Genetic diversity of the brown marmorated stink bug <Emphasis Type="Italic">Halyomorpha halys</Emphasis> in the invaded territories of Europe and its patterns of diffusion in Italy

Halyomorpha halys is an invasive stink bug pest originating from East Asia. In Europe, it was first detected in Switzerland in 2004. It is now present in thirteen countries, and seems to be spreading throughout the continent. In Italy, where it has been recorded since 2012, other than being an urban nuisance, it is causing severe damage in commercial fruit orchards. An integrated approach, using current and previous observational data in space and time and molecular information, was used to identify the genetic diversity of this pest in Europe, its invasion history, and the potential pathways of entry and diffusion. The analysis of 1175 bp of mitochondrial DNA cytochrome c oxidase I and II genes (cox1, cox2) led to the identification of twenty previously unknown haplotypes. The European distribution of H. halys is the result of multiple invasions that are still in progress, and, in some cases, it was possible to identify the specific Asian areas of origin. Moreover, secondary invasions could have occurred among European countries by a bridgehead effect. In Italy, the data were more clearly related to their temporal occurrence, allowing for a clearer reading of the patterns of invasion and dispersion. After having successfully established in localized areas, H. halys further expanded its range by an active dispersion process and/or by jump dispersal events due to passive transport. The multiple introductions from different areas of the native range together with the different patterns of diffusion of H. halys, may hamper the pest management strategies for its containment.     

Presence of the invasive brown marmorated stink bug Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) on home exteriors during the autumn dispersal period: Results generated by citizen scientists

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Predation of <Emphasis Type="Italic">Halyomorpha halys</Emphasis> (Hemiptera: Pentatomidae) from Web-Building Spiders Associated with Anthropogenic Dwellings

The brown marmorated stink bug, or Halyomorpha halys, is an invasive pest in North America and Europe that causes severe agricultural damage and nuisance problems for homeowners; and it is originally from China, Taiwan, and the Republic of Korea. While the natural enemy community of H. halys has been evaluated in several agroecosystems, it has not been examined where H. halys overwinters in anthropogenic structures. The aims of the current study were to evaluate 1) whether spider webs commonly found in the home and yard can successfully ensnare H. halys, 2) whether entanglement resulted in consumption by spiders inhabiting the webs, and 3) how frequently H. halys becomes entangled in webs under ambient conditions. To accomplish this, adult H. halys were introduced into webs in and near anthropogenic structures in West Virginia and Maryland, United States, and the behavior of spiders was observed for 5-min intervals at 0, 1, 2, and 24 h after introduction. In addition, a survey of webs was performed to determine the frequency with which spiders naturally capture H. halys inside buildings and in the landscape. Overall, the study found seven spider families in anthropogenic structures. Adult H. halys that were introduced into the webs of Theridiidae, Pholcidae, or Agelenidae had a greater than 50% chance of being ensnared and consumed. Adult H. halys were found naturally most often in webs of Theridiidae. Webs with a funnel or cob web architecture had the greatest probability of ensnaring H. halys, while those with orb structures resulted in the fewest caught. In the wild, 13–20% of spider webs contained dead H. halys. Our results suggest that spiders may be an important contributing factor for mortality of H. halys at overwintering sites, and spiders in or outside homes may help reduce nuisance problems caused by H. halys.     

Characterization of Overwintering Sites of the Invasive Brown Marmorated Stink Bug in Natural Landscapes Using Human Surveyors and Detector Canines

