Effect of the Juvenile Hormone Analog,Fenoxycarb on Termination of Reproductive Diapause in Scotinophara lurida (Burmeister) (Heteroptera: Pentatomidae)

This study was carried out to investigate a role of the juvenile hormone analog, fenoxycarb (FC) in terminating the reproductive diapause in the black rice bug, Scotinophara lurida (Burmeister) (Heteroptera: Pentatomidae). FC-treated adults collected at different dates developed their ovaries sooner than untreated ones. Topical application of FC accelerated diapause termination of field-collected S. lurida in which FC-treated adults exhibited early oviposition. In FC-treated males, development of their accessory glands and testes accelerated appeared to be prompted. These results suggest that various physiological overwintering traits related to diapause in this species may in part be under gonadotrophic endocrine control.     

Spatio-temporal dynamics of <Emphasis Type="Italic">Scotinophara lurida</Emphasis> (Hemiptera: Pentatomidae) in rice fields

Studying the spatial pattern of insect pests and the temporal stability of their patterns is important in understanding underlying ecological mechanisms and in developing pest management programs in cultivated crop systems. To elucidate the spatio-temporal pattern of the black rice bug, Scotinophara lurida, in rice fields, samplings were conducted in two rice fields over 2 years. Using spatial analysis by distance indices, the spatial pattern of each developmental stage of S. lurida and their temporal stability of the spatial pattern were identified. Most of the I _a (the index of aggregation) values for overwintered adults and eggs of S. lurda were close to 1, indicating random distribution pattern while nymphs and new adults mainly had I _a values >1, indicating an aggregated distribution pattern. According to spatial association analysis between successive samples using X (the index of spatial association), the spatial pattern of S. lurida showed strong temporal stability throughout the season. Also, there was strong association between the spatial patterns of developmental stages, indicating the great effect of the spatial pattern of the previous developmental stage on that of later developmental stage. Factors influencing the spatial pattern and spatial stability of S. lurida are discussed.     

Morphology of Immatures of Caonabo pseudoscylax (Bergroth) (Hemiptera: Pentatomidae)

Characters of immatures are potentially useful in identifying taxa, but few immatures of Pentatomidae were described. The objectives here are to describe the egg and five nymphal instars of Caonabo pseudoscylax (Bergroth) under light and scanning electron microscopy. Adults, eggs, and nymphs were collected on Homolepsis glutinosa during 2008, in Criciúma (Santa Catarina, Brazil). The egg of C. pseudoscylax is subcylindrical, chorion reddish brown, slightly translucent, and with granulate surface. Aero-micropylar processes translucent, spongy, and strongly clavate. Nymphs without punctures, spiracles placed near the lateral abdominal margin. The dorsal abdominal gland has rounded ostioles bearing cuticular valve; spout peritreme smooth, directed anteriorly; evaporatorium network-shaped; and microsculpture poorly ornamented. Humeral angles of the pronotum were produced from fourth instar. The almost marginal placement of abdominal spiracles may diagnose the nymphs of C. pseudoscylax from first instar to adulthood.     

Treatment thresholds for stink bugs (Hemiptera: Pentatomidae) in cotton

The green stink bug, Acrosternum hilare (Say), the southern green stink bug, Nezara viridula (L), and the brown stink bug, Euschistus servus (Say), were predominant phytophagous Pentatomidae detected during 1995-1997 in cotton in South Carolina. These species occurred in similar numbers in conventional and transgenic cotton 'NuCOTN33B', containing the gene for expression of CryIA(c) delta-endotoxin of Bacillus thuringiensis Berliner variety kurstaki. Adult stink bugs moved into cotton from wild and cultivated alternate hosts during July, and reproducing populations usually were detected in cotton from late July into September. Applications of either methyl parathion (0.56 kg [AI]/ha) directed for stink bugs or lambda-cyhalothrin (0.037 kg [AI]/ha) or cyfluthrin (0.056 kg [AI]/ha) for control of cotton bollworm, Helicoverpa zea (Boddie), provided effective control of pentatomids in NuCOTN33B or conventional 'DP5415' and increased yields compared with untreated plots. Fiber quality did not differ among treated or untreated plots of NuCOTN33B. The ground-cloth technique was used to estimate populations of stink bugs, and data indicated that treatment at one bug per 2 m of row adequately protected cotton from yield loss due to stink bug damage. Observations on boll damage indicated that treatment might be necessary if >20-25% reveal internal symptoms of feeding injury during mid- to late season. More detailed damage thresholds should be developed to complement an approach based on population monitoring. This study validated current recommendations for management of pentatomids in cotton, demonstrated the necessity of threshold use for stink bugs in transgenic cultivars expressing endotoxin from B. thuringiensis, and provided insight into further development of management options for pentatomids in the crop.     

