Biochemical Aspects of the Soybean Response to Herbivory Injury by the Brown Stink Bug Euschistus heros (Hemiptera: Pentatomidae)

Plant defense response is an elaborate biochemical process shown to depend on the plant genetic background and on the biological stressor. This work evaluated the soybean biochemical foliar response to brown stink bug herbivory injury through an analysis of redox metabolism and proteomic 2DE profiles of susceptible (BRS Silvania RR) and resistant (IAC-100) varieties. The activity of lipoxygenase-3, guaiacol peroxidase, catalase and ascorbate peroxidase was monitored every 24 h up to 96 h. In the susceptible variety, injury caused an increase in the activities of lipoxygenase 3 and guaiacol peroxidase, no change in ascorbate peroxidase, and a decrease in catalase. In the resistant variety, injury did not cause an alteration of any of these enzymes. The proteomic profiles were evaluated after 24 h of injury and revealed to have a similar proportion (4–5%) of differential protein expression in both varieties. The differential proteins, identified by mass spectrometry, in the susceptible variety were related to general stress responses, to plant defense, and to fungal infections. However, in the resistant variety, the identified change in protein profile was related to Calvin cycle enzymes. While the susceptible variety showed adaptive changes in redox metabolism and expression of stress-responsive proteins, the resistant showed a defense response to circumvent the biological stressor.     

Storage of Euschistus heros Eggs (Fabricius) (Hemiptera: Pentatomidae) in Liquid Nitrogen for Parasitization by Telenomus podisi Ashmead (Hymenoptera: Platygastridae)

Records in the literature with regard to the influence of freezing of pentatomid eggs on parasitism by microhymenopterans are scarce. In this research, we compared the storage of Euschistus heros (Fabricius) (Hemiptera: Pentatomidae) eggs in liquid nitrogen for different periods with the objective of optimizing the multiplication of Telenomus podisi Ashmead (Hymenoptera: Platygastridae) in the laboratory. Fresh eggs of E. heros were exposed (S3, S6) or not (NS3, NS6) to UV light for 30 min and stored in 1.5-mL plastic vials in liquid nitrogen either for 3 (S3, NS3) or 6 months (S6, NS6), and egg suitability to parasitoid development was compared to control eggs exposed (SC) or not (NSC) to UV treatment. Global data analysis showed that E. heros eggs stored in liquid nitrogen with or without UV treatment, for 3 or 6 months, were suitable for T. podisi parasitization.     

Development of a dry artificial diet for Nezara viridula (L.) and Euschistus heros (Fabricius) (Heteroptera: Pentatomidae)

Artificial diets prepared with wheat germ, soybean protein, dextrosol, potato starch, sucrose, cellulose, soybean or sunflower oil, and vitamin solution for rearing Nezara viridula (L.) and Euschistus heros (Fabricius) were tested under controlled temperature (25 +/- 1 degrees C), RH (60 +/- 10%), and photophase (14h). Three diets were tested and compared with the natural diet privet [soybean and peanut seeds and privet Ligustrum lucidum Ait. fruit (Oleaceae)]. All three artificial diets allowed full development. The diet containing sunflower oil was the most suitable for N. viridula while E. heros developed better on a diet composed of soybean oil. Data indicated that the artificial diets were inferior to the natural diet. The artificial diets were more adequate for E. heros.     

Green Stink Bug (Hemiptera: Pentatomidae) Recorded as a New Pest of Olive in India

During the survey of olive orchards in Jammu and Kashmir, various insect pests were recorded infesting olive which include, olive psylla, olive black scale, scarab beetle and green stink bug. Among these greenstinkbug, Nezara virudula (L.) [Hemiptera: Pentatomidae] has been recorded for the first time in India.     

Field responses of stink bugs to the natural and synthetic pheromone of the Neotropical brown stink bug, Euschistus heros (Heteroptera: Pentatomidae)

Abstract.The synthetic racemic mixture of methyl 2,6,10‐trimethyltridecanoate, a component of the male produced pheromone of Euschistus heros (F.) (Heteroptera, Pentatomidae), was attractive to pentatomid species in a field test, using homemade pheromone trap designs. The pentatomid Piezodorus guildinii was caught in high numbers in field traps, during two field experiments, indicating a consistent response of this species to the E. heros pheromone. A correlation was found between the range of insects caught in the pheromone‐baited traps and a random sampling method. The synthetic stereoisomeric mixture of methyl 2,6,10‐trimethyldodecanoate, a minor component of E. heros pheromone, was also field tested and caught no pentatomids. Egg parasitoids were caught in traps baited with E. heros pheromone, indicating that this pheromone can be exploited as a kairomone. A synchrony in the periodicity of trap catch, between the egg parasitoids and their host, was also recorded.     

