Firebug Pyrrhocoris Apterus Research Articles

LC‒MS/MS and transcriptome analyses reveal saliva components of the seed-feeding truebug Pyrrhocoris apterus

Saliva secretion is essential for successful feeding by piercing–sucking insects. Despite extensive studies of the saliva composition of phloem- and blood-feeding insects, less is known about the oral secretions of seed-feeding insects. The firebug Pyrrhocoris apterus is a polyphagous insect that feeds primarily on dry seeds of various plant species. Here, liquid chromatography‒mass spectrometry/mass spectrometry (LC‒MS/MS) was used to identify 165 P. apterus salivary proteins, including 110 gelling-specific proteins, 24 watery-specific proteins, and 31 proteins common to both groups. Transcriptomic analysis of saliva glands identified 567 potential salivary proteins, of which 87 overlapped with those detected by LC‒MS/MS. Comparative analysis showed that 98 out of 165 (59.4%) P. apterus saliva proteins were associated with extra-oral digestion and detoxification and had homologs in ten other species of arthropods examined. In addition, 67 proteins were specific to P. apterus, of which 22 proteins were defined with unknown functions. RNA interference-mediated gene silencing assays indicated that P. apterus-specific proteins were vital for P. apterus survival. Our findings shed light on the function of salivary proteins in feeding by seed-feeding insects and the evolution of feeding habits in piercing–sucking insects.

Parasites of firebugs in Austria with focus on the “micro”-diversity of the cosmopolitan trypanosomatid Leptomonas pyrrhocoris

In this work, we investigated parasites of the firebug Pyrrhocoris apterus in Austria and demonstrated that in addition to the extensively studied Leptomonas pyrrhocoris, it can also be infected by Blastocrithidia sp. and by a mermithid, which for the first time has been characterized using molecular methods. This diversity can be explained by the gregarious lifestyle, as well as the coprophagous and cannibalistic behavior of the insect hosts that makes them susceptible to various parasites. In addition, we showed no tight association of the L. pyrrhocoris haplotypes and geographical locations (at least, considering the relatively small scale of locations in Austria) implying that the natural populations of L. pyrrhocoris are mixed due to the mobility of their firebug hosts.

Physiological responses to honeybee venom poisoning in a model organism, the firebug Pyrrhocoris apterus

In this study, the biochemical and physiological features of the firebug Pyrrhocoris apterus were investigated to understand the impact of the honeybee Apis mellifera venom on them using physiological methods (mortality, total level of metabolism), biochemical methods (ELISA, mass spectrometry, polyacrylamide gel electrophoresis, spectrophotometry) and molecular methods (real-time PCR). Together, the obtained findings suggest that venom injection increased the level of adipokinetic hormone (AKH) in the CNS of P. apterus, indicating that this hormone plays a key role in activating defence responses. Furthermore, histamine levels in the gut increased significantly after envenomation and did not seem to be modulated by AKH. In contrast, histamine levels in the haemolymph increased after treatment with AKH and AKH + venom. In addition, we found that vitellogenin levels in haemolymph decreased in both males and females after venom application. Lipids, which are the main energy metabolites used by Pyrrhocoris, were significantly exhausted from the haemolymph after the administration of venom and the co-application with AKH reversed this effect. However, we did not find much influence on the effect of digestive enzymes after the injection of venom. Our research has highlighted the noticeable effect of bee venom on P. apterus' body and provided new insights into the role of AKH in controlling defensive responses. However, it is also likely that there will be alternative defence mechanisms.

The X chromosome still has a lot to reveal - revisiting Hermann Henking's work on firebugs.

In 1891, the existence of an X chromosome was noted for the first time. Hermann Henking was studying spermatocyte divisions of the firebug Pyrrhocoris apterus and observed that one chromosome behaved differently than all of the rest of the chromosomes. Henking called this chromosome 'Element x'. Henking's discovery of the X element (later called X chromosome) initiated more than a century of fascinating genetics and cell biology, forming the foundation of several avenues of research in biology. His work led to exploration of a number of questions in a wide range of model systems and very soon to the abandonment of the firebug as a model for studies on the behavior of chromosomes in meiosis. Here, we argue that studies on both bivalent and univalent chromosome behavior in general, and work on how to solve chromosome lagging to prevent aneuploidy in particular, should lead us back to using the firebug as a model for error correction during cell division.

