Early reduction of Otiorhynchus spp. larval root herbivory on Betula pubescens by beneficial soil fungi

• Published in: Applied soil ecology : a section of Agriculture, ecosystems & environment Vol. 45; no. 3; pp. 168 - 174
• Main Authors: Oddsdottir, Edda S., Eilenberg, Jørgen, Sen, Robin, Harding, Susanne, Halldorsson, Gudmundur
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01-07-2010; Elsevier
• Subjects: Afforestation; Agronomy. Soil science and plant productions; Betula pubescens; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Economic plant physiology; Ectomycorrhiza; Fundamental and applied biological sciences. Psychology; Hebeloma; Metarhizium anisopliae; Otiorhynchus; Otiorhynchus spp; Paxillus involutus; Phialophora; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Root herbivory; Soil science; Symbiosis (nodules, symbiotic nitrogen fixation, mycorrhiza...); Ectomycorrhiza; Root herbivory; Afforestation; Metarhizium anisopliae; Betula pubescens; Otiorhynchus spp; Entomopathogen; Herbivorous; Soil fungi; Ecology; Symbiont; Fungi; Soils; Larva; Dicotyledones; Angiospermae; Mycorrhiza; Hardwood forest tree; Spermatophyta; Soil science; Fungi Imperfecti; Betulaceae
• ISSN: 0929-1393; 1873-0272
• DOI: 10.1016/j.apsoil.2010.03.009

We present novel findings highlighting the early effects of inoculation of downy birch (
Betula pubescens Ehrh.) seedlings with factorial combinations of beneficial soil fungi, namely, ectomycorrhizal and insect pathogenic fungi, on
Otiorhynchus spp. larval root herbivory under Icelandic field conditions.
Birch seedlings were pre-treated with (1) a mixture of four ectomycorrhizal fungal species:
Paxillus involutus (Batsch: Fr.) Fr.,
Telephora terrestris Ehrh.: Fr.,
Phialophora finlandia Wang & Wilcox. and
Hebeloma sp., (2) the insect pathogenic fungus
Metarhizium anisopliae (Metschnikoff) Sorokin or (3) a combined inoculum that included the four ectomycorrhizal fungal species and
M. anisopliae. Non-inoculated seedlings served as untreated controls. Inoculated and control seedlings were transplanted into soils at three different sites representing eroded land, birch woodland and heathland.
Assessment following the first growing season indicated that the effects on
Otiorhynchus spp. larval root herbivory and seedling productivity of pre-inoculation with the ectomycorrhizal fungal species mixture and the insect pathogenic fungus,
M. anisopliae, were highly dependent on site and treatment. Inoculation with ectomycorrhizal fungi and
M. anisopliae significantly reduced root herbivory in both the birch woodland and, in particular, the eroded land sites. In the heathland site, no or even negative effects on root herbivory were observed. However, potential synergistic effects of combined inoculation with both ectomycorrhizal fungi and
M. anisopliae were not identified under these experimental conditions.
Accumulated seedling mortality ascribed to root herbivory after three growing seasons showed a significant site dependent response, but no significant treatment effect was detected.
The effects of ectomycorrhizal and insect pathogenic fungi on root herbivory are discussed and we conclude that significant, although mostly unidentified, interactions between the inoculated fungi and the naturally occurring soil microorganisms may explain these findings. Such interactions require further detailed investigation in order to develop an efficient strategy for soil inoculation with beneficial fungi.