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• Maintenance and restoration of forest ecosystems will be key to achieving necessary carbon sequestration goals, protecting biodiversity, and supporting healthy economies and societies. • Forest ecosystems are increasingly threatened by non-native forest insects and phytopathogens. • A portion of these pests are able to overcome prevention and containment efforts and become established in naive ecosystems. • Once established these pests pose a long-term large-scale threat to forest ecosystems, which current policy and response frameworks are poorly equipped to address. • We propose the creation of a federal Center for Forest Pest Control and Prevention to implement end-to-end responses to forest pest invasions using an ecologically-informed framework that fully integrates host tree resistance development and deployment.

The balsam woolly adelgid, Adelges piceae (Ratzeburg) (Homoptera: Adelgidae), is a major pest in Fraser fir, Abies fraseri (Pursh) Poir, Christmas tree plantations in the southern Appalachian Mountains. Shortly after eclosion, A. piceae larvae insert their stylets into intercellular bark tissue to ensure a constant feeding source from cortical parenchyma cells (Balch 1952, Can. Dept. Agric. Publ. No. 867, 76 pp.). Thereafter, the developing adelgid is attached at that site for the remainder of its life (Balch and Carroll 1956, Can. Dept. Agric. Publ. No. 977, 7 pp.). Insects that use a piercing-sucking mode of feeding, such as adelgids, elicit a response similar to that of fungal and bacterial plant pathogens (Walling 2000, J. Plant Growth Regul. 19: 195–216; Bernards and Spohr 2008, Pp. 189–211, In Schaller, A. (ed.), Induced Plant Resistance to Herbivory, Springer Science, Stuttgart, Germany). The synthesis of new compounds or structural barriers after herbivore-induced damage occurs, including the accumulation of proteins and secondary metabolites, are characteristics of induced defenses (Bernards and Spohr 2008). For example, the formation of cell wall modifications can be induced by wounding and herbivory (Ginzberg 2008, Pp. 131–146, In Schaller, A. (ed.), Induced Plant Resistance to Herbivory, Springer Science, Stuttgart, Germany). Host resistance mechanisms include rapid accumulation of monoterpene and juvabione-related compounds, the production of secondary periderm (Mullick 1975, Can. J. Bot. 53: 2443–2457; Hain et al. 1991, Pp. 271–287, In Baranchikov, Y.N., Mattson, W.J., Hain, F.P., Payne, T.L. (eds.), Forest Insect Guilds: Patterns of

The optimal environmental conditions for rearing the balsam woolly adelgid, Adelges piceae (Ratzeburg) (Hemiptera: Adelgidae), on its natural host, Fraser fir, Abies fraseri (Pursh) Poir, was determined by varying temperature, photoperiod, and humidity as well as by evaluating texture and geotaxic preferences. Five locations with a set temperature and relative humidity (RH) were chosen to test for optimal environmental conditions: three environmental chambers maintained at 17, 20, and 25°C with 75% RH; an insectary maintained at 21.1°C and 72% RH; and a greenhouse with varying temperature and RH levels. Overall, 20°C appeared to be the optimal temperature for development, and 25°C was the least favorable of the temperatures tested. Comparing Fraser fir cuttings to seedlings, seedlings (15.51/cm) were five times more infested than cuttings (3.02/cm), and the percentage of adult survival was higher on seedlings (67%) than on cuttings (17%). The highest percentage of adelgids reaching full developme...

The hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), is a pest of eastern and Carolina hemlocks (Tsuga canadensis (L.) Carrière and Tsuga caroliniana Engelmann, respectively) in the eastern United States and has already caused catastrophic changes to eastern forests. As one of the significant exotic forest pests, it is imperative that the basic biology of hemlock woolly adelgid be understood for use in novel and improved management techniques. Scanning and transmission electron microscopy and enzyme assays were used to elucidate the feeding biology of hemlock woolly adelgid and are discussed in the context of the pest—plant interactions and the implications for host plant resistance. Morphological characters indicate that hemlock woolly adelgids may use labial sensilla and neural canals within the mandibular stylets to guide their stylets through close-range host acceptance processes. Stylet bundle insertion is likely assisted by external sheath material that secures the stylet bundle to the plant surface and mandibular dentitions that may assist entry into or within plant tissues. In addition, results support the theory that extra-oral digestion is likely used by hemlock woolly adelgid, suggested by both a narrow food canal and the presence of four trophically related enzymes (a trypsin-like enzyme, an amylase-like enzyme, peroxidase, and polyphenol oxidase). The presence of these enzymes also has implications for causing a systemic response in host trees.

The overwintering sites and seasonal abundance of phytoseiid mites were determined in North Carolina Fraser fir Christmas tree plantations. Potential overwintering sites for the mites include Fraser fir branches, Fraser fir bark, surface litter composed of Fraser fir needles, a mixture of fescue grass (Festuca spp.) and nimblewill (Mhlenbergia schreberi J.F. Gmelin.), mixed herbaceous debris from the previous growing season, and a monocultural cover crop of white clover (Trifolium repens L.). Twelve species of mites (n = 414) in the family Phytoseiidae were collected. Arrenoseius morgani (Chant) (n = 160), Typhlodromips sessor (DeLeon) (n = 156), and Typhlodromalus peregrinus (Muma) (n = 34) were the most abundant. During the spring and summer Fraser fir plantations with a ground cover consisting of white clover were compared with plantations with bare ground to assess the abundance and species composition of phytoseiid mites. A total of 512 phytoseiids representing 8 species was collected. Phyto...

