Percorrer por autor "Cunha, Ana E."
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- Endophytes induce volatile emission in olive trees with repellent activity against Bactrocera oleaePublication . Cunha, Ana E.; Rodrigues, Nuno; Casquero, Pedro; Pereira, José Alberto; Baptista, PaulaThe olive fruit fly, Bactrocera oleae (Rossi), is a key pest of the olive tree worldwide. This study explores whether the endophytes Alcaligenes faecalis, Aureobasidium pullulans, Bacillus amyloliquefaciens, and Penicillium commune can trigger the emission of repellent volatile organic compounds (VOCs) in olive trees, targeting B. oleae. Accordingly, olive trees were inoculated with each endophyte or with buffer (control), and after 3 months, both fruits and leaves were collected to perform olfactometer assays and to evaluate VOCs by HS-SPME and GC-MS. Alcaligenes faecalis, A. pullulans, and B. amyloliquefaciens were found to significantly repel B. oleae females, with each treatment inducing a distinct VOC profile. Alcaligenes faecalis and B. amyloliquefaciens were characterized by higher levels of alkenes, including o-cymene and d-limonene, while P. commune and A. pullulans induced the emission of alkanes. Six VOCs were found to be negatively correlated with fly entries in the olfactometer assays, with beta-myrcene being the most prominent, followed by d-limonene, o-cymene, and 5-octadecene (E). These repellent VOCs were positively correlated with each other, indicating that their combined emission may produce synergistic effects, potentially enhancing their repellency. In contrast, 1, 4-hexadiene, 5-methyl-3-(1-methyl ethylidene) was identified as an attractant, showing a strong positive correlation with fly entries, and appeared to be produced through different biosynthetic pathways than the repellent VOCs. Overall, this work identifies three endophytes and a combination of repellent VOCs as promising new strategies for sustainable management of the olive fruit fly.
- Exogenous systemin peptide treatment in olive alters Bactrocera oleae oviposition preferencePublication . Sánchez, Luiza; Cunha, Ana E.; Rodrigues, Nuno; Pereira, José Alberto; Baptista, PaulaThe olive fruit fly, Bactrocera oleae (Rossi), is a key pest of the olive crop, whose control relies mostly on the use of insecticides. Plant peptides may represent a more environmentally-friendly tool to manage olive fly, due to their recognized role to activate and/or prime plant defence responses against pests. In this work, behavioural experiments (no-choice and two-choice) and analysis of volatile compounds were carried out to evaluate the impact of the exogenous application of the peptide systemin to olive tree on olive fly infestation, and to elucidate its mode of action to prime plant defence. The treatment of olive branches with 10 nM systemin showed to confer protection against olive fly, by reducing significantly the ovipositions (up to 3.0-fold) and the number of infested fruits (up to 2.9-fold) when compared to non-treated branches. This protective effect was even detected in neighbouring non-treated branches, suggesting the ability of systemin to trigger plant-to-plant communication. The deterrent activity of the primed olives was associated with the emission of the volatiles 2-ethyl-1-hexanol, 4-tert-butylcyclohexyl acetate and 1, 2, 3-trimethyl-benzene, which were negatively correlated with oviposition and fly infestation. Systemin has also showed to trigger the biosynthesis of specific volatiles (esters) in olives in response to fly attacks. Overall, the observed protection conferred by systemin against olive fly is likely due to the emission of specific volatiles that can act as a defence and/or as signalling molecules to upregulate the plant defence response. Thus, systemin represents a novel and useful tool to manage olive fruit fly.