Dieback and death of larch caused by <i>Ceratocystis laricicola</i> sp. nov. following attack by <i>Ips cembrae</i>

Redfern, D. B.; Stoakley, J. T.; Steele, H.; Minter, D. W.

doi:10.1111/j.1365-3059.1987.tb02264.x

Cited by 72 publications

(43 citation statements)

References 15 publications

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“…We predict that L. abietinum strongly stimulates spruce defenses when introduced by D. rufipennis in its host. Conversely, the aggressiveness of I. cembrae for the European larch is usually only moderate in continental Europe (Grégoire and Evans, 2004;Redfern et al, 1987), its area of origin. Certainly, C. laricicola or another highly associated fungal species stimulates larch defenses only moderately in that area.…”

Section: Group 2 -Beetles Species Using the Strategy Of Exhausting Trmentioning

confidence: 99%

Stimulation of tree defenses by Ophiostomatoid fungi can explain attack success of bark beetles on conifers

2009

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Keywords:pathogen / forest tree / physiological stress / blue stain fungi / host resistance Abstract • Our aim is to present why the hypothesis, that Ophiostomatoid fungi play an important role in the establishment of most bark beetle species on living conifers, is valuable.• After summarizing knowledge about the relationships of bark beetles with conifers and fungi, we conclude that controversy results from misinterpretations when using fungal pathogenicity to demonstrate the role of Ophiostomatoid fungi in beetle establishment on host trees.• We demonstrate that fungal pathogenicity is not the right parameter to appreciate the role of fungus in beetle establishment on host trees. We argue that artificial low density inoculations that allow the appreciation of fungus ability to stimulate tree defenses and thus to help beetles in overcoming tree resistance must be used in complement to mass inoculations. In both cases, results must be expressed in terms of tree defense stimulation rather than in terms of tree killing.(i) Fungal species stimulating tree defenses are generally not those that grow the best in the sapwood.(ii) We argue that beetle development in the phloem, fungal invasion of the sapwood and phloem, and tree death, occur after tree defenses are exhausted, and that any fungus present in the beetle gallery could thus potentially invade the sapwood after defense exhaustion.• We conclude that stimulation of the tree defense reactions in both the phloem and the superficial sapwood is a real benefit brought by fungi to the beetles during the first phase of establishment (overcoming tree resistance).• Considering the origin of the bark beetle fungus associations attacking living trees and their general functioning based on stimulation of tree defenses, we develop three hypotheses:(i) any beetle species would be helped in its establishment in a given tree species by developing an association, even loosely, with a fungus species belonging to the Ophiostomatoid flora of that tree species; (ii) the necessity of a considerably low level of tree resistance for fungus extension into the tree is the selection pressure that has led fungi to develop their intrinsic ability to stimulate tree defenses, through their ability to grow into the phloem. This association can be completed by antagonistic fungal species controlling extension of the previous fungal species in the tree tissues; (iii) Beetle species using the strategy of overcoming tree resistance are associated with a fungal complex, of which species could assume three roles regarding relationships between beetles and trees: 1-to stimulate tree defenses in the phloem and superficial sapwood, 2-to grow into the sapwood after tree resistance is overcome, and 3-to control phloem extension of the first other two categories. Bringing nutrients to the beetle progeny can be a fourth role.• We propose that bark beetle -Ophiostomatoid associations can be categorized, based on associations' frequency and complexity while taking into account beetle aggressiveness. We show...

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Section: Group 2 -Beetles Species Using the Strategy Of Exhausting Trmentioning

confidence: 99%

Stimulation of tree defenses by Ophiostomatoid fungi can explain attack success of bark beetles on conifers

2009

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“…In Europe, I. cembrae mainly infests living trees growing in regions outside the natural range of the European larch (Larix decidua), which is central Europe (Bobrov, 1972). These infestations appear to be favoured by drought and high population levels that follow after thinning and logging (Schimitschek, 1930;Crooke & Bevan, 1957;Redfern et al, 1987). I. cembrae was introduced into Scotland presumably after the second world war (Crooke & Bevan, 1957) and into Denmark during the last decade of this century (Harding, pers.…”

Section: Introductionmentioning

confidence: 99%

Phylogenetic relationships between the European and Asian eight spined larch bark beetle populations (Coleoptera, Scolytidae) inferred from DNA sequences and fungal associates

Stauffer¹,

Kirisits²,

Nussbaumer³

et al. 2001

Eur. J. Entomol.

