Mating Disruption as a Suppression Tactic in Programs Targeting Regulated Lepidopteran Pests in US.

Mating disruption, the broadcast application of sex-attractant pheromone to reduce the ability of insects to locate mates, has proven to be an effective method for suppressing populations of numerous moth pests. Since the conception of mating disruption, the species-specificity and low toxicity of pheromone applications has led to their consideration for use in area-wide programs to manage invasive moths. Case histories are presented for four such programs where the tactic was used in the United States: Pectinophora gossypiella (pink bollworm), Lymantria dispar (gypsy moth), Epiphyas postvittana (light brown apple moth), and Lobesia botrana (European grapevine moth). Use of mating disruption against P. gossypiella and L. botrana was restricted primarily to agricultural areas and relied in part (P. gossypiella) or wholly (L. botrana) on hand-applied dispensers. In those programs, mating disruption was integrated with other suppression tactics and considered an important component of overall efforts that are leading toward eradication of the invasive pests from North America. By contrast, L. dispar and E. postvittana are polyphagous pests, where pheromone formulations have been applied aerially as stand-alone treatments across broad areas, including residential neighborhoods. For L. dispar, mating disruption has been a key component in the program to slow the spread of the infestation of this pest, and the applications generally have been well tolerated by the public. For E. postvittana, public outcry halted the use of aerially applied mating disruption after an initial series of treatments, effectively thwarting an attempt to eradicate this pest from California. Reasons for the discrepancies between these two programs are not entirely clear.

Genetic diversity among eight Dendrolimus species in Eurasia (Lepidoptera: Lasiocampidae) inferred from mitochondrial COI and COII, and nuclear ITS2 markers.

BACKGROUND: Moths of genus Dendrolimus (Lepidoptera: Lasiocampidae) are among the major pests of coniferous forests worldwide. Taxonomy and nomenclature of this genus are not entirely established, and there are many species with a controversial taxonomic position. We present a comparative evolutionary analysis of the most economically important Dendrolimus species in Eurasia. RESULTS: Our analysis was based on the nucleotide sequences of COI and COII mitochondrial genes and ITS2 spacer of nuclear ribosomal genes. All known sequences were extracted from GenBank. Additional 112 new sequences were identified for 28 specimens of D. sibiricus, D. pini, and D. superans from five regions of Siberia and the Russian Far East to be able to compare the disparate data from all previous studies. In total, 528 sequences were used in phylogenetic analysis. Two clusters of closely related species in Dendrolimus were found. The first cluster includes D. pini, D. sibiricus, and D. superans; and the second, D. spectabilis, D. punctatus, and D. tabulaeformis. Species D. houi and D. kikuchii appear to be the most basal in the genus. CONCLUSION: Genetic difference among the second cluster species is very low in contrast to the first cluster species. Phylogenetic position D. tabulaeformis as a subspecies was supported. It was found that D. sibiricus recently separated from D. superans. Integration of D. sibiricus mitochondrial DNA sequences and the spread of this species to the west of Eurasia have been established as the cause of the unjustified allocation of a new species: D. kilmez. Our study further clarifies taxonomic problems in the genus and gives more complete information on the genetic structure of D. pini, D. sibiricus, and D. superans.

Genetic structure, admixture and invasion success in a Holarctic defoliator, the gypsy moth (Lymantria dispar, Lepidoptera: Erebidae).

Characterizing the current population structure of potentially invasive species provides a critical context for identifying source populations and for understanding why invasions are successful. Non-native populations inevitably lose genetic diversity during initial colonization events, but subsequent admixture among independently introduced lineages may increase both genetic variation and adaptive potential. Here we characterize the population structure of the gypsy moth (Lymantria dispar Linnaeus), one of the world's most destructive forest pests. Native to Eurasia and recently introduced to North America, the current distribution of gypsy moth includes forests throughout the temperate region of the northern hemisphere. Analyses of microsatellite loci and mitochondrial DNA sequences for 1738 individuals identified four genetic clusters within L. dispar. Three of these clusters correspond to the three named subspecies; North American populations represent a distinct fourth cluster, presumably a consequence of the population bottleneck and allele frequency change that accompanied introduction. We find no evidence that admixture has been an important catalyst of the successful invasion and range expansion in North America. However, we do find evidence of ongoing hybridization between subspecies and increased genetic variation in gypsy moth populations from Eastern Asia, populations that now pose a threat of further human-mediated introductions. Finally, we show that current patterns of variation can be explained in terms of climate and habitat changes during the Pleistocene, a time when temperate forests expanded and contracted. Deeply diverged matrilines in Europe imply that gypsy moths have been there for a long time and are not recent arrivals from Asia.

