Banca de QUALIFICAÇÃO: BIANCA DE PAULA VALÉRIO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE: BIANCA DE PAULA VALÉRIO
DATA: 23/03/2026
HORA: 09:00
LOCAL: Google meet
TÍTULO:

Role of jasmonate- and salicylate- mediated direct and indirect plant defenses against Planococcus citri in coffee

 

 

 

PALAVRAS-CHAVES:

Trophic interactions, Cryptolaemus montrouzieri, induced plant defense; salicylic acid, jasmonic acid.

PÁGINAS: 18
GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
SUBÁREA: Fitossanidade
RESUMO:

The phytohormones methyl salicylate (MeSA) and methyl jasmonate (MeJA) modulate plant defense pathways, potentially affecting herbivore performance directly and, indirectly, influencing the activity of their natural enemies. This study investigated (i) the direct effects of MeSA, MeJA, and MeSA+MeJA applied to coffee plants at different concentrations (2, 3, and 4 mM) on the biological performance of Planococcus citri, and (ii) the indirect effects of these compounds, before and after pest infestation, on the olfactory preference of the predator Cryptolaemus montrouzieri. Preference and performance assays were conducted for P. citri, and an olfactory attraction assay was conducted for C. montrouzieri. Nymphs of P. minor responded differently to the applied phytohormones in the host-choice test. MeSA consistently acted as an attractant at all tested concentrations, with nymphs preferring treated over untreated plants. In contrast, MeJA was repellent at higher concentrations, leading nymphs to prefer control plants. In the combined treatments, only the highest concentration resulted in repellence, indicating that at elevated levels the repellent effect of MeJA overrides the attractive effect of MeSA. In the performance experiment with P. citri, phytohormone application reduced the insects’ ontogenetic progress, resulting in a lower proportion of individuals reaching the second-instar, third-instar, and adult stages. These effects were more pronounced in treatments containing MeJA and MeSA+MeJA combinations, suggesting activation of defenses associated with jasmonate-dependent pathways. Survival and growth of the mealybugs were consistently reduced, indicating that hormonal induction increased plant resistance. In the olfactory preference assay, C. montrouzieri responded variably to volatiles emitted by plants treated with MeJA, MeSA, and their combinations. Plants treated with MeJA—and also with MeSA+MeJA at the highest concentrations—were attractive to the predator, whereas MeSA concentrations acted as repellents. In the presence of P. citri, attraction to MeJA-treated plants was even more pronounced at higher concentrations. However, the highest MeSA+MeJA combination resulted in repellence. These patterns indicate that the jasmonate pathway, particularly at higher concentrations, enhances the attractiveness of treated plants to C. montrouzieri, whereas MeSA tends to elicit neutral or repellent responses. Overall, the results demonstrate that phytohormone application alters both the biological suitability of P. citri and the attractiveness of plants to natural enemies. MeJA stood out by reducing mealybug development and increasing C. montrouzieri attraction after infestation, suggesting a central role of the jasmonate-mediated defense pathway in shaping tritrophic interactions in Coffea arabica. These findings provide support for the use of defense inducers as a complementary tool in the ecological management of P. citri.

MEMBROS DA BANCA:
Externo à Instituição - TIAGO MORALES SILVA - UFLA (Membro)
Externo à Instituição - NANCY DEL CARMEN BARRETO TRIANA - USP (Suplente)
Presidente - MARIA FERNANDA GOMES VILLALBA PENAFLOR (Membro)
Interno - JÚLIA ASSUNÇÃO DE CASTRO OLIVEIRA - UFLA (Suplente)
Interno - ENGGEL BEATRIZ SILVA DO CARMO - UFLA (Membro)