Brachypterous Morphs Research Articles

Taxonomical clarification of Tetrix gibberosa (Wang amp; Zheng), a high-backed pygmy grasshopper species from eastern PR China (Orthoptera: Tetrigidae).

Tetrix gibberosa (Wang Zheng) is a high-backed pygmy grasshopper species from eastern PR China. Due to its reduced hind wings and pleomorphism (length changes of hind wings and the hind pronotal process, which is generally called macropterous and brachypterous morphs), the species have been described into different species which involve several taxonomically confused genera. This study clarifies its taxonomy and distribution and provides ecological information for the species. At the same time, we comment the relationships of related genera in the subfamily Tetriginae, including Tetrix Latreille, Exothotettix Zheng Jiang, Alulatettix Liang, Aalatettix Zheng Mao, Formosatettix Tinkham, and Formosatettixoides Zheng. Additionally, we report for the first time that nematodes can parasitize pygmy grasshoppers. New synonyms are proposed: Tetrix gibberosa (Wang Zheng, 1993) = Alulatettix bulbosus Zheng Zhong, 2001, syn. nov., = Exothotettix jiangxiensis Liang Jia, 2008, syn. nov., = Tetrix glochinota Zhao, Niu Zheng, 2010, syn. nov., = Alulatettix nigromarginalis Zhang, Deng Zha, 2014, syn. nov., = Alulatettix flavotibialis Zhang, Deng Zha, 2014, syn. nov..

Piesma Costatum (Uhler) (Hemiptera: Piesmatidae): First Host-Plant Records, Seasonality, and Discovery of the Macropterous Morph

Piesma costatum (Uhler) is a rarely collected piesmatid whose adults have been known only from the brachypterous morph; its host plants also have remained unknown. During fieldwork in the Nebraska Sandhills (2016–2018), nymphs and adults were found near Valentine in Cherry County on desert goosefoot (Chenopodium pratericola Rydb.; Chenopodiaceae). Males outnumbered females (26♂: 17♀) in late June 2017, with nearly equal numbers (23♂: 24♀) observed in mid-September. The presence of fifth instars in June and September indicate that the piesmatid is bivoltine. The first macropters (1 male, 1 female) were discovered, but they represented less than 2% of adults (n 5 115). Brachypterous adults are flightless, with their hind wings rudimentary and auricular. The bug's low vagility and patchy distribution of its host plant help explain the rareness of P. costatum in collections. Nebraska's vast Sandhills are considered a stable habitat that might favor the evolution of flightlessness, which might minimize the loss of dispersing adults and be energetically advantageous in the nearly constant winds of the Sandhills.

Ecobiology of Anaphothrips obscurus, a new dweller of citrus orchards brought in by more sustainable pest management practices

Abstract The abundance and frequency of Anaphothrips obscurus (Thysanoptera: Thripidae) increased in a cover of Festuca arundinacea (Poaceae) when this plant was used to improve the biological control of the clementine key pest Tetranychus urticae (Acari: Tetranychidae). To unveil the ecological role of A. obscurus in this system, we re‐explored field data and performed laboratory studies aiming to determine its demographic parameters and feeding habits, as well as its role as a prey of predatory mites (Acari: Phytoseiidae) occurring in the Spanish citrus agreoecosystem. Field studies indicate that T. urticae populations decreased, whereas those of A. obscurus and phytoseiids, as a whole, increased. Reproductive and demographic parameters of macropterous and brachypterous morphs of A. obscurus were different and confirmed the host status of F. arundinacea. Anaphothrips obscurus could compete with T. urticae as a result of its higher intrinsic rate of increase in F. arundinacea. However, A. obscurus zoophagy on T. urticae eggs and the host status of citrus can be discarded. Anaphothrips obscurus can be a prey for Euseius stipulatus, Neoseiulus barkeri and Neoseiulus californicus (three phytoseiids preying on T. urticae), suggesting that apparent competition between A. obscurus and T. urticae could occur in citrus orchards.

Analysis of Differential Proteins in Two Wing-Type Females of Sogatella furcifera (Hemiptera: Delphacidae).