Identification of a potential third component of the male-produced pheromone of Anoplophora glabripennis and its effect on behavior.

The Asian longhorned beetle, Anoplophora glabripennis, is considered to be one of the most serious invasive pests of deciduous trees in North America. An efficient monitoring trap is needed to detect and delimit new introductions and assess population densities of established infestations. Previous studies on A. glabripennis have shown that males produce a two-component aggregation pheromone that consists of a 1:1 blend of 4-(n-heptyloxy)butan-1-ol and 4-(n-heptyloxy)butanal. Moderate attraction in field trapping studies suggested that there may be additional chemical cues missing. Volatiles from male A. glabripennis were examined to identify other potential pheromone components. Gas chromatographic / electroantennographic (GC/EAD) analyses of male aerations detected a consistent EAD-active response to a previously unidentified compound. This compound was identified as (3E,6E)-α-farnesene. Both male and female beetles were antennally responsive to this sesquiterpene, and both sexes were attracted to it in olfactometer bioassays at different doses. When (3E,6E)-α-farnesene was combined with 4-(n-heptyloxy)butan-1-ol and 4-(n-heptyloxy)butanal, attraction of both sexes increased compared to assays using 4-(n-heptyloxy)butan-1-ol and 4-(n-heptyloxy)butanal alone.

Bioreplicated visual features of nanofabricated buprestid beetle decoys evoke stereotypical male mating flights.

Recent advances in nanoscale bioreplication processes present the potential for novel basic and applied research into organismal behavioral processes. Insect behavior potentially could be affected by physical features existing at the nanoscale level. We used nano-bioreplicated visual decoys of female emerald ash borer beetles (Agrilus planipennis) to evoke stereotypical mate-finding behavior, whereby males fly to and alight on the decoys as they would on real females. Using an industrially scalable nanomolding process, we replicated and evaluated the importance of two features of the outer cuticular surface of the beetle's wings: structural interference coloration of the elytra by multilayering of the epicuticle and fine-scale surface features consisting of spicules and spines that scatter light into intense strands. Two types of decoys that lacked one or both of these elements were fabricated, one type nano-bioreplicated and the other 3D-printed with no bioreplicated surface nanostructural elements. Both types were colored with green paint. The light-scattering properties of the nano-bioreplicated surfaces were verified by shining a white laser on the decoys in a dark room and projecting the scattering pattern onto a white surface. Regardless of the coloration mechanism, the nano-bioreplicated decoys evoked the complete attraction and landing sequence of Agrilus males. In contrast, males made brief flying approaches toward the decoys without nanostructured features, but diverted away before alighting on them. The nano-bioreplicated decoys were also electroconductive, a feature used on traps such that beetles alighting onto them were stunned, killed, and collected.

Improving detection tools for emerald ash borer (Coleoptera: Buprestidae): comparison of multifunnel traps, prism traps, and lure types at varying population densities.

The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is a serious invasive pest of North American ash (Fraxinus spp.) that has caused devastating mortality since it was first identified in North America in 2002. In 2012, we conducted field trapping assays that tested the efficacy of purple prism and fluon-coated green multifunnel (Lindgren funnel) traps. Traps were baited with combinations of several lures that were previously shown to be attractive to A. planipennis: manuka oil--a sesquiterpene-rich oil, (3Z)-hexenol--a green leaf volatile, or (3Z)-dodecen-12-olide [= (3Z)-lactone], a sex pheromone. Eighty-nine blocks (trap lines) were tested throughout nine states along the outer edges of the currently known A. planipennis infestation in North America. Trap catch was highest on fluon-coated green multifunnel traps, and trap detections at sites with low A. planipennis population density ranged from 72 to 76% for all trap and lure types tested. (3Z)-hexenol and (3Z)-lactone baited traps functioned as well as (3Z)-hexenol and manuka oil-baited traps. Independent of the lure used, detection rates on green fluon-coated multifunnel traps were comparable with glued purple prism traps in areas with low A. planipennis population densities.

A comparison of electrophysiologically determined spectral responses in six subspecies of Lymantria.

