Can plant diversity reduce the need for control measures?
Plants are known to ‘communicate’ with one another via airborne molecules. These signals from insect-attacked plants can induce immune response in neighboring unattacked plants and reduce aphid infestations and attract beneficial insects that contribute to biological control. Velemir Ninkovic at the Department of Crop Production Ecology got SEK 6,8 million to develop new cropping systems that reduce the need for reactive control measures.
Velemir Ninkovic says about the project Multifunctional cropping systems - linking plant-plant interactions, insect pest control and wildlife:
Plants are known to 'communicate' with one another via airborne molecules. These airborne signals from insect-attacked plants induce immune response in neighboring unattacked plants. Our own research shows that even healthy, uninfested plants interact with each other via chemical cues, reducing aphid infestations and attracting beneficial insects that contribute to biological control. This increased resistance has been demonstrated when different varieties of barley are grown together instead of in pure stands. This knowledge opens new avenues for the development of sustainable farming systems that minimize the use of pesticides. Interest in botanical diversity in crops is increasing and may become an important component of integrated pest management as required by the new EU directive, and particularly for organic agriculture that lacks reliable control methods.
The aim of our project is to develop cropping systems that reduce the need for reactive control measures. The main tool we use is plant diversity. Our strategy is to utilize the crop's ability to respond to chemical signals from neighboring plants in two systems: barley undersown with a different plant species and mixtures of different barley varieties. In lab and field experiments, we will test the extent to which volatile chemicals emitted by plants induce morphological and physiological changes in barley seedlings, and how these changes affect aphid behavior. We will examine how landscape structural complexity and crop diversity affect biodiversity and biological control locally.
Complex landscapes with a high proportion of uncultivated land and high species richness of birds can limit plants ability to attract beneficial insects. This suggests that increased crop diversity gives the greatest benefit in homogeneous landscapes with low biodiversity. However whether landscape structure and crop diversity affects the interaction between birds and beneficial insects, and thus the risk of widespread aphid outbreaks, has not been addressed and will be studied in the project.
By linking information from these different research components we aim to develop new cropping systems with high efficiency and acceptance among farmers.