Detection of bean damage caused by Epilachna varivestis (Coleoptera: Coccinellidae) using drones, sensors, and image analysis.

The Mexican bean beetle, Epilachna varivestis Mulsant (Coleoptera: Coccinellidae), is a key pest of beans, and early detection of bean damage is crucial for the timely management of E. varivestis. This study was conducted to assess the feasibility of using drones and optical sensors to quantify the damage to field beans caused by E. varivestis. A total of 14 bean plots with various levels of defoliation were surveyed aerially with drones equipped with red-blue-green (RGB), multispectral, and thermal sensors at 2 to 20 m above the canopy of bean plots. Ground-validation sampling included harvesting entire bean plots and photographing individual leaves. Image analyses were used to quantify the amount of defoliation by E. varivestis feeding on both aerial images and ground-validation photos. Linear regression analysis was used to determine the relationship of bean defoliation by E. varivestis measured on aerial images with that found by the ground validation. The results of this study showed a significant positive relationship between bean damages assessed by ground validation and those by using RGB images and a significant negative relationship between the actual amount of bean defoliation and Normalized Difference Vegetation Index values. Thermal signatures associated with bean defoliation were not detected. Spatial analyses using geostatistics revealed the spatial dependency of bean defoliation by E. varivestis. These results suggest the potential use of RGB and multispectral sensors at flight altitudes of 2 to 6 m above the canopy for early detection and site-specific management of E. varivestis, thereby enhancing management efficiency.

Landscape-scale spatiotemporal dynamics of Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) populations: implications for spatially-based pest management.

BACKGROUND: Brown marmorated stink bug (BMSB), Halyomorpha halys (Stål), is an invasive and severe pest of specialty and row crops. A 2-year field study conducted in four Mid-Atlantic states in the USA characterized the spatial and temporal dynamics of BMSB populations and its association with landscape elements in commercial agriculture settings. In each state, two 1 km2 sites included typical landscape elements (i.e., tree fruit orchards, annual field and vegetable crops, woodlands, and human-made structures). Twenty-seven georeferenced pheromone traps were deployed per site and the number of BMSB adults and nymphs captured was counted throughout the growing season. RESULTS: Findings from spatial analysis by distance indices, along with time-series maps of BMSB distribution, showed that BMSB exhibited significant spatial aggregation, and that its distribution was spatially consistent between years. Analyses with geographic information systems (GIS) revealed that BMSB 'hot spots' occurred in different landscape elements throughout each season. Most patches (i.e., clusters of significantly higher trap captures) were found near woodlands early in the season, near tree fruit orchards in summer, and on the border of annual field crops in autumn. Buffer analysis with GIS indicated that more BMSB adults were captured closer to woodlands compared with other landscape elements. CONCLUSION: Understanding the spatial and temporal movement and distribution of BMSB is critical to predicting their potential impact and ultimately devising strategies to mitigate this risk to vulnerable crops. The results of this study can be used to design streamlined, spatially-based areawide management of BMSB in heterogeneous and complex agricultural landscapes. © 2023 Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Arthropods Associated with Invasive Frangula alnus (Rosales: Rhamnaceae): Implications for Invasive Plant and Insect Management.

The invasive shrub glossy buckthorn (Frangula alnus) has been progressively colonizing the Northeastern United States and Southeastern Canada for more than a century. To determine the dominant arthropod orders and species associated with F. alnus, field surveys were conducted for two years across 16 plots within the Allegheny National Forest, Pennsylvania, USA. Statistical analyses were employed to assess the impact of seasonal variation on insect order richness and diversity. The comprehensive arthropod collection yielded 2845 insects and arachnids, with hemipterans comprising the majority (39.8%), followed by dipterans (22.3%) and arachnids (15.5%). Notably, 16.2% of the hemipterans collected were in the immature stages, indicating F. alnus as a host for development. The two dominant insect species of F. alnus were Psylla carpinicola (Hemiptera: Psyllidae) and Drosophila suzukii (Diptera: Drosophilidae); D. suzukii utilized F. alnus fruits for reproduction. Species richness and diversity exhibited significant variations depending on the phenology of F. alnus. The profiles of volatile compounds emitted from the leaves and flowers of F. alnus were analyzed to identify factors that potentially contribute to the attraction of herbivores and pollinators. The results of our study will advance the development of novel F. alnus management strategies leveraging the insects associated with this invasive species.