Summary � 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 physiological responses to HWA infestation were sufficiently significant to induce changes in whole-plant water use and carbon uptake. � The results indicated coordinated responses of functional traits governing water relations in infested relative to healthy trees. In response to HWA, leaf water potential, carbon isotope ratios, plant hydraulic properties and stomatal conductance were affected, inducing a reduction in tree water use by > 40% and gross primary productivity by 25%. Anatomical changes also appeared, including the activation of traumatic cells. � HWA infestation had a direct effect on plant water relations. Despite some leaf compensatory mechanisms, such as an increase in leaf hydraulic conductance and nitrogen content, tree water use and carbon assimilation were diminished significantly in infested trees, which could contribute to tree mortality.

The southern pine beetle (Dendroctonus frontalis Zimmermann, Coleoptera: Curculionidae) is the most destructive insect in southern forests. States have kept county-level records on the locations of beetle outbreaks for the past 50 yr. This study determined how accurately patterns of county-level infestations in preceding years could predict infestation occurrence in the current year and if there were emergent patterns that correlated strongly with beetle outbreaks. A variety of methods were tested as infestation predictors, including quantification of either the exact locations of infested grid cells during one or two preceding years, or the neighborhood infestation intensity (number of infested cells in a neighborhood) in these years. The methods had similar predictive abilities, but the simpler methods performed somewhat better than the more complex ones. The factors most correlated with infestations in future years were infestation in the current year and the number of surrounding counties that were infested. Infestation history helped to predict the probability of future infestations in a region, but county-level patterns alone left much of the year-to-year variability unexplained.

The southern pine beetle (Dendroctonus frontalis, SPB) is the major insect pest of pine species in the southeastern United States. It attains outbreak population levels sufficient to mass attack host pines across the landscape at scales ranging from a single forest stand to interstate epidemics. This county level analysis selected and examined the best climatic and landscape variables for predicting infestations at regional scales. The analysis showed that, for a given county, the most important factor in predicting outbreaks was that the county was classified as in outbreak status in the previous year. Other important factors included minimum winter temperature and the greatest difference between the average of daily minimums and a subsequent low temperature point, precipitation history either seasonally in the previous year or difference from average over the previous 2 years, the synchronizing effect of seasonal temperatures on beetle populations and the relative percentage of total forest area composed of host species. The statistical models showed that climatic variables are stronger indicators of outbreak likelihood than landscape structure and cover variables. Average climatic conditions were more likely to lead to outbreaks than extreme conditions, supporting the notion of coupling between a native insect and its native host. Still, some extreme events (i.e., periods of very low temperature or very high precipitation) did precede beetle infestation. This analysis suggested that there are predisposing and inciting factors at the large scale but the driving factors leading to individual infestations operate at smaller scales. Published by Elsevier B.V.

Knowledge of host-insect interactions is essential for understanding host-tree mortality patterns over large areas. The response of a conifer to stem invasion is a dynamic process that consists of three components: 1. wound cleansing by the resin canal system, 2. containment of the infection by the hypersensitive response, and 3. wound healing by the formation of wound periderm. Xylem tissue is frequently rendered non-conductive by the build-up of terpenes and other compounds frequently associated with normal heartwood. In order for a tree to successfully resist or tolerate an attack, the entire response process must be completed with minimum interference from the invading organisms. Depending upon the triggering agent, particular components of the response system may be of primary importance in a successful host defense. Zusammenfassung Abwehrreaktion von Nadelbaumen auf Befall durch rindenbrutende Insekten Die genaue Kenntnis der Wechselwirkungen zwischen Insekten und ihren Wirten ist unerlaslich fur das Verstandnis des grosflachigen Verteilungsmusters der nach Befall abgestorbenen Baume. Die Reaktion von Nadelbaumen auf Stammbefall ist ein dynamischer Vorgang, der aus drei Komponenten besteht: 1. Wundreinigung durch das Harzkanalsystem, 2. Begrenzung der Infektion durch Wundharzbildung, und 3. Wundheilung durch die Bildung von Wundperiderm. Die Leitbahnen des Holzes werden oft durch Anreicherung von Terpenen und anderen Substanzen verschlossen, die auch in normalem Kernholz vorkommen. Damit ein Wirtsbaum den Befall erfolgreich abwehren oder zumindest tolerieren kann, mus die gesamte Abwehrreaktion moglichst ohne storende Einwirkung durch den eindringenden Schadling erfolgen. Je nachdem, um welchen Schadorganismus es sich handelt, konnen bestimmte Komponenten des Abwehrsystems von besonderer Bedeutung fur eine erfolgreiche Schadlingsabwehr sein.

A hypothesis is presented that atmospheric deposition is predisposing Fraser fir to balsam woolly adelgid (BWA)-caused mortality and that the amount of mortality in six Fraser fir zones is a reflection of the amount of atmospheric deposits in each zone. We argue that Fraser fir is a highly sensitive species to atmospheric pollutants, that BWA increases that sensitivity, and that the Fraser fir ecosystem is a primary depository of such pollutants. Alternative hypotheses are also discussed. It is likely that a number of factors, including patterns of atmospheric deposits, contribute to Fraser fir mortality patterns in the southern Appalachians. Zusammenfassung Die Bedeutung der Ablagerungen von Luftschadstoffen fur die Tannenmortalitat, verursacht durch die Wollaus Adelges piceae (Ratz.) (Hemipt., Adelgidae): Eine Hypothese Es wird eine Hypothese vorgestellt, die in der Ablagerung von Luftschadstoffen einen wesentlichen, auf die Mortalitat von Fraser-Tannen, verursacht durch Adelges piceae einwirkenden Faktor sieht. Der Umfang der Mortalitat in sechs Tannenzonen entsprach dem Umfang der jeweiligen Schadstoffbelastung. Es wird argumentiert, das die Fraser-Tanne hochempfindlich gegenuber Immissionen sei, das die Wollaus diese Empfindlichkeit noch erhohe, und das das Tannen-Okosystem einen primaren Ablagerungsort fur diese Schadstoffe darstelle. Alternativen hierzu werden erortert. Es ist wahrscheinlich, das eine Anzahl von Faktoren, einschlieslich der Luftschadstoffe zur Tannensterblichkeit im sudlichen Appalachengebirge beitragt.

