CHEMICAL ANALYSIS IN THE TRITROPHIC SYSTEM Azteca-Cecropia-Chaetothyriales

Abstract

Communication is important for the organization in social institutions. Nevertheless, the process of transmission and codification of these chemical compounds has been a major challenge for ecologists. In this work we aimed to investigate the similarity of ant cuticle chemical compounds with its symbiotic fungus (Chaetothyriales) and host plant (Cecropia glaziovii), in order to understand if its two main food sources could influence its cuticular composition. Furthermore, when comparing A. muelleri cuticular profile with his non-symbiont close relative of Cecropia (Azteca chartifex), we tested the importance of phylogeny in determining this chemical profile. We collected a total of 34 plants with Azteca muelleri colonies, 33 with mullerian bodies and 22 with fungus and 5 colonies of A. chartifex in three Atlantic Forest fragments in Viçosa - Minas Gerais, Brazil. To analyze the cuticle compounds we performed hexane extractions using the internal standardization method (Trans-farnesol (C15H26O)) eliminating peaks that were present in less than 50% of samples. Our results demonstrated a relatively high similarity between the fungus Chaetothyriales and workers of A. muelleri, as well as a positive relationship of three alkenes present in the fungus on the same ones present in the ants. In contrast, there is very little chemical similarity between A. muelleri, A. chartifex, C. glaziovii. These results show that the fungus Chaetothyriales, mainly via the trophic pathway, seems to have a crucial influence on the formation of A. muelleri cuticular compounds. Thus, our results seem to indicate that ant cuticle hydrocarbons are probably more related to the food ingested than other environmental or phylogenetic aspects. Further studies are needed to better understand the influence of environmental factors over phylogeny on the formation of cuticular hydrocarbons in insects.