Impact of the Invasive Brown Marmorated Stink Bug in North America and Europe: History, Biology, Ecology, and Management

Influence of deployment method and maintenance on efficacy of sticky card traps for Halyomorpha halys (Hemiptera: Pentatomidae)

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive pest which feeds on numerous economically significant crops. Many integrated pest management strategies for this species rely on effective season-long monitoring for H. halys populations, including attract-and-kill and threshold-based insecticide sprays. Previous studies have shown that a black pyramid trap effectively captures all mobile life stages of H. halys, however, these bulky, ground-deployed traps can be impractical in active orchard rows. Clear sticky cards have been used as a more practical tool for monitoring when paired with the H. halys aggregation pheromone and synergist. Here, the efficacy of deploying single- or double-sided sticky cards hanging in trees or deployed on wooden stakes was compared to standard black pyramid traps over 2 years. The efficacy of single-sided sticky cards deployed on wooden stakes was also evaluated after occlusion of 25%, 50%, or 75% of the surface area by 2D inert materials and 3D organic matter. Single-sided sticky cards were also exposed to simulated sunlight and rainfall for 0, 4, 8, and 12 wk before deployment on wooden stakes. Captures of H. halys adults using sticky cards deployed on wooden stakes were comparable to pyramid traps. Occlusion of cards by 25% or more of any material type led to a decrease in H. halys captures, however, weathering did not influence capture. These data show that clear sticky cards deployed on wooden stakes are effective for season-long monitoring of H. halys in apple orchards, and card replacement should be driven by maintenance of cleanliness.

Application of sulfur-based products reduces Halyomorpha halys infestation and damage in pome fruit orchards

BACKGROUND

The brown marmorated stink bug, Halyomorpha halys (Stål, 1855) (Hemiptera: Pentatomidae) is an invasive pest that causes economic damage on crops, decreasing fruit yield and quality. Conventional insecticides are frequently used to reduce infestations, but these are often with a limited residual effect, besides being costly and detrimental to nontarget organisms and the environment. In integrated pest management, novel strategies against H. halys are proposed, such as the use of alternative substances with an effect on insect behaviour and mobility. As one of the oldest multi-site fungicides applied against fungal pathogens and as an insecticide and acaricide to control scales and mites, sulfur is proposed here to reduce H. halys infestation in fruit orchards.

RESULTS

Field experiments were performed to evaluate the effect of repeated wettable sulfur applications on H. halys in apple and pear orchards. Sulfur-induced plant phytotoxicity effects and quanti-qualitative parameters on apple fruits were also recorded. Halyomorpha halys infestation was significantly reduced in sulfur-treated compared to untreated pears and apples. Furthermore, sulfur sprays reduced fruit damage caused by H. halys. Besides, sulfur-mediated phytotoxicity such as symptoms on leaves and fruit drop were not observed. Fruit quality was not influenced by sulfur treatments.

CONCLUSIONS

Wettable sulfur seems to be a promising formulation given the low phytotoxicity, considering the technical aspects for an effective use of sulfur-based products to counteract H. halys in pome fruit orchards. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Field abundance and spatial patterns of ear-feeding insect pests in relation to levels of defective kernels in processing sweet corn

In this study, we investigated the within-field distribution of sweet corn insect pests in relation to adjacent habitats and determined the level and specific causes of defective kernels affecting the quality of the final product at the processing cannery. Sap beetles [primarily Carpophilus lugubris (Murray, 1864) (Coleoptera: Nitidulidae)] and stink bugs [primarily Euschistus servus (Say) ((Heteroptera: Pentatomidae)] infested 27.6% and 73.6% of the fields, respectively. Densities of stink bugs were highest along field edges adjacent to wheat, soybean, vegetable crops, and woodlots. Levels of kernel injury were consistently higher in truckloads of ears harvested first from the outer rows. Earworm damage was confined to the ear tip and had no measurable impact on the quality of the final product. Sap beetles and blemished kernels were the major causes of defective kernels in the cannery, even though stink bugs were more abundant in the fields. Defective kernels were more positively related to physiological blemishes than to other causal factors. For all fields, defective kernel levels averaged less than 1%, resulting in excellent quality of the processed product throughout the entire season. Results provided a better understanding of the quality control issues, resulting in practical implications for improvements in field monitoring and decision-making in the cannery to minimize grading problems.

Electrophysiological Responses of Trissolcus japonicus, T. basalis, and T. oenone (Hymenoptera: Scelionidae) to Volatile Compounds Associated with New Zealand Stink Bugs (Hemiptera: Pentatomidae)

Parasitoid biological control agents rely heavily on olfaction to locate their hosts. Chemical cues associated with hosts and non-hosts are known to influence the expression of host preferences and host-specificity. A better understanding of how and why parasitoids attack some species and not others, based on volatile organic compounds associated with potential hosts, can provide key information on the parasitoid's host preferences, which could be applied to pre-release risk assessments for classical biological control agents. Electrophysiological techniques such as electroantennography (EAG) and GC-EAD (gas chromatography coupled with electroantennographic detection) are widely used to identify bioactive semiochemicals. But the application of these techniques to understanding how chemical ecological cues mediate parasitoid host specificity has not been as thoroughly explored. We conducted GC-EAD and EAG studies to identify olfactory-active compounds associated with adult females of nine stink bug species from Aotearoa/New Zealand on the antennae of three closely related parasitoid species: Trissolcus japonicus Ashmead, a pre-emptively (= proactively) approved biocontrol agent against brown marmorated stink bug; T. basalis (Wollaston), a biocontrol agent introduced against Nezara viridula L. in 1949; and T. oenone Johnson, a native Australasian pentatomid parasitoid. Eight compounds associated with stink bugs elicited antennal responses from all three parasitoids, and we were able to identify seven of these. (E)-2-hexenal, (E)-4-oxo-2-hexenal, (E)-2-octenal and (E)-2-decenal generally elicited stronger responses in the three parasitoids, while n-tridecane, n-dodecane, and (E)-2-decenyl acetate elicited weaker responses. We discuss how and why the results from electrophysiological experiments can be applied to non-target risk assessments within biological control programmes.

Evaluation of an Attract-and-Kill Strategy Using Long-Lasting Insecticide Nets for the Management of the Brown Marmorated Stink Bug in Northern Italy

The brown marmorated stink bug (BMSB), Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is causing extensive economic losses in tree fruit crops. Including attract-and-kill (AK) strategies targeting BMSBs in an integrated pest management framework could reduce the amounts of insecticides sprayed and benefit growers, consumers and the environment. This study evaluated the effectiveness of an area-wide AK strategy across an intensive fruticulture region of Northern Italy, comparing four paired pear sites with and without two AK stations ha-1. These stations consisted of long-lasting insecticide-treated nets containing alpha-cypermethrin, baited with the BMSB aggregation pheromone and synergist. BMSB abundance was estimated using black-standing monitoring traps, and fruit damage upon harvest was recorded across all sites. The AK stations did not decrease the BMSB abundance nor the fruit damage, while after harvest significantly lower BMSB captures were detected in the AK sites compared to the control sites. Whilst the lures' efficacy was corroborated by this research, the killing method requires improvement and refinement.

Wettable sulphur application for Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) management: laboratory and semi-field experiments

BACKGROUND

The brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is a significant threat to crop production. Alternatives to synthetic pesticides are needed for its management. Here we investigated the effect of sulphur on H. halys. Experiments were performed to evaluate both mortality and deterrence/repellence of H. halys following sulphur treatments in laboratory and semi-field conditions.

RESULTS

Brown marmorated stink bug mortality was not influenced by sulphur applications. However, in two-choice experiments in insect cages and olfactometer, more H. halys adults moved toward the untreated control rather than the sulphur-treated food sources, with a high effect as the concentration increased. A semi-field experiment using potted apple plants confirmed the results observed in the laboratory, showing a deterrent and/or repellent effect of sulphur-based products on H. halys.

