Chemical basis of a highly specific mutualism: Chiral esters attract pollinating beetles in Eupomatiaceae

Eupomatia species are pollinated exclusively by weevils of the genus Elleschodes (Col., Curculionidae), which may have their entire lifecycle linked to the host plant. Flowers produce potent fragrances, which serve as attractants for the weevils. Chemical analyses showed that the volatiles almost entirely consist of short chain, fatty acid esters; in E. laurina, methyl (2 S)-2-methylbutanoate made up over 97% of the fragrance, whereas methyl (2 R)-2-acetoxy-4-methylpentanoate dominates the blend in E. bennettii. In E. bennettii, qualitative and quantitative differences, including enantiomeric composition, were found between the sexual phases. The chemical nature of other weevil attractants, and functional properties of the floral esters are discussed.