Sogatella furcifera (Horvath) is an important rice pest with the wing dimorphism, including macropterous and brachypterous morphs. The protein expression profiles in two wing-type adults and two wing-type disc fifth-instar nymphs were analyzed using two-dimensional gel protein electrophoresis and mass spectrometry. In adults and fifth-instar nymphs, 127 and 162 protein spots were detected, respectively. Fifty-five differentially expressed protein spots were identified between the long-winged adults and the short-winged adults, and 62 differentially expressed protein spots were found between the long-winged disc fifth-instar nymphs and short-winged disc fifth-instar nymphs. In long-winged and short-winged adults, six and seven specific protein spots were identified, respectively, with five and seven protein spots having more than threefold increased level, respectively. In long-winged and short-winged disc morph nymphs, 8 and 12 specific protein spots were identified, respectively, with 11 and 17 spots containing more than threefold increased level, respectively. Among the 16 identified proteins, five proteins are associated with muscle function, suggesting that muscle is a main tissue where the genes were differentially expressed between the two wing types. In addition, the content of a peptidase with an insulinase domain was higher (by 3.02 ± 0.59 fold) in the short-winged fifth-instar nymphs than in the long-winged fifth-instar nymphs, which suggests that this peptidase may be involved in wing differentiation by regulating insulin receptors. The results of this study provide some genetic clues for the wing differential development in S. furcifera and provide more references for future studies.

Comparison of developmental and reproductive biology in wing diphenic Anaphothrips obscurus (Thysanoptera: Thripidae)

Anaphothrips obscurus (Müller) is a cosmopolitan pest feeding on cereal crops and grasses. This species exhibits wing polyphenism. Differences in the life history traits of female macropterous and brachypterous A. obscurus were compared in the laboratory for this study. Experiments were performed in climate chambers set at 20 and 25±1°C, 60±10% RH under a 16L:8D photoperiod. The duration of total pre-adult stage, adult pre-oviposition period and total pre-oviposition period of macropterous morphs were significantly longer than in the brachypterous morphs both at 20 and 25°C. No significant differences were found in adult longevity, survival rate or total fecundity between the two wing morphs, while early fecundity was significantly higher for brachypterous females compared with that for macropterous females at two temperatures.

Wing patterning genes of Nilaparvata lugens identification by transcriptome analysis, and their differential expression profile in wing pads between brachypterous and macropterous morphs

The brown planthopper, Nilaparvata lugens is an economically important pest on rice plants. This species produces macropterous and brachypterous morphs in response to environmental cues, which makes it very difficult to control. The molecular basis of wing patterning in N. lugens is still unknown. It is necessary to identify wing patterning genes of N. lugens, and also to clarify the expression differences of wing patterning genes between macropterous and brachypterous morphs. High-throughput deep sequencing of transcriptome of N. lugens wing pad yielded 116 744 580 raw reads and 113 042 700 clean reads. All the reads were assembled into 55 963 unigenes with an average length of 804 bp. With the E-value cut-off of 1.0E−5,18 359 and 2 883 unigens had hits in NCBI-NR (NCBI non-redundant protein sequences) and NCBI-NT (NCBI nucleotide sequences) databases, respectively. A total of 16 502 unigenes were assigned to GO (gene ontology) classification, 9 709 ungenes were grouped into 26 COG (cluster of orthologous groups of proteins) classifications, and 6 724 unigenes were assigned to different KEGG (Kyoto encyclopedia of genes and genomes) pathways. In total, 56 unigenes which are homologous to wing patterning genes of Drosophila melanogaster or Tribolium castaneum were identified. Out of the 56 unigenes, 24 unigenes were selected, and their expression levels across the five nymphal stages between macropterous strain and brachypterous strain were examined by qRT-PCR. Two-way ANOVA analysis showed that development stage had significant effects on the expression level of all the 24 genes (P<0.05). The expression levels of 8 genes (Nlen, Nlhh, Nlsal, NlAbd-A, Nlwg, Nlvg, Nlexd and NlUbx) were significantly affected by wing morph. This is the first transcriptome analysis of wing pads of hemimetabolous insect, N. lugens. The identified wing patterning genes would be useful resource for future exploration of molecular basis of wing development. The 8 differentially expressed wing patterning genes between macropterous strain and brachypterous strain would contribute to explain molecular mechanism of wing-morph differentiation in N. lugens.