Assessing antixenosis of soybean entries against Piezodorus guildinii (Hemiptera: Pentatomidae)

Piezodorus guildinii (Westwood) (Hemiptera: Pentatomidae) is a major soybean (Glycine max (L.) Merrill) pest and reduces grain quality and yield worldwide. In the context of integrated pest management strategies, plant resistance stands out as an extremely valuable tool for the management of pest populations. Here, we evaluated the resistance of several soybean entries to P. guildinii using tests of attractiveness and feeding preference. We also evaluated trichome number and length as well as pod hardness to evaluate the relationships between these parameters and the resistance to stink bug. D 75-10169, PI 171451, PI 229358, PI 227687, “IAC 100,” IAC 78-2318, PI 274454, PI 274453 and “IAC 19” were less attractive and less consumed by stink bugs. D 75-10169, PI 227687 and PI 274454 received low probe numbers and a short consumption duration per probe; “IAC 100” and PI 274453 received low probe numbers; PI 171451 and PI 229358 received short probe durations; and “IAC 19” received the highest number of probes. There was no correlation between trichome density and length with the attractiveness and feeding preference of the adult insects; however, pod hardness results suggested that this morphological factor may influence the number of probes performed by the insect. PI’s entries, D 75-10169, “IAC 100” and “IAC 19” expressed antixenosis resistance and should be appropriate for use in soybean breeding programs aimed at developing entries with higher resistance to pest insects.     

Description of the immature stages of Chinavia erythrocnemis (Berg) (Hemiptera: Pentatomidae)

Adults and nymphs of Chinavia erythrocnemis (Berg) were colected on Sebastiania commersoniana (Baill.) Smith & Downs in the Parque Estadual do Espinilho in Barra do Quarai county, RS, and used to establish a laboratory culture reared on green pods of Phaseolus vulgaris L. Egg coloration is light-brown, chorion is reticulated and aero-micropylar processes are clubbed and white; mean number of aero-micropylar processes is 61. Eggs are very similar to those from other Neotropical Chinavia species, but the average number of 12 eggs/mass is unique among Chinavia species. Nymphs are predominantly black, with the distal part of the head, femur, and the basal part of tibia, red. First instar has the dorsal maculae of the head and thorax in red coloration, and the abdomen with a series of 3+3 dorsal white maculae. Second to fifth instars have 1+1 white maculae on lateral margins of pronotum and 2+2 white maculae on abdome. Fourth and fifth instars show an ovate white maculae in the middle of lateral plates of abdomen. Nymph coloration and the size, number and position of the maculae on pronotum and abdomen are diagnostic to C. erythrocnemis.     

New species of Neotibilis Grazia & Barcellos (Hemiptera: Pentatomidae: Pentatomini)

Three new species of Neotibilis Grazia & Barcellos are described from Brazilian Amazon region and Ecuador, based on general and genital morphology: Neotibilis (Neotibilis) claviformis sp. nov., Neotibilis (Neotibilis) ecuadorensis sp. nov. and Neotibilis (Neotibilis) manauara sp. nov. Illustrations and a key to species of the type subgenus are given. The range of Neotibilis is expanded, with new records for N. (N.) biguttata (Walker)--Brazil (Amazonas) and N. (N.) chiapensis (Thomas & Brailovsky)--Brazil (Roraima and Pará).     

Digestive glucosidases in the midgut of Apodiphus amygdali Germar (Hemiptera: Pentatomidae)

Apodiphus amygdali or stink bug of fruit trees is one of the polyphagous species from pentatomid bugs that attack many of fruit trees and ornamental trees. In the current study, activities of α- and β-glucosidases were measured in the midgut of A. amygdali adults. It was found the higher activity of β-glucosidase than α-glucosidase in addition to different enzymatic properties of the enzymes. Optimal pHs for enzymatic activities were found to be 5 and 7 for α- and β-glucosidases, respectively. Values regarding optimal temperatures were obtained at 30?°C for both α- and β-glucosidases. Among ions used on α-glucosidase activity, K⁺ and Ca²⁺ significantly increased enzymatic activity, Na⁺ had no effect, and Cu²⁺, Fe²⁺ and Mg²⁺ had the significant negative effects on the enzyme activity. Ca²⁺ and Fe²⁺ increased β-glucosidase activity in the midgut of A. amygdali, Na⁺ had no effect, and other ions significantly decreased the enzyme activity. Ethylene glycol-bis (β-aminoethylether) N,N,N?,N-tetraacetic acid (EGTA), citric acid, ethylenediamide tetraacetic acid (EDTA) and sodium dodecylsulfate (SDS) significantly decreased α-glucosidase activity but EGTA, triethylenetetramine hexaacetic acid (TTHA), EDTA and SDS decreased β-glucosidase activity in the midgut of A. amygdali. Characterisation of digestive enzymes, especially the effect of inhibitors on enzyme activity, could be useful for better understanding of enzyme roles in nutritional physiology of insects in addition to reach safe and useful controls of insect pests.     

