Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
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| two invasive herbivores on a shared host: patterns and consequences of phytohormone induction. | herbivore-induced changes in host quality mediate indirect interactions between herbivores. the nature of these indirect interactions can vary depending on the identity of herbivores involved, species-specific induction of defense-signaling pathways, and sequence of attack. however, our understanding of the role of these signaling pathways in the success of multiple exotic herbivores is less known. eastern hemlock (tsuga canadensis) is attacked by two invasive herbivores [elongate hemlock scale ... | 2018 | 29362885 |
| environmental adaptation in an asexual invasive insect. | parthenogenetic reproduction is generally associated with low genetic variance and therefore reduced ability for environmental adaptation, and this could limit the potential invasiveness of introduced species that reproduce asexually. however, the hemlock woolly adelgid is an asexual invasive insect that has spread across a large geographic temperature gradient in its introduced range. consequently, this insect has shown significant variation in cold hardiness among populations. we hypothesized ... | 2017 | 28770052 |
| seasonal variation in effects of herbivory on foliar nitrogen of a threatened conifer. | invasive herbivores can dramatically impact the nitrogen (n) economy of native hosts. in deciduous species, most n is stored in stem tissues, while in evergreen conifer species n is stored in needles, making them potentially more vulnerable to herbivory. in eastern forests of the usa, the long-lived, foundational conifer eastern hemlock (tsuga canadensis) is under the threat of extirpation by the invasive hemlock woolly adelgid (hwa: adelges tsugae). we assessed the impact of hwa infestation on ... | 2017 | 28439394 |
| a little bug with a big bite: impact of hemlock woolly adelgid infestations on forest ecosystems in the eastern usa and potential control strategies. | 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 ev ... | 2017 | 28422072 |
| feeding by leucopis argenticollis and leucopis piniperda (diptera: chamaemyiidae) from the western usa on adelges tsugae (hemiptera: adelgidae) in the eastern usa. | leucopis argenticollis (zetterstedt) and leucopis piniperda (malloch) are known to feed on the lineage of adelges tsugae annand that is native to western north america, but it is not known if they will survive on the lineage that was introduced from japan to the eastern usa. in 2014, western leucopis spp. larvae were brought to the laboratory and placed on a. tsugae collected in either washington (north american a. tsugae lineage) or connecticut (japanese lineage). there were no significant diff ... | 2017 | 28290255 |
| induction of cold hardiness in an invasive herbivore: the case of hemlock woolly adelgid (hemiptera: adelgidae). | 2017 | 28177069 | |
| spatial and temporal distribution of imidacloprid within the crown of eastern hemlock. | systemic imidacloprid is the most widely used insecticide to control the hemlock woolly adelgid, adelges tsugae annand (hemiptera: adelgidae), an exotic pest of eastern hemlock, tsuga canadensis (l.) carriére in the united states. this study was conducted to 1) determine the effect of treatment timing (spring vs. fall) and application method (trunk injection vs. soil injection) on the spatial and temporal distribution of imidacloprid within the crown of a. tsugae-free eastern hemlock using a com ... | 2017 | 28130463 |
| ecological factors influencing the beneficial endosymbionts of the hemlock woolly adelgid (hemiptera: adelgidae). | bacterial endosymbionts of sap-sucking insects provide their host with a number of beneficial qualities, including the supply of nutrition, defense against parasitoids, and protection from heat stress. damage to these bacterial associates can therefore have a negative impact on the fitness of their insect host. we evaluated observational and experimental factors regarding the non-native hemlock woolly adelgid (adelges tsugae annand) (hemiptera: adelgidae) to help understand the roles of its thre ... | 2017 | 28791805 |
| risk assessment of imidacloprid use in forest settings on the aquatic macroinvertebrate community. | the isolated effects of a single insecticide can be difficult to assess in natural settings because of the presence of numerous pollutants in many watersheds. imidacloprid use for suppressing hemlock woolly adelgid, adelges tsugae (annand) (hemiptera: adelgidae), in forests offers a rare opportunity to assess potential impacts on aquatic macroinvertebrates in relatively pristine landscapes. aquatic macroinvertebrate communities were assessed in 9 streams in great smoky mountains national park (s ... | 2017 | 28608930 |
| numerical response and impact of laricobius nigrinus (coleoptera: derodontidae) on adelges tsugae (hemiptera: adelgidae) in their native range. | to determine if key attributes for a successful biological control agent are possessed by the predator, laricobius nigrinus fender, field studies were conducted in its native range of seattle, wa. the relationship between adult and immature l. nigrinus abundance to different densities of its prey, adelges tsugae annand, were determined. in a second study, predator and prey densities, and survivorship of each sistens a. tsugae stage were determined to gauge the impact of predation. the predator s ... | 2017 | 28444212 |
| imidacloprid movement in soils and impacts on soil microarthropods in southern appalachian eastern hemlock stands. | imidacloprid is a systemic insecticide effective in controlling the exotic pest (hemlock woolly adelgid) in eastern hemlock () trees. concerns over imidacloprid impacts on nontarget species have limited its application in southern appalachian ecosystems. we quantified the movement and adsorption of imidacloprid in forest soils after soil injection in two sites at coweeta hydrologic laboratory in western north carolina. soils differed in profile depth, total carbon and nitrogen content, and effec ... | 2017 | 22370410 |
| hemlock woolly adelgid (hemiptera: adelgidae) abundance and hemlock canopy health numerous years after imidacloprid basal drench treatments: implications for management programs. | hemlock woolly adelgid (adelges tsugae [annand]), an invasive insect in the eastern united states, has caused widespread decline of eastern hemlock, tsuga canadensis (l.) carriére. imidacloprid basal drench treatments were assessed 4-7 yr after a single treatment to determine hemlock woolly adelgid population suppression and effects on hemlock canopy health. the effects of sampling site, years post-treatment, and hemlock diameter at breast height (dbh) size classes were evaluated relative to imi ... | 2016 | 27435928 |
| fitness and physiology of adelges tsugae (hemiptera: adelgidae) in relation to the health of the eastern hemlock. | the hemlock woolly adelgid, adelges tsugae annand is an invasive insect that frequently causes hemlock (tsuga spp.) mortality in the eastern united states. studies have shown that once healthy hemlocks become infested by the adelgid, nutrients are depleted from the tree, leading to both tree decline and a reduction of the adelgid population. since a. tsugae is dependent on hemlock for nutrients, feeding on trees in poor health may affect the ability of the insect to obtain necessary nutrients an ... | 2016 | 26013546 |
| ancient and modern colonization of north america by hemlock woolly adelgid, adelges tsugae (hemiptera: adelgidae), an invasive insect from east asia. | hemlock woolly adelgid, adelges tsugae, is an invasive pest of hemlock trees (tsuga) in eastern north america. we used 14 microsatellites and mitochondrial coi sequences to assess its worldwide genetic structure and reconstruct its colonization history. the resulting information about its life cycle, biogeography and host specialization could help predict invasion by insect herbivores. we identified eight endemic lineages of hemlock adelgids in central china, western china, ulleung island (south ... | 2016 | 26880353 |