Halyomorpha halys is an invasive species from Asia causing major economic losses in agricultural production in the mid-Atlantic region of the United States. Unlike other crop pests, H. halys is also well-known for nuisance problems in urban, suburban, and rural areas, as massive numbers of adults often invade human-made structures to overwinter inside protected environments. Research efforts have focused on populations in human-made structures while overwintering ecology of H. halys in natural landscapes is virtually unknown. We explored forested landscapes in the mid-Atlantic region to locate and characterize natural overwintering structures used by H. halys. We also evaluated the use of detector canines to locate overwintering H. halys to enhance the accuracy and efficiency of surveys. From these studies, we indentified shared characteristics of overwintering sites used by H. halys in natural landscapes. Overwintering H. halys were recovered from dry crevices in dead, standing trees with thick bark, particularly oak (Quercus spp.) and locust (Robinia spp.); these characteristics were shared by 11.8% of all dead trees in surveyed landscapes. For trees with favorable characteristics, we sampled ∼20% of the total above-ground tree area and recovered 5.9 adults per tree from the trees with H. halys present. Two detector canines were successfully trained to recognize and detect the odor of adult H. halys yielding >84% accuracy in laboratory and semi-field trials. Detector canines also found overwintering H. halys under field conditions. In particular, overwintering H. halys were recovered only from dead trees that yielded positive indications from the canines and shared key tree characteristics established by human surveyors. The identified characteristics of natural overwintering sites of H. halys will serve as baseline information to establish crop economic risk levels posed by overwintering populations, and accordingly develop sustainable management programs.     

Effects of Rag1 aphid‐resistant soybean on mortality,development, and preference of brown marmorated stink bug

The brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), poses a new threat to soybean, Glycine max (L.) Merrill (Fabaceae), production in the north central USA. As H. halys continues to spread and increase in abundance in the region, the interaction between H. halys and management tactics deployed for other pests must be determined. Currently, the soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is the most abundant and damaging insect pest of soybean in the region. Aphid‐resistant soybean, mainly with the Rag1 gene, is commercially available for management of A. glycines. Here, experiments were performed to evaluate the effects of Rag1 aphid‐resistant soybean on the mortality, development, and preference of H. halys. In a no‐choice test, mortality of H. halys reared on Rag1 aphid‐resistant soybean pods was significantly lower than when reared on aphid‐susceptible soybean pods (28 vs. 53%). Development time, adult weight, and proportion females of surviving adults did not differ when reared on Rag1 aphid‐resistant or aphid‐susceptible soybean pods. In choice tests, H. halys exhibited a preference for Rag1 aphid‐resistant over aphid‐susceptible soybean pods after 4 h, but not after 24 h. Halyomorpha halys exhibited no preference when tested with vegetative‐stage or reproductive‐stage soybean plants. The preference by H. halys for Rag1 aphid‐resistant soybean pods and the decreased mortality when reared on these pods suggests that the use of Rag1 aphid‐resistant soybean may favor this emerging pest in the north central USA.     

Tracing the origin of US brown marmorated stink bugs, Halyomorpha halys

Identifying the origin of a biological invasion has important applications to the effective control of the invaders. This is more critical for invasive agricultural pests that cause severe economic losses. The brown marmorated stink bug, Halyomorpha halys, originally from East Asia, has become a principal agricultural pest in the US since its first detection in Pennsylvania in 1996. This species is responsible for crop failures on many mid-Atlantic farms and current control efforts rely on heavy insecticide applications because no other options are available. To examine the genetic diversity and identify the source region of the US introductions, we sequenced portions of the mitochondrial cytochrome c oxidase subunit II gene, 12S ribosomal RNA gene and control region in populations from the US, China, South Korea and Japan. We detected high genetic divergence among native populations and traced the origin of US H. halys to the Beijing area in China. We observed much lower genetic diversity in exotic compared to native populations—two mitochondrial haplotypes in 55 US specimens versus 43 haplotypes in 77 native specimens. A single introduction of small propagule size matches the invasion history in the US. For the effective control of the US population, we suggest that surveys on egg parasitoids and insecticide resistance in natives should focus on the Beijing area in China.     