Toxicity of insecticides to Halyomorpha halys (Hemiptera: Pentatomidae) using glass-vial bioassays

A scintillation glass-vial bioassay was used to test technical grade insecticides against the non-native stink bug Halyomorpha halys (St?l). Halyomorpha halys (St?l) (Hemiptera: Pentatomidae) is emerging as an important pest in the Mid-Atlantic States, especially in tree fruits and as a homeowner nuisance during the winter. Pyrethroid insecticides, especially bifenthrin, caused mortality against H. halys at low doses, with LC50 values of 0.03-0.49 (microg [AI]/cm2) (mg body mass(-1)). Three nicotinoids were tested against adults with LC50 values ranging between 0.05 and 2.64 (microg [AI]/cm2) (mg body mass(-1)). Phosmet had LC50 values that were up to 3.6-fold higher than other classes of insecticides tested. Fifth instars of H. halys were evaluated against selected chemicals, and they were generally susceptible at lower rates than the adults. Due to significant differences in weight, males and females were individually weighed, tested, and analyzed separately. Sex-related differences in susceptibility were found in the responses to thiomethoxam with males being less susceptible despite having a smaller body mass.     

Ovary development and maturation in Nezara viridula (L.) (Hemiptera: Pentatomidae)

Ovary development and maturation of Nezara viridula (L.) were evaluated by examining ovariole morphology and the alterations in the biochemical (protein synthesis related to reproduction) composition of the hemolymph. Quantitative and qualitative protein analyses were performed and ovary structural alterations for the pre-reproductive and reproductive stages were recorded. Total concentration of proteins in female hemolymph gradually increased until the end of the pre-mating stage, remaining unaltered thereafter. Proteins linked to reproduction (vitellogenins) appeared in the hemolymph 10 days after adult emergence and indicated the end of the pre-mating stage. After mating, total protein concentration in the hemolymph was lower compared to virgin females; vitellogenin levels were similar during most of the observation period. Oocyte development and maturation were gradual and age dependent. Ten-day-old females had chorionated oocytes ready for fertilization. Mating did not stimulate oocyte development in N. viridula, but the lack of mating activity appeared to have stimulated oocyte resorption in 17-day-old females.     

Cytochemical studies on vitellogenesis in Aspongopus obscurus (Hemiptera: Pentatomidae)

By employing cytochemical techniques it is possible to conclude that the oöcytes of Aspongopus obscurus develop fatty and compound yolks. The fatty yolk originates in close proximity to the Golgi bodies and is composed of neutral fat. Based on the source of origin, the compound yolk has been grouped into two categories: CY₁ and CY₂. While the CY₁ develops de novo in the central oöplasm, the CY₂ originates from precursors infiltrating into the oöcyte through the follicular epithelium. Both CY₁ and CY₂ are composed of carbohydrate (1:2 glycol group and glycogen), protein (tyrosine, histidine, NH₂, SH and SS groups) and RNA.     

Monitoring stink bugs (Hemiptera: Pentatomidae) in mid-Atlantic apple and peach orchards

Pyramid traps coated with industrial safety yellow exterior latex gloss enamel paint and baited with Euschistus spp. aggregation pheromone, methyl (2E,4Z)-decadienoate captured more stink bugs than all other baited and unbaited trap types in both apple and peach orchards in 2002 and 2003. Commercial sources of dispensers of methyl (2E,4Z)-decadienoate deployed in association with pyramid traps had a significant impact on trap captures. Captures in pyramid traps were four-fold greater when baited with lures from IPM Technologies, Inc. (Portland, OR) than with lures from Suterra (Bend, OR). Variation in yellow pyramid trap color (industrial safety yellow and standard coroplast yellow) and material (plywood, plastic, and masonite) did not affect trap captures. Brown stink bug was the predominant species captured (58%), followed by dusky stink bug, Euschistus tristigmus (Say) (20%); green stink bug, Acrosternum hilare (Say) (14%); and other stink bugs (Brochymena spp. and unidentified nymphs) (8%). Captures in baited pyramid traps were significantly correlated with tree beating samples in both managed and unmanaged apple orchards and with sweep netting samples in the unmanaged apple orchard. However, problems associated with trapping mechanisms of pyramid trap jar tops and jar traps likely resulted in reduced captures in baited traps. Improved trapping mechanisms must be established to develop an effective monitoring tool for stink bugs in mid-Atlantic orchards.     

