Chemical recognition of partner plant species by foundress ant queens in Macaranga-Crematogaster myrmecophytism

The partnership in the Crematogaster-Macaranga ant-plant interaction is hig hly species-specific. Because a mutualistic relationship on a Macaranga pla nt starts with colonization by a foundress queen of a partner Crematogaster species, we hypothesized that the foundress queens select their partner pl ant species by chemical recognition. We tested this hypothesis with four sy mpatric Macaranga species and their Crematogaster plant-ant species. We dem onstrated that foundress Crematogaster queen, can recognize their partner M acaranga by contact with the surface of the seedlings, that they can recogn ize compounds from the stem surface of seedlings of their partner plant spe cies, and that the gas chromatographic profiles are characteristic of the p lant species. These findings support the hypothesis that foundress queens o f the Crematogaster plant-ant species select their partner Macaranga specie s by recognizing nonvolatile chemical characteristics of the stem surfaces of seedlings.