Stink Bug Species Research Articles

Fruit Phenology of Two Hazelnut Cultivars and Incidence of Damage by Halyomorpha halys in Treated and Untreated Hazel Groves

Over the past decade, Halyomorpha halys has become one of the main threats to hazelnut production. Its trophic activity makes kernels inedible due to strongly detrimental effects on the organoleptic quality. Its management in Italy is still tricky due to the lack of effective native biocontrol agents and authorized and effective insecticides. A field test was performed on San Giovanni (SG) and Tonda Romana (TR) cultivars (early and late ripening, respectively) to assess the intensity of cimiciato damage with different pest management approaches (no insecticide and integrated pest management, IPM). Moreover, phenological analysis of fruits and the monitoring of stink bug species by traps and plant beating were carried out. In the untreated plots, the SG cv showed a higher cimiciato incidence with respect to the late TR cv (40% SG–NI vs. 23% TR–NI). This was probably due to the different phenological phases in which stink bugs injured the fruits. In fact, stink bug bites provoke different kinds of injuries (blanks, shriveled, and cimiciato) according to the fruit’s development period. Indeed, in the period of highest insect occurrence in the field, the fruits of the early cv (SG) were in kernel expansion, a phenological phase in which bug injuries are more likely in cimiciato defects. Lastly, the IPM did not provide sufficient fruit protection (19% SG–IPM vs. 11% TR–IPM). The interaction between the phenological development of hazelnuts and the brown marmorated stink bug represents a critical aspect in understanding and implementing effective strategies for controlling this key pest on hazelnut trees.

Nymph development and adult feeding on, and damage to, immature siliquae of canola by different species of stink bugs.

Studies were conducted in the laboratory and in the greenhouse with the objective of evaluating nymph development, adult body weight gain, and damage of different species of pentatomids feeding on fruit (hereafter referred to as siliqua) of canola, Brassica napus (L.) var. oleifera. Nymphs of Nezara viridula (L.) were able to reach adulthood feeding on siliquae (93.3% survivorship), while nymphs feeding on siliquae that had their seeds removed showed arrested development, only reaching the 4th instar and did not complete development to adulthood. Adults of N. viridula gained body weight feeding on canola siliquae, particularly during the first two weeks of adult life, dropping weight thereafter. Adults of another species of pentatomid, Diceraeus furcatus (F.), also gained body weight, while adults of Euschistus heros (F.) lost weight. N. viridula adults caused significantly greater damage to seeds (shrunken and with rotten aspect) within siliqua and to the siliqua walls (whitish spots with lesions in the form of starbursts, called rosettes) compared to D. furcatus and to E. heros. The amount of damaged seeds caused by N. viridula adults during the first week of adult life was greater (ca. 60%) compared to those of older females 32days of age (27%). Damage symptons caused by the feeding activity on siliqua walls (commonly known as rosettes) reached up to 10% of the total area with similar injury rates for N. viridula adults of different ages. The majority of N. viridula (70%) caused rosette, while only 20% of E. heros and 5% of D. furcatus produced similar damage.

First record of the predatory stink bug species Picromerusgriseus (Dallas) (Hemiptera, Heteroptera, Pentatomidae, Asopinae) in Japan, with an illustrated key to the Japanese species of the genus Picromerus Amyot & Serville.

The predatory stink bug genus Picromerus Amyot & Serville, 1843 (Hemiptera, Heteroptera, Pentatomidae, Asopinae) comprises 11 species found in the Northern Hemisphere. In Japan, two species have been recorded to date. However, an easy-to-understand identification method, such as an illustrated key, is lacking. Currently, Picromerusgriseus (Dallas, 1851) has been recorded in Bangladesh, Bhutan, China, Indonesia, Myanmar, Pakistan and Taiwan, but not in Japan. Picromerusgriseus was recorded in Japan for the first time, based on a single individual collected from grasslands around the fields of Ishigaki Island of the Ryukyu Islands, which belong to the Oriental Region. This discovery represents the easternmost record of the species. An illustrated key to the species of Picromerus occurring in Japan is also provided.

