Paris L. Lambdin

Insect Guild Structure Associated with Eastern Hemlock in the Southern Appalachians

Abstract 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 transient guild assignments were made. The herbivore and transient guilds were subdivided into chewers, sapsuckers, flower feeders, pollen feeders, pollen/nectar/sap feeders, and seed feeders. A significant association was found between guilds on immature and mature hemlocks at low elevations, but no significant association was found at high elevations. There was also a strong association of phytophagous insects on immature hemlocks and scavengers on mature hemlocks. The observed transient, scavenger, and predator guilds had a significantly lower co-occurrence among species indicating segregation of the species within these guilds. The herbivore guild had a significantly higher co-occurrence among species than the simulated index indicating aggregation of species within this guild across sites. Detritivore, hematophage, and parasitoid guilds did not differ significantly from the simulated community. These results document a diverse and dynamic insect community on eastern hemlock before invasion by hemlock woolly adelgid and elongate hemlock scale.

Community Response of Insects Associated with Eastern Hemlock to Imidacloprid and Horticultural Oil Treatments

ABSTRACT 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) imidacloprid soil injection, (3) imidacloprid tree injections, and (4) horticultural oil applications on multiple levels of organization (composition, overall specimen abundance and species richness, guild specimen abundance and species richness, and individual species) within the phytophagous and transient canopy insect community. Community composition differed significantly among treatments based on analysis of similarity. Mean species richness and specimen abundance were significantly reduced by one or more treatments. Soil drench applications significantly reduced species richness for the detritivore and phytophaga guilds. Furthermore, specimen abundance for species in the detritivore, fungivore, phytophaga, scavenger, and transient phytophaga guilds was significantly lower in the soil drench treatment. This trend was consistent in all insect guilds examined, with the exception of the hematophaga guild that was not significantly lower than for species on the control trees. Of the 293 species documented to be associated with eastern hemlocks, 33 species were found to be directly effected by one or more of the chemical treatments.

Spatial and temporal distribution of imidacloprid in eastern hemlock in the southern Appalachians.

ABSTRACT 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 over a two year time span, Enzyme-linked immunosorbent assays were conducted every three months posttreatment to assess imidacloprid concentration within the sap. The effect of application timing (fall versus spring) and application method (soil drench, soil injection, and tree injection) on the translocation of imidacloprid throughout the canopy, and the quantity of imidacloprid translocated in the sap of eastern hemlock branches and the terminal twig and needle tissue was determined. Concentration levels progressively declined from the bottom strata to the top strata of the canopy. This trend was consistent in all chemically treated trees. Tree injections provided the lowest concentration and the most nonuniform distribution of imidacloprid throughout the canopy. The highest insecticide concentrations within the tree across all strata over the two year period were consistently associated with the soil drench method followed by the soil injection method. Imidacloprid concentrations peaked between month 9 and 12 posttreatment, and then declined; however, at two years posttreatment, soil drench and soil injected trees contained concentrations reported as being effective for control of the hemlock woolly adelgid.

New County and State Records for Tennessee of an Exotic Pest, Halyomorpha halys (Hemiptera: Pentatomidae), with Potential Economic and Ecological Implications

Halyomorpha halys (Hemiptera: Pentatomidae), the brown marmorated stinkbug, is an exotic polyphagous species from Asia that was first collected in North America from Allentown, Pennsylvania in 1996 (Hamilton & Shearer 2003). In 2002, H. halys was reported from 6 counties in Pennsylvania (Hoebeke 2002), and by 2003, the species was reported from 2 neighboring counties in New Jersey (Bernon et al. 2004). In 2005, this species was reported from Vallejo, Solano County, California, with over a dozen individuals recovered from a storage unit rented by a new resident that had relocated from Pennsylvania. Within 10 years from the original record from Allentown, Pennsylvania, H. halys had been reported from 26 counties in Pennsylvania (Jacobs & Bernhard 2008). This pest continues to increase its range and has since been reported around Portland and Salem, Oregon (CDFA 2005), as well as in Delaware, Maryland, Virginia, and West Virginia (Khrimian et al. 2008). On 30 Oct. 2008, a single adult female was captured in the home of the first author in Knoxville, Knox County, Tennessee. The specimen, approximately 16.2 mm in length, displayed the characteristic light bands on the terminal 2 antennal segments, as well as alternating light and dark banding along the exposed lateral abdominal margins (Fig. 1). Closer examination also revealed the absence of teeth on the juga, as well as a smooth anterior pronotal margin, both of which distinguish this species

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.