This study tested the effects of cutting length and auxin (NAA) concentration on adventitious root formation in softwood stem cuttings from mature eastern hemlock, Tsuga canadensis (L.) Carr., and carolina hemlock, T. caroliniana Engelm. Overall rooting percentage (41%) and percent mortality (22%) were higher for eastern hemlock compared with carolina hemlock (10% rooting and 13% mortality). Rooting percentage of each species responded differently to varying auxin concentrations (0, 1, 2, 4, 8 mm NAA). Maximum rooting (56%) for eastern hemlock occurred at 0 mm NAA; then decreased with increasing auxin concentration. Carolina hemlock rooting percentage increased from the control to a maximum (16%) at 1 mm NAA; then decreased with increasing auxin concentration. For both species, the lowest mortality occurred at the same auxin concentration as maximum rooting. The highest rates of mortality coincided with the same concentrations as the lowest rooting percentages. At all auxin concentrations, eastern hemlock had a higher number of roots and greater total root length relative to carolina hemlock. Mortality among 6-cm stem cuttings was twice that observed for 3-cm cuttings of both species. However, 6-cm cuttings of eastern hemlock that did form adventitious roots had more roots and longer total root length compared with 3-cm cuttings. Chemical name used: 1-naphthalenacetic acid.

Summary Oleoresin flow is an important factor in the resistance of pines to attack by southern pine beetle, Dendroctonus frontalis Zimm., and its associated fungi. Abiotic factors, such as nutrient supply and water relations, have the potential to modify this plant–insect–fungus interaction; however, little is known of the effects of inoculation with beetle-associated fungi on oleoresin flow. We observed that constitutive and induced resin yield in loblolly pine, Pinus taeda L., were affected by either fungal inoculation (with the southern pine beetle-associated fungus Ophiostoma minus (Hedgcock) H. & P. Sydow) or silvicultural treatment. The effects of mass wounding (400 wounds m –2 ) and mass wounding and inoculation with O. minus were assessed by comparison with untreated (control) trees. The treatments were applied to trees in a 2 × 2 factorial combination of fertilizer and irrigation treatments. Fertilization did not significantly affect constitutive resin yield. Even as long as 105 days post-treatment, however, mass-inoculated trees produced higher induced resin yields than control or wounded-only trees, indicating a localized induced response to fungal inoculation. We noted no systemic induction of host defenses against fungal colonization. Although beetles attacking previously attacked trees face a greater resinous response from their host than beetles attacking trees that had not been previously attacked, the effect of an earlier attack may not last more than one flight season. Despite mass inoculations, O. minus did not kill the host trees, suggesting that this fungus is not a virulent plant pathogen.

In southern pines of the United States, resistance to attack by southern pine beetle, Dendroctonus frontalis Zimmermann, is believed to principally involve flow of oleoresin to beetle attack sites. Both environmental and genetic factors are known to affect the quantity of oleoresin flow in loblolly pine, Pinus taeda L., but little is known about the genetic contribution to phenotypic variation in this trait. Here we report estimates of genetic variation in oleoresin flow and growth traits for a population of this species. Oleoresin yield, total height, and diameter were measured on 10- and 11-year-old trees from an experimental test in Santa Rosa County, Florida. Trees were from 72 full-sib families produced by mating 48 parents according to a disconnected partial diallel mating design. Resin yield was determined from breast-height samples collected at two times: once in the summer of 1999 when latewood was being produced (summer resin flow), and once in the spring of 2000 during earlywood formation (spring resin flow). All traits studied were found to be highly genetically variable and to have much greater additive than dominance variance. Estimates of narrow-sense heritability for spring and summer resin flow were in the moderate range and are comparable to values obtained for the growth traits. Additive genetic correlations between oleoresin yield and the growth traits were positive and moderately high, suggesting that directional selection to improve growth in loblolly pine will also result in increased production of oleoresin.

The predation potential of small mammals, in particular mice, Peromyscus spp., and invertebrates, was evaluated from 1992 to 1995 near the leading edge of gypsy moth, Lymantria dispar (L.), spread into the southeastern United States. Two study sites were established in each of three geographic areas: the coastal plain, Piedmont, and mountains. All sites were mixed hardwood stands with varying amounts of oak, Quercus spp., and all were classified for gypsy moth susceptibility. Small mammal density was estimated using Sherman live-traps and pitfall traps within these 4.68-ha sites in early and late summer. Each site contained 75 trapping stations located on a 25-m grid. Predation was measured by offering freeze-dried gypsy moth pupae near trapping stations at four heights (0, 0.25, 1.0, and 2.0 m) on different tree boles. Pupal predation was monitored for three consecutive nights. Vertebrate predation was positively correlated with good mast production in the previous autumn. Predation data showed that when mice were at high densities they were the major source of pupal predation. However, within these southern sites, when densities of Peromyscus spp. were low, predation by invertebrates was occasionally greater than predation by vertebrates. These data suggest that in some years invertebrates may retard gypsy moth buildup when small mammals are scarce due to mast crop failures.