North vs. South: Contrasting patterns in the phenotypic plasticity of the firebug Pyrrhocoris apterus (Hemiptera: Pyrrhocoridae) at the latitudinal extremes of its distribution range

In widely distributed insects, some life-history traits are conserved across the whole distribution range and are considered species-specific while other such traits differ geographically. This interplay of geographic variation and phenotypic conservatism is poorly understood even in relatively well-studied model species. Furthermore, a careful study may reveal that conventionally stable traits, such as the lower temperature threshold for development and the sum of degree-days, are both geographically variable and environmentally plastic. We studied how photoperiodic conditions and temperature jointly affect immature development, adult body size and wing polymorphism in two populations of the firebug from the opposite latitudinal margins of this species' range. All the three traits rarely clearly differ under short-day and long-day conditions or between north and south. Instead, we find prevalent temperature-by-photoperiod and temperature-by-origin interactions, which emphasize that it is not only the absolute values of these traits but the degree of their temperature-dependence, or thermal plasticity, that varies in time (in response to seasonal changes in day length) and in space (along latitudinal gradients). These results indicate that caution should be exercised when extrapolating any life-history traits in P. apterus beyond the season when and the location where these were measured. In particular, the use of a constant lower temperature threshold coupled with a constant sum of degree-days is likely to oversimplify the diversity of current and projected phenological patterns in this species.

Cryptochrome-dependent magnetoreception in a heteropteran insect continues even after 24 h in darkness.

Sensitivity to magnetic fields is dependent on the intensity and color of light in several animal species. The light-dependent magnetoreception working model points to cryptochrome (Cry) as a protein cooperating with its co-factor flavin, which possibly becomes magnetically susceptible upon excitation by light. The type of Cry involved and what pair of magnetosensitive radicals are responsible is still elusive. Therefore, we developed a conditioning assay for the firebug Pyrrhocoris apterus, an insect species that possesses only the mammalian cryptochrome (Cry II). Here, using the engineered Cry II null mutant, we show that: (i) vertebrate-like Cry II is an essential component of the magnetoreception response, and (ii) magnetic conditioning continues even after 25 h in darkness. The light-dependent and dark-persisting magnetoreception based on Cry II may inspire new perspectives in magnetoreception and cryptochrome research.

Morphology and histology of the alimentary canal, salivary glands and Malpighian tubules in Pyrrhocoris apterus (Linnaeus, 1758) (Hemiptera: Pyrrhocoridae): a scanning electron and light microscopies study

In this study, morphological and histological studies of the alimentary canal and associated salivary gland and Malpighian tubules were conducted for the firebug Pyrrhocoris apterus (Hemiptera: Pyrrhocoridae), which is their diets are mainly linden trees and mallows. Understanding its digestive process will help elucidate the ecological and economical significance of this species. Therefore, the insects were dissected to examine all the sections under stereomicroscope, light and scanning electron microscopies. Morphological and histological results show that the salivary glands of P. apterus find in the thorax of the insect with a pair of principal glands, a pair of accessory glands, a pair of principal canals and a pair of accessory canals. The alimentary canal is divided into three regions: foregut, midgut, and hindgut. The foregut consists of oral cavity, pharynx, esophagus, and proventriculus. The esophagus consists of a long tube and is surrounded by a layer of longitudinal muscle. The proventriculus is formed by a single layer of columnar cells with oval nuclei surrounded by a layer of muscles. The midgut is divided into four regions: the first, second, third, and fourth ventriculi. The midgut is composed of monolayer epithelial cells surrounded by muscles. P. apterus midgut lacks gastric caeca. The hindgut has a pylorus followed by a well-developed rectum. The wall of the rectum is surrounded by a single layer cubic epithelium which has deep infoldings. There is a pair of Malpighian tubules linked at each side of mediolateral of pylorus. Malpighian tubules consist of two regions as proximal and distal. Malpighian tubules consist of a monolayer cuboidal epithelium with cubic nuclei in middle.

Adipokinetic Hormones Enhance the Efficacy of the Entomopathogenic Fungus Isaria fumosorosea in Model and Pest Insects.

Insect adipokinetic hormones (AKHs) are neuropeptides with a wide range of actions, including the control of insect energy metabolism. These hormones are also known to be involved in the insect defence system against toxins and pathogens. In this study, our aim was to demonstrate whether the application of external AKHs significantly enhances the efficacy of the entomopathogenic fungus Isaria fumosorosea in a model species (firebug Pyrrhocoris apterus) and pest species (Egyptian cotton leafworm Spodoptera littoralis and pea aphid Acyrthosiphon pisum). It was found that the co-application of Isaria with AKHs significantly enhanced insect mortality in comparison to the application of Isaria alone. The mode of action probably involves an increase in metabolism that is caused by AKHs (evidenced by the production of carbon dioxide), which accelerates the turnover of Isaria toxins produced into the infected insects. However, several species-specific differences probably exist. Intoxication by Isaria elicited the stimulation of Akh gene expression and synthesis of AKHs. Therefore, all interactions between Isaria and AKH actions as well as their impact on insect physiology from a theoretical and practical point of view need to be discussed further.

