Open Field Biocontrol

Open Field Biocontrol

  • Ants can secure a sustainable organic fruit production

The Danish production of organic fruits and berries is not allowed to use chemical pesticides. Therefore, the sector needs effective means to fight pests and plant diseases. If a biological alternative to the chemical substances can be found, the organic farmers can stabilize and increase their yields, hereby improve their economic conditions. The result could be a higher production of organic fruits and berries without traces of pesticides, which is in short supply for the consumers. At the same time, it can make the organic sector more attractive, causing farmers to convert from conventional to organic farming. This would mean fewer pesticides in the Danish nature, higher biodiversity, and a lesser impact on the climate.

Purpose of the project

Wood ants can work as a biological alternative to pesticides because they can protect fruits and berries against pests and plant diseases. This is due to the ants eating other insects and disease tissues as well as releasing antibiotic substances, that inhibit plant diseases.

Even so, the ants also have a negative effect because they farm aphids, which can be harmful for the production. The ants farm aphids in order to harvest and eat the sugar-rich honeydew secreted by the aphids. However, one can prevent the aphid-farming by developing and offering sugar mixtures that are more attractive than the aphids’ honeydew. If this succeeds the plantation-farmers can be content with the positive effects of the ants and thereby gain access to a biological control agent that could make the sector economically attractive. This project is working with apple trees, but the method is expected to work in most types of perennial plant systems.

The project step by step
Establishment of an experimental plantation with apple trees, wood ants, and aphids
Development of sugar solution mixtures that are attractive to wood ants   
Tests to elucidate whether feeding with artificial sugar mixtures can stop the aphid-farming
Tests to elucidate whether the ants protect the apples against pests and diseases       

Project period: 2020-2022

Project leader

Joachim Offenberg, Department of Bioscience,
Aarhus University.
Phone: + 45 25 58 06 80

Project participants

  • Christian Frølund Damgaard, Department of Bioscience, Aarhus University
  • Rikke Reisner Hansen,Department of Bioscience, Aarhus University
  • Ingelise Lauridsen, Department of Bioscience, Aarhus University