Attractiveness of stages of rice panicle development to Oebalus pugnax (Hemiptera: Pentatomidae)

Greenhouse experiments were conducted during 2004 and 2005 with male and female Oebalus pugnax (F.) (Hemiptera: Pentatomidae) caged on rice plants at different stages of panicle development with the objective of determining the most attractive stage to O. pugnax. Field-collected insects were released inside cages containing potted plants and observed during morning and afternoon hours for 5 d. Results showed that attractiveness of male and female O. pugnax to plants with panicles at milk and soft dough stages was greater than plants at preheading and heading stages. Preheading plants were the least attractive to the insects, confirming field observations. Results imply that insecticide applications during the preheading stage are likely ineffective and that monitoring efforts during the milk and soft dough stages of panicle development should be intensified.     

Three new color patterns of nymphs of Arvelius albopunctatus (De Geer) (Hemiptera: Pentatomidae)

Arvelius albopunctatus (De Geer) is widely distributed in the Neotropical region, being an important pest of Solanaceae. Color variation of nymphs was described for this and other pentatomid species and their knowledge is essential for an early identification. From December 2005 to July 2006 nymphs and adults of A. albopunctatus were collected in forest fragments in Criciúma, I?ara, Maracajá and Araranguá (SC, Brazil). Known morphs of nymphs of both 4th and 5th instars were observed, as well as three new morphs, here described and named red morph (4th and 5th instars), green morph (4th and 5th instars) and orange morph (5th instar).     

Most susceptible stage of rice panicle development to Oebalus pugnax (Hemiptera: Pentatomidae)

Oebalus pugnax (F.) (Hemiptera: Pentatomidae) damage to rice, Orya savita L., reduces rough and head rice yields, and grain quality. O. pugnax feeds on developing kernels, introducing pathogenic fungi and causing a discoloration of the grain known as "peck." The objective of this study was to determine the stage of rice panicle development most susceptible to O. pugnax attack. During 2005 and 2006, in greenhouse and field experiments, rice plants were caged at the boot stage and then infested with adult or nymphal O. pugnax. Plants were infested during one of three stages of panicle development: heading, milk, or soft dough. Insects were allowed to feed on the plants for the duration of each stage and then killed. After maturation, panicles were harvested, and grain was hulled and milled. Grain weight, percentage of pecky grain, and percentage of whole grain after milling were recorded. No differences were found in the weight of rough, brown, or milled rice infested with O. pugnax during different stages of panicle development. Number of filled grains per cage was not affected by O. pugnax, and number of empty grains per cage was affected in two of four experiments. Higher percentage of peck was found in grain from panicles infested during dough and milk than in grain from panicles infested during heading. Adult O. pugnax caused higher percentage of peck than nymphs in all stages of panicle development. An inverse relationship was found between percentage of peck and percentage of whole grain weight only in one of the experiments.     

Phylogeographic relationships of the southern green stink bug Nezara viridula (Hemiptera: Pentatomidae)

Abstract The sequences of 16S rDNA, cytochrome oxidase subunit I (COI) and cytochrome b (Cyt b) genes from nine field collections (seven provinces in China: Guangxi, Hubei, Guangdong, Guizhou, Zhejiang, Hunan, Jiangxi, and also southern and northern part of Iran), plus the sequences of Africa, Europe, Americas and Japan obtained form GenBank were used to re-analyse the genetic variation in the southern green stink bug Nezara viridula (Linnaeus). The phylogeographic re-analysis by using four algorithms (NJ, MP, ML and Bayesian) showed three main lineages. The Iranian haplotypes fell into lineage II formed from Europe and America, rather than in lineage III from Asia; the Chinese haplotypes fell into the Asian clade. Our results suggested that African and non-African gene pools have been isolated since the Miocene era with the molecular clock calibrations for Heteroptera mtDNA, and not since the Pliocene as mentioned previously. The corresponding age of the separation of the eastern and western Asia clades is estimated to be 4.0–1.6 million years ago, coinciding with the Pliocene–Pleistocene epoch and with acute rising events in the Tibet Plateau locates in the western China, which may have formed the barriers observed today.