CONCLUSIONS

Sulphur applications were associated with a deterrent/repellent effect on the brown marmorated stink bug. The use of sulphur-based products could represent a promising tool for Integrated Pest Management strategies against H. halys in fruit crops. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Evaluation of Various Inoculation Methods on the Effect of Beauveria bassiana on the Plant Growth of Kiwi and on Halyomorpha halys Infestation: A Two-Year Field Study

In this study, the bioinsecticidal action of a commercial formulation with Beauveria bassiana was evaluated on the new sucking pest in Greece: Halyomorpha halys, of the kiwifruit. Additionally, the biostimulant potential of the same formulation was studied on kiwi growth. The application was performed in three different ways in a commercial field of kiwi crop A. deliciosa "Hayward" field in Arta, Greece: (i) trunk spray, (ii) root injection, and (iii) trunk inoculation. During the 2 years seasons of the experiment, weekly measurements of the H. halys population were determined. The insect is sucking plants nutrients; therefore, the total chlorophyll content in the leaves of the treatments was recorded weekly. In addition, the percentage of infested kiwifruits was estimated at the end of the experiment. Moreover, to study the biostimulant potential of the formulation, growth measurements on stems and leaves were performed during the experiment. Finally, at the kiwi harvest point, the fruit biomass, dimensions, and weight were obtained, and the leaves' proline content was evaluated. The results encourage us to further study this EPF formulation as the bioinsecticidal effect was noted by the reduction in H. halys population, and biostimulant action was perceived by the higher plant biomass.

Aseasonal, undirected migration in insects: 'Invisible' but common

Many insect pests are long-distance migrants, moving from lower latitudes where they overwinter to higher latitudes in spring to exploit superabundant, but seasonally ephemeral, host crops. These seasonal long-distance migration events are relatively easy to recognize, and justifiably garner much research attention. Evidence indicates several pest species that overwinter in diapause, and thus inhabit a year-round range, also engage in migratory flight, which is somewhat "invisible" because displacement is nondirectional and terminates among conspecifics. Support for aseasonal, undirected migration is related to recognizing true migratory flight behavior, which differs fundamentally from most other kinds of flight in that it is nonappetitive. Migrating adults are not searching for resources and migratory flight is not arrested by encounters with potential resources. The population-level consequence of aseasonal, undirected migration is spatial mixing of individuals within the larger metapopulation, which has important implications for population dynamics, gene flow, pest management, and insect resistance management.

Adaptive sampling method to monitor low-risk pathways with limited surveillance resources

The rise of globalization has led to a sharp increase in international trade with high volumes of containers, goods, and items moving across the world. Unfortunately, these trade pathways also facilitate the movement of unwanted pests, weeds, diseases, and pathogens. Each item could contain biosecurity risk material, but it is impractical to inspect every item. Instead, inspection efforts typically focus on high-risk items. However, low risk does not imply no risk. It is crucial to monitor the low-risk pathways to ensure that they are and remain low risk. To do so, many approaches would seek to estimate the risk to some precision, but increasingly lower risks require more samples. On a low-risk pathway that can be afforded only limited inspection resources, it makes more sense to assign fewer samples to the lower risk activities. We approach the problem by introducing two thresholds. Our method focuses on letting us know whether the risk is below certain thresholds, rather than estimating the risk precisely. This method also allows us to detect a significant change in risk. Our approach typically requires less sampling than previous methods, while still providing evidence to regulators to help them efficiently and effectively allocate inspection effort.

Identifying a potentially invasive population in the native range of a species: The enlightenment from the phylogeography of the yellow spotted stink bug, Erthesina fullo (Hemiptera: Pentatomidae)

The yellow spotted stink bug (YSSB), Erthesina fullo (Thunberg, 1783) is an important Asian pest that has recently successfully invaded Europe and an excellent material for research on the initial stage of biological invasion. Here, we reported the native evolutionary history, recent invasion history, and potential invasion threats of YSSB for the first time based on population genetic methods [using double digest restriction-site associated DNA (ddRAD) data and mitochondrial COI and CYTB] and ecological niche modelling. The results showed that four lineages (east, west, southwest, and Hainan Island) were established in the native range with a strong east-west differentiation phylogeographical structure, and the violent climate fluctuation might cause population divergence during the Middle and Upper Pleistocene. In addition, land bridges and monsoon promote dispersal and directional genetic exchanging between island populations and neighboring continental populations. The east lineage (EA) was identified as the source of invasion in Albania. EA had the widest geographical distribution among all other lineages, with a star-like haplotype network with the main haplotype as the core. It also had a rapid population expansion history, indicating that the source lineage might have stronger diffusion ability and adaptability. Our findings provided a significant biological basis for fine tracking of invasive source at the lineage or population level and promote early invasion warning of potential invasive species on a much subtler lineage level.

Seasonal Dynamics and Damage of Halyomorpha halys in Italian Vineyards

The brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is an invasive polyphagous pest often observed in vineyards. In Europe, a gap needs to be filled in the knowledge on H. halys seasonal dynamics and damage on grapes. With this study, we described the seasonal dynamics of H. halys and its distribution in multi-cultivar vineyards, and we evaluated the damage on grape clusters induced by different pest densities. In vineyards, the seasonal occurrence of H. halys varied across time and grape cultivars, and the pest was more abundant on Cabernet Franc, Merlot and, to a lesser extent, Pinot gris. Moreover, higher densities of H. halys were found on red berry cultivars than on white ones, and on cultivars ripening late in the season. An edge effect was also detected in pest distribution within vineyards, with more stink bugs observed in the borders. In the study on pest infestation density, H. halys caused damage on berries, showing differences in susceptibility among different cultivars and with regard to the time of infestation (i.e., plant phenological stages). Halyomorpha halys infestation induced an increase in Botrytis cinerea and sour rot incidence, which probably represents the main issue related to the impact of brown marmorated stink bug on grapevine.

The First Records of Trissolcus japonicus (Ashmead) and Trissolcus mitsukurii (Ashmead) (Hymenoptera, Scelionidae), Alien Egg Parasitoids of Halyomorpha halys (Stål) (Hemiptera, Pentatomidae) in Serbia

Serbia has recently begun facing a serious problem with the Brown Marmorated Stink Bug, Halyomorpha halys (Stål), which was first recorded in October 2015. This species belongs to the Pentomidae family and is notorious for causing extensive damage to plants. During the winter, it tends to gather in urban areas, such as houses and different man-made facilities, which has raised concerns among producers and citizens. The population of this species has rapidly increased, causing significant economic damage to cultivated plants. However, despite the alarming situation no natural enemies have yet been identified in Serbia. Therefore, research in 2022 was focused on collecting stink bug eggs to investigate the presence of egg parasitoids. The study identified two foreign Hymenoptera species for the European region, Trissolcus japonicus (Ashmead) and Tr. mitsukurii (Ashmead) (Scelionidae), recorded for the first time in Serbia. Additionally, the list of egg parasitoid species belonging to the Hymenoptera order includes seven local species: Anastatus bifasciatus (Geoffroy), from the Eupelmidae family; Ooencyrtus sp., from the Encyrtidae family; and Telenomus turesis (Walker), Tr. basalis (Wollaston), Tr. belenus (Walker), Tr. colemani (Crawford), and Tr. semistriatus (Nees von Esenbeck), from the Scelionidae family. In total, nine egg parasitoid species were, for the first time, reported as parasitizing H. halys and related species in Serbia.

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.

The post-diapause vibrational behavior, motility, and survival of the brown marmorated stink bug Halyomorpha halys (Stål) adults at different temperatures

Substrate-borne vibrational communication is common in pentatomids. Although several works exist on the vibrational communication of Halyomorpha halys, its vibrational behavior post diapause has not been investigated. In this study, we recorded H. halys overwintered adults using laser doppler vibrometers at three temperatures: 10 °C (inactivity), 18 °C (breaking of diapause), and 25 °C (peak of mating activity). The aim was to assess the effect of temperature on the signaling, motility, and survival of H. halys. The insects were sexed into different cages and recorded separately or joined with a cage of the opposite sex. We calculated the total time spent on signaling and walking per replica. The males predominantly emitted male signal 1 (MS1) throughout the four months of recordings. The females exclusively emitted female signal 2 (FS2) when joined with the opposite sex cage the first two months of recordings. Interestingly, they also started FS2 signaling when recorded separately, after two months. No signaling was recorded at 10 °C. At 25 °C, the signaling latency time before vibrational signaling was 24 h compared to 23 days at 18 °C. The short latency time at 25 °C correlated with a higher death rate in early stages of recording. Male walking activity was significantly higher in joined cages at 18 °C and 25 °C, suggesting the increased searching behavior near the opposite sex. Overwintered H. halys could adapt to different conditions whereas low temperatures maintain the diapause which is characterized by no signaling activity. Our results provide a foundation for bioclimatic modeling of climate change effects on H. halys and insights into the use of vibrational playbacks for mass trapping and monitoring as control techniques.