Wing polymorphism in Netomocera ramakrishnai Sureshan, 2010 (Hymenoptera: Pteromalidae) in East Asia, with the first description of a brachypterous morph

Netomocera ramakrishnai Sureshan, 2010 is newly recorded from China (Taiwan), Japan (Honshu) and the Russian Far East (Sakhalin I. and Kamchatka Terr.). Females of the species also showed the first example of wing polymorphism in the genus Netomocera Boucek, 1954 and the second in the subfamily Diparinae Thomson, 1876. Female wings of N. ramakrishnai range from being fully macropterous in eastern India to macropterous or slightly brachypterous in Taiwan and fully brachypterous in Japan and eastern Russia. The previously unknown brachypterous morph of N. ramakrishnai is described and illustrated, and the distribution of the species is discussed.

Analysis of the lipids mobilized by adipokinetic hormones in the firebug Pyrrhocoris apterus (Heteroptera: Pyrrhocoridae)

Effects of two adipokinetic hormones (Pyrap-AKH and Peram-CAH-II) on the presence of diacylglycerol (DG) molecular species and their fatty acid (FA) constituents in the haemolymph of the firebug Pyrrhocoris apterus were investigated using liquid chromatography (HPLC) and electrospray ionization mass spectrometry (ESI-MS). The results show that DGs with characteristic FAs are preferentially mobilized from the fat body (FB) by the action of both the AKHs produced by P. apterus. Both the macro- pterous and brachypterous morphs have similar DG and FA profiles. A difference in the action of the Pyrap-AKH and the Peram- CAH-II, however, results in distinct differences in the distribution of FAs in the macropterous morph. It seems that C16 to a slight extent and unsaturated C18 FAs mainly play a dominant role in the AKH based action, in particular linoleic acid (18:2), which repre- sents 50-60% of the total DG mobilized. The metabolically active C16 and C18 FAs are preferentially absorbed from the linden seeds and accumulated in the FB. The relationships between AKH action and FA distribution in DGs in P. apterus, compared to other insect species are summarized and discussed in detail.

Characterization of putative soluble and membrane-bound trehalases in a hemipteran insect, Nilaparvata lugens

Trehalose is the main blood sugar of insects, and the enzyme trehalase is involved in energy metabolism and controlling trehalose levels in cells. Two forms (soluble and membrane-bound) of trehalase and the corresponding genes (NlTre-1 and NlTre-2) were identified from the brown planthopper, Nilaparvata lugens. Both NlTre-1 and NlTre-2 contain trehalase signature motifs, and NlTre-2 contains a putative transmembrane domain. Comparison of trehalase activity and gene mRNA level at different developmental stages, or following application of 20-hydroxyecdysone (20E), suggests that NlTre-1 and NlTre-2 encode a soluble trehalase and a membrane-bound trehalase respectively. Soluble trehalase activity accounted for the majority of total trehalase activity in N. lugens. Only soluble trehalase activity and NlTre-1 mRNA level could be induced by 20E. Additionally, only soluble trehalase activity was significantly higher in macropterous individuals than in brachypterous morphs. These results indicate that only soluble trehalase is differentially expressed between macropterous and brachypterous individuals and is more responsive to hormone stimulus.

Aphelocheirus (s.str.) bruneiensis sp.n., a new benthic water bug (Hemiptera: Heteroptera: Aphelocheiridae) from Brunei, and a key to Bornean Aphelocheirus

Aphelocheirus (s.str.) bruneiensis sp.n. from Brunei is described and illustrated; its type locality is described in detail. Aphelocheirus (s.str.) kinabalu Polhemus &amp; Polhemus, 1989 is recorded from Sarawak for the first time. An identification key to the brachypterous morphs of the six species known from Borneo is presented. Digital photographs of the new species and three other rare species are provided.

