The two sides of insect microbiome in the development of sustainable alternatives for the management of Spodoptera frugiperda and Euschistus heros

• Grant number: 20/01018-4
• Support Opportunities: Scholarships in Brazil - Doctorate
• Effective date (Start): May 01, 2020
• Effective date (End): February 28, 2023
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Fernando Luis Cônsoli
• Grantee: Cecília Beatriz Nascimento Lima
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

The association of insects with symbiontic 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 bacteria, such as bacteriophages, and that specific bacteriophages could be used as agents to control pest insect microbiota (phage therapy), leading to the reduction of their biological fitness or even to their death, the first objective of this study is to verify the presence, specificity and association of bacteriophages in populations of Spodoptera frugiperda and Euschistus heros, their lytic potential, and their potential for reduce the biological fitness of these pest insects, contributing to their control in the field. In addition, previous studies in our research group reported the insecticidal potential of crude extracts from different isolates of Streptomyces novaecaesareae and Streptomyces nojiriensis 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 is that the active extracts of isolates of S. novaecaesareae and S. nojiriensis are a potencial source for new bio insecticides, and that the chemical diversity found in isolates of the same phylotype is due to the phenotypic and genetic variability. Thus, our second objective of this study is to identify the active molecules responsible for the bioactivity observed against S. frugiperda and E. heros, as well as the mode of action of those active molecules in these insects. In addition to the need for the development of new control methodologies for the above-mentioned pest insects, our research will pioneer the exploration of the use of phage therapy for pest control, as well as the identification of new active molecules and their mode of action for pest management. (AU)