Landscape Factors Facilitating the Invasive Dynamics and Distribution of the Brown Marmorated Stink Bug,Halyomorpha halys (Hemiptera: Pentatomidae), after Arrival in the United States

The brown marmorated stink bug, Halyomorpha halys, a native of Asia, has become a serious invasive pest in the USA. H. halys was first detected in the USA in the mid 1990s, dispersing to over 41 other states. Since 1998, H. halys has spread throughout New Jersey, becoming an important pest of agriculture, and a major nuisance in urban developments. In this study, we used spatial analysis, geostatistics, and Bayesian linear regression to investigate the invasion dynamics and colonization processes of this pest in New Jersey. We present the results of monitoring H. halys from 51 to 71 black light traps that were placed on farms throughout New Jersey from 2004 to 2011 and examined relationships between total yearly densities of H. halys and square hectares of 48 landscape/land use variables derived from urban, wetland, forest, and agriculture metadata, as well as distances to nearest highways. From these analyses we propose the following hypotheses: (1) H. halys density is strongly associated with urban developments and railroads during its initial establishment and dispersal from 2004 to 2006; (2) H. halys overwintering in multiple habitats and feeding on a variety of plants may have reduced the Allee effect, thus facilitating movement into the southernmost regions of the state by railroads from 2005 to 2008; (3) density of H. halys contracted in 2009 possibly from invading wetlands or sampling artifact; (4) subsequent invasion of H. halys from the northwest to the south in 2010 may conform to a stratified-dispersal model marked by rapid long-distance movement, from railroads and wetland rights-of-way; and (5) high densities of H. halys may be associated with agriculture in southern New Jersey in 2011. These landscape features associated with the invasion of H. halys in New Jersey may predict its potential rate of invasion across the USA and worldwide.     

Vibratory Communication and its Relevance to Reproductive Isolation in two Sympatric Stink Bug Species (Hemiptera: Pentatomidae: Pentatominae)

Communication is in phytophagous stink bugs of the subfamily Pentatominae related to mating behavior that among others includes location and recognition of the partner during calling and courting. Differences in temporal and frequency parameters of vibratory signals contributes to species reproductive isolation. Chinavia impicticornis and C. ubica are two green Neotropical stink bugs that live and mate on the same host plants. We tested the hypothesis that differences in temporal and spectral characteristics of both species vibratory signals enable their recognition to that extent that it interrupts further interspecific communication and copulation. To confirm or reject this hypothesis we monitored both species mating behaviour and recorded their vibratory songs on the non-resonant loudspeaker membranes and on the plant. The level of interspecific vibratory communication was tested also by playback experiments. Reproductive behavior and vibratory communication show similar patterns in both Chinavia species. Differences observed in temporal and spectral characteristics of female and male signals enable species discrimination by PCA analyses. Insects that respond to heterospecific vibratory signals do not step forward to behaviors leading to copulation. Results suggest that species isolation takes place in both investigated Chinavia species at an early stage of mating behavior reducing reproductive interference and the probability of heterospecific mating.     

Adjacent Habitat Influence on Stink Bug (Hemiptera: Pentatomidae) Densities and the Associated Damage at Field Corn and Soybean Edges

The local dispersal of polyphagous, mobile insects within agricultural systems impacts pest management. In the mid-Atlantic region of the United States, stink bugs, especially the invasive Halyomorpha halys (Stål 1855), contribute to economic losses across a range of cropping systems. Here, we characterized the density of stink bugs along the field edges of field corn and soybean at different study sites. Specifically, we examined the influence of adjacent managed and natural habitats on the density of stink bugs in corn and soybean fields at different distances along transects from the field edge. We also quantified damage to corn grain, and to soybean pods and seeds, and measured yield in relation to the observed stink bug densities at different distances from field edge. Highest density of stink bugs was limited to the edge of both corn and soybean fields. Fields adjacent to wooded, crop and building habitats harbored higher densities of stink bugs than those adjacent to open habitats. Damage to corn kernels and to soybean pods and seeds increased with stink bug density in plots and was highest at the field edges. Stink bug density was also negatively associated with yield per plant in soybean. The spatial pattern of stink bugs in both corn and soybeans, with significant edge effects, suggests the use of pest management strategies for crop placement in the landscape, as well as spatially targeted pest suppression within fields.     

