Rebound of Adelges tsugae spring generation following predation on overwintering generation ovisacs by the introduced predator Laricobius nigrinus in the eastern United States

The hemlock woolly adelgid, Adelges tsugae Annand, is an invasive insect that threatens hemlock species in eastern North America. Several species from the genus Laricobius are predators of A. tsugae in its native areas of Asia and the western United States. Two Laricobius species have been released as biological control agents: Laricobius nigrinus Fender, and Laricobius osakensis Montgomery and Shiyake. Laricobius rubidus LeConte is an adelgid predator native to the Eastern United States, where it can feed and complete development on A. tsugae opportunistically. Laboratory assays were conducted to assess the cold hardiness of these three Laricobius species, including two distinct populations of L. osakensis, by measuring the supercooling points of each species from November 2016 through March 2017. This information may be useful for choosing the best-suited biological control agent for a particular region to control A. tsugae. There was a significant difference between the overall mean supercooling point of L. rubidus compared to the other Laricobius spp. There were also significant differences of supercooling points between L. rubidus and both strains of L. osakensis in January, and significant differences between L. rubidus and all other strains in February. L. rubidus appear better adapted to cold extremes in the eastern U.S. than imported Laricobius spp.

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Morphology of Laricobius nigrinus (Coleoptera: Derodontidae), a predator of the hemlock woolly adelgid

The Canadian Entomologist ◽

10.4039/n05-096 ◽

2006 ◽

Vol 138 (5) ◽

pp. 595-601 ◽

Cited By ~ 9

Author(s):

G.M.G. Zilahi-Balogh ◽

L.M. Humble ◽

L.T. Kok ◽

S.M. Salom

Keyword(s):

United States ◽

Biological Control ◽

Life History ◽

Hemlock Woolly Adelgid ◽

Adelges Tsugae ◽

Life Stages ◽

Western North America ◽

Eastern United States ◽

Ecological Information ◽

Laricobius Nigrinus

AbstractLaricobius nigrinus Fender, native to western North America, was first released in 2003 for the biological control of the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), in the eastern United States. Members of the genus Laricobius are known to feed on adelgids, but there is a lack of detailed taxonomic and ecological information on this group of insects. Detailed descriptions and illustrations of various life stages of L. nigrinus are presented in this study, accompanied by notes on its life history to facilitate its recognition.

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Confined field release of Laricobius nigrinus (Coleoptera: Derodontidae), a predator of the hemlock woolly adelgid, Adelges tsugae (Hemiptera: Adelgidae), in Virginia

Canadian Journal of Forest Research ◽

10.1139/x05-190 ◽

2006 ◽

Vol 36 (2) ◽

pp. 369-375 ◽

Cited By ~ 29

Author(s):

A B Lamb ◽

S M Salom ◽

L T Kok ◽

D L Mausel

Keyword(s):

United States ◽

Biological Control Agent ◽

Release Site ◽

Hemlock Woolly Adelgid ◽

Control Agent ◽

Adelges Tsugae ◽

Adult Survival ◽

Eastern United States ◽

Laricobius Nigrinus ◽

Field Release

Laricobius nigrinus Fender is a specialist predator of the hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae), a lethal pest of hemlock (Tsuga spp.) in the eastern United States. A release was conducted in 2003 in Virginia to evaluate survival and oviposition of L. nigrinus adults, egg development in the field, and their impact on HWA density. In March, April, and May, groups of zero, one, two, or three L. nigrinus females were caged on 64 hemlock branches. After 10 days, half the branches were removed to determine L. nigrinus adult survival, total eggs laid, and oviposition location with respect to prey abundance. Beetles on branches remaining in the field were recovered and recaged on new branches every 10 days. The estimated 10 344 eggs laid on branches left in the field represent the first field release of L. nigrinus in the eastern United States. The density of L. nigrinus adults affected the total eggs laid per female and oviposition site selection. Branches caged with L. nigrinus had lower densities of HWA than branches without predators. Although F1 adults were not recovered from this release site in fall 2003, F2 adults were recovered in fall 2004. Laricobius nigrinus shows promise as a biological control agent for HWA in the eastern United States.

