Effect of black soldier fly (Hermetia illucens L.) frass on Rhizoctonia suppression

• Grant number: 24/22441-3
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: January 01, 2026
• End date: December 31, 2028
• Field of knowledge: Agronomical Sciences - Agronomy - Crop Science
• Principal Investigator: Gustavo Habermann
• Grantee: Thayssa Rabelo Schley
• Host Institution: Instituto de Biociências (IB). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil

Abstract

The treatment of organic waste using Black Soldier Fly larvae (Hermetia illucens L., Diptera: Stratiomyidae; BSF) produces a byproduct known as frass, which has shown potential as a fertilizer and as a mitigator of both abiotic and biotic stress in plants. While previous studies have demonstrated the chemical properties of frass in various plant species and its role in alleviating abiotic stress, its function in mitigating biotic stress-particularly as a suppressor of soil-borne diseases-remains poorly understood. This project aims to fill that gap by focusing first on identifying the bacterial community present in frass, with special attention to plant-beneficial bacteria. Preliminary data (unpublished, obtained by Meruoca - Campinas, SP, Brazil) suggest that frass may reduce the incidence of infections caused by Rhizoctonia spp., a genus of fungi responsible for Rhizoctonia disease, which impacts crop development and productivity worldwide. We expect to detect beneficial bacterial genera such as Pseudomonas, Bacillus, Leuconostoc, Lactococcus, Lactobacillus, Paenibacillus, Burkholderia, and Streptomyces, many of which are known for their antifungal activity, including against Rhizoctonia spp. In addition, we will investigate how the composition of the organic waste fed to BSF larvae influences the presence of these beneficial bacteria in frass. Controlled dietary variations-maintaining the proportion of different food groups-will be tested to determine whether frass microbiota composition depends on the type of processed residue. Using a standardized substrate, we will assess whether the effectiveness of frass in suppressing Rhizoctonia in tomato (Solanum lycopersicum) cultivation is due to the presence of these microorganisms. If this hypothesis is confirmed, we will explore whether secondary metabolites produced by the beneficial bacteria are responsible for the antifungal activity through either direct release or volatilization. Beyond this antifungal effect, we will also examine whether beneficial bacteria in frass activate plant defense mechanisms against Rhizoctonia. This project integrates a multidisciplinary approach, proposing sustainable and applicable solutions to agronomic and waste management challenges by employing techniques from microbiology, molecular biology, and biochemistry in the study of soil-microorganism-plant interactions.