The spectral sensitivity of the compound eye in three gypsy moth species from six different geographical regions (Lymantria dispar asiatica Vnukovskij [Asian gypsy moth], Lymantria dispar japonica Motschulsky [Japanese gypsy moth], and Lymantria dispar dispar L. [North American gypsy moth]) was tested electrophysiologically in the wavelength region 300-700 nm. For all moths examined, a maximum response occurred in the 480-520-nm range (blue-green region) with a shoulder peak occurring at 460 nm. A smaller, secondary peak was observed for both sexes at the 340-380-nm range, which is in the region considered behaviorally maximal in night-flying insects. No peaks in sensitivity were observed between 520 and 700 nm (red region) for any of the moths tested. Based on our retinal recording data, a short wavelength blocking filter with a transition wavelength near 500 nm should reduce gypsy moth attraction to artificial lighting sources. This would help reduce the number of Lymantria-infested ships traveling to and from foreign ports.

Improving the efficiency of lepidopteran pest detection and surveillance: constraints and opportunities for multiple-species trapping.

Surveillance using attractants for invasive species can allow early detection of new incursions and provide decision support to response programs. Simultaneous trapping for multiple species, by baiting traps with several lures, is expected to increase the number of species that can be targeted in surveillance programs and improve the cost-effectiveness without affecting surveillance coverage. We tested this hypothesis by choosing four potential forest and urban lepidopteran pest species that are present in Europe but not yet in New Zealand and many other countries. We deployed traps in central and southern Europe with single lures or all possible species combinations (up to four lures per trap). There was only limited interference, apparently due to trap saturation, but no evidence for interspecific repellency among lures for gypsy moth, Lymantria dispar, fall webworm, Hyphantria cunea, pine processionary moth, Thaumetopoea pityocampa, and pine shoot moth, Rhyacionia buoliana. To assess what factors may be important in species compatibility/suitability for multiple-species trapping, we combined our results with those of previous studies conducted by the United States Department of Agriculture. For 75 combinations of pheromones, tested singly or in combination, 19 % showed no effect on trap catch for any of the species tested. In the other cases, either one or both species showed a reduction in trap catch. However, few lure combinations caused complete or nearly complete suppression. For most combinations, catches were still sufficiently high for detection purposes. Species from the same superfamily exhibited more interference than more distantly related species. Together, these results suggest that there are opportunities to improve the range of exotic pests under surveillance, at little additional cost, by multiple-species trapping for which compatibility has been demonstrated.

Improving detection tools for the emerald ash borer (Coleoptera: Buprestidae): comparison of prism and multifunnel traps at varying population densities.

The current emerald ash borer survey trap used in the United States is a prism trap constructed from a stock purple corrugated plastic. In recent years, several colors (particularly shades of green and purple) have been shown to be more attractive to the emerald ash borer than this stock color. Our goal was to determine if plastics produced with these colors and incorporated into prism traps can improve and serve as a new alternative to plastics already in use for the emerald ash borer survey. The plastics were tested in moderate to heavily infested areas in Michigan in two initial studies to test their effectiveness at catching the emerald ash borer. Because results from studies performed in heavily infested sites may not always correspond with what is found along the edges of the infestation, we compared trap catch and detection rates (recording at least one catch on a trap over the course of the entire trapping season) of several trap types and colors at sites outside the core of the currently known emerald ash borer infestation in a nine-state detection tool comparison study. Two of the new plastics, a (Sabic) purple and a medium-dark (Sabic) green were incorporated into prism traps and tested alongside a standard purple prism trap and a green multifunnel trap. In areas with lower emerald ash borer density, the new purple (Sabic) corrugated plastic caught more beetles than the current purple prism trap, as well as more than the medium-dark green (Sabic) prism and green multifunnel traps. Sabic purple traps in the detection tools comparison study recorded a detection rate of 86% compared with 73, 66, and 58% for the standard purple, Sabic green, and green multifunnel traps, respectively. These detection rates were reduced to 80, 63, 55, and 46%, respectively, at low emerald ash borer density sites.

Optimization of multifunnel traps for emerald ash borer (Coleoptera: Buprestidae): influence of size, trap coating, and color.

