Establishment, hybridization and impact of Laricobius predators on insecticide-treated hemlocks: Exploring integrated management of the hemlock woolly adelgid

Mayfield, Albert E.; Reynolds, Barbara C.; Coots, Carla; Havill, Nathan P.; Brownie, Cavell; Tait, Andrew R.; Hanula, James L.; Joseph, Shimat V.; Galloway, A. B. Lamb

doi:10.1016/j.foreco.2014.09.021

Cited by 39 publications

(26 citation statements)

References 34 publications

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“…The typical protective period for soil treatment is roughly 4 -5 years (Silcox 2002). Interestingly, traces of imidacloprid and its metabolites have been found up to 7 years post-treatment, although the concentration of these chemicals was below the previously-mentioned LC50 for HWA (Benton et al 2015, Mayfield et al 2015. Of note is the issue of surface water runoff, where imidacloprid can be carried into local waterways.…”

Section: Chemical Controls For Managing Hwamentioning

confidence: 89%

“…The deviation from this trend came in the third year of the study when the previous year's low HWA population allowed an increased spring growth by the hemlocks, followed by a surge in HWA as the insects discovered the rejuvenated food source. This phenomenon is important when a management system plans to incorporate chemical and biological treatments because the improved health of the stand from chemical treatment can allow sufficient time for regeneration while the biological control establishes (Joseph et al 2011, Mayfield et al 2015.…”

Section: Biology Of the Hemlock Woolly Adelgidmentioning

confidence: 99%

“…Joseph et al (2011) showed that trees treated with only 10% of the label rate could reduce the number of HWA ovisacs and improve tree health. Mayfield et al (2015) showed that imidacloprid administered systemically at 25% of label rate was effective at improving crown health in eastern hemlock. This could be beneficial when considering combining imidacloprid with predatory beetles as part of an IPM plan.…”

Section: Chemical Controls For Managing Hwamentioning

confidence: 99%

“…In a recent study, Mayfield et al (2015) showed that through a combination of insecticide treatment and predatory beetle releases, the health of a stand of trees could be improved within a few years. The application of the insecticide gives the surviving trees time to recover, thus providing time for predators to establish and reach high enough density to impact HWA.…”

Section: Hwa Biological Managementmentioning

confidence: 99%

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Evaluating a potential area-wide IPM strategy for managing hemlock woolly adelgid in the eastern United States

Sumpter¹

2016

2016 International Congress of Entomology

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(Academic)Use of imidacloprid has been found to be highly effective in suppressing hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae). Laricobius nigrinus Fender (Coleoptera: Derodontidae) is a predator released as a biological control in the eastern U.S. This project was designed to develop a pest management strategy that utilizes both tactics concurrently within the same site. It will assess the efficacy of this strategy in reducing HWA populations and improving the health of hemlock forests. The

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Section: Chemical Controls For Managing Hwamentioning

confidence: 89%

Section: Biology Of the Hemlock Woolly Adelgidmentioning

confidence: 99%

Section: Chemical Controls For Managing Hwamentioning

confidence: 99%

Section: Hwa Biological Managementmentioning

confidence: 99%

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Evaluating a potential area-wide IPM strategy for managing hemlock woolly adelgid in the eastern United States

Sumpter¹

2016

2016 International Congress of Entomology

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“…Several other Coccinellidae (Coleoptera) and Chamaemyiid (Diptera) predators and an insect-killing fungus are also under consideration for use to control HWA [12]. Integrating chemical and biological control has also been found to be effective and compatible [24,25].…”

Section: Introductionmentioning

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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Establishment of the predator Laricobius nigrinus, introduced as a biological control agent for hemlock woolly adelgid in Virginia, USA

et al. 2021

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Laricobius nigrinus Fender (Coleoptera: Derodontidae), a predatory beetle native to western North America, has been released since 2003 for management of hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae), a non-native pest killing hemlocks in eastern North America. Over 420,000 L. nigrinus have been released in the eastern USA from field and lab-reared sources, 14,000 of which were deployed in the Commonwealth of Virginia, USA. In order to determine the establishment rates of L. nigrinus in Virginia, surveys were conducted in 2017 and 2018 at all release sites within this state. During the study, stand-level HWA densities were estimated, and hemlock tree health and predatorprey ratios were quantified. The identification of Laricobius spp. recoveries were made using microsatellite analysis. During the period of the study, L. nigrinus were found to have established at 82% of Virginia release sites and were the primary species recovered (80%). Both Laricobius rubidus (18%) and hybrids (2%) were also recovered. Stand-level HWA densities varied greatly over sites and years but showed a general decline in year two of the study. Establishment at such a high percentage of release sites suggests that the climate in Virginia is suitable for the predator and the insect is adaptable to the wide variety of site conditions where hemlocks typically grow.

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Establishment, hybridization and impact of Laricobius predators on insecticide-treated hemlocks: Exploring integrated management of the hemlock woolly adelgid

Cited by 39 publications

References 34 publications

Evaluating a potential area-wide IPM strategy for managing hemlock woolly adelgid in the eastern United States

Evaluating a potential area-wide IPM strategy for managing hemlock woolly adelgid in the eastern United States

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

Establishment of the predator Laricobius nigrinus, introduced as a biological control agent for hemlock woolly adelgid in Virginia, USA

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