Banca de DEFESA: THAIS ALMEIDA CORREA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : THAIS ALMEIDA CORREA
DATE: 10/09/2025
TIME: 13:00
LOCAL: Google Meet
TITLE:

Interactions between entomopathogenic fungi and arthropod hosts: Immune response of Noctua pronuba larvae and gut bacteriome dynamics of Rhipicephalus microplus

KEY WORDS:

Rhipicephalus microplus; Noctua pronuba; entomopathogenic fungi; Trichoderma atroviride; gut bacteriota; innate immunity; Anaplasma marginale; biocontrol

PAGES: 110
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Medicina Veterinária Preventiva
SPECIALTY: Doenças Parasitárias de Animais
SUMMARY:

The control of arthropod vectors and agricultural pests requires sustainable alternatives in light of the limitations and impacts associated with chemical acaricides and insecticides. In this context, entomopathogenic fungi are key elements both in shaping host immune responses and as part of integrated management strategies. This thesis investigated two distinct models: (i) the cattle tick Rhipicephalus microplus, focusing on the interaction of Metarhizium anisopliae with the gut bacteriota in the presence or absence of Anaplasma marginale, and (ii) the moth Noctua pronuba, an important agricultural pest, with emphasis on its humoral immune interactions with Beauveria bassiana and Trichoderma atroviride. In Chapter I, the gut bacterial diversity of engorged R. microplus females was characterized through a metabarcoding approach targeting the V3–V4 region of the bacterial 16S rRNA gene in groups exposed or not to M. anisopliae and infected with A. marginale. Coinfection reshaped the bacteriota, with a higher number of associated taxa and a distinct microbial composition compared to control and singly infected groups. Co-occurrence network analysis revealed that the coinfected microbiome (Metarhizium and Anaplasma) exhibited greater connectivity and robustness, suggesting a compensatory response of the host and bacterial community to dual stress rather than beneficial stability. Functional prediction indicated that these shifts may represent a metabolic adaptation of the bacterial consortium to support tick and/or pathogen survival, supported by the increased abundance of functional genes associated with metabolic pathways in the coinfected group. These findings highlight the modulatory role of the gut bacteriota at the fungus–vector–pathogen interface, with direct implications for the vector competence of R. microplus, and reinforce the potential of fungi to interfere with pathogen transmission cycles. In Chapter II, the immune response of N. pronuba larvae was investigated after exposure to B. bassiana (entomopathogenic) and T. atroviride (non-entomopathogenic). The differential expression of innate immunity-related genes (cecropin1, attacin, and PGRP-A) was quantified by qPCR. B. bassiana induced a stronger early activation of attacin and PGRP-A six hours after treatment, whereas T. atroviride promoted suppression of attacin and PGRP-A at 12 and 24 hours, suggesting an ability to interact with host immune pathways despite lacking evident pathogenicity. These results expand our understanding of recognition and defense mechanisms against fungi and underscore the importance of exploring novel fungal isolates, such as Trichoderma, in biocontrol programs. The two chapters demonstrate that arthropod immune responses and gut bacteriota dynamics are central determinants in the interaction with entomopathogenic fungi and pathogens. Understanding these relationships provides a foundation for developing innovative biocontrol strategies capable of reducing dependence on chemical inputs and contributing to sustainability in animal health and agriculture.

COMMITTEE MEMBERS:
Presidente - 2221855 - PATRICIA SILVA GOLO
Interna - 3247559 - BRUNA DE AZEVEDO BAETA
Externa ao Programa - 1815763 - IRENE DA SILVA COELHO - UFRRJExterna à Instituição - PATRICIA GONZAGA PAULINO
Externa à Instituição - JÉSSICA FIOROTTI DE PAULO
Externa à Instituição - ELEN REGOZINO MUNIZ
Externa à Instituição - LARISSA ALMEIDA MARTINS