Melissa K. Fierke

Development and Comparison of Intensive and Extensive Sampling Methods and Preliminary Within-Tree Population Estimates of Red Oak Borer (Coleoptera: Cerambycidae) in the Ozark Mountains of Arkansas

Abstract Populations of red oak borer, Enaphalodes rufulus (Haldeman), a native wood-boring beetle, seem to be at unprecedented levels that are coinciding with extensive oak mortality occurring in the Ozark Mountains of Arkansas, Oklahoma, and Missouri. To quantify population levels, we developed intensive and extensive sampling methods with respect to the seasonal phenology of active and quiescent stages of the borer’s synchronous 2-yr life cycle. Intensive whole-tree sampling yields data for the entire infested tree bole and provides baseline data for development of less time-consuming sampling methods. Extensive partial-tree sampling uses a nine-sample proportional sampling scheme to estimate densities, which are extrapolated to the whole tree. Data comparison reveals extensive estimates and intensive data are not significantly different, thus verifying extensive sampling as a relatively accurate and acceptable sampling method. Preliminary data from 58 trees confirm epidemic population levels in three areas of the Ozark National Forest in northern Arkansas. Mean number of phloem galleries initiated by current generation larvae on 38 trees was 599 ± 50 (SE) per tree, average number of live red oak borer found in 57 trees was 77 ± 15 per tree, and mean number of previous generation heartwood galleries present in 38 trees was 185 ± 30. Data generated through this research will permit detailed studies of red oak borer biology and mortality, facilitate development of less time-consuming field sampling techniques, and set the stage for further study of factors contributing to the current outbreak and associated tree mortality.

Identification of a Male-Produced Aggregation Pheromone for Monochamus scutellatus scutellatus and an Attractant for the Congener Monochamus notatus (Coleoptera: Cerambycidae)

ABSTRACT We report identification and field testing of 2-(undecyloxy)-ethanol (monochamol) as a sex-specific, aggregation pheromone component produced by males of Monochamus scutellatus scutellatus (Say) (Coleoptera: Cerambycidae), a longhorned beetle native to North America. A congener, Monochamus notatus (Drury), which uses the same hosts as M. s. scutellatus, also was attracted to this compound in field trials, suggesting it may be a pheromone component for this species as well. Panel traps were deployed along transects at each of five field sites in May 2010 to test attraction of native beetle species to a suite of cerambycid pheromone components, including monochamol, 3-hydroxyhexan-2-one, (2R*,3R*)- and (2R*, 3S*)-2,3-hexanediol, racemic (E/Z)-fuscumol, and (E/Z)-fuscumol acetate. In total, 209 adult M. s. scutellatus (136 females, 73 males) and 20 M. notatus (16 females, four males) were captured, of which 86 and 70%, respectively, were captured in traps baited with monochamol (means significantly different). Analysis of headspace volatiles from adult M. s. scutellatus by coupled gas chromatography-mass spectrometry and gas chromatography-electroantennogram detection confirmed that monochamol was produced only by males. Monochamol was not found in headspace extracts from adult M. notatus. This study provides further evidence that monochamol is a pheromone component common to several species in the genus Monochamus. The pheromone component should prove useful for monitoring native species for management purposes or conservation efforts, and for quarantine monitoring for exotic species.

Invasive Species Influence Riparian Plant Diversity Along a Successional Gradient, Willamette River, Oregon

Abstract Recognizing the importance of invasive plant species is necessary to preserve, protect, and manage for biodiversity in riparian habitats. Non-metric multidimensional ordination of 28 study sites along a successional gradient on the Willamette River indicated that abundance of reed canarygrass (Phalaris arundinacea L). was strongly correlated with stand plant composition and abundance. High abundance of reed canarygrass was also correlated with lower values of understory species diversity and total species richness. Considering older stands only (n = 19), reed canarygrass presence and abundance was the most highly correlated plant species with overall stand plant species presence and abundance. This was probably due to this invasive species inhibiting establishment of understory tree, shrub, herbaceous species, and late-successional tree species during understory reinitiation. Without intervention to control the establishment and survival of reed canarygrass, and perhaps some other invasive species, such as Himalayan blackberry (Rubus armeniacus L.) and English ivy (Hedera helix L.), it is conceivable that these species will become more influential through time with adverse effects ensuing for overall biodiversity at the riverscape level.