Spatial Patterns of Frangula alnus (Rosales: Rhamnaceae): Implications for Invasive Plant Management.

Glossy buckthorn (Frangula alnus) (Rosales: Rhamnaceae) is an invasive shrub from Europe that has been invading North America for over a century and threatening native vegetation in open and disturbed habitats. The treatment of F. alnus is currently restricted to the roadside, suggesting any individual F. alnus residing within the forest would be left unmanaged and would continue to spread in the area. This research was conducted to determine the spatial patterns and relationship of F. alnus with forest roads. The presence and density of F. alnus at 1412 sample points were recorded on four sites in the Allegheny National Forest, Pennsylvania, USA. Buffer analyses were conducted along roads to determine the relationship between F. alnus density and proximity to forest roads. Geostatistics and spatial analysis by distance indices (SADIE) were used to characterize the spatial pattern of F. alnus. Results of this study showed that F. alnus was spatially aggregated and resided beyond forest roads. Both the density and presence of F. alnus decreased as the distance from the forest road increased. These results imply the potential for precision management of F. alnus by locating and managing only where F. alnus presents.

Rapid Assessment of Insect Pest Outbreak Using Drones: A Case Study with Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) in Soybean Fields.

Rapid assessment of crop damage is essential for successful management of insect pest outbreaks. In this study, we investigated the use of an unmanned aircraft system (UAS) and image analyses to assess an outbreak of the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), that occurred in soybean fields in South Korea. A rotary-wing UAS was deployed to obtain a series of aerial images over 31 soybean blocks. The images were stitched together to generate composite imagery, followed by image analyses to quantify soybean defoliation. An economic analysis was conducted to compare the cost of the aerial survey with that of a conventional ground survey. The results showed that the aerial survey precisely estimated the defoliation compared to the ground survey, with an estimated defoliation of 78.3% and a range of 22.4-99.8% in the 31 blocks. Moreover, the aerial survey followed by image analyses was found to be more economical than the conventional ground survey when the number of target soybean blocks subject to the survey was more than 15 blocks. Our study clearly demonstrated the effectiveness of using an autonomous UAS and image analysis to conduct a low-cost aerial survey of soybean damage caused by S. exigua outbreaks, which can inform decision-making for S. exigua management.

Precision Detection and Assessment of Ash Death and Decline Caused by the Emerald Ash Borer Using Drones and Deep Learning.

Emerald ash borer (Agrilus planipennis) is an invasive pest that has killed millions of ash trees (Fraxinus spp.) in the USA since its first detection in 2002. Although the current methods for trapping emerald ash borers (e.g., sticky traps and trap trees) and visual ground and aerial surveys are generally effective, they are inefficient for precisely locating and assessing the declining and dead ash trees in large or hard-to-access areas. This study was conducted to develop and evaluate a new tool for safe, efficient, and precise detection and assessment of ash decline and death caused by emerald ash borer by using aerial surveys with unmanned aerial systems (a.k.a., drones) and a deep learning model. Aerial surveys with drones were conducted to obtain 6174 aerial images including ash decline in the deciduous forests in West Virginia and Pennsylvania, USA. The ash trees in each image were manually annotated for training and validating deep learning models. The models were evaluated using the object recognition metrics: mean average precisions (mAP) and two average precisions (AP50 and AP75). Our comprehensive analyses with instance segmentation models showed that Mask2former was the most effective model for detecting declining and dead ash trees with 0.789, 0.617, and 0.542 for AP50, AP75, and mAP, respectively, on the validation dataset. A follow-up in-situ field study conducted in nine locations with various levels of ash decline and death demonstrated that deep learning along with aerial survey using drones could be an innovative tool for rapid, safe, and efficient detection and assessment of ash decline and death in large or hard-to-access areas.

Effects of Forest Management on the Insect Assemblage of Black Cherry (Prunus serotina) in the Allegheny National Forest.

