A holistic sugar beet weevil control with the entomopathogenic fungus Metarhizium (i.e. soil and leaf treatment) including a new trap groove design was tested for the first time in three new locations in the region of Tulln and Klosterneuburg in spring 2021. The concept relied on a preventive application of the insect-killing fungus Metarhizium brunneum to control all developmental stages of the sugar beet weevil in the soil; but also spray application was carried out with the aim of directly controlling the weevils with this very fungus via the sugar beet leaf, which represented another biological control approach in practice. Trap grooves were also tested and improved, which were placed around the newly planted sugar beet fields as an initial barrier for the migration. An additional treatment of the trap groove including the trench with a Metarhizium dispersion formulation should infect the mature weevils and thus reduce the sugar beet weevil population in the long term. The desired fungal density of 5,000 M. brunneum CFU g-1 dry wt soil (colony forming units per gram soil dry weight) and more could already be achieved after the first application of the fungal barley product GranMet‑PTM, alone and/or in combination with the liquid formulation. A high indigenous Metarhizium abundance was striking at all trial sites. Genotyping assays confirmed that the applied entomopathogenic production strain BIPESCO 5 was able to establish itself in the treatment plots. Spray treatment of the trap-groove systems with BIPESCO 5 dispersion formulation also resulted in high fungal persistence of M. brunneum in the soil. From over 300 weevils, which were collected immediately after passing over the applied trap grooves near the treatment zone, more than 16 percent of all isolated and quarantined individuals died from fungal mycosis. The applied BIPESCO 5 strain was detected in more than 50 percent of all weevils infected with Metarhizium. The CURCUCONT project, including initial conclusions on sustainable weevil control, was presented to the representatives of the departments of the Federal Ministry for Agriculture, Regions and Tourism (BMLRT) and the members of the monitoring group in a video conference on 29 November 2021. A follow-up project was proposed and should be launched in spring 2022. |