ABSTRACT 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. Imida-cloprid, 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 hemlock produces 12 metabolites; two of these, imidacloprid 5-hydroxy and imidacloprid olefin, are considered toxicologically important metabolites. However, little is known about the persistence of these metabolites in eastern hemlock in the southern Appalachians. Concentrations of imidacloprid, olefin, and 5-hydroxy were quantified by using HPLC/MS/MS techniques. Over the 3-yr study, concentrations of imidacloprid and consequent 5-hydroxy and olefin were highest in trees treated with a soil injection in the spring. Imidacloprid and 5-hydroxy concentrations in sap were highest at 12 mo posttreatment and in tissue at 15 mo posttreatment. Imidacloprid was detected through 36 mo posttreatment and 5-hydroxy was detected through 15 mo posttreatment. Olefin concentrations in both sap and tissue were highest at 36 mo posttreatment and were detected in high concentrations through 36 mo posttreatment. Concentrations of imidacloprid were highest in the bottom stratum of the canopy and lowest in the top stratum. Concentrations of olefin and 5-hydroxy were highest in the top stratum and lowest in the bottom stratum.

The ultrastructure of hemocytes inDactylopius confusus (Cockerell), and the role of granulocytes in the synthesis of cochineal dye

SummaryThe ultrastructural study of free circulating hemocytes in the adult cochineal scale,Dactylopius confusus (Cockerell), demonstrated five cell types: prohemocytes, typical granulocytes (T-granulocytes), oenocytoids, plasmatocytes, and granulocytes with modified sub-cellular structure to perform a special synthetic and secretory function, which we refer to as “modified granulocytes” (M-granulocytes). Prohemocytes showed undifferentiated sub-cellular structure of the basic stem cell type (i.e., high cytoplasmic density with numerous ribosomes, centrally located large nucleus with a distinct nucleolus, and poorly developed endoplasmic reticulum). The commonly observed typical granulocytes (T-granulocytes) had several smooth endoplasmic reticulum (SER) with dilated cisternae and many SER-derived membrane bounded granules of different sizes and electron density. Oenocytoids were identified by the presence of many crystals, RER-originated fine secretory granules, and an eccentric nucleus. Plasmatocytes were easily characterized by their variable shapes and irregular outline with pseudopodia-like cytoplasmic extensions, possession of an elongated lobed nucleus, multivesicular bodies, RER-derived membrane bounded, electron-dense, lysosomelike vacuoles, well-developed SER cisternae, and numerous pinocytic and SER-originated vesicles of different sizes along the peripheral region. M-granulocytes comprised the largest proportion of hemocytes in all samples observed. M-granulocytes were distinguished not only by the presence of membrane bounded granules of different sizes and electron density, but by the possession of large nuclei with distinct nucleoli, many mitochondria, and a highly developed network of rough endoplasmic reticulum (RER). M-granulocytes had abundant, rosette-shaped, RER-derived chains of fine secretory granules, which accumulated in the cytoplasm and vacuoles, and were ultimately deposited into the hemolymph by exocytosis. These fine granules gave a positive result with periodic acid-Schiff (PAS) test. Based on RER-synthesized fine secretory granules (M-granulocytes), their ultimate deposition into hemolymph, the red pigmentation of hemolymph, positive PAS histochemical test of these granules, and the high population of these hemocytes, no such cell type has been described in previous studies in insects. The sub-cellular structure of the granulocyte in this insect has been modified to perform a special synthetic and secretory function (i.e., possibly the synthesis of the red pigment found in hemolymph, which has been the source of commercially important cochineal dye).

Establishment and coexistence of two predators, Laricobius nigrinus and Sasajiscymnus tsugae, introduced against hemlock woolly adelgid on eastern hemlock

Abstract The coexistence of two introduced predatory species, Laricobius nigrinus Fender and Sasajiscymnus tsugae (Sasaji and McClure), and a native predator, L. rubidus LeConte, on eastern hemlock was documented for the first time. Details of their coexistence and implications to management of hemlock woolly adelgid, Adelges tsugae Annand, are discussed.