| field-cage evaluation of survival, reproduction, and feeding behavior of adult scymnus coniferarum (coleoptera: coccinellidae), a predator of adelges tsugae (hemiptera: adelgidae). | the hemlock woolly adelgid, adelges tsugae annand, is an invasive pest of eastern (tsuga canadensis (l.) carrière) and carolina hemlock (tsuga caroliniana engelmann) forests in the eastern united states. scymnus (pullus) coniferarum crotch (coleoptera: coccinellidae) is a lady beetle that preys on a. tsugae in the western united states, where a. tsugae infestations on western hemlocks are not lethal. it is thought that s. coniferarum could be an important predator that helps keep a. tsugae popul ... | 2016 | 28028101 |
| emergence, seasonality, and hybridization of laricobius nigrinus (coleoptera: derodontidae), an introduced predator of hemlock woolly adelgid (hemiptera: adelgidae), in the tennessee appalachians. | from 2010 through 2013, adult emergence and seasonality of laricobius nigrinus fender, an introduced predatory species native to western north america, as well as hybridization with the native species laricobius rubidus (leconte), were evaluated using emergence traps and beat-sheet sampling in areas of previous release against hemlock woolly adelgid, adelges tsugae annand. the shortest emergence period of adult l. nigrinus was 7 wk beginning 22 october 2010, and the longest emergence was 15 wk b ... | 2016 | 28028083 |
| experimental evidence for branch-to-bird transfer as a mechanism for avian dispersal of the hemlock woolly adelgid (hemiptera: adelgidae). | birds have long been hypothesized as primary dispersal agents of the hemlock woolly adelgid (adelges tsugae annand). although a. tsugae eggs and mobile first instars (crawlers) have been collected from wild birds, key mechanistic elements necessary for avian dispersal have never been examined. to evaluate the mechanisms of bird-mediated a. tsugae dispersal, we conducted both stationary (i.e., where crawlers must actively disperse) and disturbance (i.e., where crawlers may transfer from substrate ... | 2016 | 27481889 |
| seasonal phenology and abundance of leucopis argenticollis, leucopis piniperda (diptera: chamaemyiidae), laricobius nigrinus (coleoptera: deridontidae) and adelges tsugae (hemiptera: adelgidae) in the pacific northwest usa. | adelges tsugae infested western hemlock trees were sampled periodically for 1 year at two locations in oregon and washington to compare the phenology and abundance of three associated predators (leucopis argenticollis, leucopis piniperda, and laricobius nigrinus) and their host. on each sample date, two 3-10 cm long terminal twigs were collected from each tree and brought to the laboratory to count all life stages of a. tsugae and the three predators. peak larval abundance of leucopis spp. and l ... | 2016 | 27087639 |
| host range specificity of scymnus camptodromus (coleoptera: coccinellidae), a predator of hemlock woolly adelgid (hemiptera: adelgidae). | scymnus (neopullus) camptodromus yu and liu (coleoptera: coccinellidae) was brought to the united states from china as a potential biological control agent for hemlock woolly adelgid (adelges tsugae annand) (hemiptera: adelgidae). scymnus camptodromus phenology is closely synchronized with that of a. tsugae and has several characteristics of a promising biological control agent. as a prerequisite to field release, s. camptodromus was evaluated for potential nontarget impacts. in host range studi ... | 2016 | 26612409 |
| density-dependent recruitment and diapause in the spring-feeding generation of hemlock woolly adelgid (hemiptera: adelgidae) in western north america. | insect populations are affected by density-dependent and density-independent factors, and knowing how these factors affect long-term population growth is critical to pest management. in this study, we experimentally manipulated densities of the hemlock woolly adelgid on eastern and western hemlock trees in the western usa to evaluate the effects of density and host species on hemlock woolly adelgid crawler colonization. we then followed development of hemlock woolly adelgid on each hemlock speci ... | 2016 | 28028081 |
| impact of an invasive insect and plant defense on a native forest defoliator. | eastern hemlock (tsuga canadensis [l.] carriére) in the united states is threatened by the invasive hemlock woolly adelgid (adelges tsugae annand). the native hemlock looper (lambdina fiscellaria guenée) also appears to have played a role in previous population declines of this conifer. although these two insects co-occur in much of the adelgid's invaded range, their interactions remain unstudied. we assessed looper performance and preference on both uninfested and adelgid-infested foliage from ... | 2016 | 27649247 |
| assessment of imidacloprid and its metabolites in foliage of eastern hemlock multiple years following treatment for hemlock woolly adelgid, adelges tsugae (hemiptera: adelgidae), in forested conditions. | widespread decline and mortality of eastern hemlock, tsuga canadensis (l.) carrière, have been caused by hemlock woolly adelgid, adelges tsugae (annand) (hwa) (hemiptera: adelgidae). the current study is a retrospective analysis conducted in collaboration with great smoky mountains national park (grsm) to determine longevity of imidacloprid and its insecticidal metabolites (imidacloprid olefin, 5-hydroxy, and dihydroxy) in grsm's hwa integrated pest management (ipm) program. foliage samples were ... | 2015 | 26470386 |
| a 10-year assessment of hemlock decline in the catskill mountain region of new york state using hyperspectral remote sensing techniques. | the hemlock woolly adelgid is a serious pest of eastern and carolina hemlock in the eastern united states. successfully managing the hemlock resource in the region depends on careful monitoring of the spread of this invasive pest and the targeted application of management options such as biological control, chemical, or silvicultural treatments. to inform these management activities and test the applicability of a landscape-scale remote sensing effort to monitor hemlock condition, hyperspectral ... | 2015 | 26470138 |
| invasive insect effects on nitrogen cycling and host physiology are not tightly linked. | invasive insects may dramatically alter resource cycling and productivity in forest ecosystems. yet, although responses of individual trees should both reflect and affect ecosystem-scale responses, relationships between physiological- and ecosystem-scale responses to invasive insects have not been extensively studied. to address this issue, we examined changes in soil nitrogen (n) cycling, n uptake and allocation, and needle biochemistry and physiology in eastern hemlock (tsuga canadensis (l) ca ... | 2015 | 25721368 |
| mortality rates associated with crown health for eastern forest tree species. | the condition of tree crowns is an important indicator of tree and forest health. crown conditions have been evaluated during inventories of the us forest service forest inventory and analysis (fia) program since 1999. in this study, remeasured data from 55,013 trees on 2616 fia plots in the eastern usa were used to assess the probability of survival among various tree species using the suite of fia crown condition variables. logistic regression procedures were employed to develop models for pre ... | 2015 | 25655130 |
