Effects of temperature and humidity on the development and hatching of eggs of the thistle lacebug, Tingis ampliata (Heteroptera, Tingidae)

At constant temperatures in the laboratory, the rate of development (i.e. the reciprocal of the time of development in days) of eggs of T. ampliata increased with temperature in the range 15–30°C and threshold temperature for egg development was calculated to be 8.2°. The percentage of eggs hatching tended to increase with temperature, but hatching at 25° was not significantly different from that at 30° and no eggs hatched at 10°. A formula for predicting egg-developmental time at known temperature is provided.At 25° incubation period decreased and the percentage of eggs hatching increased with increase in relative humidity from 51–53% to 100 per cent. Embryonic development and egg hatching were inhibited at relative humidities below 51–53 per cent.

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Résumé La vitesse du dévelopment (c'est-à-dire la réciproque de la durée du développement en jours) des ufs de Tingis ampliata soumis au laboratoire à des conditions constantes de température, s'accroît avec cette température pour une gamme comprise entre 15 et 30°, cependant que la température limite inférieure pour le développement est de 8°2. Le pourcentage d'ufs écols tend à augmenter avec la température mais l'éclosion à 25° n'est pas significativement différente de celle à 30° et aucun uf n'éclot à 10°. Une formule est proposée permettant de prédire la durée de développement des ufs à une température donnée.Pour une température de 25°, la durée d'incubation et le pourcentage d'éclosion des ufs s'accroissent avec l'humidité relative (de 51–53% à 100%). Le développement embryonnaire et l'éclosion sont inhibés par une humidité relative inférieure à 51–53%.

     

Azalea growth in response to azalea lace bug (Heteroptera: Tingidae) feeding

The effects of azalea lace bug, Stephanitis pyrioides (Scott), feeding injury on azalea growth and development were investigated using 'Girard's Rose' azaleas during a 2-yr field study in Georgia Low, medium, and high injury treatments, which corresponded to 6, 8, and 14% maximum canopy area injury, were compared with control azaleas that received no lace bug infestation. Flower number, whole-shrub leaf and stem dry mass, and dry mass and size of new growth tissues were unaffected by treatments. In contrast, growth index measurements, a general measure of variability frequently used for horticultural differentiation, showed significant reductions for all treatments in comparison to control azaleas after 20 wk. Though not directly quantified, this apparent discrepancy may be explained as an artifact of lace bug feeding-induced leaf abscission. Growth index measurements had considerable variability and may not be the most reliable measurement of size. In July 1998, plant canopy densities among azaleas maintained in the high injury treatments were approximately 15% less full than the canopies of control shrubs. Predaceous insects had a significant negative association with azalea lace bug number during the 2-yr study. Flower and new tissue production, measured destructively during two growing seasons, revealed azalea tolerance to 14% of maximum canopy area lace bug feeding-injury levels.     

Evaluating grower, landscape manager, and consumer perceptions of azalea lace bug (Heteroptera: Tingidae) feeding injury

A survey using modified azalea stems was used to establish a "tally threshold value" for assessing azalea lace bug, Stephanitis pyrioides (Scott), feeding injury to azalea shrubs. Consumers and green-industry professionals, represented by ornamental growers, landscape architects, and landscape managers, recognized azalea lace bug injury when injured leaf area exceeded 2%. Purchase and treatment decisions of professionals and consumers were evaluated by surveying responses to Rhododendron indica variety alba 'Delaware Valley White' azaleas representing a range of damage. Survey participants also provided a brief biographical background and answers to questions regarding pesticide use, ability to identify diseases, pests, and beneficial organisms, and willingness to consider pesticide alternatives. Professionals and consumers expressed a strong interest in limiting urban pesticide use. The 2 groups indicated a hypothetically acceptable level of 6-10% plant damage by arthropod pests. A 2% injury threshold was used to determine the level of proportional damage (the percentage of leaves displaying 2% or more lace bug leaf feeding injury) resulting in either the rejection of plant purchase or initiation of treatment. A nonlinear curve was fit to treatment and no-purchase responses of professionals and consumers using a modified 3-parameter Mitscherlich nonlinear growth function. Half of the surveyed professionals and consumers indicated that damage proportions >10% (1.03% actual injury) were sufficient to reject an azalea for purchase. Proportional damage levels >43% (3.3% actual injury) would be necessary to prompt 50% of the respondents to initiate treatment of damaged azaleas to control lace bugs.     