Effects of thiamethoxam and lambda‐cyhalothrin on spermatogenesis of Euschistus heros (Heteroptera: Pentatomidae)

Euschistus heros (Fabricius, 1798) is one of the most harmful insect pests damaging Brazilian soybean crops and has become a major problem due to its high population density and resistance to insecticides. Currently, there are no data on whether alterations of testicular morphology and chromosomal behavior are associated with the resistance mechanisms related to the action of insecticides. This study integrated analyses of the testicular morphology, meiocyte cell division, and chromosomal structure and behavior in the process of spermatogenesis in E. heros. We compared these features among wild‐caught individuals, insecticide‐susceptible and ‐resistant strains. The resistant strain was established through a selection experiment exposing the bugs to insecticides (thiamethoxam + lambda‐cyhalothrin) for 15 generations. No differences were detected in the examined features among the three groups of experimental individuals: the testis comprised six lobes, with the fifth lobe thinner than the others; the karyotype was 2n = 14 (12 + XY), with no evident changes in chromosomal breakage, rearrangement or behavior in the meiosis; and abundant spermatozoa were observed in all testicular lobes. Thus, any effects of the long‐term (15 generations) experimental selection by exposure to the insecticides were not detected on the male germinal tissue and chromosomes, suggesting the irrelevancy of the examined features to insecticide‐resistance mechanisms in E. heros.     

Nuclear changes and acrosome formation during spermiogenesis in Euchistus heros (Hemiptera: Pentatomidae)

Ultrastructural and cytochemical studies were carried out on nuclear changes and acrosome formation during the spermiogenesis of the phytophagous bug Euchistus heros. The development of the nucleus involves changes in the shape and in degree of chromatin condensation: initially it is dispersed and with a low-electron density, then assumes a fibrillar arrangement and finally compacts in an electron-dense material. The acrosome is formed by the Golgi complex and presents unusual morphological features during its development. The reaction product of acid phosphatase, glucose-6-phosphatase and thiamine pyrophosphatase activities were detected during various stages of acrosome development. In contrast, residues of alpha-N-acetylgalactosamine and basic proteins were only reported in the intermediate and late stages of the differentiation process, respectively.     

Feeding Activity, Salivary Amylase Activity, and Superficial Damage to Soybean Seed by Adult Edessa meditabunda (F.) and Euschistus heros (F.) (Hemiptera: Pentatomidae)

Greenhouse and laboratory studies were conducted to evaluate feeding activity and superficial damage to soybean seed by the brown-winged stink bug, Edessa meditabunda (F.), and the Neotropical brown stink bug, Euschistus heros (F.). Soybean plants (cv. BRS 282), at R6 stage of development were used. Thirty pairs of each species were used individually for 48?h. Two daily observations (9:00?AM and 3:00?PM) were taken to record the number of bugs (feeding/resting) on plant parts. Harvested seeds imbibed in tetrazolium solution were photographed for measurement of the damaged surface. Adult E. meditabunda significantly preferred soybean stems (19.7 bugs) to pods (2.7). Feeding/resting was similar at 9:00?AM (mean number of 28.0 bugs) and 3:00?PM (24.3). Euschistus heros equally fed/stayed on stems (7.3 bugs) and pods (6.9), although most bugs (12.3) remained on the cage net; feeding/resting on all plant structures amounted to 13.7 bugs at 9:00?AM and 17.7 bugs at 3:00?PM. Amylase activity was greater for E. heros (41.61?±?0.89?U/mg) and almost none for E. meditabunda (2.35?±?0.14?U/mg). The superficial damage to seeds was significantly greater for E. meditabunda (22. 9?mm²) compared to E. heros (12.5?mm²). However, E. meditabunda caused less shrinkage of the seed tegument, while E. heros damage was deeper and seeds showed reduction in size.     

Economic Injury Level of the Neotropical Brown Stink Bug <Emphasis Type="Italic">Euschistus heros</Emphasis> (F.) on Cotton Plants

