Acibenzolar-S-methyl induces resistance against ambrosia beetle attacks in dogwoods exposed to simulated flood stress.

Xylosandrus spp. ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are important wood-boring pests of nursery trees weakened by abiotic and biotic stressors. Acibenzolar-S-methyl (ASM), a plant defense elicitor, was tested for inhibiting Xylosandrus spp. tunneling (i.e., attacks) into flood-stressed flowering dogwoods (Cornus florida L. (Cornales: Cornaceae)). Container-grown dogwoods were treated with ASM substrate drench + flooding, ASM foliar spray + flooding, ASM drench + no flooding, ASM foliar + no flooding, no ASM + flooding, or no ASM + no flooding at 3 days before flood stress in a completely randomized design under field conditions. Trees were flooded for 14 days and then drained and watered as needed. Attacks were counted every 2 days for 28 days. Plant tissue samples were collected at 7 and 14 days after flooding to determine ethanol content using solid-phase microextraction-gas chromatography-mass spectrometry. Trees were dissected to determine gallery formation and depth, fungal colonization, and the presence of eggs, larvae, and adults. The highest number of Xylosandrus beetle species attacks were recorded from plants exposed to no ASM + flooding, but attacks were reduced in ASM treated trees (drench or foliar) + flooding. Trees treated with drenches had fewer attacks than foliar sprays. Plants assigned to no flood had the fewest beetle attacks. Moreover, ASM reduced Xylosandrus spp. gallery formation and depth, fungal colonization, and presence of eggs, larvae, and adults. All flooded trees produced ethanol. In conclusion, ASM induced a plant defense response to Xylosandrus spp. tunneling in dogwoods under flood stress conditions.

Evaluation of winter cover crop methods for management of flatheaded appletree borer (Coleoptera: Buprestidae).

Winter cover crops grown at the base of red maples (Acer rubrum L.) can reduce flatheaded appletree borer (Chrysobothris femorata Olivier; Coleoptera: Buprestidae; FAB) damage by both physically blocking preferred oviposition sites and altering the environment around them. However, cover crop competition negatively affects tree growth. To investigate long-term cover crop effects, trees grown with cover crop for 2 yr were transitioned to a standard herbicide practice. After 4 yr, trees in the initial 2 yr cover crop plots were 1 yr behind in growth compared to trees grown in bare rows for all 4 yr. Most growth reduction occurred in the first year following transplant. Additional borer losses of 1-2% per year were observed in production years 3 and 4. A second experiment answered 2 questions: Can killing the cover crop once it reaches maximal height protect trees from borers while also reducing competition and thereby increase tree growth? and Do herbicide applications increase borer attacks? In this experiment, red maples were grown with (i) a standard herbicide program, (ii) a mulch mat, (iii) a cover crop that was killed early, or (iv) a cover crop allowed to senesce naturally. Evaluations after 2 yr indicated early kill of the cover crop was not enough to improve tree growth. Further, trees in the early kill cover crop treatment had the most FAB attacks. Cover crops allowed to senesce naturally reduced FAB attacks in both studies; however, more work is needed to minimize disparities in tree growth during the initial year post-transplant and determine the causal relationship between herbicide use and borer attacks.

Characterization of Solenopsis invicta virus 4, a polycipivirus infecting the red imported fire ant Solenopsis invicta.