Seasonal host alternation by the andromeda lace bug,Stephanitis takeyai (Heteroptera: Tingidae) between its two main host-plant species

I studied the seasonal occurrence of the andromeda lace bug,Stephanitis takeyai, on its two main host-plant species. In a secondary forest in Kyoto, this bug altered its hosts seasonally, i.e., from an evergreen shrub,Pieris japonica, in winter to a deciduous shrub,Lyonia elliptica, in summer. In contrast, in Nara park where fewL. elliptica were available, the bug exploited onlyP. japonica. Thus, seasonal host alternation by this bug is not obligate. A comparison of adult longevity and fecundity on the two host-plant species demonstrated the higher quality ofL. elliptica as a food resource. Corresponding to this difference in host quality, there was a dramatic difference in the seasonal population growth in the two study sites. In Nara, the population size at the beginning of the 2nd generation was almost the same as in the overwintered generation, whereas in Kyoto the population size in the 2nd generation was approximately one hundred times as large as in the overwintered generation. Thus seasonal host alternation is adaptive for the bug. In a previous study, I reported that overwintering as eggs in living leaves of their hosts is likely to be common among all the related species of this bug. Thus, this trait can be considered to be a phylogenetic constraint to the group. I speculate that host alternation by this bug has been derived because it is more adaptive from autoecy on an evergreen plant, similar to the pattern currently found in Nara, and that this bug can not only exploit deciduous host due to a phylogenetic constraint.     

外来入侵菊方翅网蝽生物学特性及实验种群生命表

为了解近年来入侵我国的菊方翅网蝽的生物学特性,并为该昆虫种群在我国未来发展的趋势及防治提供科学依据,我们在温度(25±2) ℃、湿度(80±5)%、光周期L∶D=14∶10的实验室条件下,饲养、观察并记录了其各龄幼虫的形态特征,测定了该虫生长发育历期、存活率和产卵量等,构建了实验种群繁殖特征生命表,并计算了种群动态的相关参数.结果表明: 菊方翅网蝽的卵期为(14.58±1.17) d,若虫期为(14.88±1.45) d,成虫寿命为(59.88±5.85) d,单雌产卵量为(87.2±17.8)粒.该实验种群的内禀增长率(r_m)为0.05,周限增长率(λ)为1.06,世代平均历期(T)为46.11 d,净繁殖率(R₀)为11.88,种群加倍时间(t)为12.91 d;此外,在种群的稳定年龄组配中,若虫期占59.3%,成虫期占40.7%.预计菊方翅网蝽有可能会在中国进一步扩散并造成潜在的危害.     

Flight-related metabolism and its regulatory peptides in the spittle bug Locris arithmetica (Cicadomorpha: Cercopidae) and the stink bugs Nezara viridula (Heteroptera: Pentatomidae) and Encosternum delegorguei (Heteroptera: Tessaratomidae)