Ultrastructural and phylogenetic assessment of wax glands in pit scales (Homoptera : Coccoidea)

TEM/SEM and computerized images of 5 wax glands for 3 type species of Coccoidea (Homoptera): Asterodiaspis variolosa (Asterolecaniidae), Cerococcus quercus (Cerococcidae) and Lecanodiaspis sardoa (Lecanodiaspididae) were studied. Their cuticular structures were compared with 142, 56, and 61 species in their respective families to determine relationships among pit scale taxa. Significant differences include: the morphology of the outer and inner ductule of the tubular duct gland, structure of the pores (8-shaped, multilocular and quinquelocular), and the absence or presence of cribriform plates and their structural variations. Three distinctive tubular duct shapes (asterform, ceroform and lecanoform) are common in pit scale species. Apomorphic characteristics of the asterform tubular ducts include an absence of the inner ductule and the progressive reduction of the outer ductules diameter from the pore to its inner end. These characters easily separate asterolecaniids from the cerococcid-lecanodiaspidid lineage. The constricted lecanoform tubular ducts and the curved teeth on the rim at the inner end of the outer ductule in the ceroform tubular ducts are regarded as autapomorphic. The presence of 8-shaped pores is considered a plesiomorphic condition. Specific cuticular variations of the 8-shaped pores, characterizing familial taxa, include pores even with the surface in asterolecaniids, pores with raised walls in cerococcids, and bent pores in lecanodiaspidids. The dominant 8-shaped pore patterns in pit scales are those arranged in a marginal band in lecanodiaspidids, in a swirl-like pore pattern in the cerococcids, and in a marginal row in asterolecaniids. A divergent evolutionary trend is noted for the structure of the cribriform plate; they are with micro-orifices in cerococcids, but without micro-orifices in lecanodiaspidids. The former state is considered apomorphic. Cribriform plates arranged in clusters characterize the cerococcids, while plates in longitudinal rows characterize the lecanodiaspidids. These data confirm the concept that the pit scales constitute a paraphyletic group and the Asterolecaniidae, Cerococcidae and Lecanodiaspididae are monophyletic.

Recovery of Sasajiscymnus tsugae, released against hemlock woolly adelgid, Adelges tsugae, in the southern Appalachians

Abstract Eastern hemlock in the Great Smoky Mountains National Park is currently threatened by the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae). As part of a management plan against this invasive insect pest, about 350,000 adults of the predatory beetle Sasajiscymnus tsugae (Sasaji and McClure) (Coleoptera: Coccinellidae) were released at ca. 150 sites in the Park from 2002 to 2007. Of these adult release sites, 33 were sampled in 2008 and 2009 using beat-sheet sampling for 4 man-hours. Sasajiscymnus tsugae adults (n=78) and/or larvae (n=145) were recovered from seven sites (21.2% of the release sites sampled). Recovery of S. tsugae was significantly associated with older release sites, with the most beetles recovered from 2002 release sites. These results indicate that S. tsugae may require more time (i.e., 5–7 years) than anticipated for population densities to reach readily detectable levels in some areas.

Host utilization of field-caged native and introduced thistle species by Rhinocyllus conicus.

ABSTRACT Rhinocyllus conicus Fröelich was introduced from Europe into North America as a biological control agent of the exotic weed Carduus nutans L. Concern exists over the feeding of this weevil on at least 25 species of native Cirsium thistles. Beginning in 2008, cage studies isolating adults of R. conicus on buds and flower heads of all eight thistle species (native and introduced) recorded from Tennessee were conducted to test if R. conicus could use these species for reproduction and what impacts larval feeding of R. conicus may have on seed production. Larvae of R. conicus completed development in heads of the native species C. carolinianum (Walter) Fernald and Schubert, and C. horridulum Michaux, and significant reductions in seed numbers of both species occurred during 2008. Rhinocyllus conicus oviposited on both C. carolinianum and C. horridulum at significantly greater levels than the introduced species C. arvense (L.) Scopoli and C. vulgare (Savi) Tenore. Infested heads of C. carolinianum contained numbers of R. conicus per centimeter of plant head width similar to Ca. nutans in 2008, and both native species contained numbers of R. conicus per centimeter of plant head width similar to C. arvense and C. vulgare in 2009. Body length was similar between R. conicus reared on native thistles and its target host Ca. nutans. This report is the first documentation of R. conicus feeding and reproducing on C. carolinianum and C. horridulum. Although R. conicus has been observed only on introduced thistles in naturally occurring populations in this region, the utilization of C. carolinianum and C. horridulum as host species in controlled conditions warrants continued monitoring of field populations and further investigation into factors that may influence nontarget feeding in the future.