The Development and Expansion of in vivo Germline Editing Technologies in Arthropods: Receptor-Mediated Ovary Transduction of Cargo (ReMOT Control) and Beyond

In the past 20 years, sequencing technologies have led to easy access to genomic data from nonmodel organisms in all biological realms. Insect genetic manipulation, however, continues to be a challenge due to various factors, including technical and cost-related issues. Traditional techniques such as microinjection of gene-editing vectors into early stage embryos have been used for arthropod transgenesis and the discovery of Clustered regularly interspaced short palindromic repeats and CRISPR-associated protein (CRISPR-Cas) technologies allowed for targeted mutagenesis and the creation of knockouts or knock-ins in arthropods. Receptor-Mediated Ovary Transduction of Cargo (ReMOT Control) acts as an alternative to embryonic microinjections, which require expensive equipment and extensive hands-on training. ReMOT Control's main advantage is its ease of use coupled with the ability to hypothetically target any vitellogenic species, as injections are administered to the egg-laying adult rather than embryos. After its initial application in the mosquito Aedes aegypti, ReMOT Control has successfully produced mutants not only for mosquitoes but for multiple arthropod species from diverse orders, such as ticks, mites, wasps, beetles, and true bugs, and is being extended to crustaceans, demonstrating the versatility of the technique. In this review, we discuss the current state of ReMOT Control from its proof-of-concept to the advances and challenges in the application across species after 5 years since its development, including novel extensions of the technique such as direct parental (DIPA)-CRISPR.

Effect of Entomopathogenic Fungi to Eggs and Nymphs Survival of Halyomorpha halys (Hemiptera: Pentatomidae) Under Laboratory Conditions

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is becoming a major pest of Greece's agricultural production, including tree fruit. Until now, the control of this pest has been based on conventional methods, with the application of chemical insecticides being the primary option. However, the wide distribution of H. halys, in combination with the large area of tree fruit production in Greece, raise the need for alternative control methods. In this study, we investigated the possibility of implementing microbial control agents for managing H. halys. Eggs and nymphs of H. halys were treated with 15 native entomopathogenic fungal isolates and their virulence was evaluated in the laboratory. After treatment, egg hatching time was recorded for 7 days and ranged from 4.5 to 7.0 days. Nymphal survival was recorded daily for 7 days following application and ranged from 2.1 to 6.6 days for second instar nymphs and 3.7 to 6.8 days for fourth instar ones. Beauveria varroae isolate displayed the highest toxicity to all H. halys stages that were tested and could be considered a promising biocontrol agent of this insect. Please check and confirm that the authors and their respective affiliations have been correctly identified and amend if necessary.οκ.

Characterization of Olive Fruit Damage Induced by Invasive Halyomorpha halys

The brown marmorated stink bug, Halyomorpha halys (Stål), is an invasive species causing economic crop losses. This species was recently detected attacking olive fruits. The aim of this study was to characterize feeding damage. Olive samples were initially collected from a field where H. halys was reported to cause damage to olive fruits. Hence, we conducted a field trial on the Moraiolo variety using sleeve cages to test the effect of H. halys feeding pressure on olive fruit drop and evaluated the effect of feeding on fruit quality. We tested two densities of H. halys (two or eight adults/cage) at two different stages of olive development, pre- and post-pit hardening. High pressure of H. halys before pit hardening caused a significant fruit drop compared to the control. In addition, chemical analysis of damaged and infested fruits revealed higher levels of total phenols compared to healthy fruits. These findings indicate that feeding by H. halys induced a stress response in the plants that could translate in quality variations in the olive drupes.

Distribution and prevalence of viral genomes in Italian populations of the invasive brown marmorated stink bug Halyomorpha halys

Halyomorpha halys (Stål), the brown marmorated stink bug, is a highly invasive insect species that causes significant agricultural losses, especially to orchard fruits, vegetables, herbaceous and ornamental plants. It is also a nuisance pest that seeks shelter in indoor spaces during the winter months. Harnessing the H. halys virome can result in new environmentally sustainable approaches to contain its populations and its relatated agricultural damages. In this study, RNA-Seq data were used to explore the virome associated to ten field populations collected in the Lombardy region in Northern Italy. We identified six complete viral genomes, three of which were previously unknown, belonging to the orders Reovirales, Articulavirales, Ghabrivirales, Durnavirales, and Picornavirales. The prevalence of the six viruses was evaluated by Real-time reverse transcription-quantitative PCR on eighty individuals. Halyomorpha halys ifla-like virus 2 turned out to be the most geographically widespread virus, as it was found in more than 50% of the analyzed insects and in nine out of the ten sampling locations. Moreover, in some individuals, this iflavirus was found in association with each of the other viruses in various combinations that involved up to four viruses. Further studies on such virus-virus interactions and their relationships with the insect host may open the possibility to exploit these naturally occurring viruses as specific and targeted biocontrol agents of H. halys.

Releasing and tracking the distribution of adventive Trissolcus japonicus (Hymenoptera: Scelionidae) in Virginia

Adventive populations of Trissolcus japonicus (Ashmead), an egg parasitoid of the invasive agricultural pest, brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), have been detected in the United States since 2014. Given its importance as an H. halys biocontrol agent, efforts to redistribute T. japonicus began within some US states. Our surveillance for T. japonicus in northwestern Virginia in 2016-2017 yielded annual detections only in 1 county. Thus, to promote its broader establishment, releases of H. halys egg masses parasitized by T. japonicus from Virginia occurred in 2018 (2 releases) and 2020 (1 release) at 9 sites throughout Virginia's tree fruit production regions. Monitoring of T. japonicus and H. halys, using yellow sticky cards deployed in H. halys host trees and pheromone-baited sticky traps, respectively, was conducted from 2018 to 2022. Annual captures of H. halys adults and nymphs appeared to reflect adequate populations to support T. japonicus establishment across most or all sites. Prerelease monitoring yielded a single T. japonicus at 1 site. By 2022, T. japonicus was detected at or near 7 of the remaining 8 release sites, with first detections varying between 1 and 2 yr from the releases in 2018 and 2020. Captures at most sites were very low, but establishment at several locations was indicated by detections in 2-4 seasons. In 2022, T. japonicus surveillance at 11 additional sites in northwestern Virginia yielded detections at all locations, including those at which it had not been detected in 2016-2017, providing evidence for its range expansion.

Combining Irradiation and Biological Control against Brown Marmorated Stink Bug: Are Sterile Eggs a Suitable Substrate for the Egg Parasitoid Trissolcus japonicus?

The brown marmorated stink bug (BMSB), Halyomorpha halys, is a phytophagous invasive pest native to south-eastern Asia, and it is now distributed worldwide. This species is considered to be one of the most damaging insect pests in North America and in Europe. In agriculture, the predominant approach to managing BMSB is based on the use of insecticides, specifically pyrethroids and neonicotinoids. Unfortunately, the biology of the species and its facility to develop mechanisms of resistance to available pesticides has induced farmers and scientists to develop different, least-toxic, and more effective strategies of control. In a territorial area-wide approach, the use of a classical biological control program in combination with other least-toxic strategies has been given prominent consideration. Following exploratory surveys in the native range, attention has focused on Trissolcus japonicus, a small scelionid egg parasitoid wasp that is able to oviposit and complete its larval development in a single egg of H. halys. A common method for detecting egg parasitoids in the native range involves the placement of so-called 'sentinel' egg masses of the pest in the environment for a short period, which are then returned to the laboratory to determine if any of them are parasitized. Outside of the area of origin, the use of fertile sentinel eggs of the alien species may lead to the further release of the pest species; an alternative is to use sterile sentinel eggs to record the presence of new indigenous egg parasitoids or to detect the dispersal of alien species (in this case, T. japonicus) released in a new environment to control the target insect pest species. This study evaluated the performance of three types of sterile sentinel eggs as a suitable substrate for the oviposition and larval development of the egg parasitoid T. japonicus in a context of combining classical biological control with a Sterile Insect Technique (SIT) approach.