Adelges tsugae (Hemlock Woolly Adelgid) is a small piercing-sucking insect that feeds on Tsuga spp. (hemlock ) trees. Native to Asia and the Pacific Northwest, the Hemlock Woolly Adelgid is invasive in the eastern United States where it attacks Tsuga canadensis (Eastern Hemlock) and T. caroliniana (Carolina Hemlock). It is currently found in 19 eastern states and has caused extensive mortality to hemlock forests. The ecological and economic impacts of this pest are significant, widespread, and often difficult to quantify. As the Hemlock Woolly Adelgid continues to disperse throughout the range of Eastern and Carolina Hemlocks, management techniques aimed at controlling it are being researched, implemented, and assessed. This introductory paper provides an overview of the biology, life cycle, ecology, and history of this pest in the eastern US as a foundation for this special issue.

In light of the increasing need for long-term, sustainable management for Adelges tsugae (Hemlock Woolly Adelgid), researchers are investigating host-plant resistance as part of an integrated approach to combat the pest. This paper reviews the progress made towards developing a resistant hemlock in the southern Appalachians and highlights the importance of investing research and development resources in this field. Along with describing inter- and intraspecific resistance in hemlocks, this paper reviews investigations into resistance mechanisms and outlines the many options for actions that could be or are being taken to increase resistance and restore hemlock forests.

Two juvenile hormone related compounds (JRCs), juvabione and dehydrojuvabione, were isolated from Fraser fir, Abies fraseri (Pursh) Poirit. Both juvabione and dehydrojuvabione concentrations had large variations across the tested trees and within trees. Juvabione, but not dehydrojuvabione, was much higher in stemwood then in branchwood. There was no significant difference in either chemical in relation to high, low, or middle branch position. To determine if juvabione concentration was influenced by an infestation of balsam woolly adelgid, Adelges piceae Ratz., branches from infested and uninfested 11-year-old Abies fraseri with were sampled at the bottom, middle, and top branches of each tree. While mean juvabione concentrations for each infested fir were higher than their uninfested counterparts, only the infested middle tree sections had mean juvabione values that were substantially higher (p = 0.078) than the corresponding uninfested tree section of all the infested firs. The two infested Abies fraseri that maintained apical dominance demonstrated the highest upper branch levels of juvabione of all the infested. These results indicate that juvabione may be induced in small Abies fraseri in response to adelgid attack. Trees that produce large quantities of this compound may possess tolerance to the adelgid. Further research is needed to elucidate this possibility.

There has been little research conducted on the effects of native or established predators on populations of the hemlock woolly adelgid, Adelges tsugae Annand. This study used field surveys and cage exclusion experiments to examine the relationship between established predators and A. tsugae in the southeastern United States. Predators were collected in very low densities in both years. Harmonia axyridis Pallas (Coleoptera: Coccinellidae), lacewings (Neuroptera: Chrysopidae and Hemerobiidae), and gall gnats (Diptera: Cecidomyiidae) represented 81% of the total predators collected in 1998. Cage exclusion experiments revealed no significant predator effects in all three sites in 1997 and 1998. It is unlikely that established predators are exhibiting any significant control on adelgid populations because of the low densities of predators that were encountered at a time when adelgids were abundant. Therefore, controlled releases of non-native predators into these sites should be considered.

The quality of sweetgum, Liquidambar styraciflua L., and loblolly pine, Pinus taeda L., as a foodsource for gypsy moth, Lymantria dispar (L.), larvae was evaluated using caged F 1 -sterile gypsy moths in a field study in southeastern Virginia. A 1st experiment compared host species at 3 sites. Because early instars do not feed on loblolly pine, 2nd and 3rd stadia larvae were caged only on sweetgum, and allocated to sweetgum and loblolly pine at the onset of the 4th stadium. On sweetgum, survival of L2 and L3 gypsy moths was 32% across sites and was 17% higher on the best site compared with the worst. Survival of L4 to pupae was not affected by site, but survival was significantly higher on sweetgum than loblolly pine during this period. Host species did not affect duration of the larval stage, pupal weight, duration of the pupal stage, or development time to adult of F 1 -sterile gypsy moths; however, site had a significant effect on duration of the larval period. A 2nd experiment using L4-L6 examined the effects of detaching branches, on both host species, on the duration of the larval period, relative growth rate, and pupal weight. The main effects of host species, branch detachment, and frequency of larval handling (frequent versus infrequent) were not significant for any response variable. The interactions of branch detachment by host species and larval handling by host species were significant. On loblolly pine, larvae caged on detached branches developed more slowly than those on intact branches, but those larvae caged on intact branches and moved infrequently developed the slowest of any treatment. Larvae on sweetgum were unaffected by branch detachment or frequency of handling.

Lepidopteran larvae were sampled in the field to determine levels of infection by the gypsy moth, Lymantria dispar (L.), fungal pathogen, Entomophaga maimaiga Humber, Shimazu & Soper. Lepidopteran larvae were reared from 7 plots in Virginia in which moderate density gypsy moth populations simultaneously exhibited from 40.8 to 97.5% E. maimaiga infection. From a total of 1,511 larvae from 52 species belonging to 7 lepidopteran families in 4 superfamilies, only 2 individuals, 1 of 318 forest tent caterpillars, Malacosoma disstria Hiibner (0.3% infection), and 1 of 96 Catocala ilia (Cramer) (1.0% infection), became infected by entomophthoralean pathogens. Results from genomic DNA probes and bioassays confirmed that E. maimaiga had caused these infections. Laboratory studies yielded infection over a greater diversity of species, and percentages of infection from laboratory studies were higher than findings from the field for the 1 species infected in both the laboratory and field. At all sites, the gypsy moth nuclear polyhedrosis virus also was found, occasionally causing epizootics, but viral occlusion bodies were never found in nontarget Lepidoptera that died. In addition, 279 nontarget Lepidoptera belonging to 34 species in 8 families were collected and reared from areas with low density native gypsy moth populations, and E. maimaiga infections were not found in these nontarget hosts, although E. maimaiga was active in gypsy moth populations. A survey of lepidopteran cadavers collected from 1989 to 1995 containing entomophthoralean spores documented E. maimaiga infections in 3 species of lymantriids. The Lepidoptera-specific North American endemic entomopathogen Entomophaga aulicae (Reichardt in Bail) Humber, which is morphologically identical to E. maimaiga, was found in 1 geometrid species, 1 notodontid, 2 species of arctiids, and 1 introduced lymantriid, but in none of the gypsy moth larvae tested. Our results demonstrate that data from laboratory bioassays are poor estimates for predicting nontarget impact.

