Assosiation levels between Pityophthorus pubescens and Fusarium circinatum in PCD affected plantations in northern Spain.

Bezos, D., Martínez-Álvarez, P., Diez, J.J., Fernández-Fernández, M.M. (2016) - Assosiation levels between Pityophthorus pubescens and Fusarium circinatum in PCD affected plantations in northern Spain. - Entomologia Generalis

Fusarium circinatum, the causal agent of pitch canker disease (PCD), poses a threat
to Pinus radiata plantations due to the presence of bleeding cankers on the trunk that can cause
the tree to die. This pathogen has been reported to be phoretically associated with bark beetle
species, specifically, with Pityophthorus species in California. Pityophthorus pubescens is a
secondary pest, attacking weak trees or broken branches in healthy trees. The aim of this study
was to know the association between P. pubescens and F. circinatum in PCD affected plantations
in northern Spain. Specific aims were determined: i) to assess the phoretic association
between P. pubescens and F. circinatum, ii) to study the presence of F. circinatum in P. pubescens
infested twigs and iii) to evaluate whether PCD damages were enhanced in (E)-pityol
baited P. radiata trees. Funnel traps baited with (E)-pityol were established and twigs from
infested trees were sampled to collect insects and plant tissues in PCD affected plots, with the
aim of testing the presence of F. circinatum. Moreover, an experiment was carried out in nature
in which P. radiata trees were baited with (E)-pityol and PCD symptoms were evaluated 4 times
during one year. A total of 263 specimens were collected from funnel traps between June and
September 2010, 2011, 2012 and 2013. Moreover, 215 specimens were collected from 424 galleries
within the twigs in 2012 and 2013. The pathogen appeared on 1.05% and 2% of the
insects in the funnel traps during 2010 and 2012 respectively. Regarding the collected twigs,
F. circinatum was found in 3 galleries, whilst results of the baiting experimentation showed
symptoms in the crown were more influenced by (E)-pityol than those on the trunk. This work
affirms a weak association between P. pubescens and F. circinatum in our study area.

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Tipo de Publicación: 

Artículos

ISSN: 

0171-8177

Volumen: 

36(1)

Número de páginas: 

43-54