Ant-aphid mutualism - Implication of honeydew microflora

Some ant and aphid species can present a mutualistic relationship, ants using aphid honeydew as sugar source and in exchange providing the aphid colony cleaning and protection. From a behavioral point of view, this phenomenon has been well studied from decades. However, its chemistry and semiochemical mechanisms are still largely unknown. This study aims to identify semiochemicals involved in the establishment of this relation, using both chemical and behavioral approaches. Bioassays revealed that the greatest part of ant attraction toward aphid colonies is due to honeydew volatile compounds; enabling ant scouts to find more quickly aphid colonies and distantly recognize myrmecophilous species. Many of those VOCs seeming to have microbial origins, the main honeydew microorganisms have been isolated and their roles in VOCs production and ant attraction have been investigated. It appeared that honeydew microflora holds a key role in the establishment of ant-aphids mutualistic relationship.