Electronically Monitored Labial Dabbing and Stylet ‘Probing’ Behaviors of Brown Marmorated Stink Bug,Halyomorpha halys,in Simulated Environments

Brown marmorated stink bug, Halyomorpha halys (Stål), (Hemiptera: Pentatomidae) is an invasive polyphagous agricultural and urban nuisance pest of Asian origin that is becoming widespread in North America and Europe. Despite the economic importance of pentatomid pests worldwide, their feeding behavior is poorly understood. Electronically monitored insect feeding (EMIF) technology is a useful tool in studies of feeding behavior of Hemiptera. Here we examined H. halys feeding behavior using an EMIF system designed for high throughput studies in environmental chambers. Our objectives were to quantify feeding activity by monitoring proboscis contacts with green beans, including labial dabbing and stylet penetration of the beans, which we collectively define as ‘probes’. We examined frequency and duration of ‘probes’ in field-collected H. halys over 48 hours and we determined how environmental conditions could affect diel and seasonal periodicity of ‘probing’ activity. We found differences in ‘probing’ activity between months when the assays were conducted. These differences in activity may have reflected different environmental conditions, and they also coincide with what is known about the phenology of H. halys. While a substantial number of ‘probes’ occurred during scotophase, including some of the longest mean ‘probe’ durations, activity was either lower or similar to ‘probing’ activity levels during photophase on average. We found that temperature had a significant impact on H. halys ‘probing’ behavior and may influence periodicity of activity. Our data suggest that the minimal temperature at which ‘probing’ of H. halys occurs is between 3.5 and 6.1°C (95% CI), and that ‘probing’ does not occur at temperatures above 26.5 to 29.6°C (95% CI). We estimated that the optimal temperature for ‘probing’ is between 16 and 17°C.     

Contrasting Role of Temperature in Structuring Regional Patterns of Invasive and Native Pestilential Stink Bugs

Objectives

Assessment and identification of spatial structures in the distribution and abundance of invasive species is important for unraveling the underlying ecological processes. The invasive agricultural insect pest Halyomorpha halys that causes severe economic losses in the United States is currently expanding both within United States and across Europe. We examined the drivers of H. halys invasion by characterizing the distribution and abundance patterns of H. halys and native stink bugs (Chinavia hilaris and Euschistus servus) across eight different spatial scales. We then quantified the interactive and individual influences of temperature, and measures of resource availability and distance from source populations, and their relevant spatial scales. We used Moran’s Eigenvector Maps based on Gabriel graph framework to quantify spatial relationships among the soybean fields in mid-Atlantic Unites States surveyed for stink bugs.

Findings

Results from the multi-spatial scale, multivariate analyses showed that temperature and its interaction with resource availability and distance from source populations structures the patterns in H. halys at very broad spatial scale. H. halys abundance decreased with increasing average June temperature and distance from source population. H. halys were not recorded at fields with average June temperature higher than 23.5°C. In parts with suitable climate, high H. halys abundance was positively associated with percentage developed open area and percentage deciduous forests at 250m scale. Broad scale patterns in native stink bugs were positively associated with increasing forest cover and, in contrast to the invasive H. halys, increasing mean July temperature. Our results identify the contrasting role of temperature in structuring regional patterns in H. halys and native stink bugs, while demonstrating its interaction with resource availability and distance from source populations for structuring H. halys patterns.

Conclusion

These results help predicting the pest potential of H. halys and vulnerability of agricultural systems at various regions, given the climatic conditions, and its interaction with resource availability and distance from source populations. Monitoring and control efforts within parts of the United States and Europe with more suitable climate could focus in areas of peri-urban developments with deciduous forests and other host plants, along with efforts to reduce propagule pressure.     

