Impacts of Syncephalastrum on leaf-cutting ant colonies

• Grant number: 23/05135-3
• Support Opportunities: Scholarships in Brazil - Master
• Start date: June 01, 2023
• End date: December 31, 2024
• Field of knowledge: Biological Sciences - Microbiology - Applied Microbiology
• Agreement: NSF - Dimensions of Biodiversity and BIOTA
• Principal Investigator: André Rodrigues
• Grantee: Raphael Affonso Pereira da Silva
• Host Institution: Instituto de Biociências (IB). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil
• Associated research grant: 19/03746-0 - Collaborative research: Dimensions US-São Paulo: integrating phylogeny, genetics, and chemical ecology to unravel the tangled bank of the multipartite fungus-farming ant symbiosis, AP.BTA.TEM

Abstract

Leafcutter ants are fungus-growing insects that forage for fresh plant material to nourish the mutualistic fungus. In turn, the fungus is the food source for the colony. Due to the large amounts of leaves these insects forage, leaf-cutting ants can become pests, especially in anthropized environments, such as reforestation and agricultural areas. Control of leaf-cutting ants is utilizing insecticides formulated in baits, such as sulfluramid and fipronil, which are toxic to the environment. One alternative environment-friendly method is biological control. Our research group demonstrated the existence of various filamentous fungi in ants' colonies, in addition to the mutualistic fungus. It is the case of Syncephalastrum, considered pathogenic in leafcutter ant fungus gardens, destabilizing Atta sexdens subcolonies (i.e., colonies without queens) and leading to a decrease in foraging by workers. However, we have not determined the impact of this fungus in colonies containing all the elements of eusociality (queens, workers, pupae, and fungus garden). Here we aim to describe the effects that different Syncephalastrum isolates can cause in leafcutter ant colonies, including workers, the mutualistic fungus, and the whole system. Thus, we will carry out bioassays to analyze the mortality rate of workers in the presence of culture filtrates of the different Syncephalastrum isolates and attractiveness tests. In addition, we will perform whole-colony bioassays to check whether Syncephalastrum can negatively affect colonies containing all the elements of eusociality. These essays will guide whether to propose Syncephalastrum as a biological control agent for leaf-cutting ants. (AU)