When Two Species Meet: A Potential Beetle-Yeast Facultative Mutualism

Area of Science:

• Ecology
• Microbiology
• Entomology

Background:

• Facultative mutualisms involve species interacting only during specific life stages.
• Insect-yeast interactions represent a key area for studying these flexible symbiotic relationships.
• The exploration of Brazilian beetle-associated yeasts revealed a novel interaction.

Purpose of the Study:

• To identify and characterize yeasts associated with Brazilian beetles and their host fruits.
• To investigate the ecological role and potential mutualistic relationship between Cyberlindnera yeast and Spermophthorus apuleiae.
• To establish a model system for studying the evolution of facultative mutualisms.

Main Methods:

• Isolation and identification of yeast species from beetle galleries and associated fruits.
• Quantification of yeast occurrence and abundance in relation to beetle infestation.
• Bioassays to assess yeast-beetle interactions and yeast-produced volatile compounds.

Main Results:

• Fifteen yeast and yeast-like species were isolated, primarily from the orders Phaffomycetales and Serinales.
• Cyberlindnera was the most prevalent yeast, found in 90% of infested fruit samples and comprising 79% of isolates.
• Bioassays supported a mutualistic interaction, with evidence suggesting yeast volatiles attract beetles.

Conclusions:

• The Cyberlindnera-Spermophthorus apuleiae association represents a facultative mutualism.
• Beetle activity may enhance yeast proliferation, while yeast volatiles likely attract beetles for dispersal.
• This interaction serves as a valuable model for understanding the ecology and evolution of non-obligate mutualisms.