Host choice of late instar (LA-L6) gypsy moths, Lymantria dispar (L.), was evaluated using stems and foliage of loblolly pine, Pinus taeda L., and sweetgum, Liquidambar styraciflua L. Upon release as 4th instars, larvae were free to roam within arenas, where their location was recorded several times per day until all had pupated. The number of larvae on a particular host species was highly dependent on larval age. After release into experimlintal arenas, there was nearly unidirectional movement from loblolly pine to sweetgum, resulting in 75% of larvae being found on this host after 4 d. Sweetgum remained the preferred host for most of the larval stage; however, as larvae neared pupation there was strong movement to loblolly pine, which was preferred over sweetgum ≍3 to 1 for pupation. The initial host of release had no effect on larval host-choice for pupation. Host sequence, defined by host of release and host of pupation, affected larval duration and pupal weight only in the following cases. Insects that began and pupated on loblolly pine developed at a slower rate and weighed less than those that began and pupated on sweetgum. Individuals that switched hosts for pupation generally were not significantly different (in pupal weight or development time) from either of these. Implications of the observed pattern of host use, especially the overwhelming choice of loblolly pine for pupation, on gypsy moth interactions with natural enemies in the southeastern United States are discussed.

Carbaryl-naphthyl-1- 14 C (1-naphthyl methylcarbamate) was topically applied in acetone to the prothorax of adult southern pine beetle, Dendroctonus frontalis Zimmermann, and spruce beetle, D. rufipennis (Kirby). The rate of penetration of carbaryl into both species is best described by an open, two-compartment model. The residual toxicokinetics model was established to compare the biphasic rate of penetration of carbaryl,vithin these beetles. The estimated exoskeleton residual half-life of the slow phase (phase II) for the southern pine beetle was 90 h or 13 times that of the spruce beetle (7 h). At 8 h, the accumulation of radioactivity- internally for the spruce beetle was almost double the amount for the southern pine beetle. The amount of methanolic unextractable compounds was similar for both beetle species ; unextractable compounds increased as incubation times increased. LD 50 levels for carbaryl indicated that the spruce beetle was more susceptible to carbaryl than the southern pine beetle. This information and results of the toxicity tests suggest that decreased exoskeletal penetration may be one of the major mechanisms of southern pine beetle tolerance to carbaryl.

We examined the rate of carbaryl degradation on the bark of two tree species under laboratory conditions with three temperatures and two relative humidities. Tree species and relative humidity were the main factors affecting the degradation process. We recovered 98-100% of the carbaryl residues from loblolly pine, Pinus taeda L., within all temperature and relative humidity groups after 60 d of incubation. In contrast, we recovered 67% (97% RH) and 97% (33% RH) of the residues from the bark of white spruce, Picea glauca (Moench) Voss, at 25°C after 60 d of incubation. Several metabolites of carbaryl were found on the bark of white spruce, whereas no detectable amount of carbaryl metabolites was found from loblolly pine in all treatment groups. Two major metabolites were identified based on cochromatography with standard 4-hydroxycarbaryl and 5-hydroxycarbaryl ; maximum amounts of these metabolites reached =28 and 24%, respectively.

Adult southern pine beetle, Dendroctonus frontalis Zimmermann, and spruce beetle, Dendroctonus rufipennis (Kirby), were treated topically with carbaryl-1-naphthyl- 14 C , after which metabolism of the labeled chemical was studied. Methylolcarbaryl was the major metabolite in both beetle species ; its concentration reached 5.18% in internal extracts from southern pine beetle at 8 h and 1.21 and 3.58% in internal extracts from spruce beetle at 12 and 24 h, respectively. The southern pine beetle metabolized 14 C-carbaryl and excreted its metabolites more quickly than the spruce beetle. Other methanolic extractable metabolites were tentatively identified from both species as 4-hydroxy-1-naphthyl methylcarbamate, 5-hydroxy-1-naphthyl methylcarbamate, 1-naphthyl methylcarbamate, 1-naphthol, 1,4-naphthalenediol, and 1,5-naphthalenediol. Several unidentified metabolites were also present.

Des sapins de Fraser, Abies fraseri (Pursh) Poir., furent cultives en serres et dans quatre sites au champ dans la partie sud des Appalaches dans le but d'etudier les effets des infestations du puceron lanigere, Adelges piceae (Ratz.). Le renflement de la tige principale a ete utilise comme indicateur de la production de bois anormal («rotholz») qui est declenchee par une infestation. Dans trois des quatre sites, la tige principale des semis infestes etait plus renflee que celle des semis sains. L'importance du renflement cause par le puceron lanigere n'etait generalement pas influencee par la provenance des graines (descendance uniparentale), la provenance du sol (haute ou faible altitude), ni par l'interaction de ces facteurs. Dans deux des quatre sites, l'infestation etait associee a une augmentation significative du ratio racines:tige. La variabilite du ratio racines:tige et du poids sec total des semis etait influencee par des interactions entre l'infestation, la provenance du sol et la provenance des graines. Ce resultats demontre que les caracteristiques genetiques des arbres et l'environnement jouent tous deux un role important dans la reponse en croissance des semis de sapin de Fraser infestes. Les resultats de l'etude en serres montrent que le puceron lanigere pourrait etre represente par deux biotypes ou plus dans la partie sud des Appalaches. L'augmentation du poids et du diametre de la tige etait relativement forte chez les semis du mont Mitchell infestes par le puceron lanigere du mont Rogers, et relativement faible lorsqu'ils etaient infestes par le puceron lanigere du mont Mitchell. L'inverse etait vrai pour les semis du mont Rogers. Dans l'ensemble ces resultats suggerent que l'environnement est probablement plus important que les caracteristiques genetiques des arbres ou de l'insecte pour expliquer pourquoi autant d'arbres infestes sont morts dans les montagnes Noires de la Caroline du Nord