Three species of bugs (Order: Hemiptera) belonging to different suborders and different families were investigated with respect to flight-related metabolism, and the neuropeptide hormones that regulate metabolism in Encosternum delegorguei, Locris arithmetica and Nezara viridula were characterised. The concentration of two potential metabolic fuels in the haemolymph of these bugs (at rest) revealed that lipids were more abundant than carbohydrates and that lipids increased significantly when the bugs performed extensive exercise (flight) and in the resting period following the aerobic activity. Carbohydrate levels declined during flight but recovered to the pre-flight level during a 1 h resting period post-flight. Further experiments with N. viridula revealed greater lipid accumulation in the haemolymph after a 10 min flight than after a 2 min flight and significant activation of glycogen phosphorylase was recorded in the fat body immediately after flight activity. Crude extracts of corpora cardiaca (CC) from L. arithmetica and E. delegorguei were both active in mobilising carbohydrates in the cockroach Periplaneta americana. In conspecific assays, only L. arithmetica CC extract had a significant hypertrehalosaemic effect, while CC extracts from both E. delegorguei and L. arithmetica were hyperlipaemic. By a combination of liquid chromatography and mass spectrometry two octapeptides known as Peram-CAH-I and Pyrap-AKH were identified from the spittle bug, L. arithmetica, and two octapeptides known as Panbo-RPCH and Schgr-AKH-II were identified from the edible inflated stink bug, E. delegorguei. Injection of Panbo-RPCH into E. delegorguei and into the green stink bug, N. viridula had no effect on circulating carbohydrates, although glycogen phosphorylase was activated in the fat body. The circulating lipid concentration in N. viridula did not change significantly under artificially induced hypertrehalosaemia, suggesting that lipids were not being used or mobilised.     

Using aesthetic assessments of azalea lace bug (Heteroptera: Tingidae) feeding injury to provide thresholds for pest management decisions.

Research on consumer, grower, and landscape manager perception of azalea lace bug, Stephanitis pyrioides (Scott), feeding and on plant productivity parameters, including gas exchange and growth, has increased our understanding of the nature of feeding injury. These studies made it possible to develop decision-making guidelines for cost-effective maintenance of aesthetically pleasing azaleas. Criteria were considered for three management situations: a 0.41-ha (1-acre) nursery production system that may use either insecticidal soap, acephate, or imidacloprid to control lace bugs; a landscape planting of a group of 10 azaleas; or maintenance of a single azalea in the landscape. Lace bug thresholds were calculated using a hybrid economic injury level (EIL) formula. Pesticide application decisions were determined using survey-based data from grower, landscape manager, and consumer perceptions of unacceptably injured azaleas at point-of-purchase for the nursery situation. Additional landscape scenarios incorporated the perceptions of growers, landscape managers, and consumers for those levels of lace bug feeding-injury that prompted the desire for treatment. Hybrid EIL determinations are appropriate for lace bug management in landscape systems where landscape professionals manage large plantings of azaleas and as a component of pest management among nursery production systems. Aesthetic considerations are more appropriate in determining control thresholds among a few or individual azaleas in the landscape.     

The first lace bug from Chiapas amber (Totolapa,Mexico) (Hemiptera: Tingidae)

Leptopharsa tacanae sp. nov., the first Tingidae from Mexican amber, is described and its morphological affinities are discussed.     

The complete mitochondrial genome of the sycamore lace bug Corythucha ciliata (Hemiptera: Tingidae)

The complete mitochondrial genome of the sycamore lace bug, Corythucha ciliata, was sequenced in this study. It represents the first sequenced mitogenome of family Tingidae in Heteroptera. The mitogenome of C. ciliata is 15,257 bp and contains 37 genes including 13 protein-coding genes (PCGs), 22 tRNA genes, two rRNA genes and a large non-coding region. Gene arrangement, nucleotide content, codon usage, and amino acid composition and asymmetry indicate a high degree of conservation with six other species of Cimicomorpha. The 13 PCGs initiated with ATN as the start codon and terminated with TAA, TA or T as stop codon. The evolutionary rate of each PCG was different, among which ATP8 showed the highest rate while ATP6 indicated the lowest rate. The 22 tRNAs genes apparently fold into a typical cloverleaf structure; however, the anticodon (TTC) of trnSer (AGN) differs from other Heteropteran insects. Secondary structure modeling of rRNA genes revealed similarity to other insects, except for two incomplete helices (H1648 and H2735) in lrRNA. The predicted secondary structure of lrRNA indicates 45 helices in six domains, whereas srRNA has 27 helices in three domains. Three potential stem–loops and two tandem repeats (–TCTAAT–) were identified in the A+T-rich region. Phylogenetic analysis indicated that C. ciliata is a sister group to other Heteroptera species based on analysis of the 13 PCGs.     

