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Effect of soil tillage on natural occurrence of fungal entomopathogens associated to Prays oleae Bern.

Publication . Oliveira, Ivo; Pereira, J.A.; Quesada-Moraga, Enrique; Lino-Neto, Teresa; Bento, Albino; Baptista, Paula

The olive tree is one of the most important crops in Portugal, where tillage is still a normal practice performed by the growers. This work intends to evaluate the effect of tillage practices on the diversity and abundance of entomopathogenic fungi associated to Prays oleae Bern. population in the olive grove ecosystem. In order to achieve this, three tilled and three non-tilled groves were sampled for P. oleae larvae and pupae, during two consecutive years. The fungi were isolated from diseased larvae and pupae and identified by rDNA sequencing. One hundred and twenty isolates of fungi described as entomopathogenic were found, belonging to 8 different species. The most abundant species were Beauveria bassiana (60%), Cladosporium cladosporioides (18%) and Cladosporium oxysporum (14%). Olive groves under no-till system showed higher occurrence (2.7%), diversity (7 species) and abundance (65 isolates) of entomopathogenic fungi than tilled system (2.3%, 4 species and 55 isolates). Although these differences were found to be not significant, the results suggested that no-tilled olive groves with natural vegetation presented the most suitable conditions to increase the probability of P. oleae infection by entomopathogenic fungi. The highest number of exclusive species found in non-tilled groves (4 species) when compared to tilled ones (1 species) also reinforce this fact and indicated that vegetation cover may act as a reservoir for fungal species.

2013Journal article

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Viability of Beauveria bassiana isolates after storage under several preservation methods

Publication . Oliveira, Ivo; Pereira, J.A.; Bento, Albino; Baptista, Paula

Beauveria bassiana is a worldwide distributed entomopathogenic fungus, which is used nowadays as an alternative to chemical pesticides in the control of several agriculture pests. Therefore, a preservation method must be established in order to maintain fungal culture and stocks, while fungal characteristics, like morphological features, spore production and viability, are kept well preserved. Although a large number of different storage methods are available and described, each fungus presents different characteristics, and therefore a new challenge for its preservation. In this work, we evaluate the effect of 1-year preservation by lyophilization, glycerol-freeze at −20°C and sub-culturing on growth, production and viability of spores and macro- and micro-morphology of three isolates of B. bassiana. Overall, results indicate that sub-culturing is the best method for conservation of this fungal species. However, if long-term storage is required, glycerol-freeze proved to be the most capable method of preservation.

2011Journal article

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Plant-mediated effects on entomopathogenic fungi: how the olive tree influences fungal enemies of the olive moth, Prays oleae

Publication . Oliveira, Ivo; Pereira, J.A.; Lino-Neto, Teresa; Bento, Albino; Baptista, Paula

The community of entomopathogenic fungi associated with the olive moth Prays oleae is specific for each generation of this insect. The entomopathogen Beauveria bassiana is almost exclusive to the phyllophagous or leaf generation, whereas Paecilomyces formosa mainly occurs in the carpophagous or fruit generation. The main objective of this work was to evaluate olive plant-mediated effects on the development (germination, growth, sporulation and spore viability) of both entomopathogens. While B. bassiana was strongly inhibited by olives, P. formosa development was more restricted by leaves. These inhibitory effects were caused by both volatile and diffusible compounds produced by olives and leaves. Specifically, the effects of two leaf volatile compounds, (Z)-3-hexen-1-ol and (Z)-3-hexenyl acetate were studied. The results suggest that olive plant organs affect entomopathogens by controlling their abundance and function, which may partly explain the occurrence of a fungal species in a specific P. oleae generation.

2015Journal article

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Identification of fungi isolated from the olive moth (Prays oleae Bern.) based on ITS region

Publication . Oliveira, Ivo; Pereira, J.A.; Bento, Albino; Lino-Neto, Teresa; Baptista, Paula

2010Conference object

Open access

Fungal diversity associated to the olive moth, Prays oleae Bernard: a survey for potential entomopathogenic fungi

Publication . Oliveira, Ivo; Pereira, J.A.; Lino-Neto, Teresa; Bento, Albino; Baptista, Paula

Olive production is one of the main agricultural activities in Portugal. In the region of Trás-os-Montes, this crop has been considerably affected by Prays oleae. In order to evaluate the diversity of fungi on Prays oleae population of Trás-os-Montes olive orchards, larvae and pupae of the three annual generations (phyllophagous, antophagous and carpophagous) were collected and evaluated for fungal growth on their surface. From the 3,828 larvae and pupae, a high percentage of individuals exhibited growth of a fungal agent (40.6%), particularly those from the phyllophagous generation. From all the moth generations, a total of 43 species from 24 genera were identified, but the diversity and abundance of fungal species differed between the three generations. Higher diversity was found in the carpophagous generation, followed by the antophagous and phyllophagous generations. The presence of fungi displaying entomopathogenic features was highest in the phyllophagous larvae and pupae, with Beauveria bassiana as the most abundant taxa. The first report of Beauveria bassiana presence on Prays oleae could open new strategies for the biocontrol of this major pest in olive groves since the use of an already adapted species increases the guarantee of success of a biocontrol approach. The identification of antagonistic fungi able to control agents that cause major olive diseases, such as Verticillium dahliae, will benefit future biological control approaches for limiting this increasingly spreading pathogen.

2012Journal article

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