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Abstract. The eight spined larch bark beetles infest various species of Larix in Europe and Asia. Ips cembrae is the only Ips species with larch as its main host. Ips subelongatus, Ips fallax, Ips shinanonensis and Ips cembrae var. engadinensis are treated as syno nyms of I. cembrae. These three putative species and the one variety are distinguished by their host tree and geographic distribution, as it is not possible to distinguish them on the basis of morphological differences. Beetles were collected from European and Asian populations, and from hosts and geographic areas where the species were first found and described and in their natural ranges of dis tribution. These beetles were used to study the phylogenetic relationships of the eight spined larch bark beetles. A region of the mito chondrial gene was analysed and the blue-stain fungi associated with I. cembrae in Europe were investigated and compared with those recorded as associated with the larch bark beetle in Japan. Only minor sequence differences were detected between the popula tions in Europe and Asia. However, the European populations differed by 4.3% from the Asian populations. The phylogenetic analysis placed the European and Asian haplotypes in significantly distinct clusters. This distinction was supported by the finding of an insertion/deletion in a non-coding region of the mitochondrial DNA. Furthermore, there are differences in the fungi associated with the eight spined larch bark beetles in Europe and Japan. The results suggest that the I. cembrae complex contains at least two taxa: I. cembrae infesting larch in Europe and I. subelongatus infesting larch in Asia.

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“…Ceratocystis spp., for example, are vectored by arthropods (Juzwik et al 1998;Cease & Juzwic 2001;Heath et al 2009) with which they usually have fairly loose relationships (Moller & DeVay 1968;Hinds 1972;Kile 1993). Seemingly more specialised species are found associated with bark beetles in their galleries (Redfern et al 1987;Wingfield et al 1997;Yamaoka et al 1997). Custingophora spp.…”

Section: Discussionmentioning

confidence: 99%

Mites are the most common vectors of the fungus Gondwanamyces proteae in Protea infructescences

Roets¹,

Wingfield²,

Wingfield³

et al. 2011

Fungal Biology

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Mites Sporothecae Tarsonemus a b s t r a c tEntomochoric spore dispersal is well-documented for most ophiostomatoid fungal genera, most of which are associated with bark or ambrosia beetles. Gondwanamyces spp. are unusual members of this group that were first discovered in the flower heads of the primitive angiosperm genus Protea, that is mostly restricted to the Cape Floristic region of Africa.In this study, we present the discovery of the vectors of Gondwanamyces proteae in Protea repens infructescences, which were identified using PCR, direct isolation, and light microscopy. Gondwanamyces proteae DNA and ascospores were identified on diverse lineages of arthropods including beetles (Euderes lineicolis and Genuchus hottentottus), bugs (Oxycarenus maculates), a psocopteran species and five mite (Acari) species. Based on isolation frequency, however, a mite species in the genus Trichouropoda appears to be the most common vector of G. proteae. Gondwanamyces spores were frequently observed within pit mycangia at the base of the legs of these mites. Manipulative experiments demonstrated the ability of mites to carry viable G. proteae spores whilst in transit on the beetle G. hottentottus and that these mites are able to transfer G. proteae spores to uncolonised substrates in vitro. Interestingly, this same mite species has also been implicated as vector of Ophiostoma spores on P. repens and belongs to the same genus of mites that vector Ophiostoma spp. associated with pine-infesting bark beetles in the Northern Hemisphere.

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Dieback and death of larch caused by Ceratocystis laricicola sp. nov. following attack by Ips cembrae

Cited by 72 publications

References 15 publications

Stimulation of tree defenses by Ophiostomatoid fungi can explain attack success of bark beetles on conifers

Stimulation of tree defenses by Ophiostomatoid fungi can explain attack success of bark beetles on conifers

Phylogenetic relationships between the European and Asian eight spined larch bark beetle populations (Coleoptera, Scolytidae) inferred from DNA sequences and fungal associates

Mites are the most common vectors of the fungus Gondwanamyces proteae in Protea infructescences

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