Cytogenetics of the true bug infraorder Cimicomorpha (Hemiptera, Heteroptera): a review

The Cimicomorpha is one of the largest and highly diversified infraorders of the Heteroptera. This group is also highly diversified cytogenetically and demonstrates a number of unusual cytogenetic characters such as holokinetic chromosomes; m-chromosomes; multiple sex chromosome systems; post-reduction of sex chromosomes in meiosis; variation in the presence/absence of chiasmata in spermatogenesis; different types of achiasmate meiosis. We present here a review of essential cytogenetic characters of the Cimicomorpha and outline the chief objectives and goals of future investigations in the field.     

Cold tolerance of the invasive oak lace bug,Corythucha arcuata

1. The North American oak lace bug (OLB), Corythucha arcuata, is an invasive species in Europe and a serious threat to oak-dominated forests.
2. Survival at low temperatures is one major factor determining the spread of invasive insects. Thus, we studied key traits, that is, cold-tolerance strategy, supercooling points (SCP) and chilling-related mortality, of overwintering adults to assess their potential to withstand harsh winters.
3. Samples for SCP measurements were collected once a month from November 2020 until March 2021 at three different locations in Hungary; specimens for chilling experiments were sampled in November 2020, January 2021 and March 2021.
4. SCPs of overwintering adults ranged from −29.68 to −7.49 °C, with only moderate variation among months; C. arcuata is a freeze-avoidant species.
5. Mortality rates of adults exposed to two sub-zero temperatures above the SCP (−3 and −5 °C) for 1, 2 and 3 weeks ranged between 0% and 69.1%, suggesting that OLB has a moderate risk to die from chilling injuries. Exposure time and sampling date affected mortality, with lowest survival rates after 3 weeks, collected in March 2021.

     

Morphology of the Phytophagous bug Platyscytus decempunctatus (Carvalho) (Heteroptera: Miridae)

Platyscytus decempunctatus Carvalho is a small mirid living throughout its life cicle plant Solanum cernuum Vell. (Solanaceae). The internal morphology of P. decempunctatus was studied and found that the female has a telotrophic ovary with three ovarioles in the right ovary and five in the left one. In the male reproductive trait there is a well developed tubular accessory gland. The phytophagous feeding habitat of P. decempunctatus was confirmed by the observations of chlorophyll pigments in the gut of all dissected specimens. The tubular salivary glands and the Malpighian tubules were also discussed.     

Precocene II modifies maternal responsiveness in the burrower bug, Sehirus cinctus (Heteroptera)

Abstract. The anti-Juvenile Hormone agent precocene II was used to investigate the relationship of corpora allata activity to subsocial behaviour in a burrower bug Sehirus cinctus Palisot (Heteroptera: Cydnidae). Egg-brooding females treated with a range of dosages of precocene II exhibited reliably depressed maternal defensive behaviour when treated with at least 70 μg of precocene II, but attraction to eggs was only depressed at higher dosages. This effect was not due to precocene II toxicity, as demonstrated by the prevention of depression effects through simultaneous treatments of precocene II and the Juvenile Hormone analogue methoprene. Methoprene, however, failed to reinstate maternal responsiveness in maternally depressed females that had been previously treated with precocene II. This study provides the first clear evidence that insect parental behaviour can be modified by treatment with anti-Juvenile Hormone agents, and suggests that the role of the corpora allata in governing care in S. cinctus is different from that of other maternal insects, such as earwigs.     

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.     