Over the last decade, the Allegheny National Forest (ANF) in the USA has experienced issues with the regeneration of black cherry (Prunus serotina). This study was conducted to investigate the effects of silvicultural treatment on the insect communities that may affect black cherry pollination and regeneration. We conducted a 2-year study to compare the abundance, richness, and diversity of insects in unmanaged, shelterwood seed-tree, and shelterwood clear-cut stands. Using pan traps, we sampled insects at the ground level and in the canopies of flowering mature black cherry trees. The results of this study showed significant increases in the abundance of insects captured in shelterwood seed-tree stands and in species richness and diversity of insects captured in the canopy of black cherry in shelterwood removal stands, indicating that silvicultural treatment affected the insect community significantly. The dominant insect order was Diptera (true flies, 72.91%, n = 12,668), and Anthalia bulbosa (Diptera: Hybotidae) was the dominant species comprising 33% of all insects found in the canopy of flowering black cherry. The findings in this study could help land managers in managing black cherry for its pollination and natural regeneration.

Characterization of the Insect Assemblage and Associated Floral Volatiles of Black Cherry (Prunus serotina).

Black cherry is an ecologically important high-value wood. A decline of its regeneration has been reported in the USA, which could be associated with a lack of pollination. This study was conducted to identify insects visiting black cherry flowers, to determine whether insects captured on the flowers carry black cherry pollen and to identify the volatile organic compounds (VOCs) emitted by flowers of black cherry. A two-year insect survey was conducted before, during and after the black cherry bloom. A total of 9533 insects were captured in traps and Diptera was the most abundant (64.1%). Significantly more insects in Diptera, Lepidoptera and Thysanoptera were captured in the traps installed in the canopy than those on the ground, and Anthalia bulbosa (Diptera: Hybotidae) was the dominant species. Electron microscopy analyses demonstrated that insects captured in the canopy indeed carried black cherry pollen. Black cherry flowers emitted a VOC blend that is composed of 34 compounds and dominated by ß-ocimene and several phenylpropanoids/benzenoids. This floral VOC profile is similar to that of other pollinator-dependent Prunus species. This study reports pollinator insects and associated VOCs, for the first time, that could play a significant role in the pollination and regeneration of black cherry.

Spatially Targeted Biological Control of Mile-a-Minute Weed Using Rhinoncomimus latipes (Coleoptera: Curculionidae) and an Unmanned Aircraft System.

Rhinoncomimus latipes Korotyaev is a specialist biocontrol agent of mile-a-minute weed, Persicaria perfoliata (L.) H. Gross (Caryophyllales: Polygonaceae). Currently, R. latipes is released by hand where the presence of the weed is readily detected. However, the hand-release method is not applicable to weed patches spread in hard-to-access areas. This study was conducted to develop a spatially targeted biocontrol strategy by using an unmanned aircraft system (UAS, a.k.a. drone) for the detection of P. perfoliata and aerial release of R. latipes. A ground survey was performed to locate P. perfoliata patches and then a rotary-wing UAS was flown at 15 different altitudes to determine the detectability of P. perfoliata patches. We developed an insect-release system including a pod that housed R. latipes for aerial release. The pod was 3D printed with biodegradable polyvinyl alcohol (PVA), and field tests were conducted to determine the ability of R. latipes to escape the pod and assess their post-release mortality and feeding ability. The results of this study showed that P. perfoliata patches were readily detectable on the aerial images taken at ≤15 m above the ground. More than 98% of R. latipes (n = 118) successfully escaped from the pod within 24 h after aerial deployment. There were no significant (P > 0.05) effects of PVA exposure on the mortality and feeding ability of R. latipes. These results indicate that aerial detection of P. perfoliata and deployment of R. latipes for spatially targeted biological control in hard-to-access areas can be accomplished using a rotary-wing UAS.

Detection of Monema flavescens (Lepidoptera: Limacodidae) Cocoons Using Small Unmanned Aircraft System.