Citizen science and early detection of invasive species: phenology of first occurrences of <Emphasis Type="Italic">Halyomorpha halys</Emphasis> in Southern Europe

Early detection of invasive alien species and the ability to track their spread are critical for undertaking appropriate management decisions. Citizen science surveys are potentially valuable tools for quickly obtaining information on biodiversity and species distributions. The Asian brown marmorated stink bug, Halyomorpha halys, is an invasive pest of agricultural crops and a dwelling nuisance. Halyomorpha halys was first recorded in Italy in 2012 in Emilia Romagna, one of the most important fruit producing regions of Europe. To rapidly obtain data on its distribution in the newly invaded area, a survey that combined citizen science and active search was set up using multimedia channels. Data concerning when, where and how the bugs were spotted were collected, together with photographs and specimens. The survey detected established breeding populations in different areas of Northern Italy and Southern Switzerland, indicating a potentially high risk for crop damage that extends beyond the territories of first detection. Furthermore, new data on H. halys phenology, host plants, voltinism and behaviour were obtained. The importance of citizen science in early detection of introduced pest species is highlighted. This paper also provides a picture-based key to recognize H. halys from similar pentatomids in the world.     

A native predator utilising the invasive brown marmorated stink bug,Halyomorpha halys (Hemiptera: Pentatomidae) as a food source

The nest provisions of a native predator species Bicyrtes quadrifasciata (Say) (Hymenoptera: Crabronidae) were surveyed and examined for the presence of nymphs of Halyomorpha halys, which is an invasive pest of many economically important agricultural crops in the U.S.A. We found 96% of the nest provisions of B. quadrifasciata were H. halys indicating the potential of B. quadrifasciata in biocontrol of this pest. Potential of B. quadrifasciata in regulating population dynamics of H. halys is discussed.     

Invasive brown marmorated stink bug <Emphasis Type="Italic">Halyomorpha halys</Emphasis> (Stål) (Heteroptera: Pentatomidae) in Russia,Abkhazia, and Serbia: history of invasion,range expansion,early stages of establishment,and first records of damage to local crops

Halyomorpha halys is native to Asia, but was recently accidentally introduced to North America and Europe. This species was recorded for the first time in Russia in 2013 (2014) and in both Serbia and Abkhazia in 2015. In 2015–2017, we conducted surveys in Russia, Serbia, and Abkhazia and found that H. halys had not only successfully survived its first winters in new regions, but also started to establish locally, spread, increase populations, and damage local crops. In Sochi (Russia) and Abkhazia, H. halys was recorded to feed on 32 species and cultivars from 16 plants families. In Serbia, it has so far been observed on only four species from four plant families. H. halys is already widely spread in Abkhazia and causes serious damage to many crops: in 2016, the yield of peach, mandarin orange, persimmon and other crops fell down by 13.2–87.4% if compared to the long-term means of yield. The losses are likely to be mostly caused by feeding of H. halys. We conclude that H. halys was accidentally introduced to Russia in 2012–2013 most likely with woody plants imported to Sochi from Italy or Greece for urban landscaping before the 2014 Winter Olympics. The species established in Sochi and quickly moved to Krasnodar (Russia), Abkhazia, and beyond—to Georgia. Populations in Serbia most likely arrived in 2015 traveling on railway cars or in commodities on the Bucharest–Belgrade railway line. We discuss phenology and prospects of further expansion of H. halys in Europe.     

Predatory ability of generalist predators on eggs,young nymphs and adults of the invasive Halyomorpha halys in southern Europe

