Nitrogen Budgets of Phloem-Feeding Bark Beetles With and Without Symbiotic Fungi

Ayres, Matthew P.; Wilkens, Richard T.; Ruel, Jonathan J.; Lombardero, Marı́a J.; Vallery, Erich

doi:10.1890/0012-9658(2000)081[2198:nbopfb]2.0.co;2

Cited by 263 publications

(178 citation statements)

References 68 publications

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“…Considering the near-obligate and facultative parasitic species, it is thought that fungi can improve larval diet through modifying the substrate or providing complementary nutrients such as vitamins, proteins or sterols Six, 2003). Evidence for a role of mycangial basidiomycetes in helping D. frontalis to meet its nitrogen needs has been found (Ayres et al, 2000). Similarly, the presence of the Ophiostomatoid species Grosmannia clavigera and Ophiostoma montium can increase the nitrogen levels in the phloem of trees attacked by D. ponderosae by 40%, probably through their ability to restitute nitrogen from the sapwood to the phloem (Bleiker and Six, 2007), and all larval stages and the adults of the insect can feed on the fungi (Adams and .…”

Section: Bark Beetles and Their Associated Micro-organismsmentioning

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: Bark Beetles and Their Associated Micro-organismsmentioning

confidence: 99%

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

2009

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“…Bark beetles have evolved two strategies for contending with this problem. Some construct long feeding galleries and consume large amounts of phloem relative to their final adult size (Ayres et al 2000). These species do not appear to gain benefit from feeding on fungi and the fungi they carry are not highly specific.…”

Section: Forest/savanna Insect-microbe Mutualisms Affected By Anthropmentioning

confidence: 99%

Anthropogenic effects on interaction outcomes: examples from insect-microbial symbioses in forest and savanna ecosystems

et al. 2011

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The influence of humans on ecosystem dynamics has been, and continues to be, profound. Anthropogenic effects are expected to amplify as human populations continue to increase. Concern over these effects has given rise to a large number of studies focusing on impacts of human activities on individual species or on biotic community structure and composition. Lacking are studies on interactions, particularly mutualisms. Because of the role of mutualisms in ecosystem stability, such studies are critically needed if we are to begin to better understand and predict the responses of ecosystems to anthropogenic change. Most organisms are involved in at least one mutualism, and many in several. Mutualisms facilitate the ability of partners to exploit particular habitats and resources, and play a large role in determining ecological boundaries. When change disrupts, enhances, or introduces new organisms into a mutualism, the outcome and stability of the original partnership(s) is altered as are effects of the symbiosis on the community and ecosystem as a whole. In this paper, using examples from six microbe-insect mutualisms in forest and savanna settings, we showcase how varied and complex the responses of mutualisms can be to an equally varied set of anthropogenic influences. We also show how alterations of mutualisms may ramify throughout affected systems. We stress that researchers must be cognizant that many observed changes in the behaviors, abundances, and distributions of organisms due to human activities are likely to be mediated by mutualists which may alter predictions and actual outcomes in significant ways.

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“…(Fig. 5H) (6,12,79,99,122,150) (Table 1). For example, fungi that were associated with C. columbianus activity on silver maple (Acer saccharinum) caused no significant damage on detached or intact host material when used in inoculation experiments (79).…”

Section: Ambrosia Beetle-associated Diseasesmentioning

confidence: 96%

“…And for some of the bark beetles, fungal symbionts provide sterols, nitrogen and other nutrients that are required for, or facilitate, development and reproduction (1,12,19,20).…”

Section: ) Have Extreme Impacts;mentioning

confidence: 99%

“…Some reversion to conifer hosts occurred, but most extant ambrosia beetles are found in angiosperms. Extant bark beetles are also most common on angiosperms, although the most economically important species occur on pines.Bark beetles feed on host phloem, but many species supplement their diets with symbiotic fungi (12,20,146). In contrast, most ambrosia beetles subsist entirely on fungi (14,15,17,144).…”

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confidence: 99%

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Destructive Tree Diseases Associated with Ambrosia and Bark Beetles: Black Swan Events in Tree Pathology?

et al. 2013

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Diseases that are associated with ambrosia and bark beetles comprise some of the most significant problems that have emerged on trees in the last century. They are caused by fungi in the Ophiostomatales, Microascales and Hypocreales, and have vectors in the Scolytinae (ambrosia and bark beetles), Platypodinae (ambrosia beetles) and Hylesininae (bark beetles) subfamilies of the Curculionidae (Coleoptera) (73,102,144). Some of these problems, such as Dutch elm disease (DED), have a long history, have been extensively researched, and are fairly well understood (23,56,70,113,149,168,169). In contrast, other similar diseases developed recently and are poorly or partially understood (2,3,42,51,73,89,94,98,114,127,137,154,158, 164,165). Significant data gaps may exist for the ecology, epidemiology and management of the latter diseases.The emergence and unexpected importance of these tree diseases are discussed in thisarticle. An underlying factor in most of these interactions is the absence of a coevolved history between the so-called "naïve" or "new encounter" host trees and the pathogens and/or beetles (27,128,174). For the ambrosia beetles, these interactions are associated with susceptibility to what are typically benign fungi and atypical relationships with healthy trees (ambrosia beetles favor trees that are dead or stressed). Interestingly, the pathogens for both the ambrosia and bark beetle-associated diseases often have symbiotic relationships with the insects that are not based on phytopathogenicity. Some of the most alarming and damaging of these diseases are considered below as "black swan events" (155).Black Swans. Before 1697, improbable events and situations in Europe were known as "black swans" (at the time, all swans known to Europeans were white) (134). In that year, the black swan, Cygnus atratus, was discovered in Western Australia (38). Thereafter, "black swan" developed as a metaphor for a supposed impossibility that is contradicted with new information.For example, John Stuart Mill used black swan logical fallacy when identifying falsification, a key component in the scientific method (68).In a recent book, Taleb (155) developed Black Swan Theory (BST). Unlike the "black swan" to which Mill referred (68), BST focuses on unexpected events of large magnitude and consequence (155). Taleb (155) recognized such events in diverse fields including finance, history, science and technology. He suggested that black swan events: 1) have extreme impacts; 2) lie outside the realm of regular expectations (they are rare); and 3) are unpredictable.Although all ambrosia and bark beetle-associated diseases are not black swan events, several do fulfill the above criteria since they have large impacts, are uncommon surprises and are unpredictable (2,3,51,56,73,89,94,98,114,137,154,158, 164,165) (Table 1). They are typically understood and appreciated only with the benefit of hindsight and subsequent research.The Beetles and Beetle-associated Tree Diseases. The order Coleoptera contains more species than any other or...

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Nitrogen Budgets of Phloem-Feeding Bark Beetles With and Without Symbiotic Fungi

Cited by 263 publications

References 68 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

Anthropogenic effects on interaction outcomes: examples from insect-microbial symbioses in forest and savanna ecosystems

Destructive Tree Diseases Associated with Ambrosia and Bark Beetles: Black Swan Events in Tree Pathology?

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