title: Detection of Invertebrate Suppressive Soils, and Identification of a Possible Biological Control Agent forMeloidogyneNematodes Using High Resolution Rhizosphere Microbial Community Analysis.
abstract: White clover (Trifolium repens) is the key legume component of New Zealand pastoral agriculture due to the high quality feed and nitrogen inputs it provides. Invertebrate pests constrain white clover growth and this study investigated rhizosphere-associated fungal controls for two of these pests and attempts to disentangle the underpinning mechanisms. The degree of suppressiveness of 10 soils, in a latitudinal gradient down New Zealand, to addedMeloidogyne haplaandCostelytra zealandicascarab larvae was measured in untreated soil. Most of the soils showed no suppressive activity against these pests but two showed activity againstM. haplaand two againstC. zealandica. Rhizosphere fungi responsible for pest suppressive responses were elucidated via next-generation sequencing. In theM. hapla-suppressive soils nematode-trapping Orbiliomycetes fungi were present in significantly greater abundance than non-suppressive soils and their abundance increased further with addition ofM. hapla. A comparison of plant growth and the rhizosphere fungal community between untreated and irradiated soil was carried out on 5 of the 10 soils usingPyronotaas the scarab larvae. Soil irradiation either: reduced (by 60-70%); increased (16×) or made no difference to white clover growth across the five soils tested, illustrating the range of microbial impacts on plant production. In one of theM. haplasuppressive soils irradiation resulted in a significant increase in nematode galling suggesting that Orbiliomycetes fungi were indeed responsible for the suppressive effect. Lack of consistent changes in soil macronutrients and pH post-irradiation suggest these were not responsible for plant or invertebrate responses. The use of next generation sequencing in controlled pot trials has allowed identification of a potential biological control organism and bioindicator forM. haplasuppression.
authors.affiliation: Soil Biology Team, AgResearch Ltd, Ruakura Research Centre Hamilton, New Zealand.
authors.forename: Nigel L
authors.initials: NL
authors.lastname: Bell
authors.affiliation: Soil Biology Team, AgResearch Ltd, Ruakura Research Centre Hamilton, New Zealand.
authors.forename: Katharine H
authors.initials: KH
authors.lastname: Adam
authors.affiliation: Soil Biology Team, AgResearch Ltd, Ruakura Research Centre Hamilton, New Zealand.
authors.forename: Rhys J
authors.initials: RJ
authors.lastname: Jones
authors.affiliation: Plant/Fungal Interactions Team, AgResearch Ltd, Grasslands Research Centre Palmerston North, New Zealand.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Johnson
authors.affiliation: Soil Biology Team, AgResearch Ltd, Ruakura Research Centre Hamilton, New Zealand.
authors.forename: Yeukai F
authors.initials: YF
authors.lastname: Mtandavari
authors.affiliation: Soil Biology Team, AgResearch Ltd, Ruakura Research Centre Hamilton, New Zealand.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Burch
authors.affiliation: Bioinformatics and Statistics Team, AgResearch Ltd, Ruakura Research Centre Hamilton, New Zealand.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Cave
authors.affiliation: Bioinformatics and Statistics Team, AgResearch Ltd, Ruakura Research Centre Hamilton, New Zealand.
authors.forename: Catherine
authors.initials: C
authors.lastname: Cameron
authors.affiliation: Bioinformatics and Statistics Team, AgResearch Ltd, Lincoln Research Centre Christchurch, New Zealand.
authors.forename: Paul
authors.initials: P
authors.lastname: Maclean
authors.affiliation: Soil Biology Team, AgResearch Ltd, Ruakura Research Centre Hamilton, New Zealand.
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Popay
authors.affiliation: Biotelliga Ltd, Institute for Innovation in Biotechnology Auckland, New Zealand.
authors.forename: Damien
authors.initials: D
authors.lastname: Fleetwood
keywords: Mi-Seq; Trifolium repens; biological control; grass grub; mānuka beetle; next generation sequencing; rhizosphere; white clover