Potential feeding deterrents found in hemlock woolly adelgid, Adelges tsugae

Jones, Anne C.; Mullins, Donald E.; Jones, Tappey H.; Salom, Scott M.

doi:10.1007/s00114-012-0931-3

Cited by 4 publications

(2 citation statements)

References 17 publications

(24 reference statements)

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“…Although the amount of increase in solar radiation after leaf senescence would vary considerably depending on the density of the hemlock canopy and surrounding deciduous trees, when leaf drop occurs, HWA begins producing wax which may protect it from the increased solar radiation. Jones et al [56] found that the HWA wax contains compounds that are predator deterrents. Although temperatures are much reduced during the fall, winter, and early spring compared to the summer, the production of wax may also reduce the effects of solar radiation.…”

Section: Discussionmentioning

confidence: 99%

The Effects of Shade, Fertilizer, and Pruning on Eastern Hemlock Trees and Hemlock Woolly Adelgid

McAvoy

Mays

Johnson

et al. 2017

Forests

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Hemlock woolly adelgid (HWA), Adelges tsugae Annand, an invasive insect native to the Pacific Northwest and Asia, is responsible for widespread health decline and mortality of native hemlocks (Tsuga spp.) in the eastern United States. Shading and fertilizer has been found to affect the survival and health of both HWA and hemlocks. These abiotic factors have been studied separately but not in combination. In this three year study, eastern hemlock trees (1-2 m tall) were treated with pruning, fertilizer, and shade to determine their effects on hemlock tree health and HWA survival and density. Shade cloths were erected over individual trees, granulated fertilizer was applied, and trees were pruned annually. The total number of HWA were counted during the sistens and progrediens adult stages on the low, mid, and high branches on the north, east, south, and west sides of each tree for three years. Survival of aestivating sistens was recorded in artificially, naturally, and unshaded hemlocks. The mean of percent tips alive, branches alive, and foliage density was used to calculate a hemlock health index (scale of 0-100). Shade cloth reduced solar radiation to the trees to levels similar to a naturally-forested hemlock canopy, but did not alter temperature. Trees exposed to shade alone and shade plus fertilizer maintained the greatest HWA density. On unshaded trees, branches on the west side of the tree had lower HWA densities and branches high on the tree had the lowest HWA densities. Pruning plus fertilizer and shading plus fertilizer reduced tree health. Shaded trees had reduced branchlet new growth length. Survival of summer aestivating sistens was nearly twice the survival under artificially-and naturally-shaded trees compared to unshaded trees. There was an inverse density-dependent survival response for aestivating HWA under artificially-shaded and unshaded trees but not naturally-shaded trees. Unshaded hemlock trees had lower HWA densities due to increased mortality of summer aestivating sistens. Unshaded trees had better health and longer new growth branchlets due to increased exposure to solar radiation and lower HWA densities. Silvicultural thinning of hemlocks in forest stands could increase direct sunlight reaching the trees and help decrease HWA densities and improve hemlock health.

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Section: Discussionmentioning

confidence: 99%

The Effects of Shade, Fertilizer, and Pruning on Eastern Hemlock Trees and Hemlock Woolly Adelgid

McAvoy

Mays

Johnson

et al. 2017

Forests

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“…Another factor affecting the pest’s biological control is the production of a range of chemicals by certain life stages of HWA. These chemicals (anthraquinone, chrysophanol and its anthrone precursor, chrysarobin) may function as feeding deterrents against predators [118]. …”

Section: Potential Hwa Control and Management Optionsmentioning

confidence: 99%

A Little Bug with a Big Bite: Impact of Hemlock Woolly Adelgid Infestations on Forest Ecosystems in the Eastern USA and Potential Control Strategies

Letheren

Hill

Salie

et al. 2017

IJERPH

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Hemlock woolly adelgid (Adelges tsugae Annand, HWA) remains the single greatest threat to the health and sustainability of hemlock in the eastern USA. The loss of hemlock trees leads to further negative impacts on the diversity and stability of ecosystems in the eastern part of North America. It is, therefore, urgent to develop effective control measures to reduce HWA populations and promote overall hemlock health. Currently available individual and integrated approaches should continue to be evaluated in the laboratory and in the field along with the development of other new and innovative methods.

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Characterization of Physical and Chemical Defenses in the Hemlock Woolly Adelgid

et al. 2014

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The invasive hemlock woolly adelgid (Adelges tsugae Annand, Hemiptera: Sternorrhyncha: Adelgidae) causes significant mortality to eastern and Carolina hemlock (Tsuga canadensis Carrière and T. caroliniana Engelmann, respectively) throughout the eastern United States. Adelges tsugae produces vast quantities of a wax covering that surrounds most of the instars as well as the adult and eggs. Using direct probe EI mass spectrometry, this wax covering was characterized as a diketoester wax, 17-oxohexatriacontanyl 11-oxotriacontanoate, and accounted for ≈ 42 % of A. tsugae total biomass. The presence of the anthraquinone, chrysophanol, and its precursor anthrone, chrysarobin, in A. tsugae has only been briefly described. Further study confirmed these compounds in all A. tsugae life stages. Additionally, several predatory beetles in use or under consideration as biological control agents for this species appear to ingest and excrete these compounds when feeding on A. tsugae. The production of both a physical and a chemical defense may represent a significant energy investment by A. tsugae.

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Potential feeding deterrents found in hemlock woolly adelgid, Adelges tsugae

Cited by 4 publications

References 17 publications

The Effects of Shade, Fertilizer, and Pruning on Eastern Hemlock Trees and Hemlock Woolly Adelgid

The Effects of Shade, Fertilizer, and Pruning on Eastern Hemlock Trees and Hemlock Woolly Adelgid

A Little Bug with a Big Bite: Impact of Hemlock Woolly Adelgid Infestations on Forest Ecosystems in the Eastern USA and Potential Control Strategies

Characterization of Physical and Chemical Defenses in the Hemlock Woolly Adelgid

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