Terpenes associated with resistance against the gall wasp, Leptocybe invasa, in Eucalyptus grandis

Sanushka Naidoo*, Nanette Christie, Juan J. Acosta, Makobatjatji M. Mphahlele, Kitt G. Payn, Alexander A. Myburg, Carsten Külheim

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    27 Citations (Scopus)

    Abstract

    Leptocybe invasa is an insect pest causing gall formation on oviposited shoot tips and leaves of Eucalyptus trees leading to leaf deformation, stunting, and death in severe cases. We previously observed different constitutive and induced terpenes, plant specialized metabolites that may act as attractants or repellents to insects, in a resistant and susceptible clone of Eucalyptus challenged with L. invasa. We tested the hypothesis that specific terpenes are associated with pest resistance in a Eucalyptus grandis half-sib population. Insect damage was scored over 2 infestation cycles, and leaves were harvested for near-infrared reflectance (NIR) and terpene measurements. We used Bayesian model averaging for terpene selection and obtained partial least squares NIR models to predict terpene content and L. invasa infestation damage. In our optimal model, 29% of the phenotypic variation could be explained by 7 terpenes, and the monoterpene combination, limonene, α-terpineol, and 1,8-cineole, could be predicted with an NIR prediction ability of.67. Bayesian model averaging supported α-pinene, γ-terpinene, and iso-pinocarveol as important for predicting L. invasa infestation. Susceptibility was associated with increased γ-terpinene and α-pinene, which may act as a pest attractant, whereas reduced susceptibility was associated with iso-pinocarveol, which may act to recruit parasitoids or have direct toxic effects.

    Original languageEnglish
    Pages (from-to)1840-1851
    Number of pages12
    JournalPlant, Cell and Environment
    Volume41
    Issue number8
    DOIs
    Publication statusPublished - Aug 2018

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