The multiple faces of insects microbiome and the development of new strategies to control Spodoptera frugiperda (Lepidoptera: Noctuidae)

• Ano de defesa: 2024
• Autor(a) principal: Lima, Cecília Beatriz Nascimento
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Biotechnology; Biotecnologia; Metabólitos Secundários; Secondary Metabolites; Simbiose; Symbiosis
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/11/11146/tde-12032025-161010/

The association of insects with symbiotic bacteria can influence different aspects of their biology. Symbionts may assist in the metabolism of toxins and contribute to the production of metabolites essential for host insect nutrition, for example. Thus, the exploration of interactions of insects with symbiont bacteria could contribute to the development of new control technologies for pest insects. Therefore, with the hypothesis that there are natural regulating agents of pest insects, such as virus, bacteria and fungi, and that specific microorganisms could be used as agents to control pest insect, by leading to the reduction of their biological fitness or even to their death, the first objective of this study was to verify the presence and diversity of the association of microorganisms in populations of Spodoptera frugiperda, by transcriptome analyses. In addition, previous studies in our research group reported the insecticidal potential of crude extracts from different isolates of Streptomyces against S. frugiperda. Chemometric comparisons and bioassays of insecticidal activity of these different isolates demonstrated the existence of variability in chemical profile and bioactivity of the extracts produced. Thus, our second hypothesis was that the active extracts from S. novaecaesareae isolates are a potential source for new bioinsecticides, and that the chemical diversity found in isolates of the same phylotype is due to phenotypic and genetic variability. Therefore, the second objective of this study was to identify the active molecules responsible for the observed bioactivity against S. frugiperda. The identification of the active molecules led to our third hypothesis, that these active compounds might affect the gut microbiota, leading to the death of these pest insects. Consequently, the third objective of this study was to identify the mode of action of these active molecules in S. frugiperda larvae. In addition to the need for the development of new control methodologies for the above-mentioned pest insects, our research will promote the exploration of the associated microorganisms to S. frugiperda for pest management, as well as the identification of new active molecules and their mode of action for S. frugiperda management.