Low Incidence of Avian Predation on the Brown Marmorated Stink Bug, Halyomorpha halys (Hemiptera: Pentatomidae), in Southeastern Orchard Systems

In many agroecosystems, brown marmorated stink bugs (Halyomorpha halys) (Hemiptera: Pentatomidae) are polyphagous pests that cause significant economic losses to numerous crops every year. Insectivorous birds may provide a means of sustainable predation of invasive pests, such as H. halys. In forest margins surrounding peach, pecan, and interplanted peach-pecan orchards, we monitored H. halys populations with pheromone-baited traps, mist-netted birds, and collected avian fecal samples for molecular gut content analysis. We screened 257 fecal samples from 19 bird species for the presence of H. halys DNA to determine whether birds provide the biological control of this pest. Overall, we found evidence that four birds from three species consumed H. halys, including Northern cardinal (Cardinalis cardinalisis), Tufted titmouse (Baeolophus bicolor), and Carolina wren (Thryothorus ludovicianus). Halyomorpha halys captured in traps increased over time but did not vary by orchard type. Although incidence of predation was low, this may be an underestimate as a result of our current avian fecal sampling methodology. Because birds are members of the broader food web, future studies are needed to understand avian ecosystem services, especially in terms of pest control, including H. halys and other pest species.

Factors influencing short-term parasitoid establishment and efficacy for the biological control of Halyomorpha halys with the samurai wasp Trissolcus japonicus

BACKGROUND

Classical biological control has been identified as the most promising approach to limit the impact of the invasive pest species Halyomorpha halys (Heteroptera: Pentatomidae). This study investigated the parasitism rate at sites where the biocontrol agent Trissolcus japonicus (Hymenoptera: Scelionidae) was released and where its unintentional introduction took place, in the Trentino-South Tyrol region. The effect of land-use composition was studied to understand which factors favor the establishment of hosts and parasitoids, including native and exotic species.

RESULTS

The released T. japonicus were detected a year after the start of the program, with a significant parasitoid impact and discovery, compared to control sites. Trissolcus japonicus was the most abundant H. halys parasitoid, and Trissolcus mitsukurii and Anastatus bifasciatus were recorded also. The efficacy of T. mitsukurii was lower in sites where T. japonicus was successfully established, suggesting a possible competitive interaction. Parasitism level by T. japonicus at the release sites was 12.5% in 2020 and 16.4% in 2021. The combined effect of predation and parasitization increased H. halys mortality up to 50% at the release sites. Landscape composition analysis showed that both H. halys and T. japonicus were more likely to be found at sites with lower altitude and with permanent crops, whereas other hosts and parasitoids preferred different conditions.

CONCLUSION

Trissolcus japonicus showed a promising impact on H. halys, at release and adventive sites, with minor nontarget effects, mediated by landscape heterogeneity. The prevalence of T. japonicus in landscapes with permanent crops could support IPM in the future. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Analyzing On-Farm Spatiotemporal Distribution of Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) Populations from a Precision Agriculture Perspective

The brown marmorated stink bug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), is native to Japan, China, Taiwan, and Korea. Its dispersion from Asia to the United States of America and Europe caused serious damage to fruit, vegetables, and high-value crops. In Greece, damages are reported in kiwi orchards in the regions of Pieria and Imathia, which are the main production areas of kiwifruit. Greek kiwifruit production is expected to increase twofold within the next years. The aim of this research is to study the terrain and canopy properties that may have an impact on the development of H. halys populations. Thus, five kiwi orchards in total were selected in the regions of Pieria and Imathia. Τen traps were installed from early June to late October within each selected kiwi orchard-two types of traps at every side of the orchards and the center. The installed traps were examined weekly and the number of the captured H. halys was recorded. During the same days, sentinel satellite images were analyzed to calculate the vegetation index, NDVI (Normalised Difference Vegetation Index), and NDWI (Normalised Difference Water Index). The results showed population variability within the kiwi orchards since the population of H. halys was higher in areas with high NDVI and NDWI values. Additionally, our research revealed that H. halys prefers to develop populations at higher altitudes at both regional and field scales. The results of this research can be used to reduce damages by H. halys in kiwi orchards using different rates of pesticides depending on the prediction of the population size. There are multiple benefits of the proposed practice, such as a reduction in the production cost of kiwifruits, an increase in farmers' profit, and environmental protection.

First report of Colletotrichum fioriniae infections in brown marmorated stink bugs, Halyomorpha halys

An epizootic caused by fungal pathogens occurred among Halyomorpha halys, brown marmorated stink bugs, while they were overwintering, with infections also occurring after overwintering. We report that one of the two pathogens responsible was Collectotrichum fioriniae (Marcelino & Gouli), Pennycook; a species well known as a plant pathogen and endophyte and which has only previously been reported naturally infecting elongate hemlock scales, Fiorinia externa. To prove pathogenicity, H. halys adults challenged with conidia died from infections and the fungus subsequently produced conidia externally on cadavers.

Effects of Irradiation on Biology and Mating Behaviour of Wild Males of Brown Marmorated Stink Bug Using a 6 MV Medical Linear Accelerator

The brown marmorated stink bug, Halyomorpha halys, is a pentatomid bug of Eastern Asian origin that became an economically relevant pest in the Eurasian and American continents. Management of this species is limited to use of chemical insecticides: an inefficient method due to the strong adaptability of the target pest. The sterile insect technique (SIT) is potentially a valid tactic in the search for nontoxic alternatives. In this work, we investigated the suitability of mass-trapped overwintering males, collected during the aggregation phase before the winter diapause, for their release as competitive sterile males in an SIT programme. Differently from previous studies, irradiation was applied with a linear accelerator device that produced high-energy photons. Following a similar scientific protocol with newly emerged irradiated males, the effects of X-ray irradiation on physiological parameters (longevity, fecundity and fertility) were assessed. In addition, behavioural bioassays were carried out in no-choice conditions to evaluate if irradiation interferes with mating processes. The results are very encouraging; the effects of the irradiation at 32 Gy did not differ from the controls in the longevity or fecundity of the exposed overwintering adults. The hatching rate of the eggs laid by the fertile females that had mated with the irradiated males was less than 5%. The results of behavioural bioassays showed that the irradiation did not cause a significant impact on the quality of the sterile males. More research is warranted to evaluate the mating competitiveness of sterile males in semi-field and field conditions.

Effects of three chitin synthesis inhibitors on egg masses, nymphs and adults of Halyomorpha halys (Hemiptera: Pentatomidae)

BACKGROUND

Halyomorpha halys, (brown marmorated stink bug, BMSB), is a high-concern invasive species causing severe damage to orchards in many countries outside its native Asian range. Management methods other than frequent sprays of broad-spectrum insecticides are needed to restore integrated pest management (IPM) practices in orchards. Chitin synthesis inhibitors are usually regarded as desirable options in IPM programs because of lower toxicity to beneficial insects and non-target organisms compared to neurotoxic insecticides. In this study, the activity of three chitin synthesis inhibitors (namely buprofezin, novaluron and triflumuron) was investigated on BMSB egg masses, third instars and adults by means of laboratory bioassays.

RESULTS

Novaluron and to a lesser extent triflumuron were detrimental to BMSB nymphs exposed to residues on potted peach plants. Novaluron caused high mortality among early instars that emerged from sprayed egg masses. No significant differences were found between buprofezin and water control on eggs or third instars. When sprayed on BMSB adults, none of the chitin synthesis inhibitors affected survival, fecundity, or egg hatching.

CONCLUSION

Given the activity on nymphs, but the lack of effects on adults, novaluron and triflumuron might be considered for field applications only as a tool in a wider management strategy along with other methods aimed at preventing the invasion of crops by BMSB adults. © 2023 Society of Chemical Industry.