Partial refuges from biological control due to intraspecific variation in protective host traits.

Predicting how much of a host or prey population may be attacked by their natural enemies is fundamental to several subfields of applied ecology, particularly biological control of pest organisms. Hosts or prey can occupy refuges that prevent them from being killed by natural enemies, but habitat or ecological refuges are challenging or impossible to predict in a laboratory setting-which is often where efficacy and specificity testing of candidate biological control agents is done. Here we explore how intraspecific variation in continuous traits of individuals or groups that confer some protection from natural enemy attack-even after the natural enemy has encountered the prey-could provide partial refuges. The size of these trait-based refuges (i.e., the proportion of prey that survive natural enemy encounters due to protective traits) should depend on the relationship between trait values and host/prey susceptibility to natural enemy attack and on how common different trait values are within a host/prey population. These can be readily estimated in laboratory testing of natural enemy impact on target or nontarget prey or hosts as long as sufficient host material is available. We provide a general framework for how intraspecific variation in protective host traits could be integrated into biological control research, specifically with reference to nontarget testing as part of classical biological control programs. As a case study, we exposed different host clutch sizes of target (pest) and nontarget (native species) stink bug (Hemiptera: Pentatomidae) species to a well-studied exotic biocontrol agent, the egg parasitoid Trissolcus japonicus (Hymenoptera: Scelionidae). We predicted that the smallest and largest clutches would occupy trait-based refuges from parasitism. Although we observed several behavioral and reproductive responses to variation in host egg mass size by T. japonicus, they did not translate to increases in host survival large enough to change the conclusions of nontarget testing. We encourage researchers to investigate intraspecific variation in a wider variety of protective host and prey traits and their consequences for refuge size.

Observations of the host habitat of Ophiocordyceps nutans in the Bidoup Nui Ba National Park, Lam Dong, Vietnam.

Endoparasitic Cordyceps species infect pest insects and other arthropods all throughout the world. Ophiocordyceps nutans like specimens were found in the Lat and Dung K’no of the Lac Duong district during entomogenous fungi forays in Bidoup Nui Ba National Park. However, observations made over the last two years (2021 - 2022) in various forest locations across different altitudinal ranges revealed that O. nutans only occurs in two high-altitude forests, with elevations between 1409 and 1589 m asl with the temperature fluctuating from 20,3 and 25,7°C. Morphological comparisons and molecular phylogenetic analyses using D1 - D2 led us to conclude that the neotropical specimens represent Ophiocordyceps nutans (Pat.). In this study, the parasitic host of O.nutans of Hemiptera and host habitas is the bark and leaves of Lasianthus bidoupensis (Rubiaceae). Because Ophiocordyceps nutans parasitize and kill different species of stinkbugs that pose a hazard to silviculture and agriculture, making it a viable biocontrol agent.

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.

Seleção de fungos entomopatogênicos para controle de percevejos e bicudo-do-algodoeiro

ABSTRACT Entomopathogenic fungi stand out in the biological control of several agriculturally important insects. Six isolates of Metarhizium anisopliae, Cordyceps javanica, Beauveria sp. and B. bassiana were screened to control Anthonomus grandis, Euschistus heros, Oebalus poecilus, O. ypsilongriseus and Thyanta perditor, important insect pests of soybean, cotton and rice. The bioassays were conducted in a completely randomized design, with four replications (10 insects/replication). Significant differences for virulence were observed between the tested fungal species and isolates. For A. grandis, the most virulent isolate was M. anisopliae BRM 2335, followed by Beauveria BRM 14527 and BRM 67744 [82.5 to 97.5 % of mortality; average lethal time (LT50) of 5.9 to 7.8 days]. M. anisopliae BRM 2335 was also highly virulent to the four stink bug species (75 to 97.5 % of mortality; LT50 of 5.2 to 9.7 days). For the stink bugs, Beauveria sp. BRM 67744 was infectious to O. poecilus (75 % of mortality), but failed to control E. heros (16.9 % of mortality). C. javanica BRM 27666 and BRM 14526 showed average virulence to the stink bugs and A. grandis (17.5 to 57.3 % of mortality; LT50 of 6.0 to 9.7 days). M. anisopliae was consistently more virulent to the stink bugs than the other fungi. Therefore, M. anisopliae BRM 2335 was selected for further studies under screenhouse and field conditions to control A. grandis and other stink bug species, especially E. heros.