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Factors influencing aestivation in Laricobius nigrinus (Coleoptera: Derodontidae), a predator of Adelges tsugae (Hemiptera: Adelgidae)

The Canadian Entomologist ◽

10.4039/n06-110 ◽

2007 ◽

Vol 139 (4) ◽

pp. 576-586 ◽

Cited By ~ 15

Author(s):

A.B. Lamb ◽

S.M. Salom ◽

L.T. Kok

Keyword(s):

United States ◽

Biological Control Agent ◽

Control Agent ◽

Adelges Tsugae ◽

Day Length ◽

Eastern United States ◽

Dormant Period ◽

Laricobius Nigrinus ◽

Delayed Emergence ◽

Number Of Individuals

AbstractLaricobius nigrinus Fender is being reared for release as a biological control agent for hemlock woolly adelgid (HWA), Adelges tsugae Annand. HWA is an introduced insect lethal to hemlock trees (Tsuga canadensis (L.) Carr. and T. caroliniana Engelm.) in the eastern United States. In nature, the predator (Laricobius nigrinus) and its prey (HWA) undergo a dormant period in the summer (aestivation). In the laboratory, the aestivation of L. nigrinus has not been synchronized with that of HWA, resulting in significant predator mortality. Four factors (genetics, temperature, photoperiod, and moisture) were investigated for their effects on aestivation in L. nigrinus. Both the number of individuals and the time at which they emerged from aestivation were measured in response to these factors. Temperature was the most important cue for termination of aestivation, and photoperiod was a modifying factor. High temperature and long day length delayed emergence and high moisture levels resulted in greater emergence but did not affect emergence time. Genetics, as represented by broods, was not a major factor in aestivation termination. These results have led to improvement in rearing L. nigrinus, since emergence from aestivation can now be synchronized with the active period of HWA. Increased success in rearing has expedited field releases of L. nigrinus in the eastern United States.

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Impact of the introduced predator, Laricobius nigrinus, on ovisacs of the overwintering generation of hemlock woolly adelgid in the eastern United States

Biological Control ◽

10.1016/j.biocontrol.2019.104180 ◽

2020 ◽

Vol 143 ◽

pp. 104180 ◽

Cited By ~ 2

Author(s):

Carrie S. Jubb ◽

Ariel R. Heminger ◽

Albert E. Mayfield ◽

Joseph S. Elkinton ◽

Gregory J. Wiggins ◽

...

Keyword(s):

United States ◽

Hemlock Woolly Adelgid ◽

Eastern United States ◽

Laricobius Nigrinus ◽

Introduced Predator

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Seasonal abundance and synchrony between Laricobius nigrinus (Coleoptera: Derodontidae) and its prey, the hemlock woolly adelgid (Hemiptera: Adelgidae)

The Canadian Entomologist ◽

10.4039/n02-059 ◽

2003 ◽

Vol 135 (1) ◽

pp. 103-115 ◽

Cited By ~ 40

Author(s):

G.M.G. Zilahi-Balogh ◽

L.M. Humble ◽

A.B. Lamb ◽

S.M. Salom ◽

L.T. Kok

Keyword(s):