Current unmanned aircraft system (a.k.a. drone) technology is an effective tool for aerial survey of pests including weeds, plant diseases, and insects. This study was conducted to develop an aerial survey method that can locate cocoons of the oriental moth, Monema flavescens Walker, for precise and accurate detection of the cocoons in winter to prevent defoliation in the subsequent summer. We used a rotary-wing drone for an aerial survey of M. flavescens cocoons on 15 trees at 3-5 m above the tree canopy. We also conducted a conventional ground survey of M. flavescens cocoons on the same trees for two different conditions of cocoons: open (i.e., adult moths already emerged from cocoons) and closed (i.e., adult moths were not emerged yet). A validation census with destructive sampling was conducted to determine the precision and accuracy of the aerial and ground survey methods. The results of this study showed that from the aerial survey with the drone, images of open cocoons differed from those of closed cocoons. We found higher precision and accuracy and lower type I and II error rates for closed cocoons by the aerial survey with the drone than those by the ground survey. No significant relationships of the number of cocoons with tree height and diameter at breast height were found. This is the first study to demonstrate direct detection of insects with an aerial survey by using a drone.

Characterization of Salix nigra floral insect community and activity of three native Andrena bees.

Salix nigra (black willow) is a widespread tree that hosts many species of polylectic hymenopterans and oligolectic bees of the genus Andrena. The early flowering of S. nigra makes it an important nutritive resource for arthropods emerging from hibernation. However, since S. nigra is dioecious, not all insect visits will lead to successful pollination. Using both visual observation and pan-trapping, we characterized the community of arthropods that visited S. nigra flowers and assessed differences among male and female trees as well as the chemical and visual drivers that influenced community composition across 3 years. We found that male trees consistently supported higher diversity of insects than female trees and only three insect species, all Andrena spp., consistently visited both sexes. Additionally, Andrena nigrae, which was the only insect that occurred more on female than male flowers, correlated strongly to volatile cues. This suggests that cross-pollinators cue into specific aspects of floral scent, but diversity of floral visitors is driven strongly by visual cues of yellow male pollen. Through time, the floral activity of two Andrena species remained stable, but A. nigrae visited less in 2017 when flowers bloomed earlier than other years. When native bee emergence does not synchronize with bloom, activity appears to be diminished which could threaten species that subsist on a single host. Despite the community diversity of S. nigra flowers, its productivity depends on a small fraction of species that are not threatened by competition, but rather rapidly changing conditions that lead to host-insect asynchrony.

Glandular Trichome-Derived Mono- and Sesquiterpenes of Tomato Have Contrasting Roles in the Interaction with the Potato Aphid Macrosiphum euphorbiae.

Secondary metabolites produced in glandular trichomes of tomato are involved in interactions with herbivores. In cultivated tomato (Solanum lycopersicum) glandular trichomes accumulate a blend of abundant monoterpenes and smaller amounts of a few sesquiterpenes. These mono- and sesquiterpenes are synthesized by three terpene synthases, TPS20 as well as TPS9 and TPS12, respectively. To study effects of these terpenes on performance and choice behavior of potato aphid (Macrosiphum euphorbiae), we utilized two tomato trichome mutants, hairless and odorless-2, that are differently affected in mono- and sesquiterpene production. Non-choice assays demonstrated that longevity and fecundity of M. euphorbiae were increased when kept on the trichome mutants. A principal component analysis of these aphid performance parameters and terpene production in the trichome mutants indicated that longevity and fecundity of M. euphorbiae were negatively correlated with production of the TPS12-derived sesquiterpenes ß-caryophyllene and α-humulene. While we had previously shown that addition of pure ß-caryophyllene/α-humulene to an artificial feeding diet affected M. euphorbiae apterae survivorship and feeding behavior, no such effects were observed here upon addition of a mixture of pure TPS20-derived monoterpenes. In olfactometer assays M. euphorbiae alates displayed differential choice behaviors towards the hairless and odorless-2 mutants suggesting a role of TPS20-derived monoterpenes in aphid attraction, which was further confirmed using a mixture of pure monoterpenes. Our analyses revealed contrasting roles of glandular trichome-derived terpenes in S. lycopersicum. While TPS12-derived sesquiterpenes contribute to host plant resistance against M. euphorbiae, TPS20-derived monoterpenes appear to be exploited as cue for host plant orientation by aphids.