| behavioral responses of laricobius spp. and hybrids (coleoptera: derodontidae) to hemlock woolly adelgid and adelgid host tree odors in an olfactometer. | the predatory species laricobius nigrinus (fender) and laricobius osakensis (shiyake and montgomery) (coleoptera: derodontidae) have been released for biological control of hemlock woolly adelgid (adelges tsugae; hemiptera: adelgidae) in eastern north america. l. osakensis is native to japan, whereas l. nigrinus is endemic to the pacific northwest of the united states and canada. after release, l. nigrinus was found to hybridize with the native eastern species, laricobius rubidus (leconte). the ... | 2015 | 26314036 |
| survival and near extinction of hemlock woolly adelgid (hemiptera: adelgidae) during summer aestivation in a hemlock plantation. | varying densities of the spring generation of the hemlock woolly adelgid were manipulated on 16 previously uninfested eastern hemlocks in an open-field plantation in massachusetts. in contrast to experimentally created hemlock woolly adelgid populations in a forest, as reported previously, there was no evidence of density-dependent survival on a tree-wide basis in the plantation in the spring (progrediens) generation. there was, however, comparable density-dependent survival of settled crawlers ... | 2015 | 26308818 |
| effects of light and water availability on the performance of hemlock woolly adelgid (hemiptera: adelgidae). | eastern hemlock (tsuga canadensis (l.) carriere) is a dominant shade-tolerant tree in northeastern united states that has been declining since the arrival of the hemlock woolly adelgid (adelges tsugae annand). determining where a. tsugae settles under different abiotic conditions is important in understanding the insect's expansion. resource availability such as light and water can affect herbivore selectivity and damage. we examined how a. tsugae settlement and survival were affected by differe ... | 2015 | 26308815 |
| scymnus camptodromus (coleoptera: coccinellidae) larval development and predation of hemlock woolly adelgid (hemiptera: adelgidae). | development time and prey consumption of scymnus (neopullus) camptodromus yu and liu (coleoptera: coccinellidae) larvae by instar, strain, and temperature were evaluated. s. camptodromus, a specialist predator of hemlock woolly adelgid adelges tsugae (annand) (hemiptera: adelgidae), was brought to the united states from china as a potential biological control agent for a. tsugae. this beetle has been approved for removal from quarantine but has not yet been field released. we observed that tempe ... | 2015 | 26308809 |
| canopy vegetation influences ant (hymenoptera: formicidae) communities in headwater stream riparian zones of central appalachia. | in the eastern united states, eastern hemlock tusga canadensis (l.) carriere forests are threatened by the invasive hemlock woolly adelgid, adelges tsugae, a pest that is causing widespread hemlock mortality. eastern hemlock is an essential component of forested communities. adelgid-induced hemlock mortality is causing a shift in forest composition and structure, altering ecosystem function and thereby influencing the arthropod community. using pitfall traps at three sites, we monitored ground-d ... | 2014 | 25528753 |
| terpene chemistry of eastern hemlocks resistant to hemlock woolly adelgid. | recent studies have identified a small number of individual eastern hemlock trees that demonstrate relative resistance to the introduced sap-feeding insect, the hemlock woolly adelgid. using gas chromatography, we compared concentrations of twenty-two terpenoids in susceptible and relatively resistant trees, both in the forest and in propagated cuttings in a common-garden setting. terpenoid concentrations were higher in twig tissue of resistant versus susceptible trees, across six sampling dates ... | 2014 | 25278447 |
| hemlock woolly adelgid (hemiptera: adelgidae) induces twig volatiles of eastern hemlock in a forest setting. | the hemlock woolly adelgid (adelges tsugae annand) is an invasive species causing high mortality of eastern hemlock (tsuga canadensis (l) carriere) in the forests of eastern north america. recent findings revealed that sapling eastern hemlocks artificially infested with hemlock woolly adelgid in a plantation setting responded to the insect with an array of induced resin volatile changes. here we determine if eastern hemlocks growing beneath a forest canopy respond to hemlock woolly adelgid infes ... | 2014 | 25259691 |
| biomechanical properties of hemlocks: a novel approach to evaluating physical barriers of the plant-insect interface and resistance to a phloem-feeding herbivore. | micromechanical properties that help mediate herbivore access may be particularly important when considering herbivorous insects that feed with piercing-sucking stylets. we used microindentation to quantify the micromechanical properties of hemlock, tsuga spp., to quantify the hardness of the feeding site of the invasive hemlock woolly adelgid, adelges tsugae. we measured hardness of the hemlock leaf cushion, the stylet insertion point of the adelgid, across four seasons in a 1 y period for four ... | 2014 | 26462689 |
| failure under stress: the effect of the exotic herbivore adelges tsugae on biomechanics of tsuga canadensis. | exotic herbivores that lack a coevolutionary history with their host plants can benefit from poorly adapted host defences, potentially leading to rapid population growth of the herbivore and severe damage to its plant hosts. the hemlock woolly adelgid (adelges tsugae) is an exotic hemipteran that feeds on the long-lived conifer eastern hemlock (tsuga canadensis), causing rapid mortality of infested trees. while the mechanism of this mortality is unknown, evidence indicates that a. tsugae feeding ... | 2014 | 24335663 |
| characterization of physical and chemical defenses in the hemlock woolly adelgid. | 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-oxohex ... | 2014 | 24913905 |
| impacts of trunk and soil injections of low rates of imidacloprid on hemlock woolly adelgid (hemiptera: adelgidae) and eastern hemlock (pinales: pinaceae) health. | eastern hemlocks (tsuga canadensis carrière) at two sites in southwestern virginia were treated by trunk and soil injections of imidacloprid to determine the insecticide's impact on hemlock woolly adelgid, adelges tsugae annand. treatments were 25, 50, and 100% of the highest labeled dosage rates for both stem and soil injection. three and 4 yr after treatment, the half and full rates had significantly reduced a. tsugae populations, which were accompanied by increased new hemlock shoot growth an ... | 2014 | 24665708 |
| density-dependent survival and fecundity of hemlock woolly adelgid (hemiptera: adelgidae). | the hemlock woolly adelgid (adelges tsugae annand) has decimated eastern hemlocks (tsuga canadensis carrière) in forests throughout the eastern united sates, but its densities in central new england appear to have stabilized. to find out why, we infested 64 eastern hemlocks with varying densities of adelgid ovisacs in a typical eastern hemlock forest in western massachusetts. we subsequently documented adelgid density, fecundity, and the amount of new growth on experimental trees over two consec ... | 2014 | 25203223 |
| development of a rain down technique to artificially infest hemlocks with the hemlock woolly adelgid, adelges tsugae. | the hemlock woolly adelgid adelges tsugae annand (hemiptera: adelgidae), is a non-native invasive pest that has caused widespread decline and mortality of eastern hemlock (tsuga canadensis (l.) carr. (pinales: pinaceae)) and carolina hemlock (t. caroliniana engelm.) in the eastern united states. our preliminary experiments evaluated the utility of a rain-down technique to induce artificial infestations of a. tsugae on hemlock seedlings en masse. experiments were conducted in pvc (1 m3) cages top ... | 2014 | 25199530 |