North America ◽

Pacific Northwest ◽

Biological Control Agent ◽

Seed Orchard ◽

Hemlock Woolly Adelgid ◽

Control Agent ◽

Adelges Tsugae ◽

Seasonal Abundance ◽

Eastern United States ◽

Laricobius Nigrinus

AbstractLaricobius nigrinus Fender, native to the Pacific Northwest, is being evaluated as a potential biological control agent of the hemlock woolly adelgid, Adelges tsugae Annand, in the eastern United States. Members of the genus Laricobius feed exclusively on adelgids. Adelges tsugae is found on hemlocks (Tsuga sp.) in North America and Asia, but is considered only a pest of eastern [Tsuga canadensis (L.) Carrière] and Carolina (Tsuga caroliniana Engelmann) hemlocks in eastern North America. This is the first detailed study of the life history of L. nigrinus and its interaction with A. tsugae. Results of a 2-year field study conducted in a seed orchard in British Columbia on the seasonal abundance of L. nigrinus and its prey, A. tsugae, revealed that (i) the sistens generation of A. tsugae matures 2-3 months earlier than previously reported in Virginia and Connecticut, (ii) no A. tsugae sexuparae were observed, which differs from findings in Virginia and Connecticut, (iii) L. nigrinus adults undergo an aestival diapause that coincides with diapausing first instar A. tsugae sistens, and (iv) oviposition and subsequent larval development of L. nigrinus coincides with oviposition by the A. tsugae sistens adults, indicating good synchrony between L. nigrinus and suitable prey stages of A. tsugae.

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Potential of Tsuga spp. from Western North America and Asia as Replacements for Eastern Hemlock ( Tsuga canadensis )

Arboriculture & Urban Forestry ◽

10.48044/jauf.2009.002 ◽

2009 ◽

Vol 35 (1) ◽

pp. 5-9

Author(s):

Paul Weston ◽

Richard Harper

Keyword(s):

United States ◽

New York ◽

New York State ◽

Tsuga Canadensis ◽

Hemlock Woolly Adelgid ◽

Adelges Tsugae ◽

Eastern United States ◽

Growth And Survival ◽

Managed Landscapes ◽

Species Being

Hemlock woolly adelgid (Adelges tsugae) has had a devastating impact on Tsuga canadensis and T. caroliniana in forests and managed landscapes in the eastern United States. Species of Tsuga from the western United States and Asia are reported to be tolerant or resistant to A. tsugae. We established plots containing T. canadensis, T. caroliniana, T. chinensis, T. diversifolia, T. heterophylla, T. mertensiana, and T. sieboldii in Katonah, New York, U.S., an area with high populations of A. tsugae, and monitored tree growth and infestation by adelgids over a 4-year period. Growth and survival of the hemlock species varied widely, the most vigorous species being T. canadensis and T. chinensis. Susceptibility to the adelgid also varied widely among species; some species (particularly T. canadensis) became readily infested, whereas others (e.g., T. chinensis) were apparently entirely resistant. Given the ability of T. chinensis to thrive in the climate of southeastern New York State and its apparent resistance to hemlock woolly adelgid, this species might be an appropriate replacement species, especially in managed landscapes.

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Predicting the impact of hemlock woolly adelgid on carbon dynamics of eastern United States forests

Canadian Journal of Forest Research ◽

10.1139/x09-167 ◽

2010 ◽

Vol 40 (1) ◽

pp. 119-133 ◽

Cited By ~ 58

Author(s):

Marco Albani ◽

Paul R. Moorcroft ◽

Aaron M. Ellison ◽

David A. Orwig ◽

David R. Foster

Keyword(s):

United States ◽

Insect Pest ◽

Hemlock Woolly Adelgid ◽

Adelges Tsugae ◽

Eastern Hemlock ◽

Forest Composition ◽

Eastern United States ◽

Regional Patterns ◽

Spread Model ◽

The Impact

The hemlock woolly adelgid (HWA; Adelges tsugae Annand) is an introduced insect pest that threatens to decimate eastern hemlock ( Tsuga canadensis (L.) Carriere) populations. In this study, we used the ecosystem demography model in conjunction with a stochastic model of HWA spread to predict the impact of HWA infestation on the current and future forest composition, structure, and carbon (C) dynamics in the eastern United States. The spread model predicted that on average the hemlock stands south and east of the Great Lakes would be infested by 2015, southern Michigan would be reached by 2020, and northeastern Minnesota by 2030. For the period 2000–2040, the ecosystem demography model predicted a mean reduction of 0.011 Pg C·year–1 (Pg C = 1015 g C), an 8% decrease, in the uptake of carbon from eastern United States forests as a result of HWA-caused mortality, followed by an increased uptake of 0.015 Pg C·year–1 (a 12% increase) in the period 2040–2100, as the area recovers from the loss of hemlock. Overall, we conclude that while locally severe, HWA infestation is unlikely to have a significant impact on the regional patterns of carbon fluxes, given that eastern hemlock represents a limited fraction of the standing biomass of eastern forests and that it has relatively low productivity compared with the tree species that are likely to replace it.

