Floral Cues and Foraging Preferences in Various Species of Wild Bumblebees

There are costs and benefits for plants and their pollinators. Bumblebees play a crucial role in the dynamic plant-pollinator system. Flowers co-evolved with insects, birds, and mammals toward mechanisms that benefited, described from a human perspective, both host and forager. Characteristics such color, olfactory cues, and temperature attract pollinators, with bumblebees showing preferences for blue and yellow flowers, as well as flowers that are warmer. This study aims to answer three questions: 1) How does floral temperature at different times of day predict visit length in bumblebees? 2) Does bumblebee size affect visit length? 3) Is there an interaction between floral temperature and air temperature that affects bumblebees’ foraging choices? Fifty-three bees were observed (N = 53) and 413 individual observations recorded (n = 413). Results indicate that the time of day significantly affects visit length, with longer visits recorded in the afternoon than in the morning. Furthermore, a significant three-way interaction effect for body size, floral temperature, and air temperature on visit length was found. Additionally, two two-way interaction effects were found for body size and floral temperature and floral temperature and air temperature on visit type. Bumblebees displayed preferences for varying floral temperatures depending on air temperature. Small bees showed preferences for warmer flowers in cooler air temperatures, while large bees showed more preference for cooler flowers in warm temperatures, and would also forage on warmer flowers. This work informs research on climate change by aiding in understanding the critical temperature thresholds at which bees can efficiently forage, advancing knowledge that has the potential to elucidate plant-pollinator relationships.