Herbaceous Alfalfa plant as a multipurpose crop and predominant forage specie in Pakistan

Fodder crops play an important role in agriculture as they deliver food for animals, which is eventually converted to food for humans. All over the world, Alfalfa has had utmost importance for a few decades, not only as a fodder crop due to having high nutritional value for dairy farming but also being positively involved in many health-related and environmental affairs. Medicinally, it helps in controlling diseases such as arthritis, cholesterol, anemia, and cardio-related illnesses. Furthermore, like other cereal crops (wheat, rice, corn, etc.), it could also be a great source of several healthy nutrients for humans when the proper quantity is added to daily meals. However, unlike other nations of the world such as America, China, and India, Pakistan does not utilize it directly in human meals. This crop also has eco-friendly behavior since it controls soil erosion by binding the soil particles together and makes atmospheric nitrogen available to the plants by fixing it in the soil. Other uses include its role in water purification, improved pollination, and most importantly, its tolerance against water, salt, and temperature stress, making its position even stronger in arid and semi-arid areas. This review will draw researchers' attention to its multiple uses other than fodder crop and most importantly, its nutritional availability at a very low cost, which could prove nothing short of a miracle for the economy if properly mediated.

Predation and parasitism of naturally occurring and sentinel stink bug egg masses of Halyomorpha halys (Stål) and Nezara viridula (L.) (Hemiptera: Pentatomidae) in various southeastern habitats

Stink bugs, including Halyomorpha halys (Stål) and Nezara viridula (L.), are agricultural pests that feed on fruit in a variety of crops. Monitoring predation and parasitism of stink bug egg masses furthers our understanding of potential biological control tactics. However, best practices for laboratory and field assessments of parasitism and predation of egg masses require further attention. We carried out a series of laboratory and field experiments to test whether parasitism and predation for three types of sentinel H. halys egg masses, fresh, frozen, and refrigerated, varied in agricultural commodities. In addition, we asked if predation and parasitism differed between sentinel and naturally occurring H. halys and N. viridula egg masses in soybean. In the laboratory, more H. halys eggs were parasitized by Trissolcus euschisti (Ashmead) (Hymenoptera: Scelionidae) if they were frozen or refrigerated compared to fresh eggs. Similarly, in the field, parasitism was higher for frozen egg masses than fresh. In 2018 and 2019, H. halys natural egg masses had higher parasitism and lower predation compared to sentinel egg masses in soybean. In a paired field test during 2020 and 2021, there was no difference in parasitism between H. halys natural and sentinel eggs, but much higher incidence of parasitism was detected in natural N. viridula egg masses than sentinel eggs. Collecting natural egg masses is the best methodology for field assessment of parasitism of stink bug egg masses; however, if natural egg masses are not easily available, deploying refrigerated sentinel egg masses is a good alternative.

A new model of stink bug traps: heated trap for capturing Halyomorpha halys during the autumn dispersal period

Invasive stink bug species, such as Halyomorpha halys (Stål, 1855) (Hemiptera: Heteroptera: Pentatomidae), are serious agricultural pests worldwide. During autumn dispersal, adults aggregate in large numbers in human-made structures, homes and on walls of buildings. Preferred overwintering sites are sun-warmed, well-protected shelters. Exploiting a new concept, we developed a new collection method for monitoring and controlling them in their pre-overwintering period. Our trap design exploits the heat preference of stink bugs seeking overwintering sites. As a result, significantly greater numbers of H. halys adults moved into our black box traps, equipped with a heating apparatus, than into unheated ones. Experiments were performed in October during the pre-overwintering autumn dispersal period. Traps were placed next to a building that served as an overwintering site, where stink bugs usually aggregate in large numbers. Heated traps were operated on sunny afternoon hours when stink bugs were found to be active by visual observations. Our results represent the first example of an effective collection method based on artificially heated traps placed in natural conditions.

Abundance of Halyomorpha halys (Hemiptera: Pentatomidae) and Megacopta cribraria (Hemiptera: Plataspidae) in Soybean in Areas with Few Previous Sightings in Tennessee

Halyomorpha halys (Stål) and Megacopta cribraria (Fabricius) are two exotic invasive pests that have invaded the United States in recent years. Halyomorpha halys can damage various fruits, vegetables, and field crops, such as soybean and corn, while Megacopta cribraria only attacks soybean and kudzu, a weed species. They are currently found in southeastern states and threaten soybean and other crops grown in the region. This study evaluated the seasonal abundance of H. halys and M. cribraria in soybeans in 2016 and 2017 in two counties in the central region of Tennessee, where both species had either a few sightings or none that were recorded when this research was being planned. Lures and sweep sampling were used to monitor H. halys, and sweep sampling was used to monitor M. cribraria. Halyomorpha halys was first detected in samples in late July. Their numbers increased in early to mid-September, reached the economic threshold in late Sept, and then started to decline. Megacopta cribraria was first detected in mid to late July, increased their populations in September, but did not reach the economic threshold and declined mid-October. Our results showed the seasonal abundances of H. halys and M. cribraria and their establishment in the central region of Tennessee.

Stink Bug (Hemiptera: Pentatomidae) Occurrence, Reproduction, and Injury to Fruit in an Organic Tomato Crop Bordered by Sorghum

Border rows of grain sorghum were planted along two to four sides of an organic Granadero tomato crop in North Florida to reduce fruit injury caused by native and invasive stink bugs. During the 2-yr study, 14 species of stink bugs were encountered, six only in sorghum: Piezodorus guildinii (Westwood) (Hemiptera: Pentatomidae), Thyanta spp., Oebalus pugnax (Fabricius), Chinavia hilaris (Say), C. pensylvanica (Gmelin), and Mormidea pama (Rolston). There were four species only in tomato: Euschistus obscurus (Palisot de Beauvois), E. tristigmus (Say), E. ictericus (L.), and Arvelius albopunctatus (De Geer). The three most abundant pests in tomato were collected in both crops: Nezara viridula (L.), Euschistus servus (Say), and E. quadrator Rolston, along with Proxys punctulatus (Palisot de Beauvois). Nezara viridula and P. guildinii were the most abundant stink bugs on sorghum. The border rows of sorghum did not reduce the total number of stink bug adults or nymphs in the tomato crop, although many more stink bug adults were captured in sorghum than tomato when the sorghum panicles were in the milk to soft dough stage. Generally, 30% of the females in the sorghum and tomato crops were mated and contained more than 15 eggs, indicating they could generate a considerable number of nymphs. Tomato fruit from the plot with sorghum border rows had significantly more punctures than fruit from the plot without sorghum. The stink bugs frequently probed and blemished tomato fruit in all stages of ripeness but fruit covered with probing sites were nevertheless suitable for human consumption.

Exploration of Candidate Genes Involved in the Biosynthesis, Regulation and Recognition of the Male-Produced Aggregation Pheromone of Halyomorpha halys

The aggregation pheromone of the brown marmorated stink bug, Halyomorpha halys (Stål), is produced by adult males, and plays an important role in the behavioral regulation of H. halys. However, information on the molecular mechanisms underlying this pheromone's biosynthesis is limited. In this study, HhTPS1, a key candidate synthase gene in the aggregation pheromone biosynthesis pathway of H. halys, was identified. Then, through weighted gene co-expression network analysis, the candidate P450 enzyme genes in the biosynthetic downstream of this pheromone and the related candidate transcription factor in this pathway were also identified. In addition, two olfactory-related genes, HhCSP5 and HhOr85b, involved in the recognition of the aggregation pheromone of H. halys, were detected. We further identified the key amino acid sites of HhTPS1 and HhCSP5 that interact with substrates by using molecular docking analysis. This study provides basic information for further investigations into the biosynthesis pathways and recognition mechanisms of aggregation pheromones in H. halys. It also provides key candidate genes for bioengineering bioactive aggregation pheromones necessary for the development of technologies for the monitoring and control of H. halys.

