Assessing the Precision of state-of-the-art Bee Counters

Automatic recording of bee flight activity at hive entries can provide valuable information regarding the health of the hives and has been used in many studies. However, no clear guidance regarding the calibration of such counters is available. We have recorded counts of bees entering and exiting hives during semi-field trials for honeybees (Apis mellifera), which were designed to conduct pollinator risk assessments of crop protection products. In this work, we want to share our experiences, and initial results regarding counter calibration. We compare the recorded bee activity from photoelectric counters to the number of bees counted by experts and find that counters provide a higher precision, especially at high flight activity. Furthermore, we describe our setup and show results from ‘robbers tests’ performed in 2021 and 2022 and find that the ratio of incoming and exiting bees is accurate within (1 ± 0.05) for 31 out of 34 tests (in 2021) and for 15 out of 17 tests (in 2022). Finally, we present a first snapshot of a comparison between the light-barrier counters used in our studies and a video-based method.