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1 Weevil larvae of the genus Otiorhynchus are a serious problem in agriculture and forestry, causing damage to a wide range of plant species, primarily by larval feeding on roots. Otiorhynchus larvae are a serious pest in forest plantations in Iceland, causing 10–20% mortality of newly-planted seedlings. 2 We studied the effects of soil fungi on the survival of Otiorhynchus sulcatus larvae. The larvae were introduced into pots with birch seedlings grown in: (i) nursery peat; (ii) nursery peat inoculated with three different species of ectomycorrhizal fungi; (iii) nursery peat inoculated with insect pathogenic fungi; (iv) nursery peat inoculated with ectomycorrhizal fungi and insect pathogenic fungi; and (v) nursery peat inoculated with natural forest soil from Icelandic birch woodland. 3 Larval survival was negatively affected by inoculation of: (i) the ectomycorrhizal fungus Laccaria laccata; (ii) the ectomycorrhizal fungus Cenococcum geophylum; (iii) the insect pathogenic fungus Metarhizium anisopliae; and (iv) forest soil. Inoculation with the ectomycorrhizal fungus Phialophora finlandia did not have any significant effect on larval survival. No significant synergistic effect was found between insect pathogenic and ectomycorrhizal fungi. 4 It is concluded that ectomycorrhizal and insect pathogenic fungi have a significant potential in biological control of Otiorhynchus larvae in afforestation areas in Iceland. Further studies are needed to establish the effect of these fungi in the field and to analyse how mycorrhizal fungi affect root-feeding larvae. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

Lupinus nootkatensis is an exotic plant species that has been used for large‐scale sowing all around Iceland for land reclamation of eroded surfaces protected from livestock grazing.Until the early 1990s, L. nootkatensis was free from any significant arthropod herbivory in Iceland, whereas, after 1991, many outbreaks of native insect species, primarily Ceramica pisi and Eupithecia satyrata, have been recorded. These outbreaks have caused repeated total defoliation of extensive areas of L. nootkatensis, although the effects on its development are mostly unknown.We studied the effect of: (i) reduced herbivory; (ii) increased herbivory; and (iii) simulated increased herbivory, compared with (iv) unmanipulated herbivory, on defoliation and seed production of L. nootkatensis in a 3‐year field study within two sites at contrasting ages and successional stages.The results obtained showed that: (i) seed production across all treatments was negatively related to defoliation; (ii) reduced herbivory had a positive effect on the number of flowering stems and seed yield; and (iii) these effects depended on age and/or the successional stage because they were only significant in the older L. nootkatensis site.These findings indicate that arthropod herbivory may affect the invasiveness of L. nootkatensis in Iceland by reducing the seed production and the spatial distribution rate of late successional lupin communities. [ABSTRACT FROM AUTHOR]

The broom moth Ceramica pisi, a native species in Iceland, has shown a marked expansion from south Iceland towards the north, concurrent with increasing temperatures.Winter temperatures have increased more than summer temperatures in Iceland and, in the present study, the hypothesis was that the winter warming has facilitated the range shift of C. pisi.Winter survival of pupae in Iceland was studied in the laboratory. Pupae were collected in the autumn of 2012 at five separate locations, then weighed and placed at temperatures from −6 to −18 °C. One month after the sub‐zero treatments, the pupae were placed at room temperature and pupal emergence was recorded.No significant effect of sub‐zero treatments on the survival of C. pisi pupae was found. The primary hypothesis of the present study was therefore rejected.The major factor affecting low temperature survival of C. pisi pupae, however, was their autumn weight. The response was sigmoid and the 5%, 50% and 95% likelihoods for winter survival were at 157, 274 and 393 mg autumn pupal mass, respectively.This finding indicates that factors other than winter temperature, such as summer available thermal budget for larval growth, may be a limiting factor to the spread of C. pisi in Iceland. [ABSTRACT FROM AUTHOR]