Evaluating Chemical Cues Associated with Halyomorpha halys Toward Enhanced Sensitivity of Surveillance for Trissolcus japonicus.

In Asia, Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae) is the predominant egg parasitoid of the brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae). Detections of adventive T. japonicus populations in North America since 2014, where invasive H. halys populations have impacted various specialty crops, spurred surveillance efforts to track T. japonicus, and yellow sticky cards (YSC) deployed in H. halys host trees have proven effective for this purpose. While T. japonicus exhibits positive behavioral responses to several olfactory stimuli associated with H. halys under laboratory conditions, these have not been evaluated for their potential utility to enhance surveillance of T. japonicus in the field. In northwestern Virginia, where both H. halys and T. japonicus are well-established, we examined the effect of baiting tree of heaven, Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae), with lures containing the H. halys aggregation pheromone and pheromone synergist on the abundance of H. halys egg masses and captures of T. japonicus in YSC. We also assessed the effect of baiting YSC with newly-laid H. halys egg masses or n-tridecane, a component of H. halys tarsal prints, on T. japonicus captures. Destructive sampling of pheromone-baited and nonbaited trees revealed no significant differences in H. halys egg mass abundance on foliage. Similarly, YSC deployed in pheromone-baited and nonbaited trees showed no significant differences in T. japonicus captures. Moreover, YSC augmented with H. halys egg masses or n-tridecane showed no increase in T. japonicus captures compared with nonbaited controls. The implications for surveillance of adventive T. japonicus are discussed.

Using IPM-CPR as a Management Program for Apple Orchards.

We have demonstrated how management of key orchard pests including the insect invasive species Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) can be accomplished using a systems-level approach termed IPM-CPR (Integrated Pest Management-Crop Perimeter Restructuring) in apple. We conducted on-farm comparisons of IPM-CPR to standard management program for managing H. halys, Cydia pomonella (L.) (Lepidoptera: Tortricidae), Grapholita molesta (Busck) (Lepidoptera: Tortricidae), and Lygus lineolaris Palisot de Beauvois (Hemiptera: Miridae) in commercial apple orchards in 2014, 2016, and 2017 in New Jersey, Maryland, and Virginia. The presence and abundance of key pests and fruit injury at harvest were used as a measure of success of the program. We compared the amount of insecticide applied for each management program. In majority of instances, there were no differences in the IPM-CPR and the standard management program in terms of H. halys numbers in baited pyramid traps and stink bug injury at harvest. Damage from C. pomonella and G. molesta in the IPM-CPR treatment was significantly lower than the standard management program in 2014 and 2017. Amount of active ingredient used was on average 62.1% lower in the IPM-CPR treatment compared with standard management program. Despite a reduction in insecticide use, there were minimal impacts on beneficial insects. Overall, IPM-CPR in apples successfully managed key orchard pests, including H. halys, and used significantly less insecticide than a standard insecticide-based management program and could be adopted as a systems-level approach for pest population reduction.

Sampling Methods for Adventive Trissolcus japonicus (Hymenoptera: Scelionidae) in a Wild Tree Host of Halyomorpha halys (Hemiptera: Pentatomidae).

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive pest that has established in much of the United States. Adventive populations of an effective Asian egg parasitoid of H. halys, Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae), have been detected in several states, including Virginia, and its geographic range is expanding. Documenting changes in its distribution and abundance have thus become key research priorities. For these specific purposes, surveillance of T. japonicus over large geographic areas using sentinel H. halys egg masses may not be optimally efficient, and examination of alternative sampling tactics is warranted. In 2016, sentinel H. halys egg masses were deployed as vertical transects in the canopy of female Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae) in Virginia. A brief follow-up study in 2016 using yellow sticky traps deployed in the same trees yielded captures of T. japonicus, leading to a comparison of vertical transects of sentinel eggs and yellow sticky traps in 2017. Both methods yielded T. japonicus detections only in the middle and upper tree canopies, whereas other known H. halys parasitoids were detected in the lower, middle, or upper canopies. Based on this information, a method for deploying yellow sticky traps in the middle canopy of H. halys host trees was assessed in 2017, yielding T. japonicus captures. A comparison of estimated time inputs revealed that traps were more efficient than sentinel eggs in this regard. Results are discussed in relation to the utility of each sampling method to address specific questions about the range expansion and ecology of T. japonicus.

Deltamethrin-Incorporated Nets as an Integrated Pest Management Tool for the Invasive Halyomorpha halys (Hemiptera: Pentatomidae).