Epidermis-Specific Metabolic Engineering of Sesquiterpene Formation in Tomato Affects the Performance of Potato Aphid Macrosiphum euphorbiae.

Tomato produces a number of terpenes in their glandular trichomes that contribute to host plant resistance against pests. While glandular trichomes of cultivated tomato Solanum lycopersicum primarily accumulate a blend of monoterpenes, those of the wild tomato species Solanum habrochaites produce various sesquiterpenes. Recently, we have identified two groups of sesquiterpenes in S. habrochaites accessions that negatively affect the performance and choice behavior of the potato aphid (Macrosiphum euphorbiae). Aphids are piercing-sucking herbivores that use their mouthpart to penetrate and probe plant tissues in order to ultimately access vascular tissue and ingest phloem sap. Because secondary metabolites produced in glandular trichomes can affect the initial steps of the aphid feeding behavior, introducing the formation of defensive terpenes into additional plant tissues via metabolic engineering has the potential to reduce tissue penetration by aphids and in consequence virus transmission. Here, we have developed two multicistronic expression constructs based on the two sesquiterpene traits with activity toward M. euphorbiae previously identified in S. habrochaites. Both constructs are composed of sequences encoding a prenyl transferase and a respective S. habrochaites terpene synthase, as well as enhanced green fluorescent protein as a visible marker. All three coding sequences were linked by short nucleotide sequences encoding the foot-and-mouth disease virus 2A self-processing oligopeptide which allows their co-expression under the control of one promoter. Transient expression of both constructs under the epidermis-specific Arabidopsis CER5-promoter in tomato leaves demonstrated that formation of the two sets of defensive sesquiterpenes, ß-caryophyllene/α-humulene and (-)-endo-α-bergamotene/(+)-α-santalene/(+)-endo-ß-bergamotene, can be introduced into new tissues in tomato. The epidermis-specific transgene expression and terpene formation were verified by fluorescence microscopy and tissue fractionation with subsequent analysis of terpene profiles, respectively. In addition, the longevity and fecundity of M. euphorbiae feeding on these engineered tomato leaves were significantly reduced, demonstrating the efficacy of this novel aphid control strategy.

Glandular trichome-derived sesquiterpenes of wild tomato accessions (Solanum habrochaites) affect aphid performance and feeding behavior.

Glandular trichomes of tomato produce a number of secondary metabolites including terpenes that contribute to host plant resistance against pests. While glandular trichomes of cultivated tomato Solanum lycopersicum primarily accumulate a monoterpene blend, those of wild tomato species like Solanum habrochaites produce various sesquiterpenes. Previous studies have shown that glandular trichome derived terpenes in cultivated and wild tomato species have repellent and toxic activity against multiple biting-chewing herbivores. In contrast, considerably less is known about the effect of these glandular trichome derived terpenes on piercing-sucking herbivores such as aphids. Here, we have screened a collection of S. habrochaites accessions representing five chemotypes that produce distinct sets of sesquiterpenes to identify those affecting the potato aphid (Macrosiphum euphorbiae). Non-choice assays demonstrated that the longevity and fecundity of M. euphorbiae was significantly reduced when kept on the leaf surface of S. habrochaites accessions producing ß-caryophyllene and α-humulene, or α-santalene, α-bergamotene, and ß-bergamotene, respectively. When M. euphorbiae apterae were feeding on artificial diets with added terpene containing leaf dip extracts, the same ß-caryophyllene/α-humulene and α-santalene/α-bergamotene/ß-bergamotene producing S. habrochaites accessions were found to affect aphid survivorship and feeding behavior as indicated by gel saliva investment and honeydew production. Olfactometer assays revealed that the sesquiterpenes emitted from these S. habrochaites accessions also have repellent activity against M. euphorbiae alatae affecting their choice behavior prior to landing on host plants. Assays performed with pure sesquiterpene compounds and an introgression line carrying respective S. habrochaites terpene biosynthetic genes in the S. lycopersicum background confirmed that ß-caryophyllene/α-humulene and α-santalene/α-bergamotene/ß-bergamotene were responsible for the observed effects on performance, feeding and choice behavior of M. euphorbiae.

Successful management of Halyomorpha halys (Hemiptera: Pentatomidae) in commercial apple orchards with an attract-and-kill strategy.