Field assays were conducted in southeastern and south-central Michigan in 2011 and 2012 to optimize green and purple multifunnel (Lindgren funnel) traps for use as a survey tool for the emerald ash borer, Agrilus planipennis Fairmaire. Larger sized (12- and 16-unit) multifunnel traps caught more beetles than their smaller-sized (4- and 8-unit) counterparts. Green traps coated with untinted (white) fluon caught almost four times as many adult A. planipennis as Rain-X and tinted (green) fluon-coated traps and almost 33 times more beetles than untreated control traps. Purple multifunnel traps generally caught much lower numbers of A. planipennis adults than green traps, and trap catch on them was not affected by differences in the type of coating applied. However, trap coating was necessary as untreated control purple traps caught significantly less beetles than traps treated with Rain-X and untinted or tinted (purple) fluon. Proportions of male beetles captured were generally much higher on green traps than on purple traps, but sex ratios were not affected by trap coating. In 2012, a new shade of purple plastic, based on a better color match to an attractive purple paint than the previously used purple, was used for trapping assays. When multifunnel traps were treated with fluon, green traps caught more A. planipennis adults than both shades of purple and a prism trap that was manufactured based on the same color match. Trap catch was not affected by diluting the fluon concentration applied to traps to 50% (1:1 mixture in water). At 10%, trap catch was significantly lowered.

Influence of trap color and host volatiles on capture of the emerald ash borer (Coleoptera: Buprestidae).

Field trapping assays were conducted in 2009 and 2010 throughout western Michigan, to evaluate lures for adult emerald ash borer, A. planipennis Fairmaire (Coleoptera: Buprestidae). Several ash tree volatiles were tested on purple prism traps in 2009, and a dark green prism trap in 2010. In 2009, six bark oil distillate lure treatments were tested against manuka oil lures (used in 2008 by USDA APHIS PPQ emerald ash borer cooperative program). Purple traps baited with 80/20 (manuka/phoebe oil) significantly increased beetle catch compared with traps baited with manuka oil alone. In 2010 we monitored emerald ash borer attraction to dark green traps baited with six lure combinations of 80/20 (manuka/phoebe), manuka oil, and (3Z)-hexenol. Traps baited with manuka oil and (3Z)-hexenol caught significantly more male and total count insects than traps baited with manuka oil alone. Traps baited with manuka oil and (3Z)-hexenol did not catch more beetles when compared with traps baited with (3Z)-hexenol alone. When compared with unbaited green traps our results show that (3Z)-hexenol improved male catch significantly in only one of three field experiments using dark green traps. Dark green traps caught a high number of A. planipennis when unbaited while (3Z)-hexenol was seen to have a minimal (nonsignificant) trap catch effect at several different release rates. We hypothesize that the previously reported kairomonal attractancy of (3Z)-hexenol (for males) on light green traps is not as obvious here because of improved male attractancy to the darker green trap.

Volatile profile differences and the associated Sirex noctilio activity in two host tree species in the Northeastern United States.

Sirex noctilio females are known to be attracted to stem sections of stressed pine trees for oviposition. The volatile profiles and attractiveness of Eastern white pine (Pinus strobus) and two chemotypes of Scots pine (P. sylvestris) were compared after stem injection with herbicide. In general, trap captures on herbicide-treated trees were higher than on controls. The high-carene chemotype of Scots pine captured the highest numbers of females, followed by the low-carene chemotype, and finally the Eastern white pine. Herbicide-treated trees of both species emitted larger quantities of volatiles than the controls. The herbicide treatment induced higher volatile emission rates in the Scots pine chemotypes than in white pine, although there was no difference between the two chemotypes. However, qualitative differences were found between the volatile profiles of the two species as well as between the two Scots pine chemotypes, which could account for the differential attractiveness of the species and chemotypes tested.

Male-produced pheromone in the European woodwasp, Sirex noctilio.

A male-produced pheromone that attracts both males and females was identified for the European woodwasp, Sirex noctilio, a serious pest of pine trees. Males displayed excitatory behaviors when placed in groups, and were attracted to the odors from males that were 2-5-d-old, but not to odors from males that were 0-1-d-old. An unsaturated short-chain alcohol, (Z)-3-decen-1-ol, was discovered in samples collected on SuperQ filters over groups of males and identified by using micro-derivatization reactions and gas chromatography coupled with mass spectrometry (GC-MS). The compound was not detected in volatile samples from females. Gas chromatography coupled electroantennographic detection (GC-EAD) of antennae from males exposed to male headspace odors produced strong antennal responses to the main peak of (Z)-3-decen-1-ol, as well as to an unknown minor component that had a similar retention time. Antennae from both males and females responded to synthetic (Z)-3-decen-1-ol. Several different synthetic candidates for the GC-EAD active minor components were selected based on GC-MS and GC-EAD responses to male headspace collections. These synthetic compounds were tested for antennal activity using GC-EAD, and those that produced strong responses were blended with the major component and tested for male attraction in the Y-tube olfactometer at different concentrations and ratios. Males tested in the Y-tube olfactometer were attracted to a synthetic blend of (Z)-3-decen-1-ol and (Z)-4-decen-1-ol at a ratio of 100:1. Whereas the addition of some suspected minor compounds reduced attraction, the addition of a third compound found in male emanations that produced strong male antennal responses, (E,E)-2,4-decadienal (at a ratio of 100:1:1), resulted in attraction of both males (Y-tube and wind tunnel) and females (wind tunnel).

