Desenvolvimento de formulações para controle microbiológico de pragas em culturas para biocombustíveis

Abstract

Due to the damage caused by chemical pest control, the use of biological agents has emerged as a sustainable alternative. However, this practice still faces technological challenges related to obtaining more efficient and stable products. In this context, the present study aimed to extract the microorganism by separating it from its solid substrate and to develop formulations using conidia of the fungus Trichoderma asperellum as the active ingredient. With this objective, the microorganism was recovered from rice cultivated under solid-state conditions, followed by the development of formulations in alginate-based beads and water dispersible granules (WDG). The obtained formulations were evaluated in terms of viability over time and, in the case of the alginate formulation, for efficacy in antagonism tests against phytopathogenic fungi. The alginate beads formulation presented, after 103 days, a concentration of 4.86x108 CFU/gds, a value 5.8 times higher than that obtained for the non-formulated sample and 1.2 times higher than that of another formulation containing a lower amount of liquid extract with the microorganism. Antagonism tests evidenced a greater dominance of T. asperellum against fungi that cause plant diseases, mainly through competitive mechanisms. Furthermore, although the WDG formulation did not promote an increase in viability, it presented relevant advantages, such as maintenance of the fungus in the conidial form, absence of mycelial growth, and potential contribution to plant development. Thus, the alginate beads formulation proved to be effective in increasing product viability, while both formulations met the requirement of maintaining the microorganism in its desired conidial form, a characteristic of interest for agricultural applications. Therefore, the developed formulations represent a sustainable alternative for use in biological pest control. Additionally, an analysis of starch digestibility of residual rice resulted in glucose concentrations close to 4 g/L after 120 minutes, indicating its potential as a sugar source for fermentative processes, such as ethanol production, suggesting a promising alternative for residue valorization and reduction of disposal costs.