Loblolly pine bolts sprayed with 2% carbaryl (Sevimol® 40% A. I. Flowable) and 1% chlorpyrifos were exposed to southern pine beetle, Dendroctonus frontalis Zimmermann. Chlorpyrifos treatment effectively prevented attack by southern pine beetle; however, the bolts were not protected by 2% carbaryl. For the carbaryl-treated bolts, the number of egg niches and larval mines were significantly reduced. However, the number of adult beetles entering the host, the length of the parent galleries, the number of pupal chambers, brood adults, and emergence holes were not significantly (P = 0.05) different from untreated control bolts. A bark surface assay indicated that 2% carbaryl killed < 50% of the beetles at 24 h. Filter paper assay showed that the LC50 value was 0.07% and 0.01% at 24 and 48 h, respectively.

Gypsy moth, Lymantria dispar L., oviposition and pupal survival were examined within mixed pine-hardwood stands located in the Virginia and North Carolina coastal plain and the North Carolina piedmont. Where burlap bands were not present as barriers to larval dispersal, the percentage of loblolly pine with gypsy moth egg masses present was significantly greater than expected if oviposition occurred randomly. The loblolly pine and oak components of the forests also had more total egg masses per tree compared with the other tree genera or species. However, when adjusted for tree size, egg mass density was generally similar among tree groups within an infestation. Tree size (dbh) was positively correlated with the number of egg masses present on a tree. Pupal predation, measured using freeze-dried pupae, was significantly higher over the 5-d sample period for (1) females versus males, (2) pupae placed at 0 m on the tree bole versus at 2 m, and (3) pupae placed on oak versus pine. The differential predation on oak versus pine appears to be the result of heavier vertebrate predation of the pupae placed on oak. The high rate of pupal removal, beginning the first night of exposure, from all locations suggests that predators will not have to learn to accept gypsy moth in their diets. The higher survival of pupae on pine is suggested to be one of the factors influencing the high egg-mass density on pine. Implications of these results for gypsy moth population dynamics in southern pine-hardwood forests are discussed.

A direct and sensitive high-performance liquid chromatographic (HPLC) method was developed for the detection and quantitative analysis of carbaryl and metabolites at the parts-per-billion level using a YMC stainless steel reversed-phase ODS (μBondapak C 18 ) HPLC column 1250 mm×3.9 nm i.d.), equipped with a Waters Guard-Pak C 18 precolumn module. The use of this methodology combined with radioisotopic technique is demonstrated by topically treating the southern pine beetle, Dendroctonus frontalis Zimmermann, with [naphthyl-1- 14 C] carbaryl and analyzing methanolic extracts of the exoskeleton, the vials in which beetles were held, and the whole body homogenates at various incubation time intervals after treatment

Since its introduction into the Southern Appalachians in the 1950s, the balsam woolly adelgid, Adelges piceae Ratzeburg (Hemiptera: Adelgidae), has devastated native populations of Fraser fir, Abies fraseri (Pursh) Poir. (Pinales: Pinaceae), and has become a major pest in Christmas tree plantations requiring expensive chemical treatments. Adelges piceae—resistant Fraser fir trees would lessen costs for the Christmas tree industry and assist in the restoration of native stands. Resistance screening is an important step in this process. Here, four studies directed toward the development of time— and cost—efficient techniques for screening are reported. In the first study, three methods to artificially infest seedlings of different ages were evaluated in a shade—covered greenhouse. Two—year—old seedlings had much lower infestation levels than 7 year—old seedlings. Placing infested bark at the base of the seedling was less effective than tying infested bark to the seedling or suspending infested bolts above the seedling. Although the two latter techniques resulted in similar densities on the seedlings, they each have positive and negative considerations. Attaching bark to uninfested trees is effective, but very time consuming. The suspended bolt method mimics natural infestation and is more economical than attaching bark, but care must be taken to ensure an even distribution of crawlers falling onto the seedlings. The second study focused on the density and distribution of crawlers falling from suspended bolts onto paper gridded into 7.6 × 7.6 cm cells. Crawler density in a 30 cm band under and to each side of the suspended bolt ranged from 400 to over 3000 crawlers per cell (1 to 55 crawlers per cm2). In the third study, excised branches from 4 year—old A. fraseri and A. vetchii seedlings were artificially infested with A. piceae to determine whether this technique may be useful for early resistance screening. The excised A. fraseri branches supported complete adelgid development (crawler to egg—laying adult), and very little adelgid development occurred on A. vetchii branches. The fourth study compared infestation levels and gouting response on excised versus intact branches of 4 year—old A. fraseri seedlings from three different seed sources, and excised branches from 4 year—old and 25 year—old trees. There were no differences in infestation levels between excised versus intact branches nor in very young versus mature trees; gouting response was observed only on intact branches.