Morphology of hindwing veins in the shield bug Graphosoma italicum (Heteroptera: Pentatomidae)

Light, fluorescence, and electron microscopy were applied to cross sections and -breakage and whole-mount preparations of the anterior hindwing vein of the shield bug Graphosoma italicum. These analyses were complemented by investigations of the basal part of the forewing Corium and Clavus. The integration of structural, histological, and fluorescence data revealed a complex arrangement of both rigid and elastic structures in the wall of wing veins and provided insights into the constitution of transition zones between rigid and elastic regions. Beneath the exocuticular layers, which are continuous with the dorsal and ventral cuticle of the wing membrane, the lumen of the veins is encompassed by a mesocuticular layer, an internal circular exocuticular layer, and an internal longitudinal endocuticular layer. Separate parallel lumina within the anterior longitudinal vein of the hindwing, arranged side-by-side rostro-caudally, suggest that several veins have fused in the phylogenetic context of vein reduction in the pentatomid hindwing. Gradual structural transition zones and resilin enrichment between sclerotized layers of the vein wall and along the edges of the claval furrow are interpreted as mechanical adaptations to enhance the reliability and durability of the mechanically stressed wing veins.     

A novel adipokinetic peptide in a water boatman (Heteroptera, Corixidae) and its bioanalogue in a saucer bug (Heteroptera, Naucoridae)

The corpora cardiaca (CC) of two water bug species, the water boatman Corixa punctata and the saucer bug Ilyocoris cimicoides, contain a substance that cause hyperlipemia in the migratory locust. The primary sequence of one octapeptide belonging to the adipokinetic hormone (AKH)/red pigment-concentrating hormone (RPCH) family was deduced from the multiple MS(N) electrospray mass data of CC material from each species. Whereas the saucer bug contains the known octapeptide pGlu-Val-Asn-Phe-Ser-Pro-Ser-Trp amide, code-named Anaim-AKH, the water boatman has a novel peptide identified as pGlu-Leu/Ile-Asn-Phe-Ser-Pro-Ser-Trp amide, code-named Corpu-AKH. The ambiguity about the amino acid at position 2, i.e. Leu or Ile, in Corpu-AKH was solved by isolating the peptide in a single-step by reversed-phase HPLC and establishing co-elution with the synthetic peptide containing Leu at position 2. Functionally, the peptides regulate lipid mobilization, as evidenced by an adipokinetic effect after injecting synthetic Anaim-AKH and Corpu-AKH into the respective acceptor species. Swimming activity of I. cimicoides also causes hyperlipemia.     

Pars intercerebralis promotes oviposition in the bean bug,Riptortus pedestris (Heteroptera: Alydidae)

Effects of the pars intercerebralis (PI) on the rate of oviposition were examined in adult females of Riptortus pedestris (F.) under long-day conditions that promote reproduction. When the neurosecretory cells in the PI were surgically removed from the females, they laid significantly fewer eggs than control females. When the PI from reproductive females was transplanted to PI-removed females, the number of eggs was significantly greater than that in PI-removed females without transplantation. Therefore, we suggest that the PI neurons promote fecundity or oviposition in R. pedestris.     

Enhancing incidence of Puccinia punctiformis, through mowing, to improve management of Canada thistle (Cirsium arvense)

Biological control of Canada thistle using Puccinia punctiformis has been largely unsuccessful in part due to a low incidence of systemically infected shoots and heterogeneous distribution of teliospores in the soil. The present study investigated the feasibility of strategic mowing to improve incidence of systemically infected shoots, and enhance intra- and/or inter-season disease development in two unused pastures. Mid-season mowing of plots in July lead to a greater proportion of systemically infected shoots in experimental plots observed at seasons’ end compared to unmowed plots. Late-season mowing in September resulted in the highest levels of systemically infected shoots early the next summer. Over time, September mowing treatments significantly increased the proportion of systemically infected shoots compared to no mowing. The number of healthy shoots declined over time in mowed plots, whereas the number of healthy shoots in unmowed plots either increased or remained constant. These effects were observed in experimental plots in both pastures. It is proposed that mowing followed by regrowth of systemically infected shoots may help overcome the monocyclic nature of the pathogen and enhance severity of this disease.