Halyomorpha halys (Stål, 1855) is an invasive pest causing serious damage to agricultural crops in Europe and the USA. Very little is known about H. halys predators in Europe. This survey evaluated the potential of generalist predators/omnivorous species by means of predation bioassays in tri-dimensional arenas, where the predator had to locate H. halys prey items on the leaves of a bean plant. Eleven species of different taxa were tested and the prey items consisted in fresh eggmasses, 1st and 2nd instar nymphs. One species was also tested against adults. Some predators were species commercially available as biocontrol agents against plant pests, other predators were wild, captured in habitats shared with H. halys. All tested specimens were starved 24 h before starting the experiment. The survivorship of control prey items in predator-excluding cages was compared to that of predator treatment groups to determine the effect of predator presence. According to the results, the generalist species showed a quite low acceptance of H. halys prey items, since only two species caused 80% mortality on at least one item (Eupholidoptera chabrieri and Rhynocoris iracundus) and mortality due the other species never exceed 60%. Among commercially available species only Adalia bipunctata adults and Chrysoperla carnea larvae were effective, predating the eggs and 1st instar nymphs, respectively. Among the field collected specimens, the orthopteran E. chabrieri and the predatory hemipterans R. iracundus, Nagusta goedelii and Himacerus mirmicoides showed efficacy against 1st instar nymphs, E. chabrieri and R. iracundus showed efficacy against 2nd instar nymphs, whereas only E. chabrieri and N. goedelii predated the eggs. R. iracundus was also tested on the adults and successfully predated them. By identifying some of the species that can exploit H. halys as a suitable prey in southern Europe, the present investigation provides an important contribution for conservation biological control of this pest.

     

Invasion dynamics of the glassy-winged sharpshooter <Emphasis Type="Italic">Homalodisca vitripennis</Emphasis> (Germar) (Hemiptera: Cicadellidae) in French Polynesia

The glassy-winged sharpshooter, Homalodisca vitripennis (Germar) [formerly Homalodisca coagulata (Say)] (Hemiptera: Cicadellidae), has recently emerged as a serious invasive pest. From its natural range in the southeast USA and northeast Mexico, it invaded successively California (late 1980s), French Polynesia (1999), Hawaii (2004), and recently Easter Island (2005) inadvertently through the transportation of infested plants. In French Polynesia, H. vitripennis has reached impressive densities becoming an important pest threatening agriculture, native biodiversity, as well as being a major social nuisance. Since 1999, H. vitripennis spread rapidly from Tahiti to neighboring islands, colonizing most of the archipelagos of French Polynesia. In this paper, we present the results of surveys of H. vitripennis populations from 15 islands of French Polynesia and use these data to investigate the invasion dynamics and colonization processes of this pest in a tropical climate. We found H. vitripennis present in 10 islands with two new records confirmed. Our analyses suggest that: (1) H. vitripennis abundance is strongly associated with urbanization, with highest pest densities found in the most developed coastal areas of infested islands, (2) H. vitripennis may exhibit an Allee effect during the early phase of an invasion, and (3) the invasion dynamics of H. vitripennis conform to a stratified dispersal model marked by rapid long-distance human-mediated movement.     

Development and comparison of trunk traps to monitor movement of Halyomorpha halys nymphs on host trees

Halyomorpha halys Stål (Hemiptera: Pentatomidae) has recently become a major orchard pest in the Mid‐Atlantic, USA. Large H. halys populations can develop on wild tree hosts adjacent to orchards, posing an ongoing threat to fruit. Adults and nymphs feed on tree fruit, causing economic injury. Understanding the seasonal patterns of nymphal host use among trees at the orchard‐woodland interface may aid the development of integrated pest management strategies for this pest. In laboratory and field experiments, modified versions of published trap designs – ‘Circle’, ‘Hanula’, ‘M&M’ (after Moeed & Meads) traps – were compared for their effectiveness for capturing H. halys nymphs walking up and down tree trunks. In the laboratory, second instars were released at the top and bottom of ailanthus (tree of heaven), Ailanthus altissima (Mill.) Swingle (Simaroubaceae), logs and captures were recorded after 24 h. Circle and M&M traps, respectively, were most effective for capturing nymphs walking up and down. In the field, traps were deployed on ailanthus trees next to apple orchards and captures were recorded weekly from 24 July to 11 September 2013. As in the laboratory, Circle and M&M traps captured the greatest number of upward‐ and downward‐walking nymphs. Hanula traps were least effective in both experiments. In the field, 88% of total captures were of nymphs walking up trees. This was at least partially explained by behavioral assays in the laboratory demonstrating that nymphs exhibited negative gravitaxis and positive phototaxis. Stage‐specific trends in captures of instars walking up during field sampling were observed. These results suggest that trunk traps can be used to address important ecological questions about seasonal patterns of host use by H. halys nymphs.     