Factors affecting suitability of Quercus rubra as hosts for Enaphalodes rufulus (Coleoptera: Cerambycidae).

ABSTRACT Epidemic populations of Enaphalodes rufulus (Haldeman), red oak borer, a native longhorned wood boring beetle, were implicated as a major contributor to a recent widespread oak mortality event in the Ozark National Forest of Arkansas. We assessed potential factors affecting suitability of a primary host Quercus rubra L., northern red oak, which experienced dieback and mortality throughout two successive borer cohorts. We sampled trees with various E. rufulus infestation levels during 2001–2003 when populations were at outbreak levels and 2003–2005 when borer numbers were declining. We measured phloem thickness and calculated a vigor index; the ratio of the past 5-yr basal area increment to sapwood area. We also counted established first year larval feeding galleries and outer-bark adult emergence holes and measured surface area of feeding galleries on a subset of Q. rubra to assess the importance of host susceptibility versus suitability. Phloem thickness did not exhibit any patterns among hosts of varying infestation levels and was therefore not likely an important factor limiting larval success. Less vigorous Q. rubra appeared to be the most suitable hosts, although it is unclear whether reduced vigor was initially caused by stress of E. rufulus infestation or environmental factors. Host suitability seems to be more important than host susceptibility, as numbers of initiated galleries were not consistently different among host infestation classes and between both cohorts, whereas numbers of emerging adults did differ predictably among host infestation classes.

Optimization of sampling methods for within-tree populations of red oak borer, Enaphalodes rufulus (Haldeman) (Coleoptera: Cerambycidae).

Abstract In the Ozark Mountains of northern Arkansas and southern Missouri, an oak decline event, coupled with epidemic populations of red oak borer (Enaphalodes rufulus Haldeman), has resulted in extensive red oak (Quercus spp., section Lobatae) mortality. Twenty-four northern red oak trees, Quercus rubra L., infested with red oak borer, were felled in the Ozark National Forest between March 2002 and June 2003. Infested tree boles were cut into 0.5-m sample bolts, and the following red oak borer population variables were measured: current generation galleries, live red oak borer, emergence holes, and previous generation galleries. Population density estimates from sampling plans using varying numbers of samples taken randomly and systematically were compared with total census measurements for the entire infested tree bole. Systematic sampling consistently yielded lower percent root mean square error (%RMSE) than random sampling. Systematic sampling of one half of the tree (every other 0.5-m sample along the tree bole) yielded the lowest values. Estimates from plans systematically sampling one half the tree and systematic proportional sampling using seven or nine samples did not differ significantly from each other and were within 25% RMSE of the “true” mean. Thus, we recommend systematically removing and dissecting seven 0.5-m samples from infested trees as an optimal sampling plan for monitoring red oak borer within-tree population densities. This optimal sampling plan should allow for collection of acceptably accurate within-tree population density data for this native wood-boring insect and reducing labor and costs of dissecting whole trees.

Two Novel Prey Families for the Buprestid-Hunting Wasp Cerceris fumipennis Say (Hymenoptera: Crabronidae)