Solenopsis invicta virus 4 (SINV-4), a new polycipivirus, was characterized in the host in which it was discovered, Solenopsis invicta. SINV-4 was detected in the worker and larval stages of S. invicta, but not in pupae, male or female alates, or queens. The SINV-4 titer was highest in worker ants, with a mean of 1.14 × 107 ± 5.84 ×107 SINV-4 genome equivalents/ng RNA. Electron microscopic examination of negatively stained samples from particles purified from SINV-4-infected fire ant workers revealed isometric particles with a mean diameter of 47.3 ± 1.4 nm. The mean inter-colony SINV-4 infection rate among S. invicta worker ants was 45.8 ± 38.6 in Alachua County, Florida. In S. invicta collected in Argentina, SINV-4 was detected in 22% of 54 colonies surveyed from across the Formosa region. There did not appear to be any seasonality associated with the SINV-4 infection rate among S. invicta nests. SINV-4 was successfully transmitted to uninfected S. invicta colonies by feeding. Among three colonies of S. invicta inoculated with SINV-4, two retained the infection for up to 72 days. The replicative genome strand of SINV-4 was detected in 18% (n = 11) of SINV-4-infected S. invicta colonies. Among 33 ant species examined, the plus genome strand of SINV-4 was detected in undetermined species of Dorymyrmex and Pheidole, Cyphomyrmex rimosus, Monomorium pharaonis, Pheidole obscurithorax, Solenopsis geminata, Solenopsis richteri, Solenopsis xyloni, and Solenopsis invicta. However, the replicative (minus) genome strand was only detected in S. invicta. SINV-4 infection did not impact brood production or queen fecundity in S. invicta. The mean brood rating (63.3% ± 8.8) after 31 days for SINV-4-infected colonies was not statistically different from that of uninfected colonies (48.3 ± 25.5). At the end of the 31-day test period, mean egg production was not significantly different between SINV-4-infected S. invicta colonies (287.7 ± 45.2 eggs laid/24 hours) and uninfected control colonies (193.0 ± 43.6 eggs laid/24 hours).

Effects of Color Attributes on Trap Capture Rates of Chrysobothris femorata (Coleoptera: Buprestidae) and Related Species.

Chrysobothris spp. (Coleoptera: Buprestidae) and other closely related buprestids are common pests of fruit, shade, and nut trees in the United States. Many Chrysobothris spp., including Chrysobothris femorata, are polyphagous herbivores. Their wide host range leads to the destruction of numerous tree species in nurseries and orchards. Although problems caused by Chrysobothris are well known, there are no reliable monitoring methods to estimate local populations before substantial damage occurs. Other buprestid populations have been effectively estimated using colored sticky traps to capture beetles. However, the attraction of Chrysobothris to specific color attributes has not been directly assessed. A multi-color trapping system was utilized to determine color attraction of Chrysobothris spp. Specific color attributes (lightness [L*], red to green [a*], blue to yellow [b*], chroma [C*], hue [h*], and peak reflectance [PR]) were then evaluated to determine beetle responses. In initial experiments with mostly primary colors, Chrysobothris were most attracted to traps with red coloration. Thus, additional experiments were performed using a range of trap colors with red reflectance values. Among these red reflectance colors, it was determined that the violet range of the electromagnetic spectrum had greater attractance to Chrysobothris. Additionally, Chrysobothris attraction correlated with hue and b*, suggesting a preference for traps with hues between red to blue. However, males and females of some Chrysobothris species showed differentiated responses. These findings provide information on visual stimulants that can be used in Chrysobothris trapping and management. Furthermore, this information can be used in conjunction with ecological theory to understand host-location methods of Chrysobothris.

Integration of Control Strategies to Optimize Management of Ambrosia Beetles (Coleoptera: Curculionidae, Scolytinae) and Phytophthora Root Rot (Peronosporales: Peronosporaceae) in Flowering Dogwoods (Cornalaes: Cornaceae) After Simulated Flooding.

Ambrosia beetles (Coleoptera: Curculionidae, Scolytinae) and Phytophthora root rot (Peronosporales: Peronosporaceae) cause significant damage to the ornamental industry in the United States. In this study, mefenoxam (fungicide), permethrin (insecticide), and charcoal + kaolin were used in different combinations with Phytophthora cinnamomi (Rands: Peronosporales: Peronosporaceae) inoculated and noninoculated plants to optimize the management of ambrosia beetles and Phytophthora root rot. Treatment applications were performed in two trials on 1 (mefenoxam, drench), 18 (P. cinnamomi inoculation), or 19 (permethrin, spray) days before instigating flood stress or 2 d after flood stress (charcoal + kaolin, spray), respectively. Flooding was maintained for 21 d. Ambrosia beetle attacks and plant growth data were recorded. Tree roots were rated at study end for disease severity and root samples were plated on PARPH-V8 medium to determine the percentage of pathogen recovery. In both trials, the combination of mefenoxam + permethrin treatment had reduced disease severity and ambrosia beetle attacks compared to the inoculated controls. Permethrin-treated trees had shorter galleries compared to controls in trial 1 and no gallery formation in trial 2. In both trials, no differences were observed among the treatments in numbers of galleries with eggs and adults, but mefenoxam + charcoal + kaolin had significantly fewer galleries with larvae among the noninoculated trees compared with the respective control in trial 1. Overall, treatments containing combinations of mefenoxam + permethrin had reduced disease severity and ambrosia beetle attacks.