Insights into insecticide-resistance mechanisms in invasive species: Challenges and control strategies

Threatening the global community is a wide variety of potential threats, most notably invasive pest species. Invasive pest species are non-native organisms that humans have either accidentally or intentionally spread to new regions. One of the most effective and first lines of control strategies for controlling pests is the application of insecticides. These toxic chemicals are employed to get rid of pests, but they pose great risks to people, animals, and plants. Pesticides are heavily used in managing invasive pests in the current era. Due to the overuse of synthetic chemicals, numerous invasive species have already developed resistance. The resistance development is the main reason for the failure to manage the invasive species. Developing pesticide resistance management techniques necessitates a thorough understanding of the mechanisms through which insects acquire insecticide resistance. Insects use a variety of behavioral, biochemical, physiological, genetic, and metabolic methods to deal with toxic chemicals, which can lead to resistance through continuous overexpression of detoxifying enzymes. An overabundance of enzymes causes metabolic resistance, detoxifying pesticides and rendering them ineffective against pests. A key factor in the development of metabolic resistance is the amplification of certain metabolic enzymes, specifically esterases, Glutathione S-transferase, Cytochromes p450 monooxygenase, and hydrolyses. Additionally, insect guts offer unique habitats for microbial colonization, and gut bacteria may serve their hosts a variety of useful services. Most importantly, the detoxification of insecticides leads to resistance development. The complete knowledge of invasive pest species and their mechanisms of resistance development could be very helpful in coping with the challenges and effectively developing effective strategies for the control of invasive species. Integrated Pest Management is particularly effective at lowering the risk of chemical and environmental contaminants and the resulting health issues, and it may also offer the most effective ways to control insect pests.

Performance of two egg parasitoids of brown marmorated stink bug before and after cold storage

Introduction: The genus Trissolcus includes a number of egg parasitoids that are known to contribute to the control of Halyomorpha halys. The number of progenies, particularly females, is important for the efficient mass rearing of species used in augmentative biological control programs. Cold storage is an important technique for extending the shelf life of natural enemies used in such programs. Methods: We assessed how fecundity, sex ratio, lifespan, and the number of hosts parasitized within 24 h were affected by host density for T. japonicus and T. cultratus when offered fresh H. halys eggs and how these parameters were affected if adult parasitoids were first placed in cold storage (11°C in the dark) for 19 weeks before being used for propagation. Results: The fecundity were 110.2 and 84.2 offspring emerged at 25°C, for parasitoids not placed in cold storage; among the offspring that emerged, 82.6% and 85.6% were female for T. japonicus and T. cultratus, respectively. If first placed in cold storage, T. japonicus and T. cultratus produced 35.1 and 24.6 offspring per female, respectively, although cold storage significantly extended the shelf life. The survival rates of parasitoids that were placed in cold storage were 90.3% and 81.3% for females, and 3.2% and 0.9% for males of T. japonicus and T. cultratus, respectively. The number of hosts parasitized within 24 h was not shown to be density dependent, but it was significantly lower after cold storage. Discussion: This information can be used to estimate the likely production for augmented rearing colonies for use in biological control programs.

Topical delivery of dsRNA in two hemipteran species: Evaluation of RNAi specificity and non-target effects

Double-stranded (ds) RNA-based technologies could provide novel and potential tool for pest management with efficiency and specificity of action. However, before applying this technique in the field, it is necessary to identify effective delivery methods and evaluate the non-target effects that may occur. In this article, we evaluated the effectiveness of dsRNA by topical delivery on a species of great agricultural interest, Halyomorpha halys. The specificity of action of the dsRNA was also investigated in Rhodnius prolixus, an insect phylogenetically close to H. halys. Of the three investigated genes (putative ATPase N2B, ATPase, serine/threonine-protein phosphatase PP1-β catalytic subunit, PP1, and IAP repeat-containing protein 7-B-like, IAP), IAP and ATPase were able to induce higher mortality in H. halys nymphs compared to the control, with specific concentrations for each gene targeted. However, when the same RNAs were topically delivered to both R. prolixus 2nd and 3rd instar nymphs, no gene silencing and mortality were observed. For this reason, to assess dsRNA application-mediated non-target effects, we injected both H. halys and R. prolixus specific dsRNA in R. prolixus 5th instar nymphs. When the dsRNA targeting H. halys IAP was microinjected into R. prolixus 5th instar nymphs, no mortality was observed, suggesting a strong RNAi specificity. Together, these data suggest that the topical delivery could be suitable for the dsRNA to control H. halys population. Furthermore, its specificity of action would allow treatments towards single harmful species with limited non-target effects.

Effect of Vegetable Host Plant Type on Halyomorpha halys (Hemiptera: Pentatomidae) Nymphal Development

The brown marmorated stink bug, Halyomorpha halys (Stål), is an invasive pest introduced to North America in the mid-1990's that has caused economic losses to a wide range of commodities. In vegetables, H. halys feeding damage has been well described, but the effect of different vegetable hosts on H. halys fitness is less understood. We caged 2nd instar H. halys on different vegetable hosts (e.g., tomato, sweet corn, eggplant, bell pepper, and snap bean) and monitored their development until adulthood to compare the effects of vegetable host type on H. halys nymph survival and development time. Experiments were replicated nine times over a two-year period. Survival of 2nd instars from F1 generation (early-season) eggs was low (<30%) on all vegetables resulting in no significant treatment effect. However, H. halys nymphs collected from F2 generation (late-season) eggs had higher survivorship on all vegetables except tomato. The percentage of H. halys 2nd instars that reached adulthood was greatest on corn (53%) and pepper (45%), followed by snap bean (24%), and significantly lower on eggplant (9%) and tomato (2%). Total development time from 2nd instar to adult was fastest on corn and slowest on peppers, although tomatoes were not tested due to the low survival. Trends in development rate were not seasonally-dependent. Our study compares H. halys survivability on several vegetable commodities, and provides insights into H. halys developmental success and dependence on various host plants over the season.

Evaluating invasion risk and population dynamics of the brown marmorated stink bug across the contiguous United States

BACKGROUND

Invasive species threaten the productivity and stability of natural and managed ecosystems. Predicting the spread of invaders, which can aid in early mitigation efforts, is a major challenge, especially in the face of climate change. While ecological niche models are effective tools to assess habitat suitability for invaders, such models have rarely been created for invasive pest species with rapidly expanding ranges. Here, we leveraged a national monitoring effort from 543 sites over 3 years to assess factors mediating the occurrence and abundance of brown marmorated stink bug (BMSB, Halyomorpha halys), an invasive insect pest that has readily established throughout much of the United States.

RESULTS

We used maximum entropy models to estimate the suitable habitat of BMSB under several climate scenarios, and generalized boosted models to assess environmental factors that regulated BMSB abundance. Our models captured BMSB distribution and abundance with high accuracy, and predicted a 70% increase in suitable habitat under future climate scenarios. However, environmental factors that mediated the geographical distribution of BMSB were different from those driving abundance. While BMSB occurrence was most affected by winter precipitation and proximity to populated areas, BMSB abundance was influenced most strongly by evapotranspiration and solar photoperiod.

CONCLUSION

Our results suggest that linking models of establishment (occurrence) and population dynamics (abundance) offers a more effective way to forecast the spread and impact of BMSB and other invasive species than simply occurrence-based models, allowing for targeted mitigation efforts. Implications of distribution shifts under climate change are discussed. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Natural Enemies and Biological Control of Stink Bugs (Hemiptera: Heteroptera) in North America

Stink bugs comprise a significant and costly pest complex for numerous crops in the US, including row crops, vegetables, and tree fruits and nuts. Most management relies on the use of broad-spectrum and disruptive insecticides with high human and environmental risks associated with them. Growing concerns about pesticide resistance in stink bugs are forcing pest managers to explore safer and more sustainable options. Here, we review the diverse suite of natural enemies of stink bugs in the US, noting that the egg and the late nymphal and adult stages of stink bugs are the most commonly attacked by parasitoids, whereas eggs and young nymphs are the stages most commonly attacked by predators. The effectiveness of stink bugs' natural enemies varies widely with stink bug species and habitats, influencing the biological control of stink bugs across crops. Historically, biological control of stink bugs has focused on introduction of exotic natural enemies against exotic stink bugs. Conservation and augmentation methods of biological control have received less attention in the US, although there may be good opportunities to utilize these approaches. We identify some considerations for the current and future use of biological control for stink bugs, including the potential for area-wide management approaches.