Long-lasting insecticide nets (LLINs), which have insecticide incorporated within the fibers, have been widely used for control of malaria and other insect-vectored diseases. Only recently have researchers begun exploring their use for control of agricultural pests. In this study, we evaluated the toxicity of a deltamethrin-incorporated LLIN, ZeroFly (Vestergaard-Frandsen, Washington, DC) for control of the brown marmorated stink bug, Halyomorpha halys (Stål). In the lab, exposure to the ZeroFly net for 10 s resulted in >90% mortality of H. halys nymphs and >40% mortality of H. halys adults. Longer exposure to the net resulted in higher mortality. In another experiment, a 15-cm2 sheet of ZeroFly net placed inside of the stink bug trap provided long-lasting kill of H. halys adults equal to or better than standard dichlorvos kill strip. Potential for the use of ZeroFly nets for H. halys IPM is discussed.

Flight behavior of foraging and overwintering brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae).

Brown marmorated stink bug, Halyomorpha halys (Stål), is a highly polyphagous invasive species attacking both cultivated and wild plants increasing its threat to ecosystems as a global pest. However, dispersal biology of this invasive species is not well understood. This study evaluated the flight capacity and behavior of H. halys under laboratory, semi-field, and field conditions. Flight mills were used to measure the baseline flight capacity of adults collected year round from the field and included both foraging and overwintering populations. The effects of abiotic conditions such as wind speed and temperatures on the free flight parameters of H. halys were evaluated under semi-field and field conditions. The mean flight distances over a 22-h period were 2442 and 2083 m for male and female, respectively. Most individuals (89%) flew <5 km, though some flew much further with a maximum flight distance observed of 117 km. Flight distances by H. halys increased after emergence from overwintering sites in spring and reached their highest point in June. The incidence of take off by H. halys was significantly affected by the wind speed; when provided with still air conditions, 83% of individuals took off, but the rates decreased to <10% when wind speed was increased to or above 0.75 m s-1. The incidence of take off by H. halys was significantly affected by ambient temperature and light intensity in the field, whereas relative humidity and insect sex did not. When the temperature was at 10-15°C, 3% of individuals took off, but the proportion of H. halys taking flight increased to 61, 84, and 87% at 15-20, 20-25, and 25-30°C, respectively. In the field, prevailing flight direction was biased toward the opposite direction of the sun's position, especially in the morning. The implications of H. halys flight biology are discussed in the context of developing monitoring and management programs for this invasive species.

Evaluation of tag entanglement as a factor in harmonic radar studies of insect dispersal.

The observation of insects and other small organisms entangled in the habitat after the addition of vertical or trailing electronic tags to their body has generated concerns on the suitability of harmonic radars to track the dispersal of insects. This study compared the walking behavior of adult Colorado potato beetle (Leptinotarsa decemlineata (Say) Chrysomelidae), plum curculio (Conotrachelus nenuphar (Herbst) Curculionidae), and western corn rootworm (Diabrotica virgifera virgifera (LeConte) Chrysomelidae) with and without vertical and or trailing tags in field plots or arenas. The frequency of the larger Colorado potato beetles crossing bare ground or grassy plots was unaffected by the presence of an 8 cm trailing harmonic radar tag. However, plum curculios and western corn rootworms, were either unable to walk with a 4 cm trailing tag (plum curculio) or displayed a reduced ability to successfully cross a bare ground arena. Our results revealed the significant impact of vegetation on successful insect dispersal, whether tagged or not. The vertical movement of these insects on stems, stalks, and tubes was also unaffected by the presence of vertical tags. Trailing tags had a significant negative effect on the vertical movement of the western corn rootworm. Results show that harmonic radar technology is a suitable method for studying the walking paths of the three insects with appropriate tag type and size. The nuisance factor generated by appropriately sized tags was small relative to that of vegetation.

Harmonic radar: assessing the impact of tag weight on walking activity of Colorado potato beetle, plum curculio, and western corn rootworm.