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.) Carriere (Pinales: Pinaceae), forests throughout the eastern United States for biological control of the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), also of Japanese origin. Feeding, oviposition, immature development, and adult long-term survival of S. tsugae were tested in a series of no choice (single-prey) and paired-choice experiments between the primary host prey, A. tsugae, and the alternate host prey, A. piceae. In paired-choice feeding tests, the predator did not discriminate between eggs of the two adelgid species, but in the no choice tests the predator did eat significantly more eggs of A. piceae than those of A. tsugae. S. tsugae accepted both test prey for oviposition and preferred to lay eggs on adelgid infested versus noninfested host plants. Overall oviposition rates were very low (< 1 egg per predator female) in the oviposition preference tests. Predator immature development rates did not differ between the two test prey, but only 60% of S. tsugae survived egg to adult development when fed A. piceae compared to 86% when fed A. tsugae. S. tsugae adult long-term survival was significantly influenced (positively and negatively) by prey type and the availability of a supplemental food source (diluted honey) when offered aestivating A. tsugae sistens nymphs or ovipositing aestivosistens A. piceae adults, but not when offered ovipositing A. tsugae sistens adults. These results suggest that the development of S. tsugae laboratory colonies reared on a diet consisting only of A. piceae may be possible, and that the biological control potential of the predator might be expanded to include management of A. piceae in Christmas tree plantations.

Response of Fraser fir, Abies fraseri (Pursh) Poiret, to the balsam woolly adelgid, Adelges piceae (Ratzeburg), was evaluated by studying wood cores and bark samples taken from six sites near Mount Rogers, VA, and five sites in the Black Mountains of North Carolina surrounding Mount Mitchell. For comparison, samples were also collected from silver fir, Abies alba Miller, at four sites in the Black Forest of Germany. Average A. piceae densities were higher on trees at Mount Rogers than on Mount Mitchell trees. Proportions of trees producing abnormal wood in response to low or moderate A. piceae densities was greater for Mount Mitchell trees than for trees at Mount Rogers. Results from Mount Rogers support observations made for other fir species that A. piceae infestation induces outer bark formation, leading to tree recovery. Outer bark formation in trees from the Black Mountains and the Black Forest of Germany was not correlated with A. piceae density. There was indirect evidence that the outer bark measured in Mount Mitchell trees was incompletely formed, with an indistinct boundary layer between living and nonliving bark layers.

Under laboratory conditions, Dendroctonus frontalis Zimmermann and Ips grandicollis (Eichhoff) adults became self-marked with fluorescent powders upon emergence from treated logs. The technique provided a reliable procedure for marking adult bark beetles without having to handle them. When the powder remained dry, nearly all of the emerged beetles were marked. However, the percentage of marked beetles decreased dramatically following simulated rain events. Once marked, the mark remains intact on beetles stored dry or in ethylene glycol or ethanol (95%). Marking did decrease the adult life span of both D. frontalis and I. grandicollis, but had no significant effect on flight initiation by either species or semiochemical perception by I. grandicollis. No semiochemical tests were conducted with D. frontalis. If beetles are recaptured shortly following emergence and self-marking, the technique should be useful for examining scolytid dispersal in the field.

The phytoseiid predators Neoseiulus fallacis (Garman) and Metaseiulus occidentalis (Nesbitt) were reared together and fed on Tetranychus urticae Koch to determine the possibility of coexistence and the effect of vapor pressure deficit on the two species. Additionally, developmental times for the two predators feeding on the spruce spider mite, Oligonychus ununguis (Jacobi), were determined at 14°C and vapor pressure deficits of 1, 4, 6, and 10 millibars (mb). N. fallacis and M. occidentalis respond to vapor pressure deficit in essentially opposite ways. In the interaction treatments, populations of N. fallacis reproduced rapidly at low vapor pressure deficits (high atmospheric moisture) but vapor pressure deficits of 10 mb or greater severely limited population growth of this species; M. occidentalis populations grew more readily at higher vapor pressure deficits (>10 mb). At 14°C, egg mortality for M. occidentalis was 25, 10, 20, and 45% at 1, 4, 6, and 10 mb, respectively; egg mortality for N. fallacis at these respective vapor pressure deficits was 25, 0, 15, and 80%. At 14°C, developmental periods for immature stages of N. fallacis among vapor pressure deficits were significantly different in the egg and larval stages and in the egg stage for M. occidentalis . N. fallacis is directly subject to the physical environment (vapor pressure deficit effect on egg mortality) whereas M. occidentalis is subject to differences in survival responses (less prolific than N. fallacis at a given vapor pressure deficit and temperature). The differential response of the two predators suggests that releases of both species to control O. ununguis on Fraser fir in western North Carolina can be optimally timed based on humidity conditions.

A potential problem exists when rate (1/time) is used for parameter estimation instead of time in least-squares estimation of nonlinear development models, because the squared error is the quantity that is minimized by this technique. Minimizing the squared error in the rates is not equivalent to minimizing the squared error in time. This is of particular significance in modeling insect development because, when development times are largest, rates are small and squared errors in the rates produce large errors in time predictions. The purpose of this study was to show that, in many cases, parameters should be evaluated in terms of the observed data. Using least-squares techniques on rates did not allow for the minimization of the absolute squared error in time at low temperatures. Least-squares techniques applied to development time produced good predicted values throughout the temperature range in particular cases. These results show that when parameters are not evaluated in terms of the observed data but rather in some modified form such as rate, erroneous predictions may result.

Potential sapwood flow rates were measured for Fraser fir sterns that previously had been infested by the balsam woolly adelgid. The amount of abnormal wood produced during infestation was inversely related to the flow rate and linearly related to the amount of heartwood area. These results support the hypothesis that abnormal wood production associated with adelgid infestation can lead to water stress in the crowns of infested trees. The data also suggest that adelgid infestation accelerates the formation of heartwood.

