more information fro...
Article
The developmental time of the juvenile stages of the pod gall midge (Dasyneura brassicae Winn.) was investigated in the laboratory at constant temperatures. The results were used to estimate the developmental zero (6.7°C for egg-larval stage, 8.1°C for development in the soil) and the thermal requirements (134°DD for egg-larval stage, 141°DD for th...
Article
Field investigations were made on the developmental time of eggs, 1. instar and 2. instar stages of the pollen beetle (Meligethes aeneus F.). The observations were used to estimate the parameters of the day-degree model. Developmental threshold was found to be 4 °C and the total hour-degree requirement for the 3 stages was 1510, 1390 and 1480, resp...

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Projects

Projects (3)
Archived project
The project deals with the scientific background for weaver ant biocontrol. The project investigates the chemical content and biological effects of the weaver ants „manure‟ deposits that may serve as both plant nutrient and a means of chemical communication. Results will be set into an ecological and practical context by simulation modelling
Archived project
Increased organic fruit production, integrated pest managemnet (IPM), weaver ants, agribusiness, capacity building