P-8: Monitoring cabbage stem flea beetles (Psylliodes chrysocephala) on an oilseed rape field during winter 2021/2022

Abstract: Different methods such as yellow water traps, visual counting of adults on plants and
soil at different times of day and night and photoeclectors were used to monitor the population
of Psylliodes chrysocephala between September 2021 and March 2022 on a winter oilseed rape
field in Braunschweig. In yellow water traps beetles were caught until mid-November, whereas
in visual assessments on plants, the number of beetles decreased only after the beginning of
January. Higher beetle numbers were seen in the dark compared to dawn or daylight conditions.
The number of beetles counted was independent from air temperatures between 0 and 20 °C.
Beetles were easily seen in the dark using torch light, until the leaves of plants began to overlap.
Beetle numbers differed between two monitoring areas on the field with only 50 m distance for
the whole observation period. Numbers of beetles per m² were similar comparing direct
observations in the dark and using photoeclectors.