Field evaluation of Solenopsis invicta virus 3 against its host Solenopsis invicta.

Viruses have been used successfully as biocontrol agents against several insect pests but not ants. Laboratory tests have shown that Solenopsis invicta virus 3 (SINV-3) may be an effective natural control agent against its host, the red imported fire ant (Solenopsis invicta Buren). In this field trial, SINV-3 was released into 12 active S. invicta nests within a 0.088-hectare area in Florida and the impact on the ants monitored. SINV-3 was successfully transmitted, established, and multiplied within treated colonies reaching a maximum mean value of 8.71 × 108 ± 8.26 × 108 SINV-3 genome equivalents/worker ant 77 days after inoculation. SINV-3 was not detected in any of the nests in the control group. A 7-fold decrease in nests was observed in the SINV-3-treated group compared with the untreated control. A correspondingly significant decrease in S. invicta nest size also was observed over the course of the evaluation. Based on the nest rating scale, nest size among those treated with SINV-3 decreased from 3.92 ± 1.24 on day 0 to 1.67 ± 2.06 on day 77, which represents a 57.4% decrease in size. Conversely, the nest rating for the control group increased 9.3%, from 4.42 ± 1.24 on day 0 to 4.83 ± 2.12 on day 77. A follow-up survey of SINV-3-treated and -untreated plots conducted 9 months after initial treatment revealed that fire ant populations rebounded, but at a different rate. A total of 11 and 19 nests were detected in the SINV-3-treated and -untreated areas, respectively. SINV-3 was still detected in the treated area 1.8 years after the initial virus treatment and the virus had spread into the adjacent control plot. Results demonstrate that SINV-3 is an effective natural control agent against the invasive ant, S. invicta; the virus causes no known detrimental ecological impacts, is host specific, and sustained in the environment.

Unique venom proteins from Solenopsis invicta x Solenopsis richteri hybrid fire ants.

The Solenopsis venom protein 2 transcript was amplified, sequenced, probed, and analyzed from Solenopsis invicta x Solenopsis richteri hybrid ant colonies (hybrids) collected from across Tennessee to determine the extent of introgression of each parent allele (Solenopsis invicta venom protein 2 [Soli2] and Solenopsis richteri venom protein 2 [Solr2]). Chemotaxonomic analyses of venom alkaloids and cuticular hydrocarbons were used to categorize hybrid colonies and their relative relatedness to each parent species. Hybrid colonies were chosen randomly from each chemotaxonomic hybridization category, including "very near S. richteri," "near S. richteri," "near S. invicta," and "very near S. invicta." Lateral flow immunoassays for detection of the Soli2 and Solr2 venom proteins were largely in agreement with the chemotaxonomic analyses for the very near S. richteri (100% Solr2) and very near S. invicta (80% Soli2, 20% Soli2 + Solr2 detected in the sample) groups, while Soli2 and Solr2 were reported in 60% and 40% in the near S. invicta and near S. richteri chemotaxonomic groups. Analysis of transcripts from the hybrid colonies revealed a sequence with 100% identity to Soli2 (GenBank Accession L09560) and three unique sequences, which we identify as Solenopsis hybrid venom protein 2 (Solh2; GenBank Accession MT150127), Solenopsis hybrid truncated venom protein 2 (Solh2Tr97; Genbank Accession MT150129), and Solenopsis richteri venom protein 2, D to A change at position 69 (Solr2A69; GenBank Accession MT150128). The predicted open reading frame for Solh2 and Solh2Tr97 revealed sequences unique to hybrid ants, with Solh2Tr97an alternatively spliced form. A third unique sequence, Solr2A69, is likely the correct sequence for Solr2, which appears to have been published previously with a sequencing error (GenBank Accession P35776).