Cerceris fumipennis Say, 1837 (Hymenoptera: Crabronidae: Cercerini) is native to eastern North America. It has a typical solitary digger wasp life cycle (Evans 1971). Females nest individually in compacted sandy soils constructing simple burrows. They serially provision cells with paralyzed prey and lay a single egg in each cell when it is fully provisioned. Number of prey items per cell can vary from three to 51 beetles per cell depending on prey size and larval sex (females are larger than males) (Evans 1971; Hook and Evans 1991). Larvae consume prey and then spin a cocoon in which they overwinter. In northern areas, C. fumipennis is univoltine, while in the southern end of its range it can have two generations a year (Hook and Evans 1991). Cerceris fumipennis specializes on adults of the family Buprestidae, and records indicate they catch >100 species in 13 genera (Hook and Evans 1991; Careless 2009; WH unpublished data). The wasp′s fidelity to the Buprestidae is impressive (Evans 1971; Hook and Evans 1991). There is one recorded anomalous species that females infrequently take: Neochlamisus bebbianae Brown (Coleoptera: Chrysomelidae: Cryptocephalinae: Chlamisini) (Hook and Evans 1991) (Table 1). These beetles are not effectively paralyzed by the wasp, but can be found in larval cells (Hook and Evans 1991; CER personal observation). Hartman (1905) recorded C. fumipennis catching a weevil, but Hook and Evans (1991) argued that the wasp capturing the weevil was likely either Cerceris atramontensis Banks, 1913 or Cerceris tolteca de Saussure, 1867. These are sympatric species of Cerceris Latreille that prey on weevils, and whose flight period is more consistent with the late October collection date. Cerceris fumipennis has recently gained attention as a ‘biosurveillance’ tool for the invasive emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) (Careless and Marshall 2010). In 2009 and 2010, researchers observed C. fumipennis colonies in northeastern America as part of a monitoring program for non-native buprestids. With the current large volume of collection, several other anomalous prey were recorded (see below and unless otherwise noted, specimens were collected directly from female wasps). Taxa in bold represent new prey records for C. fumipennis. Connecticut specimens are deposited in The Connecticut Agricultural Experiment Station collection. New York specimens are deposited in the State University of New York Environmental Science and Forestry museum insect collection. Maine specimens are deposited in the state insect collection at the Maine Forest Service Insect and Disease Laboratory. Bassareus mammifer (Newman, 1840) (Coleoptera: Chrysomelidae: Cryptocephalinae:

RED OAK BORER (COLEOPTERA: CERAMBYCIDAE) FLIGHT TRAPPING IN THE OZARK NATIONAL FOREST, ARKANSAS

Abstract High population densities of red oak borer, Enaphalodes rufulus (Haldeman), are believed to be a major contributor to recent widespread oak mortality in the Ozark Mountains of Arkansas. The intent of this research was to expand our knowledge on specific aspects of this insects biology, life history, and distribution by trapping flying adults in the Ozark National Forest during emergence of 2001, 2003, and 2005 cohorts. Passive flight intercept trap catches revealed that preferred flight height and thus optimal trap placement for monitoring populations was close to the base of the dominant/co-dominant northern red oak, Quercus rubra L., canopy. Flight periods and peak flight were different in 2001 and 2003. Emergence occurred a week earlier in 2001 vs. 2003. Peak flight occurred over a 3-week period from mid Jun to early Jul in 2001 in contrast to 2003 peak flight, which occurred the first week of Jul. Male to female ratios were 1.9:1 and 1.4:1 for 2001 and 2003, respectively. In 2003, sex ratios varied significantly among 5 topographic positions evaluated, north, south, east, and west-facing benches and ridges. Total numbers of red oak borers caught varied both spatially and temporally from cohort to cohort in traps placed in 3 different areas on 5 topographic positions. This research should facilitate efficient future monitoring of adult red oak borer and form a basis for investigating stand and landscape-level factors affecting population densities throughout the forest.

Susceptibility of two hymenopteran parasitoids of Agrilus planipennis (Coleoptera: Buprestidae) to the entomopathogenic fungus Beauveria bassiana (Ascomycota: Hypocreales).

