Data.zip

Food patch
To assess rover or sitter-like larval behavior, a small amount of living yeast paste was added
to standard agar plates (92 x 16 mm), creating two food patches (A and B) on the agar, each
about 1.5 cm in diameter. The distance between the yeast patches was about 3 cm. About 10
mid third instar larvae, which had been previously removed from the food and carefully
washed using small containers with a mesh on the bottom, were placed on food patch A at the
beginning of each experiment. After 20 minutes, the number of larvae that were still in food
patch A, the number of larvae in food patch B and the number of larvae not in any food patch
(elsewhere) were counted to calculate the percentage of larvae that were still in food patch A
and the percentage of larvae having left the first food patch (= larvae in food patch B or
elsewhere). All experiments were carried out at 25°C and 60% relative humidity. The data
was saved as xlsx-files.
Distance tracking
To record the locomotion of individual larvae, the setup of the Buridan apparatus was used to
maintain an environment with constant temperature and lighting, using four circular
fluorescent tubes to illuminate the larvae homogeneously. Black dyed agar plates were used to
increase the contrast to the white larvae. Larvae, removed from the food and washed with
water, were carefully placed in the centre of the agar plate. A camera, connected to a
computer running the recording software, was positioned above the agar plate in order to
record the position of each larva during the experiment. A one-minute video was recorded
immediately after the larva was placed on the agar using OBS Studio (https://obsproject.com)
as video recording software. Larvae that crawled under the agar before one minute had passed
were discarded.
The program Kinovea (https://www.kinovea.org) was used to analyze the video files recorded
by OBS studio. Kinovea is a video player for sport analysis, but provides different features
like the ability of tracking objects. After successfully tracking a larva, the program generates a
text file containing the x and y coordinates (in cm) at each point in time (in ms). For further
instructions on how to use the program see DOI: 10.17504/protocols.io.bz3ip8ke.
A script based on R (version 4.0.5) was used to evaluate the Kinovea data in order to
determine the individual travelled distances of each larva. The R-Script shortens the raw data
to the desired duration (60 s) before the distance is calculated. The R-script also detects the
time at which the larva starts moving (in ms) by determining the point in time after which the
first distance is different from zero. The mean distance (in cm) and the mean latency to first
movement (in ms) were calculated for all files within one group. For further information on
how to use the script see DOI: 10.17504/protocols.io.bz3ip8ke