The impact of electronic dipole tags on the walking activity of three insects was determined using video tracking software. Results varied within and between the three species studied. The heaviest tag mounted on the pronotum of the Colorado potato beetle, Leptinotarsa decemlineata (Say), reduced its mean horizontal speed slightly but significantly. The mean horizontal speed of plum curculio, Conotrachelus nenuphar (Herbst), was significantly reduced by a light tag but not by heavier tags. The mean horizontal speed of the western corn rootworm, Diabrotica virgifera virgifera (LeConte), increased slightly when a tag was attached. A tag mounted to the dorsum of the Colorado potato beetle and the plum curculio slightly changed their climbing speed. Changes in the walking speed were variable but remained well within the range of values recorded in the literature. The impact of the additional tag weight was within the range of constraints to movement (e.g., slopes, barriers, etc.) normally experienced by insects in their environment. The results confirm that tags presently available will have minimal impact on the walking behavior of Colorado potato beetle, provide an estimate of the optimal tag weight for the plum curculio and show that a lighter tag and a better attachment method are required for the western corn rootworm. Because of the ability of insects to adapt to a wide range of landscapes and to their own body weight changes, the additional tag weight had a limited impact compared with the value of the ecological information gathered using this technology.

Effectiveness of glues used for harmonic radar tag attachment and impact on survival and behavior of three insect pests.

The ability of three cyanoacrylate glues to ensure a durable bond between the Colorado potato beetle, Leptinotarsa decemlineata (Say), the plum curculio, Conotrachelus nenuphar (Herbst), or the corn rootworms (Western Corn Rootworm, Diabrotica virgifera virgifera LeConte and Northern Corn Rootworm, Diabrotica longicornis Smith and Lawrence) and the harmonic radar tag without impact on behavior and survival was assessed as part of a study on the use of harmonic radar technology to track these insect pests. Droplets of 0.1 mg of Krazy Glue, Loctite, and Bowman FSA applied to the pronotum had no effect on the survival of the Colorado potato beetle or plum curculio after 5 and 7 d, but caused > 40% mortality after only 4 h with both the western and northern corn rootworms. The three glues created an effective bond lasting 4-5 d between the harmonic radar tag and the Colorado potato beetle in > 85% of cases and the plum curculio in almost 50% of cases. There was no detectable impact of the glue treatment on feeding or walking behavior of the Colorado potato beetle. Analysis of the same behaviors with the plum curculio showed no impact on the ability to walk on a vertical surface, the speed of travel, or the duration of travel. There was no significant impact on feeding by female plum curculio but indication that males treated with Krazy Glue fed less. Overall, results quantified the effectiveness of the cyanoacrylate glues at providing a durable bond with no significant impact on mobility or behavior of the Colorado potato beetle or plum curculios. However, the toxicity of the glues against the corn rootworms suggests that similar toxicity or sublethal effects may exist with other insects.

Postmating behavior of female dogwood borer (Lepidoptera: Sesiidae) in apple orchards.

The postmating behavior of female dogwood borer, Synanthedon scitula (Harris) (Lepidoptera: Sesiidae), was examined in a young apple orchard planted on size-controlling rootstock in Virginia. All female dogwood borers captured while exhibiting casting flight near the base of trees were mated, based on the presence of a spermatophore. Surveys of female activity within orchards were conducted at regular intervals throughout the daylight hours, showing a diel periodicity that peaked between 1700 and 1900 hours, with most females located below the graft union of trees. A transition matrix based on 1,108 behavioral sequences exhibited by 66 females was used to produce a first-order Markov chain of behavioral events that occurred significantly more often than expected by chance. Casting flight, probing with ovipositor, and oviposition were the most frequent behaviors observed, representing 31.7, 30.0, and 18.1% of all behaviors recorded, respectively. Our observations showed that 88, 99, and 99% of casting flight, probing with the ovipositor, and oviposition, respectively, occurred below the graft union. Observed behaviors considered not directly related to oviposition site selection or oviposition included antennal grooming, noncasting flight, and resting, representing 1.3, 8.3, and 10.6% of all behaviors recorded, respectively. Mated females spent significantly more time resting than in other behaviors and significantly more time in that state within the apple tree canopy than on other parts of the tree. Results are discussed in relation to the influence of insect-host plant interactions on oviposition site selection by female dogwood borer.

Dogwood borer (Lepidoptera: Sesiidae) abundance and seasonal flight activity in apple orchards, urban landscapes, and woodlands in five eastern states.