| the pine bark adelgid, pineus strobi, contains two novel bacteriocyte-associated gammaproteobacterial symbionts. | bacterial endosymbionts of the pine bark adelgid, pineus strobi (insecta: hemiptera: adelgidae), were investigated using transmission electron microscopy, 16s and 23s rrna-based phylogeny, and fluorescence in situ hybridization. two morphologically different symbionts affiliated with the gammaproteobacteria were present in distinct bacteriocytes. one of them ("candidatus annandia pinicola") is most closely related to an endosymbiont of adelges tsugae, suggesting that they originate from a lineag ... | 2014 | 24271164 |
| future species composition will affect forest water use after loss of eastern hemlock from southern appalachian forests. | infestation of eastern hemlock (tsuga canadensis (l.) carr.) with hemlock woolly adelgid (hwa, adelges tsugae) has caused widespread mortality of this key canopy species throughout much of the southern appalachian mountains in the past decade. because eastern hemlock is heavily concentrated in riparian habitats, maintains a dense canopy, and has an evergreen leaf habit, its loss is expected to have a major impact on forest processes, including transpiration (e(t)). our goal was to estimate chang ... | 2013 | 23865229 |
| effects of introduced insects and diseases on forest ecosystems in the catskill mountains of new york. | repeated invasions of non-native insects and pathogens have altered the structure and function of forest ecosystems in the catskill mountains of new york state, and will continue to do so in the future. gypsy moth, beech bark disease, and hemlock woolly adelgid are among the insects and diseases currently established in the catskills that are having significant effects on forests. many others, including emerald ash borer, asian long-horned beetle, phytophthora ramorum, and sirex wood wasp, are e ... | 2013 | 23844706 |
| diversity of proteobacterial endosymbionts in hemlock woolly adelgid (adelges tsugae) (hemiptera: adelgidae) from its native and introduced range. | knowledge of intraspecific variation in symbioses may aid in understanding the ecology of widespread insects in different parts of their range. we investigated bacterial symbionts of adelges tsugae, a pest of hemlocks in eastern north america introduced from asia. amplification, cloning, and sequencing of bacterial 16s rdna, in situ hybridizations, and electron microscopy revealed that a. tsugae harbours up to five bacterial phylotypes, according to population. three gammaproteobacteria species ... | 2013 | 23452267 |
| entomopathogenic fungi associated with exotic invasive insect pests in northeastern forests of the usa. | mycopathogens of economically important exotic invasive insects in forests of northeastern usa have been the subject of research at the entomology research laboratory, university of vermont, for the last 20 years. elongate hemlock scale, european fruit lecanium, hemlock woolly adelgid and pear thrips were analyzed for the presence of mycopathogens, in order to consider the potential for managing these pests with biological control. fungal cultures isolated from insects with signs of fungal infec ... | 2013 | 26462527 |
| spatial and temporal distribution of residues of imidacloprid and its insecticidal 5-hydroxy and olefin and metabolites in eastern hemlock (pinales: pinaceae) in the southern appalachians. | widespread mortality of eastern hemlock, tsuga canadensis (l.) carrière, resulting from infestation by hemlock woolly adelgid, adelges tsugae annand (hemiptera: adelgidae), has occurred throughout the native range of eastern hemlock within the eastern united states. imidacloprid, a systemic insecticide, is one of the primary chemical compounds used to control hemlock woolly adelgid in both urban and, in a limited manner, in natural forest environments. the metabolism of imidacloprid in eastern h ... | 2013 | 24498740 |
| factors affecting establishment and recovery of sasajiscymnus tsugae (coleoptera: coccinellidae), an introduced predator of hemlock woolly adelgid (hemiptera: adelgidae) on eastern hemlock (pinales: pinaceae). | to reduce populations of hemlock woolly adelgid, adelges tsugae annand (hemiptera: adelgidae), >500,000 sasajiscymnus tsugae (sasaji and mcclure) (coleoptera: coccinellidae) have been released in the great smoky mountains national park since 2002. to determine factors affecting establishment and recovery of these predatory beetles, 65 single release sites were sampled using beat sheets from 2008 to 2012. several abiotic and biotic factors were evaluated for their association with establishment a ... | 2013 | 24468557 |
| foundation species loss affects vegetation structure more than ecosystem function in a northeastern usa forest. | loss of foundation tree species rapidly alters ecological processes in forested ecosystems. tsuga canadensis, an hypothesized foundation species of eastern north american forests, is declining throughout much of its range due to infestation by the nonnative insect adelges tsugae and by removal through pre-emptive salvage logging. in replicate 0.81-ha plots, t. canadensis was cut and removed, or killed in place by girdling to simulate adelgid damage. control plots included undisturbed hemlock and ... | 2013 | 23638378 |
| hemlock woolly adelgid and elongate hemlock scale induce changes in foliar and twig volatiles of eastern hemlock. | eastern hemlock (tsuga canadensis) is in rapid decline because of infestation by the invasive hemlock woolly adelgid (adelges tsugae; 'hwa') and, to a lesser extent, the invasive elongate hemlock scale (fiorinia externa; 'ehs'). for many conifers, induced oleoresin-based defenses play a central role in their response to herbivorous insects; however, it is unknown whether eastern hemlock mobilizes these inducible defenses. we conducted a study to determine if feeding by hwa or ehs induced changes ... | 2013 | 23900803 |
| hemlock woolly adelgid (adelges tsugae) infestation affects water and carbon relations of eastern hemlock (tsuga canadensis) and carolina hemlock (tsuga caroliniana). | hemlock woolly adelgid (hwa) is an exotic insect pest causing severe decimation of native hemlock trees. extensive research has been conducted on the ecological impacts of hwa, but the exact physiological mechanisms that cause mortality are not known. water relations, anatomy and gas exchange measurements were assessed on healthy and infested eastern (tsuga canadensis) and carolina (tsuga caroliniana) hemlock trees. these data were then used in a mechanistic model to test whether the physiologic ... | 2013 | 23560452 |
| ecosystem function in appalachian headwater streams during an active invasion by the hemlock woolly adelgid. | forested ecosystems in the southeastern united states are currently undergoing an invasion by the hemlock woolly adelgid (hwa). previous studies in this area have shown changes to forest structure, decreases in canopy cover, increases in organic matter, and changes to nutrient cycling on the forest floor and soil. here, we were interested in how the effects of canopy loss and nutrient leakage from terrestrial areas would translate into functional changes in streams draining affected watersheds. ... | 2013 | 23613803 |
| effects of temperature and photoperiod on the aestivo-hibernal egg diapause of scymnus camptodromus (coleoptera: coccinellidae). | three sequential studies were conducted on the interacting effects of exposure to low (5°c) temperature for 0, 7, 28, 56, or 84 d followed by incubation at 10, 15, or 20°c on the egg diapause of scymnus (neopullus) camptodromus yu and liu (coleoptera: coccinellidae). this beetle was imported from china as a potential biological control agent for hemlock woolly adelgid, adelges tsugae (annand) (hemiptera: adelgidae). very few eggs laid and held at a constant 15 or 20°c showed any indication of de ... | 2012 | 23321116 |