Host Plant Use by the Invasive Halyomorpha halys (St?l) on Woody Ornamental Trees and Shrubs

The brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive plant-feeding insect native to eastern Asia. This herbivore is highly polyphagous, feeding on and damaging diverse plants, including field crops, vegetables, tree fruits, and ornamentals. Woody ornamental plants provide early- and late-season resources for adults emerging from and returning to overwintering sites, as well as feeding and breeding sites for H. halys throughout the growing season. In this study, we quantify the use of diverse plants by H. halys in two commercial nurseries in Maryland, recording data on the abundance of egg masses, early and late instar nymphs, and adults over a three-year study period. Our specific goals were to provide a quantitative comparison of the use of diverse plant species and cultivated varieties, identify non-hosts that could be used to create landscapes refractory to H. halys, and determine whether the use of plants varied across life stages of H. halys or the taxonomic status of plants. We found broad use of diverse plants in this study, identifying 88 host plants used by all life stages of H. halys. We also highlight the 43 plant taxa that did not support any life stage of H. halys and are thus classified as non-hosts. Interestingly, some of these plants were congeners of highly-used plants, underscoring high intrageneric and intraspecific variation in the use of plants by this polyphagous herbivore. We discuss how the selective planting of non-hosts, especially gymnosperms, may aid in reducing the agricultural and nuisance pest status of this invasive insect.     

Insecticide Resistance Status of United States Populations of Aedes albopictus and Mechanisms Involved

Aedes albopictus (Skuse) is an invasive mosquito that has become an important vector of chikungunya and dengue viruses. Immature Ae. albopictus thrive in backyard household containers that require treatment with larvicides and when adult populations reach pest levels or disease transmission is ongoing, adulticiding is often required. To assess the feasibility of control of USA populations, we tested the susceptibility of Ae. albopictus to chemicals representing the main insecticide classes with different modes of action: organochlorines, organophosphates, carbamates, pyrethroids, insect growth regulators (IGR), naturalytes, and biolarvicides. We characterized a susceptible reference strain of Ae. albopictus, ATM95, and tested the susceptibility of eight USA populations to five adulticides and six larvicides. We found that USA populations are broadly susceptible to currently available larvicides and adulticides. Unexpectedly, however, we found significant resistance to dichlorodiphenyltrichloroethane (DDT) in two Florida populations and in a New Jersey population. We also found resistance to malathion, an organophosphate, in Florida and New Jersey and reduced susceptibility to the IGRs pyriproxyfen and methoprene. All populations tested were fully susceptible to pyrethroids. Biochemical assays revealed a significant up-regulation of GSTs in DDT-resistant populations in both larval and adult stages. Also, β-esterases were up-regulated in the populations with suspected resistance to malathion. Of note, we identified a previously unknown amino acid polymorphism (Phe → Leu) in domain III of the VGSC, in a location known to be associated with pyrethroid resistance in another container-inhabiting mosquito, Aedes aegypti L. The observed DDT resistance in populations from Florida may indicate multiple introductions of this species into the USA, possibly from tropical populations. In addition, the mechanisms underlying DDT resistance often result in pyrethroid resistance, which would undermine a remaining tool for the control of Ae. albopictus. Continued monitoring of the insecticide resistance status of this species is imperative.     

