Stable isotope investigation of a cryptic ant-plant association: Myrmelachista flavocotea (Hymenoptera, Formicidae) and Ocotea spp. (Lauraceae)

K. McNett, J. Longino, P. Barriga, O. Vargas, K. Phillips, C. L. Sagers

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


An obligate symbiosis between Ocoteadendrodaphne Mez and O. atirrensis Mez & Donn. Sm. (Lauraceae) and their cryptic ant symbiont, Myrmelachistaflavocotea, is common in lowland wet forests of Costa Rica, yet it is unclear whether the association is typically mutualistic or parasitic. Ants impose costs by tending trophobionts inside the plant body and further compromise the structural integrity of their host by hollowing its stems. Benefits to the host, including anti-herbivore defense and nutrient provisioning, must outweigh these costs for the association to be mutualistic, but benefits in this system are largely unknown. We adopted a stable isotope approach to investigate trophic relationships among Ocotea hosts, coccoid trophobionts, and worker and larval ants in the understory of mature forest at La Selva Biological Station, Costa Rica. In addition, a natural stable isotope marker (tuna) was made available to M. flavocotea colonies to determine whether ants are fortuitous scavengers and/or provision their host. In this system, we found unusual patterns of isotopic fractionation. For coccoids, nitrogen isotopes are only slightly enriched, and carbon isotopes were depleted relative to the host signature. Moreover, nitrogen signatures of the timid Myrmelachista ants are high, suggesting a substantial degree of carnivory and/or scavenging in this species. In the provisioning study, ant colonies provided with baits demonstrated a significant shift in carbon isotopic composition relative to untreated colonies indicating uptake and assimilation of the bait. These results suggest that these timid ants are patrolling the plant for food and concentrating nutrients in Ocotea's hollowed stems. Further studies are required to confirm if M. flavocotea provides a net benefit to its host by providing nutrients, reducing herbivory, or by removing detrimental debris from the plants surface.

Original languageEnglish (US)
Pages (from-to)67-72
Number of pages6
JournalInsectes Sociaux
Issue number1
StatePublished - 2010
Externally publishedYes


  • Ant-plant
  • Coccoid
  • La Selva Biological Station
  • Stable isotope
  • Trophic level fractionation

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Insect Science


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