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Factors affecting Velcro-covered balls when used as a sampling device for wool of Adelges tsugae (Hemiptera: Adelgidae)

The Canadian Entomologist ◽

10.4039/tce.2018.50 ◽

2018 ◽

Vol 151 (1) ◽

pp. 101-114 ◽

Cited By ~ 1

Author(s):

Jeffrey G. Fidgen ◽

Ronald E. Fournier ◽

Mark C. Whitmore ◽

Chris J.K. MacQuarrie ◽

Jean J. Turgeon

Keyword(s):

United States ◽

Nova Scotia ◽

Surface Area ◽

United States Of America ◽

Forest Floor ◽

Adelges Tsugae ◽

Eastern United States ◽

Sampling Device ◽

Factors Affecting ◽

Routine Sampling

AbstractAdelges tsugae Annand (Hemiptera: Adelgidae) has caused extensive mortality of hemlocks (Tsuga (Endlicher) Carrière; Pinaceae) in the eastern United States of America and was discovered recently in Nova Scotia, Canada. We evaluated the use of a Velcro-covered racquetball as a sampling device for A. tsugae wool. Specifically, we report on improvements to an earlier design and evaluate several factors seen in routine sampling that influence the ability of the ball to trap and retain adelgid wool. Velcro was found to be critical for trapping and retaining adelgid wool on the ball during flight and landing. Wooden beads, inserted in the ball, reduced deflection during flight and bounce during landing. Higher probability of trapping wool on the ball was associated with an ascent through the crown, with increasing diameter and density of ovisacs on branch tips, and with increasing abundance of woolly twigs on the forest floor. Higher probability of retaining wool on the ball was associated with Velcro surface area and with amount and location of wool loaded on the ball. These modifications improved detection surveys for A. tsugae in general.

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First Report on Establishment of Laricobius osakensis (Coleoptera: Derodontidae), a Biological Control Agent for Hemlock Woolly Adelgid, Adelges tsugae (Hemiptera: Adelgidae), in the Eastern U.S.

Forests ◽

10.3390/f9080496 ◽

2018 ◽

Vol 9 (8) ◽

pp. 496 ◽

Cited By ~ 7

Author(s):

Ashley Toland ◽

Carlyle Brewster ◽

Katlin Mooneyham ◽

Scott Salom

Keyword(s):

United States ◽

Biological Control ◽

Biological Control Agent ◽

Polar Vortex ◽

Hemlock Woolly Adelgid ◽

Control Agent ◽

Adelges Tsugae ◽

Eastern United States ◽

Cold Temperatures ◽

Eastern Usa

The hemlock woolly adelgid (HWA) is an invasive insect species native to Japan causing significant hemlock mortality in the eastern United States. Laricobius spp. have been targeted as biological control agents because they are adelgid specialists. Laricobius osakensis Montgomery and Shiyake is native to the same region of Japan from which the strain of HWA found in the eastern United States originated. Studies in Japan found that it is phenologically synchronous with HWA. Following approval to release L. osakensis from quarantine in 2010, approximately 32,000 were released at a total of 61 sites starting in 2012. In winter of 2014 and 2015, periods of extreme cold temperatures throughout the eastern USA, as well as the polar vortex, resulted in extensive mortality to HWA, which likely delayed the establishment of L. osakensis. The ability of the beetle to survive and establish in the eastern United States is reported here. In the first year of this study (2015–2016), limited numbers of L. osakensis were recovered, as HWA populations were still rebounding. In the second year (2016–2017), 147 L. osakensis were collected at 5 of 9 sites sampled, coinciding with rebounding HWA populations. Larval recovery was much greater than adult recovery throughout the study. HWA density was directly correlated with warmer plant hardiness zones and recovery of Laricobius beetles was significantly correlated with HWA density. Our results suggest that L. osakensis is successfully establishing at several of the sampled release sites and that the best predictor of its presence at a site is the HWA density.

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