Occurrence of some stink bug species (Hemiptera: Pentatomidae) associated with rice fields in Argentina

Occurrence of some stink bug species (Hemiptera: Pentatomidae) associated with rice fields in Argentina

First record of Halyomorpha halys (Heteroptera: Pentatomidae) from Uzbekistan

The invasive stink bug species Halyomorpha halys (Stål, 1855) (Heteroptera: Pentatomidae), a dangerous pest of many agricultural plants, is recorded from Uzbekistan for the first time. Several imagines and larvae were found in the Khorezm and Ferghana provinces in 2020 and 2022.

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.

Disentangling a Neotropical pest species complex: genetic diversity and population structure of the native rice stink bug Oebalus poecilus and the invasive O. ypsilongriseus.

A first step in any pest management initiative is recognizing the existing problem - identifying the pest species and its abundance and dispersal capacities. This is not simple and even more challenging when insidious (invasive) species are involved constituting a pest complex. Understanding a species' population diversity and structure can provide a better understanding of its adaptation and relative pest potential. Such is the need for the native rice stink bug Oebalus poecilus and the invasive O. ypsilongriseus in low and high flatlands of South America. The genetic structure differed between both rice stink bug species (FST =0.157, P=0.001), where 84% of the overall genetic variability takes place within species and three genetic groups were recognized through Bayesian approach (K=3). Oebalus poecilus exhibited slightly higher genetic diversity (HE =0.253) and structuring (FST =0.050, P=0.001) than the invasive O. ypsilongriseus (HE =0.211; FST =0.038, P=0.013). Nonetheless, only the former exhibited significant correlation between genetic and geographic distances (r=0.48, P=0.013). Despite the pointed peculiarities, the obtained results indicate overlap in both species' occurrence and similar genetic structure allowing for a compound problem to be dealt with as the complex requires managing without, as yet, a prevailing species or a niche specialization. © 2022 Society of Chemical Industry.

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

Simple SummaryStink bugs are important pests of many crops in the US, including row crops, vegetables, and tree fruits and nuts. Most stink bug management relies on broad-spectrum, disruptive insecticides with high human and environmental risks associated with them. These issues and increasing pesticide resistance in stink bugs are forcing pest managers to explore safer and more sustainable options. Here, we review the 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 the 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.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.

Was the decline of saltmarsh tabanid populations after the 2010 oil spill associated with change in the larval food web?

AbstractHorse flies of the species Tabanus nigrovittatus and Tabanus acutus are native to coastal marshlands. Their larvae are apex invertebrate predators, and their development is dependent on the food web in the marsh sediment. Surveillance of T. nigrovittatus after the 2010 Deepwater Horizon Oil Spill in the Gulf of Mexico showed population crashes of adult flies in southeast Louisiana marshes near oil landfall, but not in southwest Louisiana where oil did not reach. Sediment collection in 2011 from Louisiana marshes showed a near‐complete absence of larvae in the southeast yet high numbers in the southwest. We hypothesized that oil contamination destroyed critical components of the larval food web and/or residual toxicity led to larval death. We used 18S rRNA gene metagenomics to identify components of the food web in larval guts and sediment from southeast and southwest Louisiana marshes. Sediment oil contamination, biochemistry, and toxicity could not explain the lack of larvae in the southeast, because oiling at our high‐tide mark sites was low at the time of the study and toxicity was independent of sediment biochemistry. Hexapods were the main food web components in tabanid larval guts. Abundance of stink bug, vinegar fly, and mosquito species in the sediment was positively associated with the presence of larvae. However, these taxa were enriched in southeastern (near oil) versus southwestern (unoiled reference) sediment, and thus, lack of major food web components due to oiling could not explain lack of larva in the east. We conclude that the immediate crash in adult populations in oiled regions was the main cause for the absence of larvae the following year. While most saltmarsh arthropod groups had rebounded within a year after the oil spill, recovery of saltmarsh horse flies was ongoing for 5 years.