Energy Allocation in Brachypterous versus Macropterous Morphs of the Pygmy Grasshopper Tetrix subulata (Orthoptera: Tetrigidae)

In wing dimorphic insects, there exists a trade-off between dispersal and reproduction. The brachypterous or short-winged morph reproduces faster while the macropterous or long-winged morph is better able to colonize new habitats. In the present study, energy reserves (carbohydrates, proteins and lipids) and energy consumption (derived from the electron transport activity) were quantified in brachypterous and macropterous males and females of the pygmy grasshopper Tetrix subulata (Linnaeus 1758). It was found that the macropterous morph consumes significantly more energy and has a significantly higher protein content in comparison with the brachypterous morph. Both parameters are probably related to better developed wing muscles in the macropterous morphs. No differences were found in carbohydrate and lipid content. It was also observed that energy consumption and protein content were significantly higher in males compared to females. These findings are probably related to the higher activity of males, which spend most of the time searching for females.

Offspring production and development in the parasitoid wasp Melittobia clavicornis (Cameron) (Hymenoptera: Eulophidae) from Japan

AbstractThe development time, sex ratio and offspring production of Melittobia clavicornis reared with wild, facultative and factitious hosts are presented. Known hosts and different biological aspects presented in previously published reports are summarized and clarified. Immature development time was equivalent or slightly longer than that of other Melittobia species, and the sex ratio was approximately 97% female. Total offspring numbers were considerably lower than that of other Melittobia species using the same hosts. We report female dimorphism in this species for the first time. The number and relative proportion of brachypterous morph females produced was higher than that in other species of the genus.

Sexual activity in macropterous and brachypterous males of a flightless bug, Pyrrhocoris apterus (Heteroptera)

The long-winged (macropterous) and short-winged (brachypterous) adult males of Pyrrhocoris apterus (L.) from temperate (Czech Republic) and Mediterranean (Israel) populations were analysed for the sexual activity and the functional activity of their accessory glands. The sexual activity of the males reared either under long-day (18L : 6D) or short-day (12L : 12D) conditions was determined by their capability to mate with 5-day-old reproductive females of the brachypterous morph and to fertilize the eggs. The functional activity of accessory glands was characterized by the presence of a specific immuno-marker. Sexual activity of fasting macropterous males from both temperate and Mediterranean populations was almost as high as that observed in the reproductive brachypterous ones. These findings were also confirmed by an immunotest. Contrary to the temperate macropterous males, the feeding arrest in temperate macropterous females was coupled with a non-diapause inhibition of reproduction in spite of long days. A similar kind of difference was observed also in the Mediterranean macropterous bugs reared under short-day conditions. The results showed the sexual difference in reproductive activity of the macropterous morph in P. apterus.

Locomotor activity in adult Pyrrhocoris apterus (Heteroptera) in relation to sex, physiological status and wing dimorphism

Summary The pattern of locomotor (walking) activity was studied in adult males and females of short-winged (brachypterous) and long-winged (macropterous) morph of the flightless bug Pyrrhocoris apterus (Linnaeus) (Heteroptera: Pyrrhocoridae) under constant laboratory conditions. Walking activity was measured with a computerized video system and analysed with respect to sex, physiological status (reproduction, diapause and reproductive arrest of non-diapause type) and wing dimorphism of the bugs. The largest duration was observed in the macropterous females with reproductive arrest of non-diapause type (average 6 h per day) and the shortest duration in diapausing brachypterous females and males (average less than 2 h per day). This was reflected also in the overall time spent by walking during the first 14 days after imaginal ecdysis. The time spent by walking significantly increased in the macropterous morph as the bugs aged, whereas in diapausing brachypters the time spent by walking decreased with age. No linear relationship between walking activity and age was found in reproductive brachypterous morph. The bugs of all experimental groups moved mostly during the photophase and were almost inactive during the scotophase. Thus, walking activity in P. apterus is diurnal, irrespective of the wing morph, physiological status, sex and age. Contrary to the macropterous morph, where the locomotor activity of females during photophase was significantly higher than in males, no significant differences were found between the locomotor activities of brachypterous males and females. The observed differences in locomotor activity are discussed in relation to different roles of two wing morphs in the life history of this heteropteran.

