In this project we have developed, tested and improved methods to reduce crop losses due to root feeding flies. Each method can be seen as a single "tool" that conributes to a "toolbox" to provide an integrated approach to protecting the plants from damage.
Scientists from nine different research institutions in the United Kingdom, France, Denmark, Germany, Switzerland, Ireland, Norway, and Slovenia have collaborated on this project, working together to improve the management of root-feeding fly larvae infesting outdoor vegetable crops using an integrated pest management (IPM) approach.
The key pest insects of interest for Norway are cabbage root fly and turnip fly. These species greatly reduce crop yield and quality if not managed effectively. Control in Europe still relies mainly on the use of insecticides, most of which are not registered for use in Norway. Most of these insecticides will be removed from the European market within a short time. Thus, it is imperative to find alternative methods for to protect plants from these flies.
Some of the approaches that have been investigated previously are host plant resistance, sterile insect release, companion planting and biological control. Monitoring systems have been developed for all the key root fly pests. Forecasting and dissemination systems for some of the root flies are available in some of the partner countries.
The project has further developed monitoring and decision support systems for the root flies that are reliable, cost-effective and simple. We have developed alternative control strategies with fewer side effects on beneficial organisms and alternative ways of applying treatments.
The project had a holistic approach to improving root fly control through the following actions:
- Creating, gathering, and coordinating knowledge about the pests´ life cycles and about monitoring and forecasting models.
In autumn 2017 and 2018, the Norwegian team received cabbage root fly pupae (the overwintering stage of the flies) from 5 of the participating countries. The pupae were kept at controlled temperatures in the phytotron at NIBIO Holt in Tromsø until hatching as adult flies. The results indicated that all populations had similar temperature requirements for hatching. This information will be incorporated into models in Norway and the partner countries for predicting when the flies will be swarming and laying eggs on the plants.
- Development and refinement of biological control methods using fungi and nematodes.
Studies were done at NMBU and Copenhagen Life to determine the effectiveness of an insect-killing fungus against cabbage root fly larvae. The fungus was added in the soil at planting in a field experiment and at sowing in a greenhouse experiment. The fly larvae that developed on the plants are being cultured to see if they are infected with the insect-killing fungus.
- Developing methods to reduce the likelihood of adult insects finding and infesting susceptible crops.
An experiment was conducted in a windtunnel at the NIBIO research facility in Ås. Mated female flies were released in the windtunnel, where they could choose between plants that were grown in pots with or without an insect-killing fungus. In this experiment, the flies preferred to land on the plants grown with the fungus. This finding means that the flies are more attracted to plants that may be defended from the fly larvae by the fungus!
- Integration of existing and newly developed control methods into IPM strategies.
A large experiment was conducted over two seasons in a research field at NMBU in Ås. Several methods from the "toolbox" were tested individually or combined to see if there was a greater effect to protect the plants. The methods compared were: 1) cauliflower grown alone without plant protection; 2) caulifower grown with Chinese cabbage as a "trap crop" to attract the flies from the cauliflower; 3) cauliflower with a repellent to push the flies from the cauliflower to the trap crop; 4) cauliflower enclosed by a fence of insect netting to keep the flies from reaching the plants; 5) cauliflower with a fence and a trap crop.
There were clear differences in the number of cabbage root fly eggs layed depending on the control method. The most eggs were found on cauliflower plants grown alone, slightly fewer with a trap crop (with or without repellent), and fewest inside the fences (with or without trap crop).
- Dissemination of information to farmers, advisors and other stakeholders.
The activities and results from this project are communicated by "field days" at the research sites attended by students at NMBU and extension agents from the advisory service. Articles are published in the farmers' journals in Norway and in the partner countries. The project and results have been presented in teaching at NMBU and for the advisory service in Normandy in France. In addition, the work has been presented at 2 scientific meetings in the UK.
The project improved collaboration between the partner countries including understanding of the research fields, information to stakeholders in each country and routes to disseminate that information. The partners increased their expertise in the different experimental approaches used and how their own research will fit into an IPM programme in the future and has led to the formation of new partnerships. More time/development will be required before the information can be used by growers, for example the novel push-pull system and the approaches using a combination of IPM tools. As a result of a visit from Norway to the advisors in Normandy, the IPM tool of exclusion fences is being investigated for practical use in France. Information transfer to the research/development community has been effective and it has been an excellent project to raise the profile of IPM strategies amongst that community.
The aim of the proposed project is to improve the management of root-feeding fly larvae infesting outdoor vegetable crops using an integrated approach (IPM). The key pest insects are Delia radicum, D. floralis, D. antiqua, D. platura and Psila rosae and all considerably reduce crop yield and quality if not managed effectively. We will improve the management of these pests by 1) assimilating and synthesising information on pest life-cycles and on monitoring and forecasting approaches to improve integration of control methods; 2) developing methods to reduce the likelihood of adult insects finding and/or infesting susceptible crop plants; 3) developing and refining methods for biological control of larval and adult insects with entomopathogenic fungi (EPF) and nematodes; 4) integrating existing and newly-developed methods of control into IPM strategies and 5) disseminating information to a community of stakeholders to improve pest management at field and farm level. This will reduce the need for, and improve the performance of, insecticidal methods of control, increase the quality of produce, minimise waste both pre- and post-farmgate and reduce insecticide use and the resulting adverse effects on the environment and human health. The main outcomes of the project will be 1) improved understanding of pest and natural enemy phenology, together with refinement of existing monitoring and forecasting approaches; 2) scientific progress from research on methods of manipulating pest insect behaviour which may lead to novel methods of control; 3) scientific progress in pest control with entomopathogens and on plant-EPF-insect interactions which may lead to new and more efficacious approaches to their application and 4) integration of control methods under field conditions leading to improved control; 5) information and techniques will become more freely available within Europe.