Data and R scripts for the article: "Insect visitation patterns in diploid Centaurea aspera L., tetraploid C. seridis, and their triploid hybrids C. x subdecurrens Pau: similar rates but distinct assemblages".

The study was conducted in the dunes of El Saler, located in the Natural Park of l’Albufera in Valencia, (E Spain, 39º21’41.67’’N, 0º19’05.53’’E), within a 1.77 ha area where C. aspera, C. seridis, and C. x subdecurrens had previously been recorded and mapped at a microspatial scale (Garmendia et al., 2018). In April 2020, we selected five blocks, each consisting of three Centaurea plants —one of C. aspera, one of C. seridis, and one of C. x subdecurrens— with plants spaced less than 3 meters apart, except for two blocks in which one plant was spaced up to 7 meters from the others, allowing insects to select capitula based on their preferences. Each plant was labeled with a neutral sand-colored string and located using GPS. The diameter of each plant was estimated by averaging its longest width and its perpendicular.

Over a 14-week period, from April 23rd (when the first plants began to flower) to July 23rd, 2020 (when most C. seridis plants stopped setting flowers), the study area was visited weekly. On each visit, we selected the day with the highest forecasted air temperature and the lowest cloud cover, avoiding rainy days. During each visit, wind intensity and direction were estimated, and the mean temperature and relative humidity were recorded using a digital thermometer. Visits took place between 09:30 and 15:00, when pollinator activity was at its peak. However, as spring progressed, the timing of visits was adjusted earlier to avoid excessively high temperatures.

Since phenology varies among taxa, the number of open capitula was recorded for each plant on every visit. The number of flowers per plant was estimated by counting the flowers on six random capitula for each taxon, and then multiplying the mean number of flowers by the total number of open capitula: 22 flowers per capitulum in C. aspera, 43 in C. seridis, and 39 in C. x subdecurrens.

Each plant was observed for 10 minutes by two independent observers, including at least one entomologist. Visits from any flying flower visitors were recorded, counting a visit each time an insect landed on a capitulum while actively searching for pollen and/or nectar. If the same insect landed on different capitula of the same plant, two visits were counted. Unknown insects were photographed, captured with a butterfly net, and brought to the Elytra Agroscience laboratory (Valencia, Spain) for identification by specialized entomologists, who determined the species, genus, or family.