Research Group: Applied Entomology
Our research group has roots to more than a century ago based on the importance of insects and other arthropods related to man made production systems and other systems strongly managed by man.
The research is anchored in the populations of insect pests and their interactions with other populations of plants and animals (e.g. beneficials) as well as the production ways in agriculture, horticulture and forestry, and the climatic conditions affecting the dynamics. This research platform has over the last decades developed further towards the effects of agricultural practices on all animals in arable land.
Integrated Pest Management (IPM)
The IPM concept includes as one of the major aims to reduce the use chemical control to an absolute minimum and employ sound decision making on the basis of monitoring and scientifically founded thresholds. In order to achieve this development of monitoring-forecasting-systems is a must and a scientific challenge, selected by this group as one of its priority areas.
Also the utilisation in different way of natural enemies is a major issue of the IPM concept dealt with by the group.
Population monitoring, threshold development and forecasting
Monitoring of populations by stratified counting and trapping is employed both for scientific purpose and for further development of practical monitoring.
Particular attention is devoted to sex trapping as the basis of monitoring for further development of forecasting. This include work on pheromones and kairomones, and development of traps.
In order to establish background for building of action thresholds the most important factors for population dynamics like fertility, developmental requirements (e.g. thermal sums) and the most important abiotic and biotic mortality factors are studied. In addition controlled experiments and fields assessments of levels of injury related to pest abundance are carried out. In some cases perennial series of assessments of abundance and injuries are used both to fine tune thresholds and to check the validity of forecasts.
Agricultural practices and biodiversity
The use of pesticides in particular but also other agricultural practices may negatively affect the biodiversity of insects and birds. This includes direct effects of e.g. insecticides on non-target insects but also indirect effects of herbicides affecting plants and subsequently also herbivorous insects, their natural enemies, and birds at the upper level of the food web.
Studies have been undertaken of influence of dosage levels on different layers of the food web in terms of species related biodiversity, biomass changes of selected elements, and tritrophic interactions. A follow up has been undertaken by also studying selected organisms of the food web, when pesticides are omitted and when herbicide treatments are replaced by more or less frequent application of mechanical weed treatments.
The most recent angle of the research on larger agricultural areas is studies on the biodiversity improving effect of establishing non-fertilized and pesticide free buffer zones of four different width’s in cereal fields. This includes identification of potential indicator species for more general improvements of biodiversity.
Functional biodiversity and tritrophic interactions
Bees and natural enemies of insect pests provide an important resource for natural pest control. Central elements for the research are interactions, plant –pest insect – natural enemies as well as plant –pollinator interactions, and at a system level interactions between these populations and the full landscape. This is further investigated with focus on tritrophic interactions through field manipulations (e.g. flower strips) in more intensive production of high value crops as for instance strawberry and apple. This work also includes studies on effects of improved conditions for pollinators in strawberry and the effects of the landscape on biodiversity and pollination services.
Insect populations under global climate change
Until recently the focus of research on climate effects has been on conditions which potentially open for outbreaks of particular insect pests as well in annual crops as in perennial crops. With the global climate change, the scope of research is broadened and the focus is now on effects on changing status of known insect pests and immigration of new. Changed climate conditions of particular interest are for instance mild winters and dry, hot summers. These conditions are predicted to be more frequent in Denmark due to the global climate change and in addition a general rise of temperature of 1.5-4.5°C predicted during the present century. This rise has already started, and the phenological effects and potential changes of pest status of the rising average temperature is analysed by using trapping data from several decades of monitoring of selected insects. Furthermore experimental studies are starting on how the change to milder winters improve conditions for some insect pests and hamper the overwintering success and subsequent performance of others.
For further information - please contact Professor Peter Esbjerg