BACKGROUND: Introduction of Halyomorpha halys (Stål) in the USA has disrupted many established integrated pest management programs for specialty crops, especially apple. While current management heavily relies on insecticides, one potential alternative tactic is attract-and-kill (AK), whereby large numbers of H. halys are attracted to and retained in a circumscribed area using attractive semiochemicals and removed from the foraging population with an insecticide. The goal of this study was to evaluate if AK implementation in commercial apple orchards can result in levels of H. halys damage that are equal to or less than those from grower standard management programs. RESULTS: Over 2 years at farms in five Mid-Atlantic USA states, we found that the use of AK resulted in 2-7 times less damage compared with grower standard plots, depending on year and period. At selected trees on which AK was implemented, over 10,000 H. halys individuals were killed in two growing seasons, and the use of AK reduced the crop area treated with insecticide against H. halys by 97%. Using AK had no impact on the natural enemy or secondary pest community over the same period. CONCLUSIONS: Overall, the use of AK was effective at managing low to moderate H. halys populations in apple orchards, but must be optimized to increase economic feasibility for grower adoption. © 2018 Society of Chemical Industry.

Aerial release of Rhinoncomimus latipes (Coleoptera: Curculionidae) to control Persicaria perfoliata (Polygonaceae) using an unmanned aerial system.

BACKGROUND: Rhinoncomimus latipes (Coleoptera: Curculionidae) is a major biological control agent against the invasive plant Persicaria perfoliata. Release of R. latipes is challenging with the current visit-and-hand release approach because P. perfoliata shows a high degree of patchiness in the landscape, possesses recurved barbs on its stems, and often spreads into hard-to-access areas. This 3-year study developed and evaluated unmanned aerial systems (UAS) for precise aerial release of R. latipes to control P. perfoliata. RESULTS: We have developed two UAS (i.e. quad-rotor and tri-rotor) and an aerial release system to disseminate R. latipes. These include pods containing R. latipes and a dispenser to accommodate eight pods. Results of field tests to evaluate the systems showed no significant (P > 0.05) effects on survivorship and feeding ability of R. latipes after aerial release. CONCLUSION: Our study demonstrates the potential of UAS for precision aerial release of biological control agents to control invasive plants. The aerial deployment systems we have developed, including both pods and a dispenser, are low cost, logistically practical, and effective with no negative effects on aerially released R. latipes. © 2017 Society of Chemical Industry.

Spatial and Temporal Distribution of Imidacloprid Within the Crown of Eastern Hemlock.

Systemic imidacloprid is the most widely used insecticide to control the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), an exotic pest of eastern hemlock, Tsuga canadensis (L.) Carriére in the United States. This study was conducted to 1) determine the effect of treatment timing (spring vs. fall) and application method (trunk injection vs. soil injection) on the spatial and temporal distribution of imidacloprid within the crown of A. tsugae-free eastern hemlock using a competitive enzyme-linked immunosorbent assay (ELISA), 2) compare ELISA to gas chromatography-mass spectrometry (GC/MS) for the detection of imidacloprid in xylem fluid, and 3) determine the concentration of imidacloprid in leaf tissue using high performance liquid chromatography with tandem mass spectrometric (LC/MS/MS) detection methods. Xylem fluid concentrations of imidacloprid were found to be significantly higher for spring applications than for fall applications and for trunk injections than soil injections in the first year posttreatment. A total of 69% of samples analyzed by ELISA gave 1.8 times higher concentrations of imidacloprid than those found by GC/MS, leading to evidence of a matrix effect and overestimation of imidacloprid in xylem fluid by ELISA. A comparison of the presence of imidacloprid with xylem fluid and in leaf tissue on the same branch showed significant differences, suggesting that imidacloprid moved intermittently within the crown of eastern hemlock.

Effects of Temperature on Development and Voltinism of Chaetodactylus krombeini (Acari: Chaetodactylidae): Implications for Climate Change Impacts.

