Intraspecific variation in foraging niche can drive food web dynamics and ecosystem processes. In particular, male and female animals can exhibit different, often cascading, impacts on their interaction partners. Despite this, studies of plant-pollinator interaction networks have focused on the partitioning of the floral community between pollinator species, with little attention paid to intraspecific variation in plant preference between male and female bees. We designed a field study to evaluate the strength and prevalence of sexually dimorphic foraging, and particularly resource preferences, in bees. We observed bees visiting flowers in semi-natural meadows in New Jersey, USA. To detect differences in flower use against a shared background of resource (flower) availability, we maximized the number of interactions observed within narrow spatio-temporal windows. To distinguish observed differences in bee use of flower species, which can reflect abundance patterns and sampling effects, from underlying differences in bee preferences, we analyzed our data with both a permutation-based null model and random effects models. We found that the diets of male and female bees of the same species were often dissimilar as the diets of different species of bees. Furthermore, we demonstrate differences in preference between male and female bees. We show that intraspecific differences in preference can be robustly identified among hundreds of unique species-species interactions, without precisely quantifying resource availability, and despite high phenological turnover of both bees and plant bloom. Given the large differences in both flower use and preferences between male and female bees, ecological sex differences should be integrated into studies of bee demography, plant pollination, and coevolutionary relationships between flowers and insects.

This .zip file contains all the data and code from Roswell et al. 2019 PLoS One, along with a README file with metadata. The file 2016_male_bee_dataset.csv contains large, highly resolved bee-plant interaction networks. Each sampling round consists of three full days of sampling (almost always at least 180 minutes of timed collection), and at six of the sites there are five such sampling rounds, with approximately 10 days between rounds. Observers walked timed, 30-minute transects through semi-natural fields and looked into each flower within 1m of the transect. Any bee detected was caught, killed, and the species identity of the flower it was collected from was recorded. No independent abundance or availability data were collected.