Emerald ash borer (EAB), Agrilus planipennis Fairmaire, native to Asia, is killing ash trees (Fraxinus spp.) across 15 states and southeastern Canada. Integrated pest management using biological control is the only viable long-term approach for controlling the spread of EAB outside of host resistance. Three hymenopteran parasitoids, Spathius agrili Yang, Tetrastichus planipennisi Yang, and Oobius agrili Zhang and Huang were discovered attacking EAB in China and were approved for release in the United States in 2007. The objective of this study was to assess susceptibility of the larval parasitoid species S. agrili and T. planipennisi, relative to that of EAB, to Beauveria bassiana, an entomopathogenic fungus that infects and kills EAB adults when sprayed on ash bark or foliage. Adult EAB and parasitoids were exposed to B. bassiana inoculated ash twigs for 2 h and then monitored daily for death and signs of infection for up to 10 days. All EAB adults exposed to B. bassiana were fatally infected while mean survival for control EAB was 77%. Average survival in the treatment groups for T. planipennisi and S. agrili were 99% and 83%, respectively, indicating these parasitoids are relatively unaffected by exposure to B. bassiana. This research elucidates interactions between a fungal pathogen and two parasitoids of EAB, and provides data necessary to developing a successful multi-stage integrated management approach to control of EAB.

Evaluating Buprestid Preference and Sampling Efficiency of the Digger Wasp, Cerceris fumipennis, Using Morphometric Predictors

Abstract In-ground colonies of the native digger wasp, Cerceris fumipennis Say (Hymenoptera: Crabronidae), were sampled over two years in four New York State counties to characterize prey range, primarily their preying on beetles in the metallic wood-boring family, Buprestidae. These records were also used to evaluate beetle sampling efficiency by comparing collected beetles to historic county records and to identify limitations of wasp-mediated sampling in study areas. Overall, 1,530 beetles representing three families and 44 beetle species were collected from C. fumipennis . Five of these species ( Agrilus cuprescens (Ménétriés) (Coleoptera: Buprestidae), A. pensus Horn , Buprestis nutalli Kirby , Chrysobothris scabripennis Gory and Laporte , Dicerca pugionata (Germar)) were new prey records for C. fumipennis . The wasps exhibited a strong preference for larger beetle genera (e.g., Dicerca, Buprestis ), which accounted for 68% of beetles caught. Agrilus and Chrysobothris were the next dominant genera, accounting for 16% and 11%, respectively. A 4–19 mm prey size range is proposed, as all beetles collected were within this range despite the availability of prey outside of this range. Cerceris fumipennis caught 43% of the 42 buprestids species present in museum records from the four census counties as well as an additional 23 buprestid species that were not represented in museum records. Of the 22 buprestid species identified in museum collections that were not caught by C. fumipennis in the census counties, only one was within the proposed size range and active during the C. fumipennis flight season (late June through August). Overall, sampling C. fumipennis colonies over two summers at five sites resulted in 32% of the recorded buprestid species in New York State being caught, indicating that monitoring colonies is an efficient and viable means of quantifying buprestid assemblages.

Detection and Identification of Two New Native Hymenopteran Parasitoids Associated with the Exotic Sirex noctilio in North America

Abstract. Rhyssa crevieri (Provancher), a primary parasitoid of Siricidae wasps, and the Holarctic poemeniine ichneumonid, Pseudorhyssa nigricornis (Ratzeburg), a cleptoparasitoid of Siricidae via its parasitoids (Ichneumonidae: Rhyssinae), were reared from two stands of Scots pine (Pinus sylvestris L.) and red pine (P. resinosa Ait.) infested with the exotic siricid Sirex noctilio F. near Tully (Onondaga Co.), New York, in 2010. Previously, P. nigricornis has been recorded from the primary siricid parasitoids Rhyssa persuasoria (in Europe and North America) and R. howdenorum Townes and Townes and R. lineolata (Kirby) (in North America). Peak emergence of P. nigricornis occurred in early May concurrently with R. persuasoria and R. crevieri. A second peak occurred in late May, which overlapped peak emergence of R. lineolata and Megarhyssa nortoni (Cresson). Although 14 individuals of two native siricids, Sirex nigricornis F. and S. edwardsii Brullé, emerged from sampled trees, the number of S. noctilio recovered was far higher (372), suggesting cleptoparasitism of the exotic woodwasp rather than native siricids. Approximately 26% of rhyssine parasitoids in pine stands were cleptoparasitized by P. nigricornis. This study marks the first association of R. crevieri and P. nigricornis with S. noctilio in North America. A diagnosis, color images of characters, and a key are provided to aid in the identification of all parasitoids in this study.