Temperature plays an important role in the growth and development of arthropods, and thus the current trend of climate change will alter their biology and species distribution. We used Chaetodactylus krombeini (Acari: Chaetodactylidae), a cleptoparasitic mite associated with Osmia bees (Hymenoptera: Megachilidae), as a model organism to investigate how temperature affects the development and voltinism of C. krombeini in the eastern United States. The effects of temperature on the stage-specific development of C. krombeini were determined at seven constant temperatures (16.1, 20.2, 24.1, 27.5, 30.0, 32.4 and 37.8°C). Parameters for stage-specific development, such as threshold temperatures and thermal constant, were determined by using empirical models. Results of this study showed that C. krombeini eggs developed successfully to adult at all temperatures tested except 37.8°C. The nonlinear and linear empirical models were applied to describe quantitatively the relationship between temperature and development of each C. krombeini stage. The nonlinear Lactin model estimated optimal temperatures as 31.4, 32.9, 32.6 and 32.5°C for egg, larva, nymph, and egg to adult, respectively. In the linear model, the lower threshold temperatures were estimated to be 9.9, 14.7, 13.0 and 12.4°C for egg, larva, nymph, and egg to adult, respectively. The thermal constant for each stage completion were 61.5, 28.1, 64.8 and 171.1 degree days for egg, larva, nymph, and egg to adult, respectively. Under the future climate scenarios, the number of generations (i.e., voltinism) would increase more likely by 1.5 to 2.0 times by the year of 2100 according to simulation. The findings herein firstly provided comprehensive data on thermal development of C. krombeini and implications for the management of C. krombeini populations under global warming were discussed. *Scientific Article No. 3278 of the West Virginia Agricultural and Forestry Experiment Station, Morgantown, West Virginia.

Distribution of Chaetodactylus krombeini (Acari: Chaetodactylidae) within Osmia cornifrons (Hymenoptera: Megachilidae) nests: implications for population management.

Chaetodactylus krombeini (Baker) (Acari: Chaetodactylidae) is a cleptoparasitic mite that negatively affects propagation of Osmia spp. (Hymenoptera: Megachilidae) for orchard pollination in the USA. This study was conducted to determine the effect of C. krombeini on mortality of male and female Osmia cornifrons, the Japanese hornfaced bee. A total of 107 O. cornifrons nests were examined to determine within-nest distribution of C. krombeini with regression analyses. A total of 30 mite-free O. cornifrons nests were observed and within-nest distribution of male and female O. cornifrons was determined with non-linear regression analyses. In addition, cocoons from 20 mite-infested O. cornifrons cells were examined to determine whether C. krombeini could be found inside cocoons of O. cornifrons. The results of this study showed that female O. cornifrons and C. krombeini were found more frequently in the inner part of the nest, and male O. cornifrons were found mostly in the center of the nest. No C. krombeini were found inside O. cornifrons cocoons. These results indicate that C. krombeini have a greater negative impact on mortality in the egg and larval stages of female O. cornifrons than in male O. cornifrons. Implications for management of C. krombeini and O. cornifrons populations for orchard pollination are discussed in this article.

Temperature-dependent emergence of Osmia cornifrons (Hymenoptera: Megachilidae) adults.

Japanese hornfaced bees Osmia cornifrons (Radoszkowski) (Hymenoptera: Megachilidae) are used for pollination of spring blooming fruit crops such as apple, pear, and blueberry. Because O. cornifrons has a short adult life span, synchronization of bee emergence with bloom is critical to maximize crop pollination. This study was conducted to determine lower temperature thresholds (LTDs), optimum temperatures, and required degree-day accumulation for emergence of O. cornifrons adults. Patterns of temperature-dependent emergence of O. cornifrons adults at seven temperatures (3.9, 12.0, 18.6, 26.6, 30.3, 35.6, and 42.5 degrees C) were modeled and simulated with linear and nonlinear regression analyses. Results of this study showed that required degree-days (DD) for emergence of male and female O. cornifrons adults were 125.2 DD, with LTD of 8.9 degrees C and 179.8 DD, with LTD of 8.6 degrees C, respectively. The optimum temperatures for emergence were 36.5, 30.2, and 35.7 degrees C for male, female, and both sexes combined, respectively. This study indicated that emergence of O. cornifrons adults could be manipulated to synchronize with pollination periods of target fruit crops.