Diversity and Molecular Barcoding of Stink Bugs (Hemiptera: Pentatomidae) Associated with Macadamia in South Africa.

Simple SummaryStink bugs inflict extensive damage leading to significant yield and economic loss in the South African macadamia industry. There is currently a need for alternative control strategies to replace the reliance on chemical control in South Africa. Accurate identification and knowledge of species composition are important to inform these management practices. In this study, we identified stink bug species associated with macadamia orchards in the three main growing regions of South Africa. This was performed based on morphology and DNA barcoding. A total of 21 stink bug species were found in macadamia orchards, and Bathycoelia distincta was the dominant species found. A group of Boerias spp. were found to be dominant in KwaZulu-Natal, and this is the first report of these species associated with macadamia. Evidence of cryptic species diversity was also found within Pseudatelus raptorius and an unidentified Boerias sp. (Boerias sp. 1). Species composition fluctuated over three growing seasons and between growing regions, highlighting the need for ongoing monitoring of these important pest species. The DNA barcode database developed in this study will be valuable for future monitoring, identifications and the implementation of informed management strategies.Stink bugs are major pests of macadamia in South Africa. Accurate identification and knowledge of species composition are important to inform management practices. The overall aims of this study were to identify stink bug species from macadamia orchards in South Africa using morphology, and to establish a DNA database based on the cytochrome c oxidase subunit 1 gene region. A total of 21 stink bug species were found in macadamia orchards in KwaZulu-Natal, Limpopo and Mpumalanga provinces. Bathycoelia distincta Distant, 1878, was the dominant species throughout all three growing regions. Two unidentified species of Boerias Kirkaldy, 1909, here designated as Boerias sp. 1 and Boerias sp. 2, were the second and third most abundant species found in KwaZulu-Natal. No species of Boerias has previously been reported in association with macadamia. Evidence of a cryptic third species of Boerias was also found. Species composition fluctuated over three growing seasons in Limpopo and differed between the three growing regions during the 2019–2020 season, highlighting the need for ongoing monitoring of these important pest species. The DNA barcode database developed in this study will be valuable for future monitoring and identifications, including cryptic or polymorphic stink bug species and different life stages.

Assessment of Injury by Four Major Pests in Soybean Plants Using Hyperspectral Proximal Imaging

Arthropod pests are among the major problems in soybean production and regular field sampling is required as a basis for decision-making for control. However, traditional sampling methods are laborious and time-consuming. Therefore, our goal is to evaluate hyperspectral remote sensing as a tool to establish reflectance patterns from soybean plants infested by various densities of two species of stinkbugs (Euschistus heros and Diceraeus melacanthus (Hemiptera: Pentatomidae)) and two species of caterpillars (Spodoptera eridania and Chrysodeixis includens (Lepidoptera: Noctuidae)). Bioassays were carried out in greenhouses with potted plants placed in cages with 5 plants infested with 0, 2, 5, and 10 insects. Plants were classified according to their reflectance, based on the acquisition of spectral data before and after infestation, using a hyperspectral push-broom spectral camera. Infestation by stinkbugs did not cause significative differences in the reflectance patterns of infested or non-infested plants. In contrast, caterpillars caused changes in the reflectance patterns, which were classified using a deep-learning approach based on a multilayer perceptron artificial neural network. High accuracies were achieved when the models classified low (0 + 2) or high (5 + 10) infestation and presence or absence of insects. This study provides an initial assessment to apply a non-invasive detection method to monitor caterpillars in soybean before causing economic damage.

Citizen Science Meet South American Tachinids: New Records of Feather-Legged Fly Trichopoda (Galactomyia) pictipennis Bigot (Diptera: Tachinidae) from Chile.

