Olfactory versus visual cues in a floral mimicry system.

Area of Science:

• Ecology
• Evolutionary Biology
• Chemical Ecology

Background:

• Fungal mimicry involves Puccinia monoica Arth. inducing crucifer hosts to form pseudoflowers.
• These pseudoflowers visually resemble buttercups but possess a distinct sweet fragrance.

Purpose of the Study:

• To investigate the roles of olfactory and visual cues in insect attraction to floral mimics.
• To determine the specific chemical compounds responsible for attracting different insect visitors.

Main Methods:

• Experiments using artificial flowers with and without fragrance to assess cue importance.
• Bioassays to identify attractive fragrance compounds.
• Observing insect visitor responses to pseudoflowers and synthetic fragrance blends.

Main Results:

• Pseudoflower fragrance alone can attract insect visitors.
• Insect responses varied: Halictid bees showed a stronger visual response, while flies relied more on olfactory cues.
• Halictid bees were attracted to a blend of specific volatile compounds, but flies were not.

Conclusions:

• Both visual and olfactory cues are important for insect attraction to floral mimics, with relative importance varying by insect species.
• The identified fragrance compounds attract some visitors, but key attractants for flies remain unidentified.
• Insect olfactory perception of pseudoflower fragrance may be crucial for the evolution of this mimicry system.