When methods matter: solvent effects on pollinator responses to quantum‐dot–labelled pollen

In our study we ask whether, and how, insect pollinators respond to flowers whose anthers have been treated with quantum dots (QDs) and their solvent carrier. Using a common-garden experiment with genetically uniform Brassica napus, we compared pollinator visitation and foraging behaviour among flowers bearing QD–solvent treatments, solvent-only controls, and untreated controls. The experiment was conducted on 160 Brassica napus plants grown under controlled conditions. Five treatments were applied: (1) control, (2) pollen treated with hexane only, and (3–5) pollen labeled with QDs inducing radiation of three lengths: 530, 590, or 700 nm. Freshly opened flowers were labeled each morning by applying hexane or a QDs-hexane solution to anthers. Pollinator activity was recorded between 09:30 and 13:00 using digital cameras for 1.5 h per plant on two consecutive days, resulting in a total sampling effort of 480 h. In the laboratory, videos were reviewed for frequency of pollinator visits, time of the visit and the number of visited flowers. Visit frequency (visits/h) was computed as the number of visits per 90-min recording multiplied by 2/3. Visitors were assigned to morphogroups: honeybees (Apis mellifera), solitary bees, bumblebees (Bombus), hoverflies (Syrphidae), muscoid flies (Muscoidea), and butterflies.To assess whether hexane altered optical properties, reflectance of anthers (350–700 nm) was measured with a Jaz spectrometer for untreated and hexane-treated samples.Dataset descriptionThe dataset includes three primary data files covering pollinator visit frequency, visit duration, and the number of flowers visited. An additional file contains the results of spectral reflectance measurements of anthers."Frequency.csv" fileColumns:date – date in format YYYYMMDDplant – unique identifier of the planttreatment – experimental treatment (control, hexane, 530, 590, 700)hour – time when plant was recorded (HH:MM)n.of.flowers – number of flowers on the plantfreq.syrphidae – frequency of hoverfly (Syrphidae) visits (number of visits per hour)freq.beetle – frequency of beetle (Coleoptera) visits (number of visits per hour)freq.others – frequency of unidentified pollinator visits (number of visits per hour)freq.butterfly – frequency of butterfly visits (number of visits per hour)freq.fly – frequency of fly (Diptera) visits (number of visits per hour)freq.honeybee – frequency of honeybee (Apis mellifera) visits (number of visits per hour)freq.solitarybee – frequency of solitary bee visits (number of visits per hour)freq.bumblebee – frequency of bumblebee visits (number of visits per hour)freq.all – frequency of all pollinator visits (number of visits per hour)"Number_of_flowers_visited.csv" fileColumns:date – date in format YYYYMMDDplant – unique identifier of the planttreatment – experimental treatment (control, hexane, 530, 590, 700)hour – time when plant was recorded (HH:MM)n.of.flowers – number of flowers on the plantpollinator – identifier of the pollinator visiting the plantpollinator.morphogroup – pollinator’s assigned morphogroup ("0" means no visits to the plant)n.of.flowers.visited – number of flowers visited by the pollinator"Time_of_visit.csv" fileColumns:date – date in format YYYYMMDDplant – unique identifier of the planttreatment – experimental treatment (control, hexane, 530, 590, 700)hour – time when plant was recorded (HH:MM)n.of.flowers – number of flowers on the plantpollinator.id – identifier of the pollinator visiting the flowerpollinator.morphogroup – pollinator’s assigned morphogroup (0 means no visits to the flower)flower.visited – sequence number of the flower visited by the pollinator on a given planttime.of.visit – time of pollinator visit in seconds [s]"Hexane_test.csv" fileColumns:wavelength_nm – wavelength of light at which the measurement was taken by the spectrophotometer [nm]processed_signal – processed signal from the spectrophotometeranther – identifier of the anther measuredtype – sample treatment: "hexane" (anthers treated with hexane) or "control" (untreated anthers)