| potential feeding deterrents found in hemlock woolly adelgid, adelges tsugae. | the nonnative hemlock woolly adelgid (adelges tsugae annand, hemiptera: sternorrhyncha: adelgidae) has been a significant mortality agent of eastern hemlock (tsuga canadensis carriere) throughout a large portion of its geographic range. during a study investigating adelgid vigor in relation to host health, it was noted that adelgid extracts ranged from a yellow to a deep red color. analysis by gc-ms identified the presence of the anthraquinone, chrysophanol and its anthrone precursor, chrysarobi ... | 2012 | 22722375 |
| modeling range dynamics in heterogeneous landscapes: invasion of the hemlock woolly adelgid in eastern north america. | range expansion by native and exotic species will continue to be a major component of global change. anticipating the potential effects of changes in species distributions requires models capable of forecasting population spread across realistic, heterogeneous landscapes and subject to spatiotemporal variability in habitat suitability. several decades of theory and model development, as well as increased computing power and availability of fine-resolution gis data, now make such models possible. ... | 2012 | 22611848 |
| exotic herbivores on a shared native host: tissue quality after individual, simultaneous, and sequential attack. | plants in nature are often attacked by multiple enemies whose effect on the plant cannot always be predicted based on the outcome of individual attacks. we investigated how two invasive herbivores, the hemlock woolly adelgid (adelges tsugae) (hwa) and the elongate hemlock scale (fiorinia externa) (ehs), alter host plant quality (measured as amino acid concentration and composition) when feeding individually or jointly on eastern hemlock (tsuga canadensis), an important long-lived forest tree tha ... | 2012 | 22311255 |
| false ring formation in eastern hemlock branches: impacts of hemlock woolly adelgid and elongate hemlock scale. | herbivores can alter plant physiology through the induction of abnormal wood formation. feeding by some insects induces the formation of false rings, a band of thick-walled latewood cells within the earlywood portion of the tree ring that reduces water transport. hemlock woolly adelgid (adelges tsugae annand) and elongate hemlock scale (fiorinia externa ferris) are invasive insects that both feed on eastern hemlock [tsuga canadensis (l.) carrière]. adelges tsugae has a greater effect on tree hea ... | 2012 | 22732610 |
| orientation behavior of the predator laricobius nigrinus (coleoptera: derodontidae) to hemlock woolly adelgid and host tree odors in a multi-chambered olfactometer. | we studied the adult ambulatory response of the predator, laricobius nigrinus fender (coleoptera: derodontidae), to odors from its prey, adelges tsugae annand, the hemlock woolly adelgid, and foliage of hemlock woolly adelgid, host hemlocks (tsuga spp.), and other conifers. both the predator and hemlock woolly adelgid are apparently native to western north america, but the predator is being released in the eastern united states, which has different hemlock species, for biological control of a l ... | 2011 | 22251687 |
| prey suitability and phenology of leucopis spp. (diptera: chamaemyiidae) associated with hemlock woolly adelgid (hemiptera: adelgidae) in the pacific northwest. | leucopis spp. (diptera: chamaemyiidae) from the pacific northwest previously were identified as potential biological control agents for the hemlock woolly adelgid, adelges tsugae annand (hemiptera: adelgidae), in the eastern united states. we collected leucopis spp. larvae from a. tsugae infested western hemlocks in oregon and washington and reared them on an unidentified pineus spp., pineus strobi (hartig), adelges cooleyi (gillette), adelges piceae (ratzeburg), and a. tsugae in three no-choice ... | 2011 | 22217756 |
| laboratory studies of feeding and oviposition preference, developmental performance, and survival of the predatory beetle, sasajiscymnus tsugae on diets of the woolly adelgids, adelges tsugae and adelges piceae. | the suitability of the balsam woolly adelgid, adelges piceae ratzeburg (hemiptera: adelgidae) as an alternate mass rearing host for the adelgid predator, sasajiscymnus tsugae sasaji and mcclure (coleoptera: coccinellidae) was studied in the laboratory. this predator is native to japan and has been introduced to eastern hemlock, tsuga canadensis (l.) carrière (pinales: pinaceae), forests throughout the eastern united states for biological control of the hemlock woolly adelgid, adelges tsugae anna ... | 2011 | 21867435 |
| variation in plant defense against invasive herbivores: evidence for a hypersensitive response in eastern hemlocks (tsuga canadensis). | herbivores can trigger a wide array of morphological and chemical changes in their host plants. feeding by some insects induces a defensive hypersensitive response, a defense mechanism consisting of elevated h(2)o(2) levels and tissue death at the site of herbivore feeding. the invasive hemlock woolly adelgid adelges tsugae ('hwa') and elongate hemlock scale fiorinia externa ('ehs') feed on eastern hemlocks; although both are sessile sap feeders, hwa causes more damage than ehs. the rapid rate o ... | 2011 | 21573865 |
| arboreal spiders in eastern hemlock. | eastern hemlock [tsuga canadensis (l.) carrière] is a foundation species in forests of eastern north america that plays a key role in ecosystem function. it is highly susceptible to the exotic invasive hemlock woolly adelgid (adelges tsugae annand), which is causing widespread hemlock mortality. we surveyed the spider communities of eastern hemlock and deciduous canopies over 2 yr, collecting over 4,000 spiders from 21 families. we found that eastern hemlock canopies harbored a more abundant, ri ... | 2011 | 22217752 |
| effects of fertilizer and low rates of imidacloprid on adelges tsugae (hemiptera: adelgidae). | healthy hemlock trees, tsuga canadensis (l.) carrière, and hemlock woolly adelgid, adelges tsugae annand (hemiptera: adelgidae), populations should favor retention and population growth of adelgid predators such as laricobius nigrinus fender (coleoptera: derodontidae) and sasajiscymnus tsugae (sasaji & mcclure) (coleoptera: coccinellidae). eastern hemlock trees between 15 and 38 cm diameter at breast height (dbh) were treated with 0, 10, or 25% of 1.5 g imidacloprid (merit 75 wp) per 2.5 cm dbh ... | 2011 | 21735906 |
| effects of fertilization of four hemlock species on adelges tsugae (hemiptera: adelgidae) growth and feeding preference of predators. | understanding how fertilization affects host resistance to hemlock woolly adelgid, adelges tsugae annand (hemiptera: adelgidae), is important because fertilizers are often used to grow resistant selections to a suitable size for testing. we evaluated four hemlock species (tsuga) under three different fertilizer regimes to assess whether fertility affected resistance to the adelgid and to determine whether it affected feeding preferences of the adelgid predators laricobius nigrinus fender and sas ... | 2011 | 21404870 |
| distribution and abundance of adelges tsugae (hemiptera: adelgidae) within hemlock trees. | we studied the distribution of hemlock woolly adelgid, adelges tsugae annand (hemiptera: adelgidae), within hemlock trees for three summer (progrediens) and two winter (sistens) generations in northern georgia. eastern hemlock, tsuga canadensis (l.) carrière, trees were treated with 0, 10, or 25% of 1.5 g of imidacloprid per 2.5 cm of tree diameter at breast height and fertilized or not in a factorial design. adelgid ovisacs per centimeter of branch were more abundant from june 2007 to june 2008 ... | 2011 | 22299353 |
| visual ability and searching behavior of adult laricobius nigrinus, a hemlock woolly adelgid predator. | very little is known about the searching behavior and sensory cues that laricobius spp. (coleoptera: derodontidae) predators use to locate suitable habitats and prey, which limits our ability to collect and monitor them for classical biological control of adelgids (hemiptera: adelgidae). the aim of this study was to examine the visual ability and the searching behavior of newly emerged l. nigrinus fender, a host-specific predator of the hemlock woolly adelgid, adelges tsugae annand (hemiptera: p ... | 2011 | 22220637 |
