title: The bark beetle, Ips grandicollis, disrupts biological control of the woodwasp, Sirex noctilio, via fungal symbiont interactions.
abstract: The corticoid fungus, Amylostereum areolatum, is deposited in pine trees by the woodwasp, Sirex noctilio, at the time of oviposition. This fungus is essential in S. noctilio larval growth and it is also a food source for Beddingia siricidicola, the nematode used for S. noctilio biological control. In recent years, the historically successful biological control programme has been disrupted in Australia by the bark beetle, Ips grandicollis. This study investigated whether the mechanism of this disruption involves a fungus, Ophiostoma ips, which I. grandicollis introduces into trees. In artificial and wood media, A. areolatum was unable to grow in areas occupied by O. ips. The latter fungus was faster growing, especially at 25 °C rather than 20 °C. Larval galleries of S. noctilio in field-collected samples were strongly associated with wood infested by A. areolatum and absent from areas affected by O. ips. The nematode failed to survive and reproduce on O. ips as it can on A. areolatum. Competitive interactions between O. ips and A. areolatum within the trap trees are demonstrated to be key factors in the negative effect of I. grandicollis on S. noctilio biological control programmes.
authors.affiliation: School of Agricultural & Wine Sciences, Charles Sturt University, Orange, NSW, Australia.
authors.forename: Fazila
authors.initials: F
authors.lastname: Yousuf
authors.forename: Geoff M
authors.initials: GM
authors.lastname: Gurr
authors.forename: Angus J
authors.initials: AJ
authors.lastname: Carnegie
authors.forename: Robin A
authors.initials: RA
authors.lastname: Bedding
authors.forename: Richard
authors.initials: R
authors.lastname: Bashford
authors.forename: Catherine W
authors.initials: CW
authors.lastname: Gitau
authors.forename: Helen I
authors.initials: HI
authors.lastname: Nicol
mesh_terms: D000818:Animals; D001315:Australia; D001487:Basidiomycota / Q000254:growth & development; D061046:Biological Control Agents; D001517:Coleoptera; D003163:Competitive Behavior; D005260:Female; D009348:Nematoda; D028223:Pinus; D014197:Trees; D014863:Wasps / Q000382:microbiology; D014934:Wood
chemical_list: D061046:Biological Control Agents
keywords: Pinus radiata; biological control; fungal associations; larval galleries; trap trees