Common mortality factors of woodwasp larvae in three northeastern United States host species.

Very little is presently known about the natural enemies and mortality factors associated with siricids (Hymenoptera: Siricidae) in the United States of America (USA), especially those that may directly affect the woodwasp, Sirex noctilio Fabricius (Hymenoptera: Siricidae). S. noctilio is an invasive woodwasp, is considered a major economic pest of pine, and has a severe effect on North American pine species planted in the Southern hemisphere. The mortality factors of siricid larvae were determined in three host species (Pinus sylvestris, Pinus resinosa, and Pinus strobus) from naturally infested trees in the northeastern USA. Siricid larvae were classified at the time of sampling as: (1) healthy, (2) parasitized by rhyssines (Hymenoptera: Ichneumonidae), (3) parasitized by Ibalia spp. (Hymenoptera: Ibaliidae), (4) parasitized by nematodes (Tylenchida: Neotylenchidae), and (5) dead from unknown causes. Combining data from the three host species, the average percentage of larvae that were healthy was 66%, 10% of the larvae were parasitized by rhyssines, 18% were parasitized by Ibalia spp., 1% were infected with unidentified nematodes, and about 5% of the larvae were dead in the galleries. Information from this study has important implications for understanding population regulation mechanisms in an invasive species, and will be critical for developing integrated pest management plans for S. noctilio.

Efficacy of multifunnel traps for capturing emerald ash borer (Coleoptera: Buprestidae): effect of color, glue, and other trap coatings.

Tens of thousands of adhesive-coated purple prism traps are deployed annually in the United States to survey for the invasive emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae). A reusable, more user-friendly trap is desired by program managers, surveyors, and researchers. Field assays were conducted in southeastern Michigan to ascertain the feasibility of using nonsticky traps as survey and detection tools for emerald ash borer. Three nonsticky trap designs, including multifunnel (Lindgren), modified intercept panel, and drainpipe (all painted purple) were compared with the standard purple prism trap; no statistical differences in capture of emerald ash borer adults were detected between the multifunnel design and the prism. In subsequent color comparison assays, both green- and purple-painted multifunnel traps (and later, plastic versions of these colors) performed as well or better than the prism traps. Multifunnel traps coated with spray-on adhesive caught more beetles than untreated traps. The increased catch, however, occurred in the traps' collection cups and not on the trap surface. In a separate assay, there was no significant difference detected between glue-coated traps and Rain-X (normally a glass treatment)-coated traps, but both caught significantly more A. planipennis adults than untreated traps.

Optimization of trap color for emerald ash borer (Coleoptera: Buprestidae).

Field assays were performed to determine the optimal color for Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) traps. Previous studies have found that more A. planipennis are caught on purple or green traps than traps of other colors. In three studies, we evaluated various shades of purple, wavelengths of green (500-570 nm), and greens of different reflectance (from 9 to 66%). In all tests, traps of corrugated plastic in standard, commercially available purple (currently used to survey A. planipennis) and a customized green color were used as bases for comparison. Among purple traps, a paint color previously shown to be generally attractive to buprestids caught significantly more A. planipennis adults than traps coated with paints containing more blue or red, or traps constructed of the standard purple plastic. Among traps with maximum reflectance at varying green wavelengths, those ranging in wavelength from 525 to 540 nm caught significantly more adult A. planipennis than traps of other wavelengths. In the 530-540 nm range of the electromagnetic spectrum, there was no significant difference among traps in the 23-66% reflectance range, but traps painted with a peak reflectance of 49% caught more beetles than purple or the custom green plastic traps. Male to female ratio was highest on green traps.

Chemical ecology of the emerald ash borer Agrilus planipennis.

