Does facilitating pollinator learning impede deceptive orchid attractiveness? A multi-approach test of avoidance...

Area of Science:

• Ecology
• Evolutionary Biology
• Behavioral Ecology

Background:

• Nectarless deceptive orchids often exploit naive pollinators, with floral trait variation potentially prolonging learning and increasing reproductive success.
• Anacamptis morio, a European deceptive orchid, exhibits significant variation in its fragrance bouquet.

Purpose of the Study:

• To investigate the role of avoidance learning in the reproductive success of the deceptive orchid Anacamptis morio.
• To determine if facilitating pollinator learning to avoid A. morio impacts visitation rates and reproductive success.

Main Methods:

• Conducted three experiments using artificial arrays, natural populations, and bumblebee behavioral observations.
• Facilitated pollinator avoidance learning by adding anisaldehyde, a strong scent cue from a related nectar-producing species, to A. morio inflorescences.
• Compared visitation rates and reproductive success between scent-added and control inflorescences.

Main Results:

• No significant difference in reproductive success or visitation rates was observed between scent-added and control inflorescences.
• The expected decrease in reproductive success over time in artificial populations was less pronounced than anticipated.
• Data suggest pollinators do not fully learn to avoid deceptive orchids.

Conclusions:

• Pollinator avoidance behavior, rather than learning, may primarily explain the lower reproductive success of deceptive orchids.
• The proposed benefit of intraspecific floral trait variation in deceptive orchids, driven by avoidance learning, is challenged by these findings.
• Further research into pollinator cognition and learning abilities is needed to fully understand deceptive pollination strategies.