In Brazil, the Neotropical brown stink bug, Euschistus heros (F.) (Hemiptera: Pentatomidae), commonly disperses from soybeans to cotton fields. The establishment of an economic treatment threshold for this pest on cotton crops is required. Infestation levels of adults of E. heros were evaluated on cotton plants at preflowering, early flowering, boll filling, and full maturity by assessing external and internal symptoms of injury on bolls, seed cotton/lint production, and fiber quality parameters. A completely randomized experiment was designed to infest cotton plants in a greenhouse with 0, 2, 4, 6, and 8 bugs/plant, except at the full-maturity stage in which only infestation with 8 bugs/plant and uninfested plants were evaluated. Results indicated that the preflowering, early-flowering, and full-maturity stages were not affected by E. heros. A linear regression model showed a significant increase in the number of internal punctures and warts in the boll-filling stage as the population of bugs increased. The average number of loci with mottled immature fibers was significantly higher at 4, 6, and 8 bugs compared with uninfested plants with data following a quadratic regression model. The seed and lint cotton was reduced by 18 and 25% at the maximum level of infestation (ca. 8 bugs/plant) in the boll-filling stage. The micronaire and yellowing indexes were, respectively, reduced and increased with the increase of the infestation levels. The economic injury level of E. heros on cotton plants at the boll-filling stage was determined as 0.5 adult/plant. Based on that, a treatment threshold of 0.1 adult/plant can be recommended to avoid economic losses.     

Kairomonal effect of walking traces from Euschistus heros (Heteroptera: Pentatomidae) on two strains of Telenomus podisi (Hymenoptera: Scelionidae)

Abstract.  The semiochemical cues used by geographically isolated strains of the parasitoid, Telenomus podisi (Ashmed), to find eggs of the stink bug Euschistus heros were investigated. Two strains of Te. podisi , maintained on eggs of a South American host ( E. heros ) were studied. One parasitoid strain originated from specimens collected near Brasilia, Brazil (SA strain), and a second strain originated from specimens collected at Beltsville, Maryland (NA strain). Cold tolerance tests of adults from the NA and SA Te. podisi strains, analyses of the cuticular hydrocarbons between the two strains, and crossing experiments between strains each indicated consistent differences between the NA and SA strains. Subsequent experiments using E. heros showed that SA Te. podisi females specifically recognize traces left on the substrate by walking E. heros females and then search intensively the area of the 'footprints', apparently looking for an egg mass to parasitize. By contrast, Te. podisi females of the NA strain are incapable of recognizing the footprints of E. heros females despite the fact that these parasitoids were reared from eggs of E. heros . The possibility that the two strains are actually different species is discussed.     

Comparison of Substrate-Borne Vibrational Signals of Two Congeneric Stink Bug Species, Thyanta pallidovirens and T. custator accerra (Heteroptera: Pentatomidae)

Vibrational signals (songs) were recorded and compared for two stink bug species, Thyanta pallidovirens and T. custator accerra. Females of both species produced two songs. Male T. pallidovirens also produced two songs, whereas male T. c. accerra produced four. Songs emitted by females of both species were comparable in structure and function, as was one of the male-produced songs. During the courtship phase of mating behavior, males of both species emitted a song with similar function but different temporal and spectral properties. Basic properties of songs, such as the dominant frequencies, were similar to those of songs of other pentatomid species, but the extensive use of frequency modulation and overlapping duets were novel. Differences in songs, combined with differences in male-produced pheromones, may play a role in the reproductive isolation of these congeners.     

Total evidence phylogenetic analysis and reclassification of Euschistus Dallas within Carpocorini (Hemiptera: Pentatomidae: Pentatominae)

Robust phylogenetic hypotheses have become key for studies addressing the evolutionary biology and ecology of various groups of organisms. In the species‐rich heteropteran superfamily Pentatomoidea, phylogenies at lower taxonomic levels are still scarce and mostly employ exclusively morphological data. In this study, we conducted a total evidence phylogeny focusing on the tribe Carpocorini (Pentatomidae), using morphological data and four DNA markers (COI, Cytb, 16S and 28S rDNA; ～2330 bp; 32 taxa) in order to investigate the relationships within Euschistus Dallas, one of the most speciose pentatomid genera, and between Euschistus and related genera. Our hypotheses generated by maximum likelihood and Bayesian inference show that the current taxonomic composition and classification of Euschistus and allied genera are in need of revision. Euschistus was recovered as nonmonophyletic, with the subgenera forming four independent lineages: Euschistus (Euschistus) and Euschistus (Lycipta) Stål are sister groups; Euschistus (Euschistomorphus) Jensen‐Haarup is more closely related to Dichelops Spinola and Agroecus Dallas; and Mitripus Rolston is divided into two clades closely related to Sibaria Stål and Ladeaschistus Rolston. We chose not to change the classification of E. (Euschistomorphus) until further data become available, and propose to split Euschistus into three genera with the exclusion of Euschistus (Mitripus) and all of its species. Here we elevate Mitripus to genus rank to include M. acutus comb.n. , M. convergens comb.n. and M. legionarius comb.n. , and propose Adustonotus Bianchi gen.n. to include A. anticus comb.n. , A. latus comb.n. , A. tauricornis comb.n. , A. grandis comb.n. , A. hansi comb.n. , A. paranticus comb.n. , A. irroratus comb.n. and A. saramagoi comb.n. We also provide identification keys to the genera Adustonotus gen.n. , Ladeaschistus, Mitripus n. rank and Sibaria, here defined as the Mitripus genus group, and to the species of Mitripus and Adustonotus gen.n. Our results provide insights into the current status of the classification of the Pentatomidae, suggesting the need for phylogenetic analyses at different taxonomic levels within stink bugs. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:E09D2675‐0F2B‐4AAE‐9837‐257E0B18BC52 .     