Wing morph-related physiological differences in adults of temperate population of Pyrrhocoris apterus (L.) (Heteroptera: Pyrrhocoridae)

The reproductive and diapausing adult females of brachypterous morph and macropterous females with reproductive arrest of non-diapause type, originating from the laboratory cultures of Pyrrhocoris apterus, were studied for their feeding and drinking behaviour, digestive enzyme activities, and carbohydrate and lipid contents. The highest feeding and drinking activities were observed in reproductive brachypters, the lowest in macropters. Macropters also differed from brachypters by lower activities of gut lipase, peptidase and protease, lower concentration of haemolymph sugars, and lower weight of fat body, which probably reflects their low feeding activity. The total content of fat body lipids was also lower in macropters (0.6 mg) than in reproductive and diapausing brachypters (4.6 and 7.5 mg, respectively) on day 14. A very high amount of glycogen was found in the fat body of diapausing brachypters, 363 μg on day 14, as opposed to 15 and 80 μg in macropterous and reproductive brachypterous females, respectively. The obtained data indicate that the most important difference between macropterous and brachypterous females with different types of reproductive arrest consists of an enhanced mobilization of lipids for dispersal in macropters and accumulation of energetic reserves for hibernation in brachypters.

Macroptery in Altitudinal Specialists Versus Brachyptery in Generalists-A Paradox of Alpine Scandinavian Carabid Beetles (Coleoptera: Carabidae)

Non-riparian alpine carabid beetle assemblages in Scandinavia are usually dominated by a set of seventeen species. Five of these species are more or less restricted to the alpine and subalpine regions (altitudinal specialists), whereas the remaining twelve species are widespread also in lowland (altitudinal generalists). Flight-wing length differs between these two groups of species, i.e. all altitudinal specialists are macropterous, whereas seven of the generalists are brachypter- ous or dimorphic with the brachypterous morph strongly dominating. Generalists abundant in lowland forests are all brachypterous, whereas the macropterous species in lowland are confined to open, dry habitats. The dominance of macroptery among altitudinal specialists is paradoxical as the alpine environment generally is supposed to select for brachyptery, and the specialists should be better adapted to their habitat than the generalists are. Available subfossil evi- dence suggests that the specialist species reached the Scandinavian Mountain Range from a continental refugium south of the ice sheet. The macroptery of the specialists can be explained by the relative recentness of the last glaciation and the lower dispersal power of the brachypterous or apterous tundra species that have not been able to colonize Scandinavia from their glacial refugia. The time available for colonization of generalist species following deglaciation was probably much longer than for specialists, and consequently brachypter- ous species were successful. Wing dimorphism as a tool for reconstructing faunal history is discussed.

Differences in juvenile hormone esterase activity between presumptive macropterous and brachypterous Gryllus rubens: Implications for the hormonal control of wing polymorphism

The developmental profile of haemolymph juvenile hormone esterase activity was compared between presumptive macropterous and brachypterous morphs of the cricket, Gryllus rubens. Activities were measured during the penultimate and last stadia, two stadia where winglength development is sensitive to both exogenous juvenile hormone and crowding. Ester hydrolysis was the exclusive or nearly exclusive route of juvenile hormone degradation in the haemolymph. Individuals of a genetic stock nearly pure-breeding for long wings exhibited substantially higher enzyme activity during the last stadium compared with individuals of a stock pure-breeding for short wings. High juvenile hormone esterase activity strongly cosegregated with long wings in F 1 interstock crosses and in F 2 backcrosses. Crickets of the macropterous stock whose winglength development was redirected to short wings by crowding exhibited low juvenile hormone esterase activity during the last stadium, similar to individuals of the brachypterous stock. Rates of juvenile hormone hydrolysis (epoxide hydrase plus esterase activity) were also higher in wingbud homogenates from last-stadium macropterous versus brachypterous females. In contrast, haemolymph enzyme activity was similar in presumptive macropterous and brachypterous morphs during the penultimate stadium. Results suggest that variation in haemolymph juvenile hormone esterase activity during the last stadium may play an important role in wingmorph determination in Gryllus rubens.

