Bumblebees can detect floral humidity.

Area of Science:

• Plant-pollinator interactions
• Sensory ecology
• Behavioral ecology

Background:

• Floral humidity, an increase in a flower's headspace moisture, is present in many species and contributes to their overall display.
• The ability to detect floral humidity has been documented in hawkmoths for nectar foraging, but its role for other pollinators is less understood.

Purpose of the Study:

• To investigate whether generalist pollinators, specifically bumblebees, can detect and respond to floral humidity cues.
• To determine if floral humidity can be used by bumblebees to differentiate between rewarding and non-rewarding flowers.

Main Methods:

• Artificial flowers were created to emit humidity levels comparable to those found in natural flowers.
• Experiments involved observing bumblebee preferences for artificial flowers with varying humidity levels.
• Learning experiments were conducted to assess bumblebees' ability to associate humidity with rewards.

Main Results:

• Bumblebees exhibited a spontaneous preference for artificial flowers emitting higher levels of humidity.
• Bumblebees successfully learned to distinguish between rewarding and non-rewarding flowers based on humidity differences.
• These results demonstrate bumblebee sensitivity to floral humidity cues.

Conclusions:

• Floral humidity is a detectable cue for bumblebees, influencing their flower visitation.
• This sensory modality can enhance floral displays and impact pollinator behavior more significantly than previously recognized.
• Floral humidity represents an important, yet underappreciated, factor in plant-pollination ecology.