Scent and adhesion drive insect dispersal of environmental yeast.

Abstract

Insects and terrestrial fungi have lived on planet earth together for over 400 My. Different insect species are commonly associated with distinct mycobiomes. These insect-fungal associations are thought to provide a major dispersal mechanism for fungi in the environment. The <i>Rhodotorula</i> genus of pigmented basidiomycetous yeasts is commonly found in association with insects. Here, we demonstrate that yeasts of <i>Rhodotorula</i> spp. are highly attractive to the vinegar fly <i>Drosophila melanogaster</i> and the African malaria mosquito <i>Anopheles gambiae</i>. We characterized strains of the environmental yeast <i>Rhodotorula taiwanensis</i> that emit simple scent signatures predominated by the common microbial volatile 3-methyl-1-butanol (isoamyl alcohol) alongside other characteristic volatiles including acetone and acetaldehyde. Insect odorant receptors are required for attraction to <i>R. taiwanensis</i> and promote yeast dispersal to new growth niches. In addition to scent, dispersal is also likely mediated by the adhesive qualities of these yeasts to insect cuticles via hydrophobic interactions, as well as consumption. Strikingly, <i>Rhodotorula</i> dispersal was also facilitated by <i>An. gambiae</i>, although mosquitoes often died after becoming stuck to slimy lawns of these yeasts. Our work reveals that scent and adhesion drive insect dispersal of these environmental yeasts.