THE EVOLUTION OF WING DIMORPHISM IN INSECTS.

Wing-dimorphic insects are excellent subjects for a study of the evolution of dispersal since the nondispersing brachypterous morph is easily recognized. The purpose of this paper is to develop a framework within which the evolution of wing dimorphism can be understood. A review of the literature indicates that the presence or absence of wings may be controlled by a single locus, two-allele genetic system or a polygenic system. Both types of inheritance can be subsumed within a general threshold model. An increase in the frequency of a brachypterous morph in a population may result from an increased relative fitness of this morph or the emigration of the macropterous type. The abundance of wing-polymorphic species argues for an increased fitness of the brachypterous form. An analysis of the life-history characteristics of 22 species of insects indicates that the brachypterous morph is both more fecund and reproduces earlier that the macropterous morph. Unfortunately, data on males are generally lacking. It is suggested that suppression of wing production results when some hormone, perhaps juvenile hormone, exceeds a threshold value during a critical stage of development. Further, it is known that in the monomorphically winged species Oncopeltus fasciatus both flight and oviposition are regulated by the titer of juvenile hormone. These observations are used to construct a possible pathway for the evolution of wing dimorphism. This suggests that evolution to a dimorphic species requires both an increase in the rate of production of the wing suppressing hormone and a change in the threshold level at which wing and wing-muscle production are suppressed. The stage in this evolutionary sequence that an organism will reach depends on the stability of the habitat.

The influence of environmental factors on wing polymorphism in females of Leptopterna dolobrata (Heteroptera, Miridae).

The females of Leptopterna dolobrata (Heteroptera, Miridae) occur either as flightless brachypters or as macropterous individuals, whereas all the males are longwinged and capable of flight. The expression of this alary dimorphism is influenced by both genetic and environmental factors. Population density and temperature conditions prevailing during larval development both affect the formation of macropterous females. The larval instars L4 and/or L5 are particularly sensitive to these environmental stimuli and are thus decisive for the determination of wing-morphs.Experimentally crowded larvae developed a greater proportion of macropterous females than individuals reared at lower densities, and lower temperatures seem to counteract the stimulating effect of crowding. Larvae from different local populations varied in the proportion of macropters which developed, which could be ascribed to differences in the genetic constitution, although the genetic basis of wing-morph determination in L. dolobrata is not yet understood.There is strong evidence that in crowded populations a high percentage of the emerging macropterous females will emigrate and perform dispersal flights to new habitats. The sexual maturation of macropterous females is retarded compared with the brachypterous morph, and the dispersal flights are likely to occur during the pre-reproductive period.The underlying physiological mechanism of wingmorph determination and the adaptive significance of its environmental control are discussed on the basis of information available from other polymorphic species.

Environmental Influence on Reproduction, Diapause, and Morph Determination of Anaphothrips obscurus (Thysanoptera: Thripidae) 1 , 2

Reproductive diapause was induced in adults of the grass thrips, Anaphothrips obscurus Müller, by exposing larvae to short days. Diapause was maintained by holding the adults in the short-day regimen for ca. 60 days at 21°C but thereafter adults terminated diapause and initiated reproduction. Short days and 15°C retarded but did not prevent termination of diapause. Diapausing adults collected from the grass fields in March and exposed to long days in the laboratory produced substantially more macropterous progeny than similar adults exposed to short days. The proportion of macropterous to brachypterous adults increased as a result of crowded conditions on their host plant (‘Exeter’ bentgrass) during development, but temperature or the quality of food did not appreciably affect the ratio of macropterous to brachypterous morphs. Temperatures that exceeded 25°C drastically increased the rate of reproduction and undoubtedly controls population density when other requisites are optimum. No males of A. obscurus developed in these experiments.