Females of Halyomorpha halys (Hemiptera: Pentatomidae) Experience a Facultative Reproductive Diapause in Northern Greece

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is a native pest of East Asia that overwinters as an adult in natural and human-made structures. Adult emergence from overwintering sites starts in spring, whereas females produce offspring in early summer on host plants, where most feeding occurs. In this study, we investigated the reproductive physiology of overwintering females of H. halys in Northern Greece, by determining the duration of the preoviposition period and fecundity of individuals that were left to overwinter in natural conditions and were subsequently transferred to chambers with standard conditions monthly, from December 2020 to March 2021. According to our results, overwintering H. halys females do not initiate egg laying once they emerge from overwintering sites, but rather need some additional time to exit diapause and mature reproductively. The mean preoviposition period of overwintering females that were transferred from their overwintering sites to the chambers in December 2020 was 29.0 days, which was significantly longer by 8.3 days than that of females that overwintered until March 2021, and by 13.2 days than the control (26 °C, 60% RH and a 16:8 h light: dark photoperiod). No significant difference among the average number of eggs per egg mass laid by overwintering individuals brought in the chambers in different time intervals and the laboratory colony was observed. However, females that were left to overwinter until March laid a significantly higher number of eggs in total, compared to the ones whose overwintering was disrupted in February. Based on our findings, overwintering females of H. halys experience a facultative reproductive diapause in Northern Greece. Our study was the first to determine the occurrence of diapause of H. halys in N. Greece and our findings could be very valuable for assessing the damage of this pest to early-season crops and designing successful management practices.

Survey of overwintering Halyomorpha halys (Hemiptera: Pentatomidae) in ports of export and natural landscapes surrounding the ports in Republic of Korea

Halyomorpha halys (Hemiptera: Pentatomidae), an important agricultural and nuisance pest, is highly invasive with peculiar hiding behavior in human-made structures for overwintering. To evaluate the contamination risk of overwintering H. halys in non-agricultural export goods, we conducted a two-year field survey in Republic of Korea to locate overwintering H. halys in two major ports of export, Ulsan and Pyeongtaek ports, and monitored both active and overwintering H. halys population levels with varying distances from the ports ranging from 1 km to 48 km. First, we deployed wooden shelters in the two ports to catch dispersing H. halys for overwintering and conducted visual inspections for human-made structures in the ports to locate overwintering H. halys. In addition, we sampled dead trees to find overwintering H. halys in wooded areas. Second, we monitored active H. halys populations using pheromone traps with varying distances from the ports. From the survey of overwintering populations, no H. halys was collected from wooden shelters deployed in the two ports. However, we found four adults overwintering in human-made structures in Pyeongtaek port in the first year of survey. One dead adult was also found from a dead tree located in a wooded area adjacent to Pyeongtaek port in the second year. For active populations, results of pheromone trapping indicated that H. halys populations were present during autumn dispersal period not only in agricultural areas, but also in wooded areas adjacent to the two ports. This study reports for the first time that overwintering H. halys were found from the inside the port of export in its native areas with a low density. The results were discussed for evaluating contamination risk of overwintering H. halys in export goods shipping from the Republic of Korea.

Spatiotemporal Distribution of Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) Across a Fruit and Tree Nut Agricultural Ecosystem

The invasive brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is a mobile, polyphagous agricultural pest that feeds on a variety of plants. In orchard systems, seasonal monitoring of adults and nymphs in fruit and nut trees and noncrop host plants in surrounding habitat can be used to identify, in time and space, areas of high-density aggregations to develop targeted pest management strategies. We explored the spatiotemporal distribution of H. halys adults and nymphs and assessed whether seasonal distribution patterns varied according to habitat. From 2018 to 2021, pheromone-baited traps were placed in orchard and noncrop plants to first document the establishment of H. halys at this site and to describe seasonal development. In addition, stink bugs were monitored weekly during 2019-2020 across a grid of baited traps placed within the orchard ecosystem. Based on grid data, we used Spatial Analysis by Distance Indices (SADIE) to identify significant clusters of H. halys and visualized aggregations with interpolated maps. Overall, the distribution of H. halys adults and nymphs were similar; both aggregated primarily in peach and adjacent woodlands followed by pecan. Timing of aggregations was consistent across years and reached the highest levels in July and August. Moreover, we document that H. halys is an established pest within this orchard ecosystem, and that noncrop host plants likely play an important role in maintaining populations of H. halys. To manage H. halys in southeastern orchard systems, growers may need to account for host plants in habitats that surround fruiting trees.

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.

New Records and Updated Checklist of the Pentatomoidea (Hemiptera: Heteroptera) of Greece

Eight species of the superfamily Pentatomoidea are recorded from Greece for the first time: Aelia germari Küster 1852, Eurygaster hottentotta (Fabricius 1775), Eysarcoris aeneus (Scopoli 1763), Neottiglossa lineolata (Herrich-Schaeffer 1830), Neottiglossa pusilla (Gallen 1789), Picromerus bidens (Linnaeus 1758), Podops (Podops) inunctus (Fabricius 1775) and Tarisa pallescens (Jakovlev 1871). A complete updated species checklist with distributional data notes for all the new species for Greece are provided.

Analysis of the Destructive Effect of the Halyomorpha halys Saliva on Tomato by Computer Tomographical Imaging and Antioxidant Capacity Measurement

Simple Summary

Halyomorpha halys is a devastating agricultural pest, and digestion starts with an extra-oral phase as the injury is inflicted by injected saliva enzymes into the plant tissues. We carried out a noninvasive imaging assay assisted by computer tomography (CT) of through damaged tomatoes caused by H. halys. It was intended to support the imaging results by further laboratory analytical approaches, such as the antioxidant capacity, which have been used as a stress indicator. Our results confirmed that the noninvasive approach may provide new data for the cognition of the degree of damage induced by this important pest. The important finding is the proof of escalation of the lesions as a function of bug number and the exposure time. Volume and structure deviation in tomatoes were justified by the antioxidant activity. In summary, our method can be suitable for the qualitative inspection of tomato items.

Abstract

Qualitative and quantitative parameters of tomatoes are impaired by Halyomorpha halys Stål (Hemiptera: Pentatomidae), which cause severe economic losses worldwide. Our aims were to assess H. halys-induced tissue damage in tomatoes via computer tomography and to confirm the results of imaging obtained by analytical methods. Our examination confirmed the intensification of the change in the inner structure of damaged tomatoes as a function of time. The tendency of this destruction triggered by bug saliva grew exponentially from the exocarp layer to the inner placenta. The destruction of the plant tissue was aggravated by an increase in the number of bugs, as it was unequivocally evinced by the shell thickness assays. The results of the assessment of the antioxidant capacity of tomato mesocarp showed a distinct decrease in the antioxidant capacity of the samples obtained from H. halys-infested tomatoes. This indicates that the ferric-reducing antioxidant power value was related to the degradation processes of the mesocarp tissue in tomato fruit caused by the watery saliva released by H. halys. The presented experimental method can be suitable for the qualitative control of the vegetable items intended for trade, which can help for the isolation of tomatoes damaged by bugs immediately after harvest.

To Every Thing There Is a Season: Phenology and Photoperiodic Control of Seasonal Development in the Invasive Caucasian Population of the Brown Marmorated Stink Bug, Halyomorpha halys (Hemiptera: Heteroptera: Pentatomidae)

Studies on the phenology of local populations of invasive insects are necessary for monitoring and predicting their dispersion. We investigated the phenology of the brown marmorated stink bug, Halyomorpha halys, in the Sochi region (Krasnodar Territory, Russia) from 2018 to 2021 by regular field sampling and dissecting. The results of the sampling suggest that H. halys is at least partially bivoltine in the studied region: the main period of mass oviposition (by the overwintered females) occurs from June to July; the second, much shorter period of egg-laying (by females of the new, i.e., the first generation) occurs in August. Reproductively active individuals (i.e., females with developed ovaries and filled spermatheca and males with filled ectodermal sac) were recorded from the end of May to the beginning of September. Such a seasonal pattern correlated with day length: when the natural photoperiod decreased below the experimentally determined critical day length (15.0−15.5 h), the proportions of females with fully developed ovaries sharply dropped to zero. Both the rate of H. halys pre-adult development and the timing of the induction of winter adult diapause observed under natural conditions fully agreed with the earlier predictions that had been based on the results of laboratory experiments.