Evaluation of Systemic Imidacloprid and Herbicide Treatments on Flatheaded Borer (Coleoptera: Buprestidae) Management in Field Nursery Production.

The flatheaded appletree borer, Chrysobothris femorata (Olivier) (Coleoptera: Buprestidae), and related species are deciduous tree pests. Female beetles prefer to oviposit at tree bases, and larvae tunnel beneath the bark, which weakens or kills young or newly transplanted trees. In the first objective of this study, Discus N/G (2.94% imidacloprid + 0.7% cyfluthrin) applied at six lower-than-labeled rates (0.0, 0.98, 1.97, 3.94, 5.91, and 7.87 ml/cm of average trunk dia.) was evaluated for protection of field-grown maples. A second objective evaluated imidacloprid with and without herbicides to assess the impact of weed competition at the tree base on insecticide effectiveness. A third objective determined relative imidacloprid concentrations in leaf tissue samples with ELISA and related to insecticide rates, herbicide treatments, and the level of flatheaded borer protection. In two trials, higher rates of insecticide were more effective at protecting trees, with rates ≥3.94 ml product/cm trunk diameter performing equivalently. Weed-free trees had more borer attacks and grew faster than trees in weedy plots. Imidacloprid content in leaf tissues had a trend for higher concentrations in smaller, weedy trees in the first season, but that pattern disappeared in subsequent years. Based on fewer attacks in weedy versus weed-free trees (60-90% reduction), it was concluded that weed presence can reduce borer attack success in nurseries independent of insecticide treatment, but tree growth was reduced by weed presence. In addition, Discus applied at rates >3.94 ml/cm did not confer added borer damage protection in weedy plots.

Permethrin Residual Activity Against Ambrosia Beetle (Coleoptera: Curculionidae: Scolytinae) Attacks Following Field Aging and Simulated Rainfall Weathering.

Adult ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) bore into ornamental nursery trees resulting in trunk vascular tissue damage, which can potentially kill trees. Ambrosia beetle exposure to surface-applied insecticides is minimal after internal trunk galleries are formed, so effective management requires insecticide treatments to be applied near the time of infestation or to have residual activity on the bark. Tree trunk sections (bolts) were used to determine the effect of field aging or irrigation (i.e., simulated rainfall weathering) on permethrin residual activity against ambrosia beetles. In all experiments, 30-cm-long bolts from Liriodendron tulipifera L. (Magnoliales: Magnoliaceae) were hollowed and filled with 70% ethanol at field deployment to induce ambrosia beetle attacks over a 2-wk period. To evaluate insecticide residual activity, permethrin was sprayed onto tree bolts at 0, 8, 17, or 24 d before ethanol addition, and then bolts were deployed along a wooded border in fall 2017 and spring 2018. Tree bolts with permethrin residues ≤17 d old had significantly fewer ambrosia beetle attacks than bolts with 24-d-old residues or the non-permethrin-treated control bolts. To evaluate simulated rainfall weathering, permethrin was applied to tree bolts 8 or 22 d before ethanol (spring 2018) or 10 or 24 d before ethanol (fall 2018) with half of the bolts receiving regular irrigation events. Irrigation had no significant effect on permethrin residual activity against ambrosia beetles during either test. This study determined ambrosia beetle control was affected by permethrin residue age more than simulated rainfall weathering, and a reapplication interval of ≤17 d maximized beetle control.

Long-Lasting Insecticide Netting for Protecting Tree Stems from Attack by Ambrosia Beetles (Coleoptera: Curculionidae: Scolytinae).

Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are destructive wood-boring insects of horticultural trees. We evaluated long-lasting insecticide netting for protecting stems against ambrosia beetles. Container-grown eastern redbud, Cercis canadensis, trees were flood-stressed to induce ambrosia beetle attacks, and deltamethrin-treated netting was wrapped from the base of the stem vertically to the branch junction. Trees were deployed under field conditions in Ohio, Virginia, Tennessee, and Mississippi with the following treatments: (1) flooded tree; (2) flooded tree with untreated netting; (3) flooded tree with treated 'standard mesh' netting of 24 holes/cm2; (4) flooded tree with treated 'fine mesh' netting of 28 holes/cm2; and/or (5) non-flooded tree. Treated netting reduced attacks compared to untreated netting and/or unprotected trees in Mississippi in 2017, Ohio and Tennessee in 2018, and Virginia in 2017-2018. Inconsistent effects occurred in Mississippi in 2018. Fewer Anisandrus maiche, Xylosandrus germanus, and Xyleborinus saxesenii were dissected from trees deployed in Ohio protected with treated netting compared to untreated netting; trees deployed in other locations were not dissected. These results indicate long-lasting insecticide netting can provide some protection of trees from ambrosia beetle attacks.

Minimizing Bee (Hymenoptera: Apoidea) Bycatch in Japanese Beetle Traps.

Native and introduced bees were attracted to and captured in commercially available Japanese beetle, Popillia japonica Newman (Coleoptera: Scarabaeidae), traps baited with floral lure components: geraniol, eugenol, and phenethyl propionate [PEP] in Rhode Island, Ohio, and Tennessee. Studies in Rhode Island showed that Bombus impatiens Cresson (Hymenoptera: Apidae) was significantly more attracted to geraniol alone and as a component in floral lure blends than to either eugenol or PEP alone. Xylocopa virginica (L.) (Hymenoptera: Apidae) was more selective in being primarily attracted to traps baited with higher amounts of geraniol in 2016. Removing geraniol from the floral lure blend did not significantly reduce Japanese beetle captures in 2017 and 2018 in Rhode Island and Ohio but did significantly reduce bee captures in Rhode Island in 2017 and 2018. Green, black, brown, and red traps captured significantly fewer bees than clear or standard yellow vane and green cage traps in 2018 in Rhode Island and Tennessee; however, there were no significant differences between Japanese beetle captures in any of the colored or clear traps. Our results show that using all green traps with a lure composed of eugenol and PEP and the Japanese beetle female produced sex pheromone can effectively capture Japanese beetles while minimizing bycatch of bees.

Comparative Performance of Fungicides, Biofungicides, and Host Plant Defense Inducers in Suppression of Phytophthora Root Rot in Flowering Dogwood During Simulated Root Flooding Events.

During flooding events in nurseries, Phytophthora root rot caused by Phytophthora cinnamomi Rands often causes damage that leads to complete crop loss. In this study, we evaluated the efficacy of fungicides, biofungicides, and host plant defense inducers for preventive and curative control of Phytophthora root rot on flowering dogwood (Cornus florida L.) seedlings exposed to a simulated flood event of 1, 3, or 7 days. In two greenhouse trials, preventive (7 days before flooding) or curative (1 day after flooding) drench treatments were applied to dogwood seedlings artificially inoculated with P. cinnamomi. The plants were flooded by maintaining standing water for 1, 3, or 7 days. After the trials, plant growth data (total plant weight, root weight, plant height, and plant width) were recorded, and root systems were assessed for disease severity using a scale of 0 to 100% of roots affected, and subsamples were plated on PARPH-V8 medium to determine the percent recovery of the Phytophthora pathogen. Plants preventively treated with Subdue MAXX had reduced disease severity relative to the nontreated, inoculated plants (positive control) flooded 1, 3, or 7 days in both trials. Pageant Intrinsic and Segovis treatments also had lower disease severity than the positive control at all flooding durations in trial two, but not trial one. In trial one, preventive and curative treatments of Orkestra Intrinsic had reduced disease severity compared with the positive control at 1 and 3 days of flooding, whereas curative treatments of Empress Intrinsic and Tartan Stressgard also were effective at 1 and 3 days of flooding in trial one. The host plant defense inducers (Aliette 80 WDG, Signature Xtra, and Actigard) were inconsistent and ineffective at reducing disease severity when applied as preventive or curative treatments. Preventive treatments of the biofungicides RootShield Plus+ and MBI-110 had consistently lower disease severity than the positive control at 1 day of flooding but not 3 or 7 days of flooding. Potentially, growers can use information from this study to manage Phytophthora root rot during flooding or in areas of the nursery that often experience high soil moisture levels.

