Periodic Reporting for period 1 - AMIABLE (Advanced MIcroscopy of Attine ant BacteriaL Endosymbionts) Reporting period: 2015-09-01 to 2017-08-31 Summary of the context and overall objectives of the project Symbiosis, a diverse range of interactions between different species, has shaped life on earth: from the first eukaryote evolving as cooperation between several prokaryote elements, to the bacterial biofilms that define gut community of any organism. Colonies of advanced eusocial insects are second in complexity only to our own human societies, and among these the Latin American fungus-growing ants stand out because they have in common with human societies that they farm their own food. Because the fungus-growing ants have a very specialized diet, their gut bacterial communities are simpler than those of humans, making them an auspicious model system for gut microbiota studies. To enable humans to manipulate insect populations for the benefit of society, it will be crucial to better understand why and how symbiotic bacteria including gut microbiota are necessary for insect survival as these bacteria are believed to be a major reason for the overall abundance of both pest and beneficial insects in most terrestrial environments. The central aim of this project was to understand the nature of the symbiosis between leaf-cutting attine ants and their gut bacteria, the functional role of which was to a large extent unknown. Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far In the project, abundance and composition of the bacterial community in larval, pupal, and adult guts of two Panamanian leaf-cutting ants were analyzed, and mechanisms of acquisition and changes in bacterial abundance were monitored across developmental stages. The structural adaptations of dominant bacterial species to life within the leaf-cutting ant host were resolved using advanced transmission electron microscopy. The results have already been published in two manuscripts, and three more manuscripts are in preparation for submission as a result of fellow’s collaborative studies with colleagues from the host Centre for Social Evolution (CSE) group. The results of the project were reported at 5 conferences. The researcher supervised a BSc student project and also trained colleagues in microscopy at the host CSE group. The fellow gave a lecture and organized a workshop during the course for international PhD students hold by the host group. The researcher contributed to outreach activities by participating in CSE’s yearly stand at the Copenhagen Culture Night, participating in the International science visualization contest ARTiS 2017 (3000 visitors of the exhibition during the Copenhagen Culture Night) and writing a popular article about the project in collaboration with a CORDIS journalist. Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far) The results of the project are fundamental science, but in perspective might be applied to help Europe to meet both its environmental and food safety goals by reducing the use of harmful pesticides. Leaf-cutting ants are major agricultural and forest pests in Latin America. In several neotropical countries, leaf-cutting ants are important limiting agents for forestry, affecting conifer and eucalyptus plantations, and ant control is estimated to represent 75% of the total budget for all pest management efforts. Particularly for leaf-cutting ants that are pests of coffee, cacao and sugar cane, the disruption of bacterial symbionts may offer a new approach to control them in an environmentally friendly way, and could thus give economic benefits for both producers and consumers, directly in Latin America and indirectly in Europe. Wolbachia bacteria (blue) tightly interact with a mitochondrium in a cell of a leaf-cutting ant