| lethal and sublethal effects of imidacloprid on hemlock woolly adelgid (hemiptera: adelgidae) and two introduced predator species. | eastern hemlock, tsuga canadensis (l.) carrière, branchlets were systemically treated with imidacloprid and bioassayed with hemlock woolly adelgid, adelges tsugae (annand) (hemiptera: adelgidae), and predators. after 10 d, two hemlock woolly adelgid predators, laricobius nigrinus fender (coleoptera: derodontidae) and sasajiscymnus tsugae sasaji & mcclure (coleoptera: coccinellidae), were allowed to feed on remaining hemlock woolly adelgid for 20 d on branches systemically treated with 1, 10, or ... | 2010 | 20857731 |
| spatial and temporal distribution of imidacloprid in eastern hemlock in the southern appalachians. | the hemlock woolly adelgid, adelges tsugae annand (hemiptera: adelgidae), is an exotic insect species dramatically reducing populations of eastern hemlock, tsuga canadensis (l.) carrieré, throughout the eastern united states. systemic imidacloprid is one of the primary chemicals used to successfully control infestations of the hemlock woolly adelgid. the concentration levels for this systemic insecticide present in the sap of eastern hemlocks were evaluated from three strata within the canopy ov ... | 2010 | 20429450 |
| maximizing oviposition efficiency when mass rearing the coccinellid, sasajiscymnus tsugae, a predator of the hemlock woolly adelgid, adelges tsugae. | sasajiscymnus tsugae sasaji and mcclure (coleeptera: coccinellidae), is a biological control agent imported for management of hemlock woolly adelgid, adelges tsugae annand. in mass rearing s. tsugae, accurate estimation of egg numbers is important because larvae are cannibalistic, especially at higher densities. to determine the most accurate means of estimating egg production, three brands of gauze were compared as oviposition substrates. curad® gauze provided the most accurate estimate of egg ... | 2010 | 21070172 |
| establishment of the hemlock woolly adelgid predator, laricobius nigrinus (coleoptera: derodontidae), in the eastern united states. | the hemlock woolly adelgid, adelges tsugae annand (hemiptera: adelgidae), native to western north america and asia, was accidentally introduced from japan to the eastern united states. to potentially establish biological control of a. tsugae, we released a predator endemic to western north america, laricobius nigrinus fender (coleoptera: derodontidae), from 2003 to 2005, in 22 localities from georgia to massachusetts. release sites spanned the invasive range of the adelgid across five united sta ... | 2010 | 20388273 |
| web orientation and prey resources for web-building spiders in eastern hemlock. | we examined the arthropod community on eastern hemlock, tsuga canadensis (l.) carr, in the context of its role in providing potential prey items for hemlock-associated web-weaving spiders. using sticky traps simulating spider webs, we evaluated what prey items are available to web-weaving spiders in eastern hemlock based on web orientation (horizontal versus vertical) and cardinal direction. we found that the overwhelming majority (>70%) of prey items available to spiders in hemlock canopies wer ... | 2010 | 22546441 |
| effects of hemlock woolly adelgid and elongate hemlock scale on eastern hemlock growth and foliar chemistry. | in the eastern united states, two invasive specialist insects share a native host plant, eastern hemlock, tsuga canadensis. in recent years, much research has focused on the impacts of the hemlock woolly adelgid (adelges tsugae) because of the detrimental effects it has on hemlock growth and survival. in contrast, the invasive elongate hemlock scale (fiorinia externa) is thought to have only minor impacts on hemlock. we infested hemlock saplings with each insect and compared them with control (i ... | 2010 | 20388282 |
| permanent genetic resources added to molecular ecology resources database 1 august 2009-30 september 2009. | this article documents the addition of 238 microsatellite marker loci and 72 pairs of single nucleotide polymorphism (snp) sequencing primers to the molecular ecology resources database. loci were developed for the following species: adelges tsugae, artemisia tridentata, astroides calycularis, azorella selago, botryllus schlosseri, botrylloides violaceus, cardiocrinum cordatum var. glehnii, campylopterus curvipennis, colocasia esculenta, cynomys ludovicianus, cynomys leucurus, cynomys gunnisoni, ... | 2010 | 21565018 |
| ecological boundary detection using bayesian areal wombling. | the study of ecological boundaries and their dynamics is of fundamental importance to much of ecology, biogeography, and evolution. over the past two decades, boundary analysis (of which wombling is a subfield) has received considerable research attention, resulting in multiple approaches for the quantification of ecological boundaries. nonetheless, few methods have been developed that can simultaneously (1) analyze spatially homogenized data sets (i.e., areal data in the form of polygons rather ... | 2010 | 21302814 |
| fungi associated with the hemlock woolly adelgid, adelges tsugae, and assessment of entomopathogenic isolates for management. | fungi associated with the hemlock wooly adelgid, adelges tsugae annand (hemiptera: adelgidae), were collected throughout the eastern usa and southern china. twenty fungal genera were identified, as were 79 entomopathogenic isolates, including: lecanicillium lecanii (zimmermann) (hypocreales: insertae sedis), isaria farinosa (holm: fries.) (cordycipitaceae), beauveria bassiana (balasamo) (hyphomycetes), and fusarium spp (nectriaceae). the remaining fungal genera associated with insect cadavers we ... | 2010 | 20672977 |
| assessing the potential impacts to riparian ecosystems resulting from hemlock mortality in great smoky mountains national park. | hemlock woolly adelgid (adelges tsugae) is spreading across forests in eastern north america, causing mortality of eastern hemlock (tsuga canadensis [l.] carr.) and carolina hemlock (tsuga caroliniana engelm.). the loss of hemlock from riparian forests in great smoky mountains national park (gsmnp) may result in significant physical, chemical, and biological alterations to stream environments. to assess the influence of riparian hemlock stands on stream conditions and estimate possible impacts f ... | 2009 | 19495859 |
| variation in winter survival of the invasive hemlock woolly adelgid (hemiptera: adelgidae) across the eastern united states. | the hemlock woolly adelgid (adelges tsugae annand) is a small, aphid-like insect native to east asia and western north america. first documented in the eastern united states in richmond, va, in 1951, it has spread to at least 17 states, where it causes increased mortality among both eastern and carolina hemlocks (tsuga canadensis carrière and t. caroliniana engelmann., respectively). previous work has suggested low temperatures may limit northward spread of the adelgid. using recent surveys of a ... | 2009 | 19508766 |
| acceleration of exotic plant invasion in a forested ecosystem by a generalist herbivore. | the successful invasion of exotic plants is often attributed to the absence of coevolved enemies in the introduced range (i.e., the enemy release hypothesis). nevertheless, several components of this hypothesis, including the role of generalist herbivores, remain relatively unexplored. we used repeated censuses of exclosures and paired controls to investigate the role of a generalist herbivore, white-tailed deer (odocoileus virginianus), in the invasion of 3 exotic plant species (microstegium vi ... | 2009 | 19183209 |
