Precocious induction of vitellogenin with JH III in the twospotted stink bug, Perillus bioculatus (Heteroptera: Pentatomidae)

The effect of juvenile hormone (JH) III on the hemolymph composition of vitellogenin was examined in Perillus bioculatus. Adult females were treated topically with JH III, and the premature presence of vitellogenin in the hemolymph was then detected using electrophoresis and Western blot analyses. JH III treatment resulted in a dose-dependent early production of vitellogenin that was detectable 48 h before vitellogenin was present in non-treated insects. Vitellogenin was not observed in the hemolymph of JH III-treated adult males. The techniques reported here may be useful for the detection, isolation and characterization of compounds with JH-like activity in P. bioculatus and other species of Heteroptera (which are thought to have JH-like substances other than the JHs with known chemical identity). These same techniques may also provide a method for researchers to investigate the interactions of JH-like compounds and other substances, such as ecdysteroid, in the regulation of vitellogenesis in Heteroptera.     

Life history and cost analysis for continuous rearing of Perillus bioculatus (Heteroptera: Pentatomidae) on a zoophytogenous artificial diet

The impact of a zoophytogenous, insect-free artificial diet on the developmental rate, life history parameters, and fertility was examined over 11 consecutive generations for domesticated Perillus biocullatus (F.) (Heteroptera: Pentatomidae). This study showed that when fed an insect-free artificial diet during both the nymphal and adult stages, developmental times were prolonged, and the net reproductive rates (R0) and the intrinsic rates of increase (r(m)) were significantly lower than when fed larval Trichoplusia ni at both nymphal and adult stages. Moreover, the cost to rear P. bioculatus on the artificial diet approached 1.1 times the cost of rearing P. bioculatus on natural prey. These results demonstrate the effectiveness and potential cost-savings of the zoophytogenous artificial diet for rearing a beneficial pentatomid.     

Cotton boll age influences feeding preference by brown stink bug (Heteroptera: Pentatomidae)

Cotton plants were infested with brown stink bug, Euschistus servus (Say), to define cotton boll age classes (based on heat unit accumulation beyond anthesis) that are most frequently injured during each of the initial 5 wk of flowering. Bolls from each week were grouped into discrete age classes and evaluated for the presence of stink bug injury. Brown stink bug injured significantly more bolls of age class B (approximately 165-336 heat units), age class C (approximately 330-504 heat units), and age class D (approximately 495-672 heat units) during the initial 3 wk in both years and in week 5 in 2002 compared with other boll ages. Generally, the frequency of injured bolls was lowest in age class A (< or = 168 heat units) during these periods. The preference by brown stink bug for boll age classes B, C, and D within a week was similar when ages were combined across all 5 wk. Based on these data, bolls that have accumulated 165.2 through 672 heat units beyond anthesis (approximately 7-27-d-old) are more frequently injured by brown stink bug when a range of boll ages are available. The boll ages in our studies corresponded to a boll diameter of 1.161-3.586 cm with a mid-range of 2.375 cm. A general protocol for initiating treatments against stink bugs is to sample bolls for evidence of injury as an indicator of presence of infestations in cotton. Sampling bolls within a defined range, which is most likely to be injured, should improve the precision of this method in detecting economic stink bug infestations in cotton.     

Mating aggregation of a stink bug,Megacopta punctissimum (Montandon) (Heteroptera: Plataspidae)

Summary Adults of a stink bug,Megacopta punctissimum, form aggregations on stems of the bush-clover,Lespedeza crytobotria, in spring. They do not oviposit there, but feed and mate within aggregations. Oviposition is made on other leguminous plants such as the kudzu-vine,Pueraria lobata. Mean size of aggregations (groups of two or more individuals which sit on a stem at distance less than 3 cm from their nearest neighbors) consisted of 4.4 individuals. The sex ratios within aggregations were similar to overall sex ratio of the population including solitary individuals (0.58). More than 50% of females found in aggregations were copulating. Percentage of femalesin copula in larger aggregations was higher than that in smaller aggregations, and this difference was considered to be caused by the higher chance of sexual enconters in larger aggregations. It was suggested that the aggregation of this species on the bush-clover is not a ‘harem’ (a male monopolizes a group of females reported in some other stink bugs) but is mating aggregation to raise the chance of mating. This work was partially supported by Grant-in-Aid (No. 56480039) from the Ministry of Education, Science and Culture.     