The species of Gymnosomatini (Diptera: Tachinidae) are specialized to attack stink bugs (Hemiptera: Pentatomidae). Some of these flies, such as those in the genus Trichopoda Berthold, are conspicuous and represent target species to study with citizen science. Here we report for the first time the distribution range of T. (Galactomyia) pictipennis Bigot, a newly introduced biological control species of tachinid for use against stink bugs in Chile using data obtained through the citizen science method. Additionally, we update the distribution of T. arcuata (Bigot), a native biological control species of tachinid, and assess the grade of overlap between the flies and their main stink bug hosts. We obtained data regarding the occurrence of flies and stink bugs from the citizen science program "Moscas Florícolas de Chile," from Facebook groups, and from iNaturalist. We standardized our data to avoid temporal, spatial, and geographic biases. We report the extent of occurrence (EOO) and area of occupancy (AOO) for each fly and stink bug species. The EOOs for T. pictipennis and T. arcuata are 85,474 km2 and 20,647 km2 through central Chile ecosystems, respectively. The EOO of T. arcuata is overlapped by 53% with the introduced species. Trichopoda pictipennis has a high percentage of overlap with the EOO of Nezara viridula Linnaeus (61%), whereas T. arcuata has low percentages of overlap with different native Acledra species and with N. viridula. We discuss the potential of citizen science to detect (1) areas with higher diversity or gaps of occurrences, (2) new biological control agents, (3) prey records, (4) negative impacts on non-target species, (5) changes in composition at long-term, and (6) areas to promote conservation biological control in agricultural landscapes.

RNAi-induced knockdown of white gene in the southern green stink bug (Nezara viridula L.)

The southern green stink bug (SGSB) Nezara viridula L. is one of the most common stink bug species in the United States and can cause significant yield loss in a variety of crops. A suitable marker for the assessment of gene-editing tools in SGSB has yet to be characterized. The white gene, first documented in Drosophila, has been a useful target to assess the efficiency of introduced mutations in many species as it controls pigmentation processes and mutants display readily identifiable phenotypes. In this study we used the RNAi technique to investigate functions and phenotypes associated with the white ortholog in the SGSB and to validate white as a marker for genetic transformation in this species. This study revealed that white may be a suitable marker for germline transformation in the SGSB as white transcript knockdown was not lethal, did not impair embryo development and provided a distinguishable phenotype. Our results demonstrated that the white ortholog in SGSB is involved in the pathway for ommochrome synthesis and suggested additional functions of this gene such as in the integument composition, management of hemolymph compounds and riboflavin mobilization.

Natural biological control of Bagrada hilaris by egg predators and parasitoids in north-central California

Bagrada bug, Bagrada hilaris Burmeister (Hemiptera: Pentatomidae), is an invasive stink bug from Asia that has become a major pest of cruciferous crops (Brassicaceae) in California. Conventional insecticides are currently the most effective means for controlling this pest. In organic production, options are limited and generally ineffective. As part of an effort to develop a biological control program for bagrada bug, we documented attack rates by resident parasitoids and predators on sentinel bagrada bug eggs throughout north-central California, including the Salinas Valley, which is the largest cruciferous crop growing region in the US. A total of 51 sites were sampled over three years. Sentinel eggs were placed on the ground, where bagrada bug lays most of its eggs, and in foliage, where all other known stinkbug species deposit their eggs and resident egg parasitoids are most likely to search. Predation rates exceeded 20% per day on some sample dates (averaging 7.2, 7.4 and 6.3% per day in 2017, 2018 and 2019, respectively) and were generally higher on the ground than in the foliage, although temporal patterns were inconsistent and predation levels varied among the sampled regions. Burying eggs in sand did not consistently reduce predation rates, indicating that bagrada bug’s habit of burying its eggs provides only partial protection from predators. Of the 25,387 eggs deployed over the three years of this study that were not predated or missing (out of the 35,673 total eggs that were deployed), only 47 (0.19%) were parasitized. Gryon aetherium Talamas (Scelionidae), a biological control agent for bagrada bug that is currently undergoing testing, was found at one site. Only five of the parasitized sentinel eggs were on the ground, suggesting that few resident parasitoids in north-central California attack bagrada bug eggs, particularly on the ground. These results show that a parasitoid that co-evolved with bagrada bug in its native range is necessary to provide successful biological control of bagrada bug in California.