The relative abundance and seasonal flight activity of dogwood borer, Synanthedon scitula Harris (Lepidoptera: Sesiidae), was measured using weekly records from traps baited with its sex pheromone and deployed in apple orchards, urban landscapes, and native woodland sites in New York, West Virginia, Virginia, North Carolina, and Tennessee in 2005 and 2006. The mean total number of moths captured per site in apple orchards was 3,146 +/- 644 and 3095 +/- 584 SE in 2005 and 2006, respectively, exceeding captures at urban sites by 16 and 13 times and at woodland sites by 210 and 206 times in 2005 and 2006, respectively. Mean total captures at urban sites exceeded those in woodland habitats by 13 and 16 times in 2005 and 2006, respectively. The mean duration (wk) of the flight period did not differ significantly between apple orchards (22.6 +/- 0.6 SE) and urban sites (20.3 +/- 1.2 SE). The onset of flight was somewhat later in New York (around early June) than further south (around early to mid-May), but moth captures continued into October in all states. Captures in apple orchards and at urban sites with higher populations were essentially continuous throughout the flight period, with substantial weekly fluctuations, and tended to show a bimodal pattern with peaks from late May through mid-July and from late August through mid-September. Captures at woodland sites tended to occur predominantly from mid-May through about mid-June and were very sporadic thereafter.

Monitoring stink bugs (Hemiptera: Pentatomidae) in mid-Atlantic apple and peach orchards.

Pyramid traps coated with "industrial safety yellow" exterior latex gloss enamel paint and baited with Euschistus spp. aggregation pheromone, methyl (2E,4Z)-decadienoate captured more stink bugs than all other baited and unbaited trap types in both apple and peach orchards in 2002 and 2003. Commercial sources of dispensers of methyl (2E,4Z)-decadienoate deployed in association with pyramid traps had a significant impact on trap captures. Captures in pyramid traps were four-fold greater when baited with lures from IPM Technologies, Inc. (Portland, OR) than with lures from Suterra (Bend, OR). Variation in yellow pyramid trap color ("industrial safety yellow" and "standard coroplast yellow") and material (plywood, plastic, and masonite) did not affect trap captures. Brown stink bug was the predominant species captured (58%), followed by dusky stink bug, Euschistus tristigmus (Say) (20%); green stink bug, Acrosternum hilare (Say) (14%); and other stink bugs (Brochymena spp. and unidentified nymphs) (8%). Captures in baited pyramid traps were significantly correlated with tree beating samples in both managed and unmanaged apple orchards and with sweep netting samples in the unmanaged apple orchard. However, problems associated with trapping mechanisms of pyramid trap jar tops and jar traps likely resulted in reduced captures in baited traps. Improved trapping mechanisms must be established to develop an effective monitoring tool for stink bugs in mid-Atlantic orchards.

Evaluation of individual components of plum odor as potential attractants for adult plum curculios.

We evaluated olfactory attraction of overwintered plum curculio (PC) adults, Conotrachelus nenuphar, to 16 individual volatile components of unripe plum odor in the laboratory using a still-air dual-choice bioassay system and in the field using baited cotton dental wicks attached to boll-weevil traps placed on the ground beneath the canopy of unsprayed apple trees. Two compounds, ethyl isovalerate and limonene, were significantly attractive in both laboratory bioassays and field experiments. In laboratory bioassays, as concentration was decreased across five orders of magnitude, a greater number of compounds elicited responses suggestive of attractancy (except at the lowest concentration). Even so, linalool, 2-hexanone, and 3-hydroxy-2-butanone were the only other compounds showing significant attractiveness in laboratory bioassays, but none of these (nor any other compounds) were significantly attractive in field assays. We suggest that the use of ethyl isovalerate and/or limonene as odor attractants offers potential to increase the efficacy of current traps for monitoring PCs immigrating into fruit orchards during spring.

Attraction of adult Rhagoletis indifferens (Diptera: Tephritidae) to unbaited and odor-baited red spheres and yellow rectangles.

Five sizes of red spheres (4, 6, 8, 10, and 12 cm diameter) and 2 orientations of yellow rectangles (vertical and V) were evaluated as unbaited sticky-coated traps for western cherry fruit flies, Rhagoletis indifferens Curran, in unmanaged cherry trees in Washington and Oregon. Red spheres that were 10 cm in diameter attracted more flies than red spheres that were 8 or 12 cm in diameter and significantly more flies than 4- or 6-cm spheres and yellow rectangles of either orientation. In a 2nd test, red spheres (10 cm diameter) baited with ammonium carbonate alone or ammonium carbonate plus putrescine attracted significantly more R. indifferens than similar spheres baited with ammonium acetate alone, putrescine alone, 3-methyl-1-butanol alone, or combinations of these substances. In a 3rd test, vertical yellow rectangles baited with ammonium carbonate alone attracted numerically more R. indifferens than any of the aforementioned substances alone or in combination. We discuss the potential value of 10-cm red spheres baited with ammonium carbonate for monitoring and direct control of R. indifferens.