Two Meridic Diets for Perillus bioculatus (Heteroptera: Pentatomidae), a Predator of Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)

Two artificial diets, devoid of insect components, were developed for the predator Perillus bioculatus (Fabricius). The diets based on chicken liver and tuna fish were designed to approach the nutritional characteristics of the primary insect prey, Leptinotarsa decemlineata (Say) eggs. P. bioculatus was reared on diet 2 for 11 consecutive generations without cumulative detrimental effects on its biology. Developmental time and preovipositional period were significantly longer, and egg viability, survival from egg to adult, and fecundity were significantly lower in P. bioculatus individuals reared on artificial diets than in those reared on L. decemlineata eggs. A significant reduction in developmental time, increase in survival from egg to adult, and reduction in length of the preovipositional period were observed after 11 generations of in vitro reared P. bioculatus on diet 2. These changes may indicate that the predators experience some degree of adaptation to the diet after several consecutive generations of in vitro rearing. No changes in egg viability were observed after 11 generations of in vitro rearing. Adult female weight was unaffected when reared on artificial diet, but a significant increase was observed after 11 generations of in vitro rearing. Females under all treatments weighed an average of 11.6 mg more than the males.     

Tarsal attachment devices of the southern green stink bug Nezara viridula (Heteroptera: Pentatomidae)

Based on analyses with cryo‐scanning and transmission electron microscopy, the present study reports on the morphology and ultrastructure of the attachment structures of the green stinkbug Nezara viridula L. (Heteroptera: Pentatomidae), a cosmopolitan pest of different crops in most areas of the world. In addition, the presence and distribution of large proportions of the elastic protein resilin in these structures was revealed by confocal laser scanning microscopy. The attachment structures of each leg comprise two sclerotised claws, a pair of smooth flexible pulvilli and a hairy adhesive pad located at the ventral side of the basitarsus. No sexual dimorphism is evident. Contact areas of resting individuals on a smooth surface show that N. viridula creates contact to the substrate with the ventral surface of (a) the distal portions of the pulvilli, (b) the setae of the hairy adhesive pad, (c) the two paraempodia representing mechanosensory setae, and (d) the tips of the claws. Each pulvillus is a sac‐like structure formed by complex cuticular layers that vary in their structure and resilin content. The dorsal side consists of sclerotised chitinous material, while the ventral cuticle consists mainly of resilin and shows a very thin epicuticle and a thick exocuticle. The setae of the hairy adhesive pad are pointed and socketed. They exhibit a pronounced longitudinal gradient in the material composition, with large proportions of resilin being present in the setal tips. In most of these setae, especially in those of the distal‐most part of the pad, also a transverse gradient in the material composition is visible.     

Parasitism and predation of stink bug (Heteroptera: Pentatomidae) eggs in Georgia corn fields

Nezara viridula L. and Euschistus servus (Say) are the predominant species of phytophagous stink bugs on corn, Zea mays L., in Georgia. Oebalus pugnax pugnax (F.) occurs in relatively low numbers, and the predatory stink bug Podisus maculiventris (Say) is commonly found. Limited information is available on natural biological control of these four stink bug species in Georgia corn fields; therefore, a 6-yr study of parasitism and predation of their eggs was initiated in 2003. Naturally occurring stink bug eggs were parasitized by six scelionid species, Trissolcus basalis (Wollaston), T. thyantae Ashmead, T. brochymenae (Ashmead), T. euschisti (Ashmead), Telenomus podisi Ashmead, Telenomus calvus Johnson, and one encyrtid species, Ooencyrtus sp. T. basalis was the most prevalent parasitoid of N. viridula, parasitizing E. servus and P. maculiventris eggs at low levels. T. podisi, the predominant parasitoid species emerging from eggs of E. servus and P. maculiventris, also parasitized O. p. pugnax eggs exclusively and parasitized N. viridula eggs at low levels. T. euschisti and T. thyantae parasitized E. servus egg masses. T. brochymenae parasitized eggs of both E. servus and P. maculiventris. T. calvus parasitized only P. maculiventris eggs. The same species of egg parasitoids that parasitized naturally occurring eggs of N. viridula and E. servus parasitized sentinel eggs of these bugs, except that no T. calvus and Ooencyrtus sp. were obtained from sentinel eggs, and T. thyantae and T. brochymenae emerged from sentinel eggs of N. viridula. Generally, parasitization of an egg mass was either greater than or equal to predation of sentinel eggs of N. viridula and E. servus. However, on some dates in late June and July, predation of sentinel egg masses was numerically approximately twice as high as parasitism. Results indicate stink bug egg parasitoids and predators are significant factors in the natural biological control of stink bugs in corn fields.     

