Population Dynamics of Bark Beetles

Coulson, Robert N.

doi:10.1146/annurev.en.24.010179.002221

Cited by 200 publications

(120 citation statements)

References 37 publications

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“…Establishment is said to begin (i.e. beetles bore galleries and begin to lay eggs) when host resistance stops and death is assured (Berryman, 1982;Coulson, 1979;Wood, 1982). However, these early propositions have often been misinterpreted as it is necessary for the tree to be already killed by fungi for beetle establishment to begin.…”

Section: Controversiesmentioning

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: Controversiesmentioning

confidence: 99%

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

2009

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“…Oviposition and brood development then occur in the girdled (and ultimately dead) tree. Once a tree is fully colonized, the attack process typically shifts to adjacent trees in the stand, the result being a cluster of freshly attacked trees, trees containing brood, and dead and vacated trees (Coulson, 1980). Mass attack and brood development occur more or less continuously throughout the year in the southern Correspondence: John D. Reeve.…”

Section: Introductionmentioning

confidence: 99%

Complex emergence patterns in a bark beetle predator

Reeve

2000

Agri and Forest Entomology

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1 The emergence pattern of Thanasimus dubius (F.) (Coleoptera: Cleridae), a common predator of the southern pine beetle, Dendroctonus frontalis Zimmermann (Coleoptera: Scolytidae), was studied under field conditions across different seasons. A simple statistical model was then developed to characterize the emergence data, using the truncated geometric distribution. Data are also presented on the mortality of T. dubius eggs at various temperatures and humidities in an effort to explain certain aspects of emergence behaviour. 2 Emergence of 7'. dubius from a given tree usually occurred in several discrete episodes across a two-year period, with most individuals emerging in spring or autumn. Almost no emergence occurred in July and August, which may be an adaptation to avoid high temperature mortality. Emergence patterns appeared similar across seasons, with the time of year serving mainly to shift the pattern through time. 3 Cycles in D. frontalis abundance may be the result of delayed density dependence generated by its natural enemy complex. The predator T. dubius is likely to be an important component of this delayed density dependence, because of its lengthy development time and apparent impact on D. front&s.

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“…These beetles normally have no impact on healthy pines, since such trees are able to generate a sufficient resin defensive response to kill or eject small numbers of beetles that may penetrate the bark and breach the resin ducts of the living host tissue. However, in the case of the aggressive, tree-killing bark beetle species, populations may reach outbreak densities sufficient for overwhelming host defences and permitting unimpeded colonization of bark tissue of entirely healthy, vigorous trees (Coulson, 1979). Tree death is assured by the girdling of the phloem tissue by the beetles' mining activities as well as the mass inoculation of weakly pathogenic fungi that the beetles carry into the host.…”

mentioning

confidence: 99%

Semiochemicals in the Natural History of Southern Pine Beetle Dendroctonus frontalis Zimmermann and Their Role in Pest Management

Sullivan

2016

Advances in Insect Physiology

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Population Dynamics of Bark Beetles

Cited by 200 publications

References 37 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

Complex emergence patterns in a bark beetle predator

Semiochemicals in the Natural History of Southern Pine Beetle Dendroctonus frontalis Zimmermann and Their Role in Pest Management

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