The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is a serious invasive pest that has caused devastating mortality of ash trees (Fraxinus sp., Oleaceae) since it was first identified in North America in 2002. Shortly after its discovery, surveys were conducted, based on the visual inspection of trees. The shortcomings of visual surveys have led to a critical research need to find an efficient survey method for detecting A. planipennis infestations. Here, we present a review of research that has led to the development of effective trapping methods for A. planipennis. Studies on the insect's biology and behavior have led to the identification of several potential attractants as well as the design of a visually attractive trap. The ongoing challenge in developing an optimally efficient trapping methodology for A. planipennis will involve finding the best combination of variables, such as trap shape, trap color (or other visual properties), trap placement, lure components, as well as the ratios and release rates of those components.

Improved synthesis of (3E,6Z,9Z)-1,3,6,9-nonadecatetraene, attraction inhibitor of bruce spanworm, Operophtera bruceata, to pheromone traps for monitoring winter moth, Operophtera brumata.

The winter moth, Operophtera brumata (Lepidoptera: Geometridae), is an early-season defoliator that attacks a wide variety of hardwoods and, in some cases, conifers. The insect is native to Europe but has become established in at least three areas of North America including southeastern New England. The female-produced sex attractant pheromone of the winter moth was identified as (3Z,6Z,9Z)-1,3,6,9-nonadecatetraene (1), which also attracts a native congener, the Bruce spanworm, Operophtera bruceata . Dissection, or (for certainty) DNA molecular testing, is required to differentiate between males of the two species. Thus, a trapping method that is selective for winter moth would be desirable. A geometric isomer of the pheromone, (3E,6Z,9Z)-1,3,6,9-nonadecatetraene (2), can reportedly inhibit attraction of Bruce spanworm to traps without affecting winter moth catch, but use of the pheromone and inhibitor together has not been optimized, nor has the synthesis of the inhibitor. This paper presents two new syntheses of the inhibitor (3E,6Z,9Z)-1,3,6,9-nonadecatetraene based on the intermediate (3Z,6Z)-3,6-hexadecadien-1-ol (4), which has also been utilized in the synthesis of the pheromone. The syntheses combine traditional acetylenic chemistry and Wittig olefination reactions. In one approach, 2 was synthesized in 80% purity (20% being pheromone 1), and in the second, tetraene 2 of 96% purity (and free of 1) was produced in 25% overall yield from dienol 4. The last method benefitted from a refined TEMPO-mediated PhI(OAc)(2) oxidation of 4 and a two-carbon homologation of the corresponding aldehyde 7.

Monoalkenes as contact sex pheromone components of the woodwasp Sirex noctilio.

A pheromone on the cuticle of females of the woodwasp Sirex noctilio, a recently introduced pest of pines in North America, induces conspecific males to attempt copulation. Dead females washed with hexane did not elicit copulation attempts from males, whereas reapplication of a female hexane body wash onto the cuticle of dead females elicited copulation attempts by 65% of males tested. Analysis of the hexane extract revealed saturated and unsaturated hydrocarbons as major components of the female cuticle. Behavior-guided fractionation of the female body wash led to the identification of three components, (Z)-7-heptacosene, (Z)-7-nonacosene, and (Z)-9-nonacosene, of the sex pheromone of S. noctilio that elicited copulatory responses from males.

Effectiveness of differing trap types for the detection of emerald ash borer (Coleoptera: Buprestidae).

The early detection of populations of a forest pest is important to begin initial control efforts, minimizing the risk of further spread and impact. Emerald ash borer (Agrilus planipennis Fairmaire) is an introduced pestiferous insect of ash (Fraxinus spp. L.) in North America. The effectiveness of trapping techniques, including girdled trap trees with sticky bands and purple prism traps, was tested in areas with low- and high-density populations of emerald ash borer. At both densities, large girdled trap trees (>30 cm diameter at breast height [dbh], 1.37 m in height) captured a higher rate of adult beetles per day than smaller trees. However, the odds of detecting emerald ash borer increased as the dbh of the tree increased by 1 cm for trap trees 15-25 cm dbh. Ash species used for the traps differed in the number of larvae per cubic centimeter of phloem. Emerald ash borer larvae were more likely to be detected below, compared with above, the crown base of the trap tree. While larval densities within a trap tree were related to the species of ash, adult capture rates were not. These results provide support for focusing state and regional detection programs on the detection of emerald ash borer adults. If bark peeling for larvae is incorporated into these programs, peeling efforts focused below the crown base may increase likelihood of identifying new infestations while reducing labor costs. Associating traps with larger trees ( approximately 25 cm dbh) may increase the odds of detecting low-density populations of emerald ash borer, possibly reducing the time between infestation establishment and implementing management strategies.