Black Cherry as A Host Plant For Stink Bugs (Hemiptera: Pentatomidae) in Agroecosystems in Georgia, USA

Stink bugs (Hemiptera: Pentatomidae) are polyphagous pests that disperse from woodland habitats into crops following food availability. Black cherry (Prunus serotina Ehrh.; Rosaceae) is common in the southeast US. In this 3-yr study, our principal objective was to determine if black cherry acts as a reproductive host as well as a source of food for stink bugs in woodland habitats adjacent to crops in Georgia, USA. Each yr, black cherry trees were examined visually for stink bug species and stages in addition to using pheromone-baited canopy and ground traps to capture them. In 2016, we compared the number of stink bugs captured in canopy traps versus ground-based traps. Chinavia hilaris Say, Euschistus servus (Say), Euschistus tristigmus (Say), and Nezara viridula (L.) (all Hemiptera: Pentatomidae) were detected in traps each yr of the study. Total number of stink bugs was significantly higher in ground traps (1.53 ± 0.07) compared to canopy traps (0.71 ± 0.07) in the 2016 test. Only C. hilaris (99.2%) and N. viridula (0.8%) were found on trees during visual sampling. Over both types of sampling methods, egg masses, most instars, and both sexes of adults of C. hilaris were detected in black cherry. The nymph to adult ratio for this species was 1:1 in traps and nymph biased in visual samples. Anastatus reduvii (Howard) (Hymenoptera: Eupelmidae) (44%), Trissolcus edessae Fouts (Hymenoptera: Scelionidae) (35%), and Ooencyrtus sp. (Hymenoptera: Encyrtidae) (21%) emerged from C. hilaris egg masses. The nymph to adult ratio for N. viridula was adult biased. Both nymphs and adults of E. servus and E. tristigmus were captured in traps; however, the majority of individuals were adults. We conclude that black cherry is a significant reproductive host and a food source for C. hilaris. However, our results indicate that it serves as a food source more so than a reproductive host for the other 3 stink bug species.

Natural incidence of pathogenic fungi on stink bug pests in Argentinian rice paddies

AbstractEntomopathogenic fungi (EF) are important biocontrol agents due to their wide host range, easy application, and compatibility with phytosanitary products. Stink bugs (Hemiptera: Pentatomidae) are the most important rice pests in Argentina. Although there is information on the pathogenicity of EF against stink bug pests in rice fields, the natural incidence of EF, and especially their association with stink bug species and plant characteristics, is largely unexplored. The aims of this study were: (1) to monitor the natural incidence of EF on Pentatomidae pests in Argentinian rice paddies; (2) to assess the relationship between the incidence of EF, stink bug feeding guild, and rice cultivar; and (3) to perform a phylogenetic analysis of the EF recorded. Sampling was conducted in target rice fields throughout the rice‐growing season (2017–2018), during which adult individuals of Tibraca limbativentris Stål and Oebalus spp. were manually collected and visually examined for evidence of mycelial development. Of the 780 individuals examined, 182 infected individuals were recorded, from which 12 strains of EF were isolated and identified based on molecular characterization: three strains of Beauveria bassiana sensu lato (Bals.‐Criv.) Vuill., five of Metarhizium anisopliae s.l. (Metschn.) Sorokin, and four of Purpureocillium lilacinum (Thom) Luangsa‐ard et al. (Hypocreales). The occurrence of the three EF species was significantly higher in stem‐feeding T. limbativentris than in seed‐feeding Oebalus spp., thus, differed between feeding guilds. For T. limbativentris, the occurrence of EF was higher when feeding on a short than on a tall rice variety, thus, differed between plant varieties. The results illustrate the potential of using native strains of EF in integrated management of stink bugs in rice.