Semiochemical and physical stimuli involved in host recognition by Telenomus podisi (Hymenoptera: Scelionidae) toward Euschistus heros (Heteroptera: Pentatomidae)

The egg parasitoid, Telenomus podisi, was shown to recognize its host, Euschistus heros, through both chemical and physical cues. These were determined in short-range bioassays. The cues comprised fertile and infertile host eggs, egg extracts, crude extracts of adult males and females and successive dilutions of the synthetic racemic mixture of methyl 2,6,10-trimethyltridecanoate, a male-produced pheromone of E. heros. Some of the treatments used induced a selection process in T. podisi, through host recognition behaviour, indicating a consistent response of this species to E. heros. The possibility that some of these compounds could be exploited as long-range kairomones, by T. podisi, is discussed. Using GC analysis, an unidentified compound (Rt 24.8 min), possibly from the egg adhesive material, was detected from E. heros egg extracts. Its retention time compared to the methyl 2,6,10-trimethyltridecanoate showed a lower volatility, suggesting that the egg adhesive may act as a short-range kairomone. Physical cues appeared to be an important component in the host selection process by T. podisi. The parasitoid discriminated infertile eggs which are differently shaped and smaller than fertile eggs.     

Field attraction of the stink bug Euschistus conspersus (Hemiptera: Pentatomidae) to synthetic pheromone-baited host plants.

The attraction of the stink bug Euschistus conspersus Uhler to sources of the synthetic pheromone component methyl (2E,4Z)-decadienoate was investigated in a series of field experiments in native vegetation surrounding commercial apple orchards in Washington. In experiments with pheromone lures placed inside two different tube-type traps, stink bugs were attracted to the immediate area around traps in large numbers, but very few were caught in the traps. Pheromone lures attached directly to the host plant mullein, Verbascum thapsus L., demonstrated that these 'baited" plants attracted significantly more E. conspersus than unbaited plants. Spring (reproductive) and summer (reproductively diapausing) E. conspersus adults, both males and females, were attracted to pheromone-baited plants. There was no significant difference in the number of male or female E. conspersus attracted to pheromone-baited traps or plants in any of the experiments, further characterizing methyl (2E,4Z)-decadienoate as an aggregation, and not a sex pheromone. Stink bug aggregations formed within 24-48 h of lure placement on mullein plants and remained constant until the lure was removed after which aggregations declined over 3-4 d to the level of unbaited plants. The implications of these studies for E. conspersus monitoring and management are discussed.     

Feeding preference and movement of Nezara viridula and Euschistus serous (Hemiptera: Pentatomidae) on individual cotton plants

Experiments were conducted in an environmental growth chamber to determine the movement and feeding preferences of Nezara viridula (L.) and Euschistus serous (Say) on individual cotton plants. Fifth instars were caged by species on a single cotton plant (FM 9063 B2F) containing four discrete boll sizes ranging from 1.1 to 3.0 cm in diameter over a period of 5 d per replication. Two digital video cameras were simultaneously focused on each of the four bolls per plant to visually confirm stink bug resting and movement. During the study, a total of 4,080 h of video footage was recorded and analyzed. Results showed that N. viridula and E. serous did not prefer the exact same boll sizes. In a trial with eight stink bugs per plant, N. viridula spent more time on the three larger boll classes, 1.6-2.0, 2.1-2.5, and 2.6-3.0 cm. In a separate trial with one stink bug per plant, N. viridula spent more time on the larger boll classes while E. serous exhibited the strongest preference for 1.1-1.5 and 2.1-2.5 cm bolls. N. viridula moved more often than E. serous and both species moved more often during photophase compared with scotophase. Regardless of species or number of bugs released, bolls in the smallest boll size class fell off the plant about 3 d after the bugs were released. These results confirm that scouts who are estimating stink bug damage should select bolls in the 2.1-2.5 cm diameter boll size class.