Light-trap and soil-sampling studies were conducted at higher elevations in the Appalachian Mountains of northwestern North Carolina to determine adult flight patterns and white grub population densities and instar ratios of three scarab species: Phyllophaga anxia (LeConte) Glasgow, P. fusca (Froelich) Glasgow, and Polyphylla comes Casey. Flights of the two Phyllophaga species overlapped (May–June), preceding Polyphlla flights (July–August). Multiple flights of Phyllophaga anxia and P. fusca occurred over periods of 10 and 12 weeks, respectively. Multiple flights of Polyphylla comes lasted for 6 weeks. For all three species, peak flight densities occurred 3 to 4 weeks after initial flights. Phyllophaga males and females were captured in large numbers, but very few female Polyphylla were caught. Most Phyllophaga were caught before midnight, most Polyphylla between midnight and 0400 h. White grubs were found in the root zone from early May to late September. The mean (±SEM) and maximum grub densities observed were 14.6 ± 1.7 and 34.0 grubs per m2, respectively.

A study was performed to evaluate the potential of the egg parasitoid Trichogramma exiguum Pinto and Platner (Hymenoptera: Trichogrammatidae), the newly registered insect growth regulator (IGR) tebufenozide (Confirm), and a modified spray technique (top whorl only pesticide application) for suppression of Nantucket pine tip moth, Rhyacionia frustrana (Comstock) (Lepidoptera: Tortricidae), damage in Virginia pine, Pinus virginiana Mill., Christmas trees. Augmentative releases of T. exiguum failed to increase parasitism levels in release plots compared with controls, and significant reduction in tip moth damage did not occur. High predation levels on released T. exiguum may have contributed to the failure of parasitoid augmentations. Whole-tree and top whorl tebufenozide treatments provided significantly greater damage control than corresponding applications of acephate (Orthene), a commonly used pesticide in Christmas trees. Damage to trees receiving whole-tree chemical applications did not differ significantly from trees receiving top whorl treatments for most measurements of damage. Top whorl chemical treatments resulted in a 67% reduction in time required for application and a 70% reduction in pesticide used.

Fraser fir (Abiesfraseri (Pursh) Poir.) seedlings were artificially infested with balsam woolly adelgid, Adelgespiceae (Ratz.), then subjected to drought-stress treatments. Infestation caused a distinct swelling in the main stem, caused by the accumulation of abnormal wood (i.e., "rotholz"). As expected, drought stress reduced diameter growth in the main stem. However, the reduction in wood increment caused by drought stress was relatively small for infested seedlings as compared with uninfested seedlings, owing to the production of rotholz. This implies that infested trees expend considerable energy and nutrients for the production of poorly functioning wood even during periods of stress. The implications of this research for interpreting patterns of tree mortality in the southern Appalachian Mountains are discussed.

The potential interactions among abiotic and biotic factors in southern pine forests are extremely complex, particularly when one considers these interactions over a tree’s lifetime. We know from experimental data that individual factors tend to impact trees either negatively or positively: Only factors that show a response tend to be published. Interactions among factors and their impact on trees can be antagonistic, neutral, additive, or synergistic, resulting in a continuum of tree response. When considering these complex relationships, four critical features must be considered (Table 7.1). The first consists of the abiotic aspects associated with the forest environment, whereas the other three encompass various levels of organization within the biotic features from the individual organism through the ecosystem level.

Twenty-five full-length papers and 19 poster papers on the interactions of different forest insect guilds with their host plants are presented in this proceedings, which is the result of an International Union of Forestry Research Organization Symposium that took place in Abakan, Siberia, U.S.S.R. in August 1989.

Research on tree decline has shown that the proportion of sapwood area to heartwood area is an important measure of tree health. Infestation by the balsam woolly adelgid (BWA), Adelges piceae (Ratz.), causes the formation of abnormal wood, which is thought to conduct sap poorly. BWA infestation is also associated with lower (more negative) xylem pressure potentials and increased areas of heartwood. We hypothesize that lower pressure potentials (a consequence of abnormal wood production) increase the rate of cavitation (gas-filling) of sapwood tracheids, thereby accelerating heartwood formation. If this hypothesis is correct, adelgid attack causes loss of functional sapwood both directly and indirectly. There is evidence that the balsam woolly adelgid is an important factor causing the decline of Fraser fir, Abies fraseri (Pursh) Poiret, in the southern Appalachians. However adelgid damage is probably interacting with many other environmental factors to cause reductions in per cent sapwood area. Determining the relevance of this pest to tree decline can be accomplished by examing the relationship that exists between adelgid infestation, increment growth, and per cent sapwood area.

Single applications of 0.51% insecticidal soap/diazinon (40%:0.4% AI), 0.52% insecticidal soap/methoxychlor (38.7%:3.0% AI), 0.01% fenvalerate, 0.01% permethrin, and one and two applications of 0.63% Safer’s insecticidal soap were tested against the egg, crawler, nymph, and adult of the balsam woolly adelgid, Adelges piceae (Ratzeburg). With the exception of the soap/methoxychlor, all materials appeared to be effective against nonegg stages. The residual toxicity of fenvalerate and permethrin killed all nonegg stages, resulting in no egg production in later samplings. Fenvalerate and insecticidal soap did not adversely affect nontarget organisms in the litter. Fenvalerate showed no phytotoxicity applied to Fraser fir, Abies fraseri (Pursh) Poir. Christmas trees at 0.01, 0.02, 0.04, and 0.08% concentrations. A soap discoloration study indicated that succulent foliage (June growth) may be sensitive to soap treatments, but multiple sprays of either high or low concentrations may be used with little discoloration at times later than June.