Bee Tracker -- an open-source machine-learning based video analysis
software for the assessment of nesting and foraging performance of
cavity-nesting solitary bees
Abstract
1. The foraging and nesting performance of bees can provide important
information on bee health and is of interest for risk and impact
assessment of environmental stressors. While radio-frequency
identification (RFID) technology is an efficient tool increasingly used
for the collection of behavioral data in social bee species such as
honey bees, behavioral studies on solitary bees still largely depend on
direct observations, which is very time-consuming. 2. Here, we present a
novel automated methodological approach of individually and
simultaneously tracking and analyzing foraging and nesting behavior of
numerous cavity-nesting solitary bees. The approach consists of
monitoring nesting units by video recording and automated analysis of
videos by a machine learning based software. This Bee Tracker software
consists of four trained deep learning networks to detect bees that
enter or leave their nest and to recognize individual IDs on the bees’
thorax as well as the IDs of their nests according to their positions in
the nesting unit. 3. The software is able to identify each nest of each
individual nesting bee, which permits to measure individual-based
measures of reproductive success. Moreover, the software quantifies the
number of cavities a female enters until it finds its nest as a proxy of
nest recognition, and it provides information on the number and duration
of foraging trips. By training the software on 8 videos recording 24
nesting females per video, the software achieved a precision of 96%
correct measurements of these parameters. 4. The software could be
adapted to various experimental setups by training it to an according
set of videos. The presented method allows to efficiently collect large
amounts of data on cavity-nesting solitary bee species and represents a
promising new tool for the monitoring and assessment of behavior and
reproductive success under laboratory, semi-field and field conditions.