| community response of insects associated with eastern hemlock to imidacloprid and horticultural oil treatments. | the hemlock woolly adelgid, adelges tsugae annand, is an invasive species reducing the populations of eastern hemlock, tsuga canadensis l. carrière, throughout the eastern united states. systemic imidacloprid and horticultural oil are the primary chemicals used to control infestations of this invasive pest; however, the impact of these two chemicals on nontarget canopy insects is unknown. this study was initiated in november 2005 to assess the effects of (1) imidacloprid soil drench, (2) imidacl ... | 2009 | 19791598 |
| evaluation of hemlock (tsuga) species and hybrids for resistance to adelges tsugae (hemiptera: adelgidae) using artificial infestation. | hemlock (tsuga) species and hybrids were evaluated for resistance to the hemlock woolly adelgid, adelges tsugae annand (hemiptera: adelgidae). the adelgid was accidentally introduced from asia to the eastern united states, where it is causing widespread mortality of the native hemlocks, tsuga canadensis (l.) carrière and tsuga caroliniana engelm. these two native species plus the asian species tsuga chinensis (franch.) e. pritz and t. dumosa (d.don) eichler and tsuga sieboldii carrière, and the ... | 2009 | 19610445 |
| evaluation of elisa for imidacloprid detection in eastern hemlock (tsuga canadensis) wood and needle tissues. | imidacloprid is the primary insecticide used against the exotic invasive insect hemlock woolly adelgid, adelges tsugae annand, a pest of eastern hemlock [tsuga canadensis (l.) carrière] trees in the eastern united states. a competitive enzyme-linked immunosorbent assay (elisa) was evaluated for quantification of imidacloprid in eastern hemlock wood and needle tissues. | 2009 | 18924117 |
| propagation, synchrony, and impact of introduced and native laricobius spp. (coleoptera: derodontidae) on hemlock woolly adelgid in virginia. | synchrony and impact of the predators laricobius nigrinus fender and laricobius rubidus leconte, on hemlock woolly adelgid, adelges tsugae annand, were studied in an eastern hemlock field insectary in virginia. first, a field insectary for propagation of the introduced l. nigrinus was established by planting hemlocks in 2001, infesting them with hemlock woolly adelgid in 2002 and 2003, followed by releasing 258 l. nigrinus in 2003. initial sampling showed that the native l. rubidus was present i ... | 2008 | 19161693 |
| isolation and characterization of microsatellite markers for carolina hemlock (tsuga caroliniana). | we describe the isolation and characterization of 31 polymorphic di- and trinucleotide microsatellite marker loci for carolina hemlock (tsuga caroliniana englem.). in addition, primer pairs for 16 loci amplified scoreable alleles in six other tsuga species. in eastern north america, both carolina hemlock and eastern hemlock (tsuga canadensis [l.] carr.) populations are declining due to infestation by hemlock woolly adelgid, adelges tsugae. the markers described here should enhance population gen ... | 2008 | 21586049 |
| exploitative competition between invasive herbivores benefits a native host plant. | although biological invasions are of considerable concern to ecologists, relatively little attention has been paid to the potential for and consequences of indirect interactions between invasive species. such interactions are generally thought to enhance invasives' spread and impact (i.e., the "invasional meltdown" hypothesis); however, exotic species might also act indirectly to slow the spread or blunt the impact of other invasives. on the east coast of the united states, the invasive hemlock ... | 2008 | 18959304 |
| hydraulic responses to environmental perturbations in tsuga canadensis and betula lenta. | eastern hemlock (tsuga canadensis (l). carr.) is a late-successional species found across the northeastern united states of america that is currently threatened by the exotic pest, hemlock woolly adelgid (adelges tsugae annand). because whole-tree physiological characteristics may scale to influence ecosystem processes, we considered whole-tree hydraulic controls in eastern hemlock and the replacement species black birch (betula lenta l.). through a series of misting perturbations, whole-tree re ... | 2008 | 18595846 |
| deer herbivory alters forest response to canopy decline caused by an exotic insect pest. | hemlock woolly adelgid (hwa; adelges tsugae) infestations have resulted in the continuing decline of eastern hemlock (tsuga canadensis) throughout much of the eastern united states. while the initial impacts of hwa infestations have been documented, our understanding of forest response to this disturbance remains incomplete. hwa infestation is not occurring in isolation but within a complex ecological context. the role of potentially important interacting factors, such as elevated levels of whit ... | 2008 | 18488602 |
| predators associated with the hemlock woolly adelgid (hemiptera: adelgidae) in the pacific northwest. | the hemlock woolly adelgid, adelges tsugae annand (hemiptera: adelgidae), is causing widespread mortality of eastern hemlock, tsuga canadensis l. carrière, in the eastern united states. in western north america, feeding by a. tsugae results in negligible damage to western hemlock, tsuga heterophylla (raf.) sargent. host tolerance and presence of endemic predators may be contributing to the relatively low levels of injury to t. heterophylla caused by a. tsugae. field surveys of the predator commu ... | 2008 | 18419922 |
| oak seedling growth and ectomycorrhizal colonization are less in eastern hemlock stands infested with hemlock woolly adelgid than in adjacent oak stands. | invasive, non-indigenous, phytophagous insects have caused widespread declines in several dominant tree species. the decline in dominant tree species may lead to cascading effects on other tree and microbial species and their interactions, affecting forest recovery following the decline. in the eastern usa, eastern hemlock (tsuga canadensis (l.) carr) is declining because of infestation by the hemlock woolly adelgid (hwa; adelges tsugae annand). northern red oak (quercus rubra l.) is a common re ... | 2008 | 18244948 |
| water use and carbon exchange of red oak- and eastern hemlock-dominated forests in the northeastern usa: implications for ecosystem-level effects of hemlock woolly adelgid. | water use and carbon exchange of a red oak-dominated (quercus rubra l.) forest and an eastern hemlock-dominated (tsuga canadensis l.) forest, each located within the harvard forest in north-central massachusetts, were measured for 2 years by the eddy flux method. water use by the red oak forest reached 4 mm day(-1), compared to a maximum of 2 mm day(-1) by the eastern hemlock forest. maximal carbon (c) uptake rate was also higher in the red oak forest than in the eastern hemlock forest (about 25 ... | 2008 | 18244947 |
| parasitoids reared from predators of hemlock woolly adelgid (hemiptera: adelgidae), and the hymenopterous parasitoid community on western hemlock in the pacific northwest. | in western north america, infestations of the hemlock woolly adelgid, adelges tsugae annand (hemiptera: adelgidae), are common on orchard, ornamental, and roadside western hemlock, tsuga heterophylla (raf.) sargent. however, these infestations rarely cause t. heterophylla mortality. host tolerance and presence of endemic predators may be contributing to the relatively low levels of injury to t. heterophylla caused by a. tsugae. field surveys of the arthropod community associated with a. tsugae i ... | 2008 | 19161691 |
| insect guild structure associated with eastern hemlock in the southern appalachians. | an assessment of the insect guild structure associated with immature and mature eastern hemlock, tsuga canadensis (l.) carrière, at high and low elevations was made before the invasion by the hemlock woolly adelgid, adelges tsugae (annand), and elongate hemlock scale, fiorinia externa ferris. guild dynamics were determined among 243 insect species associated with eastern hemlock in the southern appalachians. detritivore, hematophage, herbivore, fungivore, parasitoid, predator, scavenger, and tra ... | 2007 | 18284768 |
