Color choice and preference in the tropical orchid bee Euglossa dilemma

Pollinators assess their environment and make decisions on which flowers to visit. Several factors can affect flower choices, such as floral availability throughout a season, time of day, and temperature. Biological factors particular to a pollinator, such as the pollinator’s sex, their previous experiences during a foraging trip, and learning, can also play a role in decision-making mediated by color. Orchid bee pollination is intimately linked to foraging behavior. This paper presents the first study of orchid bee color vision use in Euglossa dilemma, and we focused on two aspects of color vision: (individual) color choice and preference (overall bias for a color). Blue and yellow emerged as the most effortless pair of colors to test, with 26.3% of males and 32.3% of females tested on this color completing the protocol. Our results show that humidity and time of day played a role on color choice. Individual male and female orchid bees showed variability in their color preferences in our tested colors. However, no clear patterns emerged for these bees overall. We also found that the preferences of bees are not significantly affected by the abiotic or biotic factors measured. Further, a bee’s preference was not predicted by its initial color choice. Decision-making and preference are complex aspects of pollinator behavior, with fitness consequences for the pollinator and the plants they visit. By testing orchid bees in the field with non-invasive tests, we can better understand how these tropical pollinators interact with their environment and make decisions based on their color vision.