Influence of Trap Location in the Tree Canopy on Captures of Adventive Trissolcus japonicus (Hymenoptera: Scelionidae)

Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae) is an egg parasitoid of the invasive Asian pest, brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae). Also native to Asia, adventive T. japonicus populations have been detected in North America since 2014, and are currently reported from 15 U.S. states, the District of Columbia, and two Canadian provinces. Yellow sticky cards (YSC) have proven effective for monitoring the presence, seasonal abundance, and distribution of these adventive populations. Our research has utilized YSC deployed in the midcanopy of H. halys host trees, following a study in which all leaves on felled tree of heaven, Ailanthus altissima (Mill.) Swingle, were inspected for H. halys egg masses, yielding eggs parasitized by T. japonicus only from mid- and upper-canopy leaves. However, given that other investigators have captured T. japonicus using YSC deployed in the lower-canopy, and that the effect of YSC placement in trees on T. japonicus captures had not been examined, captures of T. japonicus on YSC in the mid- and lower-canopy of individual A. altissima were compared. Traps were replaced weekly for five weeks and assessed for scelionid species. In 2020 and 2021, T. japonicus represented ≥53% of all Scelionidae captured, and there was not a significant effect of YSC location in the canopy on its captures. Deploying YSC at either canopy height was effective for measuring the relative abundance of T. japonicus, but sampling from the lower canopy substantially improved the efficiency and convenience of T. japonicus surveillance.

Improved Captures of the Invasive Brown Marmorated Stink Bug, Halyomorpha halys, Using a Novel Multimodal Trap

Simple Summary

Pest monitoring using traps is a key component of integrated pest management. For several insects, trapping is achieved using visual or olfactory stimuli. Although the combination of both is supposed to provide higher efficacy, this has often been overlooked in trap design. Through laboratory bioassays and field experiments we evaluated the use of UV-A and visible light in combination with olfactory stimuli to improve trapping of the invasive brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae). Our results may be useful for the improvement of monitoring strategies for early pest detection. Additionally, the higher efficacy of the multimodal traps would allow their use in attract-and-kill or push–pull strategies within integrated pest management.

Abstract

Capture strategies for the brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae), are challenging. Here we developed and evaluated a multimodal trap which combines visual and olfactory stimuli. Visual stimuli consisted of LEDs emitting UV-A and visible light. Olfactory stimuli were comprised of the synthetic aggregation pheromone and odours from trapped H. halys individuals. Stink bug attraction at different wavelengths was evaluated in laboratory two-choice bioassays, and different prototypes of the trap were tested in 2021 in natural, agricultural, and urban settings. Traps with a combination of UV-A and blue or green visible wavelengths provided higher H. halys attraction (up to ~8-fold) compared to traditional sticky or small pyramidal traps. The concurrent presence of synthetic pheromone and LED had a synergistic effect on H. halys positive phototaxis. Further development and implementation of the multimodal trap is discussed for prospective use in attract-and-kill or push–pull strategies.

Flying over Eurasia: Geographic Variation of Photoperiodic Control of Nymphal Development and Adult Diapause Induction in Native and Invasive Populations of the Brown Marmorated Stink Bug, Halyomorpha halys (Hemiptera: Heteroptera: Pentatomidae)

Simple Summary

The brown marmorated stink bug is an invasive true bug that originates in eastern Asia and is considered now one of the most harmful invasive insect pests in North America and Europe. Similar to the many species that produce more than one generation per year, this bug responds to day length: under short-day conditions (which predict the approaching of autumn), adults form a special overwintering (diapause) physiological state, whereas, under long-day conditions (typical for summer), they reproduce. Critical day length is the condition that induces diapause in 50% of adults. This critical day length is usually strongly correlated with the latitude of the population origin. In this study, we compared the critical day lengths of one native (Andong, South Korea) and three invasive (Torino, Italy; Basel, Switzerland; and Sochi, Russia) populations. The critical day lengths of both sexes fell between 14.5 and 15.0 h in the Korean population, and between 15.0 and 15.5 h in the three European populations. The results demonstrate that microevolution was possibly ‘too slow to keep up’ with the rapid spread of the invader across Eurasia. It is expected that in the near future, the critical day length of invasive H. halys populations will gradually change to adapt better to the local conditions.

Abstract

Facultative winter adult diapause in Halyomorpha halys is regulated by a long-day photoperiodic response. Day length also influences nymphal development, which slows down at the critical (near-threshold) day lengths. We compared the photoperiodic responses of one native (Andong, South Korea) and three invasive (Torino, Italy; Basel, Switzerland; and Sochi, Russia) populations in a laboratory common-garden experiment. Nymphs developed and emerging adults were reared at 24 °C in a range of photoperiods with day lengths of 14.0, 14.5, 15.0, 15.5, and 16.0 h. The critical day lengths of the photoperiodic responses of both sexes fell between 14.5 and 15.0 h in the native Korean population and between 15.0 and 15.5 h in three invasive European populations. The differences between the three invasive populations were not significant, despite their distant origins. Moreover, the difference between the Korean and European populations was much smaller than was expected. The microevolution was possibly ‘too slow to keep up’ with the rapid spread of the invader across Eurasia. It is expected that soon the critical day length of the invasive H. halys populations will gradually change to adapt better to local conditions. At present, the critical day length for diapause induction of 15 h 15 min can be used to model the phenology, further spread, and response to climate change for all European populations of the pest.

Attraction of Egg Parasitoids Trissolcus mitsukurii and Trissolcus japonicus to the Chemical Cues of Halyomorpha halys and Nezara viridula

Simple Summary

When an alien species reaches a new environment, the natural enemies present in that habitat might fail to regulate its population as they might not be host-adapted. Hence, the best solution might be the use of alien biological control agents that are co-evolved with the exotic pest in question. This is the case of Halyomorpha halys, which is native to Asia and has recently invaded Europe and the Americas. Trissolcus japonicus and Trissolcus mitsukurii are among its main parasitoids. Adventive populations of the latter were found in Northern Italy, suggesting its employment within augmentative biological control. Homologous programs with T. japonicus are already ongoing in Italy. This procedure implies releasing the parasitoid to increase its population and spread to new areas invaded by H. halys. However, a fundamental aspect that must be investigated is the risk-assessment beforehand, i.e., the systematic process of identifying the hazard associated with such a procedure. In this context, the preference of T. japonicus and T. mitsukurii between two stinkbugs was evaluated in this study. We found that T. japonicus preferred the naturally released traces of H. halys while T. mitsukurii exhibited a higher preference for the natural and synthetic chemical cues of N. viridula.

Abstract

Trissolcus mitsukurii and Trissolcus japonicus are two Asian egg parasitoids associated with different pentatomids such as Halyomorpha halys. Adventive populations of T. mitsukurii were found in Northern Italy, suggesting its employment as a biological control agent (BCA) against H. halys. Nevertheless, to reduce the latter’s population, T. japonicus was released in Italy. Releasing an exotic parasitoid requires investigating the interaction between the BCA and the environment to avoid negative impacts on the entomofauna of the new habitat. Trissolcus mitsukurii is mainly associated with Nezara viridula in its native area. Therefore, we investigated and compared the ability of female T. mitsukurii and T. japonicus to distinguish between naturally released cues of H. halys and N. viridula. A single parasitoid was exposed to contact kairomones of both pests to evaluate its modifications in orthokinetic and locomotory behaviour. The behaviour of female T. mitsukurii was also tested on synthetic compounds simulating the cues of the two pentatomids. When naturally released cues were used, T. japonicus preferred the traces of H. halys, while T. mitsukurii preferred N. viridula’s cues. Moreover, the attraction of T. mitsukurii to N. viridula’s cues was confirmed with synthetic cues. Additional studies are needed to judge if this parasitoid can be used as a BCA.