No Broccoli without a Head: Evaluating UV Light Traps as Pull Mechanism for the Control of Contarinia nasturtii

Summary in the original language of the document

Contarinia nasturtii, commonly known as Swede midge, is a specialist insect on brassicaceous plants, causing up to 85% yield losses in broccoli production. Due to its small size, short lifespan, and larval behaviour of feeding on hidden points of the plant, its control is challenging. This thesis aimed at evaluating the capturing rate of C. nasturtii with UV lighttraps to reveal their potential as pull mechanism in Push-Pull-Systems. Push-Pull-Systems are a pest management strategy, which combines different stimuli to manipulate pest distribution and abundance. To test the potential of UV light traps, the following experiments were designed: (i) two traps were installed in a polytunnel simulating semi-field conditions, testing the recapturing rate of the traps after a release of Swede midges, (ii) one trap was installed in the same tunnel to test at which distances the traps emain effective, and (iii) a field experiment using four traps to test the capturing efficacy of naturally occurring midges under open field conditions. Due to low numbers of C. nasturtii adults in the laboratory colony, experiment (i) could only be carried out twice, while experiment (ii) was not performed at all. Numerous midges were captured in the field experiment (iii), which shows that the traps are able to capture midges. Pheromone traps and plant damage evaluation data were collected, and used to supplement capturing rates data of UV traps. The outcomes of this project lay a foundation for the implementation of UV light traps as pull mechanism for the control of pests that commonly occur in the Brassicaceae, and highlight research questions that remain to be
investigated.