Oosorption in the stink bug,Plautia crossota stali: induction and vitellogenin dynamics

Oosorption, resorption of developing oocytes in the ovary, in P. c. stali is characterized by changes in appearance of oocytes from opaque greyish green or orange to transparent, degeneration of yolk granules and disappearance of oocyte contents. Starvation and virginity were indicated to be factors that induce oosorption. SDS PAGE/Western blotting analysis using anti-vitellogenin antiserum detected two major and many minor bands in haemolymph samples. Egg extracts showed a more complicated set of positive bands in the same analysis. Yolk protein, vitellin, therefore, seemed to be formed after complicated processing of vitellogenin following its uptake by the oocytes. In starved, oosorption-induced females, vitellogenin concentration in the haemolymph was lower than that of fed females, and Western blotting failed to detect either oosorption-specific or ovary-specific peptide fragments in haemolymph samples collected from those females. These results suggest that once oosorption was induced vitellogenin/vitellin in oocytes was degraded rapidly and released into the haemolymph in the form of amino acids or small peptides too small to be recognized by the anti-vitellogenin antiserum.     

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.     

Formation and maintenance of mating aggregations in a stink bug,Megacopta punctissimum (Montandon) (Heteroptera: Plataspidae)

Adults of a stink bug,Megacopta punctissimum, formed mating aggregations on their host plants: a few pairs in copula and a few bachelor males (males not in copula) stayed in the aggregation and the bachelor males waited for arriving females to mate with. The processes of formation and maintenance of the aggregations were observed using the individual marking technique. Aggregations initiated by 2 males or by 1 male and 1 female were usually joined by 1 or more individuals and lasted for several days, but aggregations initiated by 2 females broke up within 1 h. Aggregations were not maintained by the same members. The residence time (time from joining an aggregation to leaving the aggregation without copulating) of males was longer than that of females. There was a negative correlation between the residence time of males and the number of bachelor males in an aggregation when bugs joined it, while the residence time of females was positively correlated with the number of bachelor males in the aggregation. When bugs copulated after joining an aggregation, the postcopulatory residence time (time from completing copulation to leaving the aggregation) was longer in males than in females. Thus, males had a stronger tendency to initiate and maintain aggregations than females.     

Impact of brown stink bug (Heteroptera: Pentatomidae) feeding on corn grain yield components and quality

Brown stink bug, Euschistus servus (Say) (Heteroptera: Pentatomidae), damage on developing corn, Zea mays L., ears was examined in 2005 and 2006 by using eight parameters related to its yield and kernel quality. Stink bug infestations were initiated when the corn plants were at tasseling (VT), mid-silking (R1), and blister (R2) stages by using zero, three, and six in 2005 or zero, one, two, and four bugs per ear in 2006, and maintained for 9 d. The percentage of discolored kernels was affected by stink bug number in both years, but not always affected by plant growth stage. The growth stage effect on the percentage of discolored kernels was significant in 2006, but not in 2005. The percentage of aborted kernels was affected by both stink bug number and plant growth stage in 2005 but not in 2006. Kernel weight was significantly reduced when three E. sercus adults were confined on a corn ear at stage VT or R1 for 9 d in 2005, whereas one or two adults per ear resulted in no kernel weight loss, but four E. servus adults did cause significant kernel weight loss at stage VT in 2006. Stink bug feeding injury at stage R2 did not affect kernel damage, ear weight or grain weight in either year. The infestation duration (9 or 18 d) was positively correlated to the percentage of discolored kernels but did not affect kernel or ear weight. Based on the regression equations between the kernel weight and stink bug number, the gain threshold or economic injury level should be 0.5 bugs per ear for 9 d at stage VT and less for stage R1. This information will be useful in developing management guidelines for stink bugs in field corn during ear formation and early grain filling stages.     

Induction of diapause in a migratory seed bug,Neacoryphus bicrucis (Say) (Heteroptera: Lygaeidae)

Summary Neacoryphus bicrucis hibernates in the adult stage and exhibits a facultative reproductive diapause. Constant photoperiods of the durations encountered in the field do not evoke the diapause response but Shortening of the photoperiods does, providing the decrease in daylength is of a certain length and occurs within a certain photoperiodic interval. The sensitive stages are larval instars II to V. The percentage of diapausing bugs increases as temperature is lowered.It is suggested that the response to daylength shortening in N. bicrucis is an adaptation to ensure seasonal synchronization in a highly migratory species where successive generations may breed at different latitudes.     