Surveying native egg parasitoids and predators of the invasive Halyomorpha halys in Northern Italy

The invasive Halyomorpha halys (Heteroptera: Pentatomidae) is a key pest of fruits in the Emilia‐Romagna region of Italy. For the development of a sustainable management programme, knowledge of its native natural enemy community and its efficacy is essential. A three‐year field survey was conducted exposing H. halys egg masses in different types of habitats to investigate the efficacy of native natural enemies in reducing the H. halys populations in the Emilia‐Romagna region, where the stinkbug was first detected in 2012. Over the first year of the study, sentinel eggs from laboratory cultures were stapled to the underside of leaves in various host trees, whereas in following years H. halys adults were directly caged on branches in sleeve cages to allow natural oviposition. Over the examined years, low rates of parasitism (1%–3%) and predation (2%–5%) were observed. Parasitism was caused exclusively by the generalist parasitoid Anastatus bifasciatus.     

Dispersal Capacity and Behavior of Nymphal Stages of Halyomorpha halys (Hemiptera: Pentatomidae) Evaluated Under Laboratory and Field Conditions

The invasive brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is a highly polyphagous and mobile pest causing crop damage aggregated at the perimeters of crop fields. Understanding the dispersal biology of H. halys is critical for the development of reliable monitoring and management strategies. In this study, dispersal ecology of H. halys nymphs was studied under laboratory and field conditions. In the laboratory, horizontal and vertical walking capacity was quantified for mobile nymphal stages (i.e., 2nd through 5th instars) and compared with adults. There was a significant difference in the horizontal distance moved by H. halys among the life stages tested. Third instars exhibited significantly greater walking distances compared with adults; horizontal walking distances by other nymphal stages were not significantly different from adults. A similar pattern was observed from vertical climbing tests of H. halys. Third and 4th instars climbed significantly greater distances compared with 2nd instars and adults, while distances climbed by 5th instars were intermediate. In the field, the walking distance of 3rd and 5th instar nymphs on mowed grass was quantified based on direct observation of individuals for 30 min. Under these conditions, 5th instars moved nearly two-fold greater distances compared with 3rd instars, but surface temperature affected both nymphal stages similarly. Shorter bouts of movement were common at surface temperatures below 25 °C, whereas individuals showed longer walking distances above 25 °C. In mark-release-recapture studies, 4th and 5th instars were released and recaptured in traps baited with attractive pheromonal-based stimuli to estimate dispersal rates under field conditions. When insects were released 5 m from traps, both instars were first recaptured within 2 h after release, with the recapture rates of 54 and 69 % for 4th and 5th instars over 24 h, respectively. When insects were released 20 m from traps, 4th and 5th instars were first recaptured in less than 5 h, with the recapture rates of 27 and 51 %, respectively. The results of this study indicate that H. halys nymphs have strong dispersal capacity with which populations can easily move among host plants and other attractive stimuli at farmscape levels.     

Biological control of invasive stink bugs: review of global state and future prospects

Invasive stink bugs (Hemiptera: Pentatomidae) are responsible for high economic losses to agriculture on a global scale. The most important species, dating from recent to old invasions, include Bagrada hilaris (Burmeister), Halyomorpha halys (Stål), Piezodorus guildinii (Westwood), Nezara viridula (L.), and Murgantia histrionica (Hahn). Bagrada hilaris, H. halys, and N. viridula are now almost globally distributed. Biological control of these pests faces a complex set of challenges that must be addressed to maintain pest populations below the economic injury level. Several case studies of classical and conservation biological control of invasive stink bugs are reported here. The most common parasitoids in their geographical area of origin are egg parasitoids (Hymenoptera: Scelionidae, Encyrtidae, and Eupelmidae). Additionally, native parasitoids of adult stink bugs (Diptera: Tachinidae) have in some cases adapted to the novel hosts in the invaded area and native predators are known to prey on the various instars. Improving the efficacy of biocontrol agents is possible through conservation biological control techniques and exploitation of their chemical ecology. Moreover, integration of biological control with other techniques, such as behavioural manipulation of adult stink bugs and plant resistance, may be a sustainable pest control method within organic farming and integrated pest management programs. However, additional field studies are needed to verify the efficacy of these novel methods and transfer them from research to application.