Trap Tree and Interception Trap Techniques for Management of Ambrosia Beetles (Coleoptera: Curculionidae: Scolytinae) in Nursery Production.

The majority of wood-boring ambrosia beetles are strongly attracted to ethanol, a behavior which could be exploited for management within ornamental nurseries. A series of experiments was conducted to determine if ethanol-based interception techniques could reduce ambrosia beetle pest pressure. In two experiments, trap trees injected with a high dose of ethanol were positioned either adjacent or 10-15 m from trees injected with a low dose of ethanol (simulating a mildly stressed tree) to determine if the high-dose trap trees could draw beetle attacks away from immediately adjacent stressed nursery trees. The high-ethanol-dose trees sustained considerably higher attacks than the low-dose trees; however, distance between the low- and high-dose trees did not significantly alter attack rates on the low-dose trees. In a third experiment, 60-m length trap lines with varying densities of ethanol-baited traps were deployed along a forest edge to determine if immigrating beetles could be intercepted before reaching sentinel traps or artificially stressed sentinel trees located 10 m further in-field. Intercept trap densities of 2 or 4 traps per trap line were associated with fewer attacks on sentinel trees compared to no traps, but 7 or 13 traps had no impact. None of the tested intercept trap densities resulted in significantly fewer beetles reaching the sentinel traps. The evaluated ethanol-based interception techniques showed limited promise for reducing ambrosia beetle pressure on nursery trees. An interception effect might be enhanced by applying a repellent compound to nursery trees in a push-pull strategy.

Management of flatheaded appletree borer (Chrysobothris femorata Olivier) in woody ornamental nursery production with a winter cover crop.

BACKGROUND: The flatheaded appletree borer (Chrysobothris femorata Olivier) (FHAB) is a native pest of fruit, shade and nut trees throughout the United States. Use of cover crops is an effective pest management tool for some key insect pests in vegetable and cereal production systems, but its impact in woody ornamental production systems has not been investigated. The goal of this study was to evaluate the effectiveness of a winter cover crop for management of FHAB in nursery production. Red maple trees (Acer rubrum L.) grown under four treatment regimes (cover crop, cover crop + insecticide, bare row and bare row + insecticide) were evaluated for damage by FHAB and impact on tree growth parameters. RESULTS: The cover crop reduced FHAB damage, with results equivalent to standard imidacloprid treatments. The reduction in FHAB attacks in cover crop treatments may be due to microclimate changes at preferred oviposition sites, trunk camouflage or interference with access to oviposition sites. Tree growth was reduced in the cover crop treatments due to competition for resources. CONCLUSION: Physical blockage of oviposition sites by cover crops and subsequent microclimate changes protected against FHAB damage. Therefore, cover crops can be an alternative to chemical insecticides. © 2019 Society of Chemical Industry.

Complete Genome Sequence of a New Isolate of Solenopsis invicta virus 3 from Solenopsis invicta × richteri Hybrid Ants.

Solenopsis invicta virus 3 (SINV-3) is a positive-sense, single-stranded RNA virus that infects the red imported fire ant, Solenopsis invicta Buren. We report here the full genome (10,383 nucleotides) of an isolate infecting Solenopsis invicta × richteri hybrid ants, which we have identified as SINV-3 hybrid.

Trap Style, Bait, and Height Deployments in Black Walnut Tree Canopies Help Inform Monitoring Strategies for Bark and Ambrosia Beetles (Coleoptera: Curculionidae: Scolytinae).