| characterization of terpenoid volatiles from cultivars of eastern hemlock (tsuga canadensis). | the volatile terpenoid fraction from needles in 13 cultivars of tsuga canadensis l. (carriere) was analyzed by gas chromatography with mass spectrometry (gc-ms). the results of this study are considered along with previously reported results for foliar terpenoid levels of the asian (t. sieboldii, t. chinensis, t. diversifolia), western north american (t. mertensiana, t. heterophylla), and eastern north american species (t. canadensis, t. caroliniana) of hemlock to draw conclusions about the pote ... | 2007 | 18052093 |
| behavior and daily activity patterns of specialist and generalist predators of the hemlock woolly adelgid, adelges tsugae. | the behavior and daily activity patterns of two specialist predators, laricobius nigrinus fender (coleoptera: derodontidae) and sasajiscymnus tsugae, sasaji and mcclure (coleoptera: coccinellidae), and a generalist predator, harmonia axyridis pallas (coleoptera: coccinellidae), of hemlock woolly adelgid, adelges tsugae (hemiptera: adelgidae), were examined using digital video recording in the laboratory. the two specialists are part of a biological control program for a. tsugae, and it is not kn ... | 2007 | 20345314 |
| tsuga canadensis (l.) carr. mortality will impact hydrologic processes in southern appalachian forest ecosystems. | eastern hemlock (tsuga canadensis (l.) carr.) is one of the principal riparian and cove canopy species in the southern appalachian mountains. throughout its range, eastern hemlock is facing potential widespread mortality from the hemlock woolly adelgid (hwa). if hwa-induced eastern hemlock mortality alters hydrologic function, land managers will be challenged to develop management strategies that restore function or mitigate impacts. to estimate the impact that the loss of this forest species wi ... | 2007 | 17555225 |
| temporal and spatial variation of terpenoids in eastern hemlock (tsuga canadensis) in relation to feeding by adelges tsugae. | the terpenoid content of eastern hemlock (tsuga canadensis) foliage was measured over an annual cycle of development from bud opening, shoot elongation, shoot maturation, to bud-break at the start of the next growing season. the objective was to determine if variation in terpenoid composition is linked with spatial and temporal feeding preferences of the hemlock woolly adelgid (hwa; adelges tsugae). the hwa has two periods of feeding over the course of 1 yr spanning two complete generations. the ... | 2006 | 17078000 |
| binomial sequential sampling plan for hemlock woolly adelgid (hemiptera: adelgidae) sistens infesting individual eastern hemlock trees. | the hemlock woolly adelgid, adelges tsugae annand (hemiptera: adelgidae), is an exotic insect pest that is killing eastern hemlock, tsuga canadensis (l.) carrière, and carolina hemlock, tsuga caroliniana engelmann, in the eastern united states. we used the sequential interval procedure to develop a binomial sequential sampling plan for a. tsugae sistens on individual eastern hemlock trees that uses nondestructive sampling of new shoots. the actual a (type i) and beta (type ii) error rates were e ... | 2006 | 16937709 |
| activity and residues of imidacloprid applied to soil and tree trunks to control hemlock woolly adelgid (hemiptera: adelgidae) in forests. | we studied imidacloprid application methods and timing to control the hemlock woolly adelgid, adelges tsugae annand (hemiptera: adelgidae), in forests. the methods compared were 1) soil injection near the trunk; 2) soil injection dispersed throughout the area under the canopy; 3) soil drench near the base of the trunk; and trunk injection with the 4) arborjet, 5) wedgle, and 6) mauget systems. the applications were made in the fall and the following spring. adelgid populations on the hemlocks (t ... | 2006 | 16937680 |
| the ecology of energy and nutrient fluxes in hemlock forests invaded by hemlock woolly adelgid. | the hemlock woolly adelgid (hwa, adelges tsugae annand) is currently causing a severe decline in vitality and survival of eastern hemlock in north american forests. we analyzed the effects of light hwa infestation on vertical energy and nutrient fluxes from the canopy to the forest floor. canopy throughfall, litter lysimeters, and laboratory litter microcosms were used to examine the effects of hwa-affected and unaffected throughfall on litter type, leachate, and litter chemistry. early in the s ... | 2006 | 16922328 |
| assessing hemlock decline using visible and near-infrared spectroscopy: indices comparison and algorithm development. | near-infrared reflectance spectroscopy was evaluated for its effectiveness at predicting pre-visual decline in eastern hemlock trees. an asd fieldspec pro fr field spectroradiometer measuring 2100 contiguous 1-nm-wide channels from 350 nm to 2500 nm was used to collect spectra from fresh hemlock foliage. full spectrum partial least squares (pls) regression equations and reduced stepwise linear regression equations were compared. the best decline predictive model was a 6-term linear regression eq ... | 2005 | 16053550 |
| feeding preference of three lady beetle predators of the hemlock woolly adelgid (homoptera: adelgidae). | in a laboratory study, we tested the feeding preferences of three coccinellid predators of hemlock woolly adelgid, adelges tsugae annand, an introduced pest of hemlock in the eastern united states. the species tested were sasajiscymnus tsugae sasaji & mcclure (formerly pseudoscymnus tsugae) from japan, scymnus ningshanensis yu & yao from china, and harmonia axyridis (pallas), a generalist species introduced from asia that is currently widespread in eastern hemlock, tsuga canadensis carriere, for ... | 2004 | 15568353 |
| comparison of numerical response and predation effects of two coccinellid species on hemlock woolly adelgid (homoptera: adelgidae). | the hemlock woolly adelgid, adelges tsugae annand, is an introduced pest in north america that is native to asia, and is causing extensive damage to eastern hemlock (tsuga canadensis carriere) and carolina hemlock (tsuga caroliniana englemann) in the eastern united states. we compared two coccinellids imported for biological control of the adelgid: scymnus ningshanensis yu et yao from china and pseudoscymnus tsugae sasaji and mcclure from japan. in a laboratory study, we measured the numerical r ... | 2003 | 12852614 |
| volatile emissions of eastern hemlock, tsuga canadensis, and the influence of hemlock woolly adelgid. | the volatile emissions of eastern hemlock, tsuga canadensis carriere, were identified and quantified using standard and chiral gas chromatography and mass spectrometry. all of the identified compounds were monoterpenes, and included alpha-pinene, myrcene, tricyclene, camphene, alpha-phellandrene, beta-pinene, limonene, beta-phellandrene, terpinolene, and bornyl acetate. alpha-pinene, myrcene, and camphene comprised greater than 75% by mass of the total release. infestation by the exotic insect, ... | 2003 | 12482453 |
| discriminating tsuga canadensis hemlock forest defoliation using remotely sensed change detection. | the eastern hemlock (tsuga canadensis) is declining in health and vigor in eastern north america due to infestation by an introduced insect, the hemlock woolly adelgid (adelges isugue). adelgid feeding activity results in the defoliation of hemlock forest canopy over several years. we investigated the application of landsat satellite imagery and change-detection techniques to monitor the health of hemlock forest stands in northern new jersey. we described methods used to correct effects due to a ... | 2002 | 19265936 |