Do mycorrhizal fungi facilitate root defence signalling in belowground predator-prey interactions?

James Hourston

Research output: ThesisDoctoral Thesis

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The presence of arbuscular mycorrhizal fungi (AM fungi) in plant roots can have varied effects on insect herbivores. This thesis focused on the root feeding Otiorhynchus sulcatus, a pest of the perennial soft fruit crop Rubus idaeus, and subsequent interactions with two of its natural enemies, the entomopathogenic nematodes (EPNs) Heterorhabditis megidis and Stienernema kraussei. These interactions were thought to be mediated by plant signalling in the form of volatile organic compounds (VOCs) that are known to be modified by the presence of AM fungi.
A series of experiments were conducted to test the efficacy and taxis behaviour of EPNs when AM fungi were present or excluded from the root zone and to see if this was driven by plant VOC emissions. Stienernema kraussei was found to be the most effective EPN at controlling O. sulcatus under glasshouse conditions and in combination with resistant R. idaeus cultivars efficacy was even greater. When H. megidis taxis to R. idaeus plants was tested, the addition of AM fungi increased attraction of H. megidis regardless of O. sulcatus feeding pressures but this was not easily attributed to a difference in VOC production. Captured VOCs including the known semiochemicals, α-pinene and carene, were elevated under high O. sulcatus herbivory pressure indicating that EPNs in this system were indeed responding to herbivore induced VOCs. When EPN attraction was tested with a commercial inoculum however, similar effects were not seen, and EPNs were instead attracted by higher R. idaeus root biomass.
As this experimental system was developed to become more ecologically relevant, it was found that the effects seen under more controlled conditions were not reproduced. This indicates that while this system has promise, further study is required to unlock the potential of AM fungi to provide novel pest management options in agriculture.
Original languageEnglish
Awarding Institution
  • Royal Holloway, University of London
  • Gange, Alan, Supervisor
Award date1 Sept 2015
Publication statusUnpublished - 2015

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