Knowledge about which bark and ambrosia beetle species are active and at what heights in black walnut canopies is not well understood. Neither is the role of these beetles in spreading Thousand Cankers Disease. To assist with future planned research, which will assess the extent to which these beetle species are associated with Geosmithia morbida Kolarík, Freeland, Utley, and Tisserat (Ascomycota: Hypocreales: Bionectriaceae), experiments were undertaken to monitor bark and ambrosia beetles in urban landscapes and parks in Tennessee between 2011 and 2013. Within mature walnut tree canopies, sticky panel, modified soda bottle, and Lindgren traps were deployed at different heights, with and without ethanol as an attractant and with and without walnut stem sections, or in situ limbs that had been girdled or injection with ethanol to simulate stressed tree tissues. Bark and ambrosia beetle species (Coleoptera: Curculionidae: Scolytinae) collected in greatest abundance included Ambrosiodmus rubricollis (Eichhoff), Ambrosiophilus atratus (Eichhoff), Cnestus mutilatus (Blandford), Dryoxylon onoharaense (Murayama), Euwallacea validus (Eichhoff), Monarthrum fasciatum (Say), Monarthrum mali (Fitch), Xyleborinus saxesenii (Ratzeburg), Xyleborus affinis Eichhoff, Xyleborus ferrugineus (Fabricius), Xylosandrus crassiusculus (Motschulsky), and Xylosandrus germanus (Blandford). C. mutilatus, X. saxesenii, and X. crassiusculus were more active higher in trees than most other species and were strongly attracted to ethanol via all means of lure deployment. C. mutilatus, which were captured from April through October and increased in abundance across the 3-yr study, were most abundant in late May with a second activity period in late August.

Movement of Xylosandrus germanus (Coleoptera: Curculionidae) in Ornamental Nurseries and Surrounding Habitats.

Some exotic ambrosia beetles are damaging pests in ornamental nurseries. Xylosandrus germanus (Blandford) is the most problematic ambrosia beetle in Ohio nurseries. Movement of X. germanus in nurseries has not been characterized, and knowledge is lacking on whether infestations originate from within nurseries or surrounding habitats. Flight activity of X. germanus was monitored in nurseries and adjacent wooded areas to determine the source of beetles infesting nurseries, and characterize their movement within nurseries. Ethanol-baited bottle traps were positioned within wooded areas adjacent to commercial nurseries and within nurseries at various distances from the nursery woodlot interface. Flight activity of overwintered X. germanus occurred in wooded areas adjacent to nurseries before occurrence within nurseries. There was a direct relationship between degree-days and the distance from woodlots when X. germanus were first found in traps in spring, with earlier captures closest to wooded areas and latest ones furthest away into the nursery. X. germanus appeared to move into nurseries from adjacent wooded areas, with numbers trapped within nurseries decreasing with distance away from wooded areas. Trees in the interior of nurseries would appear to be subjected to less attack pressure than trees near the nursery border. Intercepting beetles as they move into nurseries might be an effective strategy to reduce attack pressure on valuable trees.

Monitoring attack and flight activity of Xylosandrus spp. (Coleoptera: Curculionidae: Scolytinae): the influence of temperature on activity.

Wood-boring ambrosia beetles (Coleoptera: Curculionidae: Scolytinae), including Xylosandrus spp., are key pests in ornamental nurseries. Knowledge of their activity in spring is important for nursery growers to effectively time their protective sprays. We measured the reliability of ethanol-baited bottle traps for monitoring emergence of overwintered Xylosandrus spp. in ornamental nurseries. Detection of initial flight activity by traps was compared with initial attacks on ethanol-injected trap trees. To develop tools for forecasting Xylosandrus germanus (Blandford) activity, the relationships between temperature and their attack and flight activity were examined, and the bloom sequence of ornamental plants was examined as phenological indicators of X. germanus emergence in Ohio. Captures of X. germanus coincided with attacks on trap trees on seven of eight occasions over 2 yr in four nurseries. Xylosandrus crassiusculus (Motshulsky) were detected in only one nursery and captures coincided with attacks each year. There was a strong relationship between maximum daily temperatures 20 and 21degrees C and X. germanus attack and flight activity. No attack or flight activity were detected in a monitoring period unless there were 1 or 2 d of at least 20 degrees C. Emergence of X. germanus always began after and within 6 d of full bloom on Cornelian cherry dogwood, and usually after and within 4 d of first bloom on Norway maple and full bloom on border forsythia. The traps or phenological indicators can be used by growers to monitor emergence of X. germanus to time their initial protective sprays. The relationship between X. germanus activity and temperature can be used by growers to make decisions on timing subsequent treatments.