Aging and food source effects on mandibular stylets teeth wear of phytophagous stink bug (Heteroptera: Pentatomidae)

Studies were conducted to test the effect of age and food sources on wear of the mandibular teeth of the phytophagous pentatomid, Euschistus heros (F.). The total length (μm) of the area bearing the mandibular teeth, the length of the 1st tooth, and the height of the 2nd tooth for teneral (< 1 day-old) adults were significantly greater than that of adults fed on natural [green bean, Phaseolus vulgaris pods, raw shelled peanuts, Arachis hypogaea, and mature soybean, Glycine max seeds] for 30 or 60 days. Adults fed on artificial dry diet showed, in general, similar results to those of teneral adults. Force (Newtons) required penetrating the natural foods was significantly greater than that required penetrating the artificial diet. The greater hardness of the natural foods caused increased mandibular serration wear.     

Toxicity of Chromobacterium subtsugae to southern green stink bug (Heteroptera: Pentatomidae) and corn rootworm (Coleoptera: Chrysomelidae)

Diabrotica spp. (Coleoptera: Chrysomelidae) beetles and southern green stink bugs, Nezara viridula (L.) (Heteroptera: Pentatomidae), are pests on corn, Zea mays L., and soybean, Glycine max (L.) Merr., as well as on cucurbits. Control of these insects has depended on chemicals. An alternative to chemical control is the use of biologicals. Use of bacteria, fungi, viruses, pheromones, and metabolites to control these insects can potentially improve resistance management and reduce pesticide use. Other than Bacillus thuringiensis Berliner, few bacteria have been discovered that are lethal to either of these pests. Chromobacterium subtsugae Martin et al., a newly described bacterium that is known to be toxic to Colorado potato beetle, Leptinotarsa decemlineata (Say), larvae, was found to be toxic to both diabroticite adult beetles and southern green stink bug adults. In laboratory assays, toxins produced by these bacteria kill 80-100% of the adults of two species of diabroticite beetles, Diabrotica undecimpunctata howardi Barber and Diabrotica virgifera virgifera LeConte, and 100% of southern green stink bug adults within 6 d. For green stink bug, live bacteria were not needed for toxicity.     

The effect of vibratory disturbance on sexual behaviour of the southern green stink bug Nezara viridula (Heteroptera, Pentatomidae)

The effect of vibratory disturbance on sexual behaviour and substrate-borne sound communication of the southern green stink bug, Nezara viridula L. was studied. Disturbance signals do not change the time N. viridula males need to locate the source of vibratory signals, but decrease the number of males responding with the calling and courtship song to calling females. Female N. viridula proceed calling during stimulation with disturbance signals but some of them change the song rhythm by skipping one or more signal intervals or emitting the repelling signals. The number of females which change the dominant frequency of the calling song decreases proportionally with increasing differences between the dominant frequency of the disturbance signals and the emitted female calling song. Variation of the song dominant frequency probably serves females to avoid interference by increasing the signal to noise ratio. Signal duration and repetition rate do not change significantly when the female is stimulated with the disturbance signals. This indicates that frequency shift by calling females is the main strategy for reducing interference by competitive signalers in N. viridula vibrational communication.     

Seasonal occurrence and diapause induction of a predatory bug Andrallus spinidens (F.) (Heteroptera: Pentatomidae)

The bug Andrallus spinidens (F.) (Heteroptera: Pentatomidae) is a polyphagous predator of insect larvae, which is distributed in tropical and warm temperate zones worldwide. Seasonal occurrence and diapause induction of this bug were studied in a population in Miyazaki, southern Kyushu, Japan. The field research showed that A. spinidens produces three or four generations a year and is most abundant from mid‐summer to autumn. Reproductive activity of field‐collected adults decreased from late summer to autumn, indicating that this bug enters adult diapause in autumn. Only adults were found in early spring and these were reproductive. Laboratory experiments showed that, irrespective of photoperiod, adult diapause is induced at lower temperatures (≤22.5°C), whereas it is avoided at higher temperatures (≥25°C). Ambient temperature falls across the critical range from late summer to autumn. Thus, the bug clearly overwinters in adult diapause induced by low temperatures and this diapause is terminated during the course of winter.     

