Variation in Larch Sawfly Attack of Different Species and Geographic Strains of Larch, Exhibiting Diverse Growth Rates12

Genys, John B.; Harman, Dan M.

doi:10.1093/jee/69.5.573

Cited by 4 publications

(1 citation statement)

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“…In the case of the N. lecontei-P. resinosa interaction, this response could result in continued herbivore pressure. During the early phases of population increase, oviposition is often highly clustered on a few trees despite the availability of adjacent, apparently healthy trees (Genys andHarman 1976, Krause 1994). Oviposition is particularly concentrated among trees showing signs of previous defoliation (Codella and Raffa 1995a).…”

Section: Discussionmentioning

confidence: 99%

Long-Term Effects of Defoliation on Red Pine Suitability to Insects Feeding on Diverse Plant Tissues

Raffa

Krause

1998

Ecology

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Evidence that defoliation can induce long‐term responses in perennial plants that can regulate insect population dynamics is based largely on studies using deciduous trees and folivores, particularly Lepidoptera. Studies with evergreen trees, and with insects feeding on other plant parts, have yielded more variable results. This study examined the effects over several seasons of controlled defoliation on the suitability of an evergreen conifer, red pine (Pinus resinosa) to insects and pathogens that exploit foliage, stem phloem, and root tissue. Test insects included a folivorous sawfly (Hymenoptera) and two species of stem‐ and root‐colonizing beetles (Coleoptera). Each of these species undergoes periodic population irruptions. Controlled defoliations were administered to 10‐yr‐old trees at levels that mimic naturally occurring sawfly outbreaks. Additional studies were conducted on seedlings in a glasshouse. Foliar suitability to the redheaded pine sawfly (Neodiprion lecontei) varied in a nonlinear fashion with defoliation intensity one year after treatment. However, not all parameters of sawfly success were equally affected. Female cocoon mass was related to foliar concentrations of nutrients, but not monoterpenes or diterpene acids. Suitability to the stem boring pine engraver (Ips pini) increased 2 yr after defoliation. Moderate defoliation reduced stem resin flow rate by 50% and increased stem phloem colonization rate by the beetle’s mutualistic fungus, Ophiostoma ips. Defoliation also affected host suitability to adult pales weevils, Hylobius pales. Weevil feeding increased 1 yr after defoliation, but this response dissipated 2 yr after treatment. The observation that intermediate defoliation stress can either decrease or increase foliar suitability in an evergreen conifer, depending on intensity, is consistent with elements of both the plant stress and carbon:nutrient balance hypotheses. Moreover, host responses to a single stress agent may significantly and differentially influence the population dynamics of insects and pathogens that exploit different plant tissues. Implications of these results for plant stress and carbon:nutrient theories, plant‐herbivore interactions, and chronic forest declines are discussed.

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Section: Discussionmentioning

confidence: 99%

Long-Term Effects of Defoliation on Red Pine Suitability to Insects Feeding on Diverse Plant Tissues

Raffa

Krause

1998

Ecology

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Comparison of insect, fungal, and mechanically induced defoliation of larch: effects on plant productivity and subsequent host susceptibility

Krause

Raffa

1992

Oecologia

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Larch sawfly, Pristiphora erichsonii Hartig, and larch needlecast fungus, Mycosphaerella laricinia (R. Hartig) Neg., are early season defoliators restricted only to Larix host trees. Larch defoliation (100%) by either the fungus or insect, but not mechanical removal, induced systemic responses that reduced sawfly consumption and digestion rates one year later. In a feeding behavior assay, larvae quickly abandoned seedlings previously defoliated by M. laricinia. Adult female oviposition choice and egg deposition were unaffected. Seedling growth was not affected during the year of defoliation by M. laricinia, but was significantly reduced one year later. Defoliation by M. laricinia reduced stem volume, radial growth, root biomass and new shoot production. The latter tissue is the only oviposition resource for larch sawfly, and, in contrast, is not influenced by sawfly feeding. We hypothesize that M. laricinia infection may limit larch sawfly populations where both species coexist. However, this reduction is at a substantial net cost to larch productivity.

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Management of exotic timber trees in temperate regions of eastern North America: An assessment

DeHayes

Dickmann

Lemmien

1980

Forest Ecology and Management

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Variation in Larch Sawfly Attack of Different Species and Geographic Strains of Larch, Exhibiting Diverse Growth Rates12

Cited by 4 publications

References 0 publications

Long-Term Effects of Defoliation on Red Pine Suitability to Insects Feeding on Diverse Plant Tissues

Long-Term Effects of Defoliation on Red Pine Suitability to Insects Feeding on Diverse Plant Tissues

Comparison of insect, fungal, and mechanically induced defoliation of larch: effects on plant productivity and subsequent host susceptibility

Management of exotic timber trees in temperate regions of eastern North America: An assessment

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