Preharvest quarantine treatments of chlorantraniliprole, clothianidin, and imidacloprid-based insecticides for control of Japanese beetle (Coleoptera: Scarabaeidae) and other scarab larvae in the root zone of field-grown nursery trees.

Japanese beetle, Popillia japonica Newman (Coleoptera: Scarabaeidae), is an important quarantine pest of nurseries. Nursery plant movement from P. japonica-infested regions is regulated by the U.S. Domestic Japanese Beetle Harmonization Plan (DJHP), which classifies states by risk categories. Treatments for category 2 states include preharvest soil surface treatment of nursery plants grown in field soil using Discus SC, Marathon (1G or 60 WP), or Flagship (0.22G or 25 WG). In this study, Discus, Marathon 60 WP, or Flagship 0.22G DJHP standards were compared with labeled rates of non-DJHP-approved insecticides, including neonicotinoids clothianidin (Arena 50WDG), generic imidacloprid (Quali-Pro Imidacloprid 2 F T&O Insecticide, Mallet 2 F T&O Insecticide, and Lada 2 F Insecticide), and imidacloprid + bifenthrin (Allectus SC), as well as the anthranilic diamide, chlorantraniliprole (Acelepryn Insecticide). Arena provided 100% P. japonica control in May, June, and July over four test years, but had one larva recovered during August in two of those 4 yr. Acelepryn did not provide DJHP-acceptable P. japonica control. During July, Allectus provided 100% P. japonica control in three of four test years, but had four larvae in one test year. Other treatments tested only during July, which provided 100% P. japonica control, included Discus (five tests); Marathon, Quali-Pro, and Mallet (two tests); and Lada and Flagship (one test). Generic imidacloprid 2 F formulations were equivalent in P. japonica control to DJHP-approved insecticides. Insecticides generally performed poorly on other scarabs or curculionid larvae. The study supports Arena, Allectus, and generic imidacloprid 2 F products as suitable candidates for the DJHP.

Interruption of the semiochemical-based attraction of ambrosia beetles to ethanol-baited traps and ethanol-injected trap trees by verbenone.

We examined the extent to which verbenone, a bark beetle antiaggregation pheromone, interrupted the semiochemical-based attraction of ambrosia beetles. Field trapping studies conducted in Ohio showed that a verbenone dispenser with a release rate of 50 mg/d at 25°C reduced the attraction of Anisandrus sayi Hopkins, Euwallacea validus (Eichhoff), Hypothenemus dissimilis (Zimmermann), Xylosandrus germanus (Blandford), and Xyleborinus saxesenii (Ratzeburg) to ethanol-baited traps. A verbenone dispenser attached to ethanol-injected Magnolia virginiana L. trap trees deployed in Ohio also reduced ambrosia beetle attacks compared to trap trees without a verbenone dispenser. Subsequent field trials demonstrated a direct relationship between distance from a verbenone dispenser and ambrosia beetle attacks on trap trees in Ohio in 2011 and 2012 and Tennessee in 2012, but not in Tennessee and Virginia in 2011. Assessment of the influence of verbenone on the probability of attacks above a density threshold found that although attacks occurred on trap trees regardless of their proximity to a verbenone dispenser, the higher density of attacks per tree occurred on trap trees farthest away from the verbenone source in Ohio and Tennessee. Verbenone alone could be somewhat useful for discouraging ambrosia beetle attacks on individual trees or on a small spatial scale, but deployment of verbenone might be most effective when integrated as part of a "push-pull" strategy.