Cyanoprotein: Quantitative changes and synthesis in diapause and juvenile hormone analog treated bean bug,Riptortus clavatus

Quantitative changes of cyanoproteins (CPs) in diapause and juvenile hormone (JH) analog treated bean bug, Riptortus clavatus, were analyzed by rocket immunoelectrophoresis (RIE). In diapause-oriented nymphal females and males, CP-A (CP-1, 2 and 3) and CP-B (CP-4) increased and reached a maximum level just before nymphal-adult ecdysis, which was the same in non-diapause female and male nymphs. Both CP-A and B disappeared immediately after adult emergence. After this initial decline CP-4 appeared again in the hemolymph, followed after a few days by CP-1, 2 and 3. CP-A and B then increased slowly but constantly in both diapause female and male adults. Both diapause females and males at day 30 after adult emergence had large amounts of CP-A (CP-1, 2 and 3) and CP-B (CP-4). Treatment of diapause females (day 30) with methoprene induced only CP-1 synthesis and increased CP-A content about twice in both the whole body and the hemolymph, but did not effect on CP-B content. Methoprene treated females developed ovaries which accumulated yolk containing CPegg and vitellin (Vn). In diapause males treated with methoprene CP-A and B were not induced and decreased gradully in concentration, eventually disappearing completely, similar to post-diapause males (30 days after transferred to long day condition) in which CPs were not detected. These results show that methoprene treatment of diapause females and males induced the same dynamical situations of CP-A and B seen in non-diapause adults, i.e. only CP-A was induced in females and CPs disappeared in males. This suggests that CP synthesis is regulated by juvenile hormone.     

Boll injury and yield losses in cotton associated with brown stink bug (Heteroptera: Pentatomidae) during flowering

Brown stink bug, Euschistus servus (Say), was infested on cotton, Gossypium hirsutum L., plants during reproductive stages to determine the effects on boll injury and seedcotton yield. During each week in 2002 and 2003, significantly more bolls with > or = 1 injured locule, bolls with > or = 2 injured locules, and bolls with discolored lint were recorded on stink bug-infested plants compared with that on noninfested plants. Significantly fewer bolls displayed external injury on the boll exocarp compared with bolls with only internal locule injury. Boll injury was significantly underestimated by the presence of external symptomology. The boll population increased 6.6- and 5.1-fold from weeks 1-5 in 2002 and 2003, respectively. There was a corresponding 6.2- and 4.6-fold increase in 2002 and 2003, respectively, for total bolls injured from weeks 1-5. Percentage of boll injury ranged from 10.7 (week 4) to 27.4 (week 2) in 2002 and from 9.2 (week 3) to 16.0 (week 2) in 2003. Percentage of injury was greatest during weeks 1 and 2 in both years and also in week 5 in 2002. Brown stink bug significantly reduced seedcotton yield of bolls present on cotton plants during weeks 1, 2, and 5 in 2002 and in weeks 4 and 5 in 2003. However, total seedcotton yield, as a function of bolls exposed to brown stink bug and subsequent bolls produced on plant in the absence of stink bugs, was not significantly different for plots infested during weeks 1-4 in 2002 and weeks 1-3 in 2003. Flowering period and boll population influence the severity of stink bug injury on seedcotton yield. Infestation timing and number of bolls should be considered, in addition to insect densities, when initiating treatments against brown stink bug.     

Possible egg positioning and gluing behavior by ovipositing southern green stink bug, Nezara viridula (L.) (Heteroptera: Pentatomidae)

From March 2002 to January 2004, a colony of southern green stink bug, Nezara viridula (L.), was kept in the laboratory, and its oviposition behavior was observed. During oviposition, soon after the egg is expelled, the female touches the egg mass with the dorsal surface of the last tarsomere; this movement of one leg of the hind pair occurred once. This small component of the oviposition behavior of this pentatomid is little known and not yet fully understood; it may help to position and glue the newly deposited egg to the others.     

Identification,purification, and partial characterization of vitellin from the eggs of Eurygaster integriceps putton (heteroptera,pentatomidae)

A single vitellin was identified in the eggs of the wheat bug, Eurygaster integriceps, and purified by a two-step procedure including ion exchange and gel permeation chromatography. Its nondenatured molecular mass is estimated to be 385 kDa. Under reducing conditions—SDS-PAGE—the wheat bug vitellin gives five polypeptides at 110 kDa, 80 kDa, 69 kDa, 53 kDa, and 38 kDa. Its amino acid composition is characterized by high content of aspartic acid/asparagine and glutamic acid/glutamine and low content of methionine and histidine. The lipid moiety (5.65% by weight) includes diacylglycerols, cholesterol, phosphatidylethanolamine, phosphatidylcholine, and sphingomyelin. Carbohydrate content amounts to 4.54% by weight. A part of the wheat bug vitellin is dimerized during the course of deposition into the yolk granules. © 1995 Wiley-Liss, Inc.