Discovery and characterization of a novel alphavirus-like RNA virus from the red firebug Pyrrhocoris apterus L. (Heteroptera)

Recent studies have shown that insects harbor numerous viruses of various taxa and that viral infections are often latent without noticeable symptoms. The red firebug Pyrrhocoris apterus, a true flightless bug from the family Pyrrhocoridae, is widely used for physiological studies on insect metabolism, endocrinology, and digestion. While exploring the transcriptome of P. apterus salivary glands, a nearly complete genomic sequence of a novel RNA virus was reconstructed. The virus, provisionally named Pyrrhocoris apterus virus 1 (PaV1), possesses eight potential open reading frames (ORFs) encoding for an array of proteins, some of which are involved in virus replication while others ensure success of the virus in multiple ways, including evasion of the host immune response. In addition to the information obtained from sequence analyses, we documented virus transmission, virus-induced mortality, host response upon persistent PaV1 infection, virion morphology, and putative virus-induced structures in salivary gland cells in a laboratory culture of red firebug. We propose that PaV1 belongs to a novel viral species of a new, yet-to-be established family.

Changes in vitellogenin expression caused by nematodal and fungal infections in insects.

This study examined the expression and role of vitellogenin (Vg) in the body of the firebug Pyrrhocoris apterus (Heteroptera, Insecta) during infection elicited by two entomopathogenic organisms, the nematode Steinernema carpocapsae and the fungus Isaria fumosorosea Infection by S. carpocapsae significantly upregulated Vg mRNA expression in the male body. The corresponding increase in Vg protein expression was also confirmed by electrophoretic and immunoblotting analyses. Remarkably, in females, the opposite tendency was noted. Nematodal infection significantly reduced both Vg mRNA and Vg protein expression levels in fat body and hemolymph, respectively. We speculate that infection of reproductive females reduces Vg expression to a level that is still sufficient for defense, but is insufficient for reproduction. This circumstance reduces energy expenditure and helps the individual to cope with the infection. Importantly, purified Vg significantly inhibited growth of Xenorhabdus spp., an entomotoxic bacteria isolated from S. carpocapsae. However, the effect of Vg against I. fumosorosea was not so obvious. The fungus significantly stimulated Vg gene expression in males; however, a similar increase was not recapitulated at the protein level. Nevertheless, in females, both mRNA and protein Vg levels were significantly reduced after the fungal infection. The obtained data demonstrate that Vg is probably an important defense protein, possibly with a specific activity. This considerably expands the known spectrum of Vg functions, as its primary role was thought to be limited to regulating egg development in the female body.

Perception of olfactory aposematic signals by jumping spiders

AbstractStudies of aposematism are mostly focused on visual aspects of warning signalization and based on experiments with avian predators. This study presents results of experiments with an arthropod predator, a jumping spider Evarcha arcuata (Araneae: Salticidae) and olfactory (i.e., noncontact chemical) aposematic signals. Spiders were presented with chemically protected firebug Pyrrhocoris apterus (Heteroptera: Pyrrhocoridae). After acquiring the negative experience with the bugs, the spiders were offered a choice between the firebug olfactory signal and a scentless control. Spiders actively avoided the firebug signal, showing that they are able to recognize an unprofitable prey by means of olfactory chemoreception. The results show that olfactory signals alone may function as effective means of aposematic signalization to spiders.

Leptomonas pyrrhocoris: Genomic insight into Parasite's Physiology.

Background: Leptomonas pyrrhocoris is a parasite of the firebug Pyrrhocoris apterus. This flagellate has been recently proposed as a model species for studying different aspects of the biology of monoxenous trypanosomatids, including host – parasite interactions. During its life cycle L. pyrrhocoris never tightly attaches to the epithelium of the insect gut. In contrast, its dixenous relatives (Leishmania spp.) establish a stable infection via attachment to the intestinal walls of their insect hosts.Material and Methods: This process is mediated by chemical modifications of the cell surface lipophosphoglycans. In our study we tested whether the inability of L. pyrrhocoris to attach to the firebug’s midgut is associated with the absence of these glycoconjugates. We also analyzed evolution of the proteins involved in proper lipophosphoglycan assembly, cell attachment and establishment of a stable infection in L. pyrrhocoris, L. seymouri, and Leishmania spp. Our comparative analysis demonstrated differences in SCG/L/R repertoire between the two parasite subgenera, Leishmania and Viannia, which may be related to distinct life strategies in various Leishmania spp. The genome of L. pyrrhocoris encodes 6 SCG genes, all of which are quite divergent from their orthologs in the genus Leishmania. Using direct probing with an antibody recognizing the β-Gal side chains of lipophosphoglycans, we confirmed that these structures are not synthesized in L. pyrrhocoris.Conclusion: We conclude that either the SCG enzymes are not active in this species (similarly to SCG5/7 in L. major), or they possess a different biochemical activity.

The effect of social learning on avoidance of aposematic prey in juvenile great tits (Parus major).

Social learning plays an important role in acquiring new foraging skills and food preferences in many bird species but its potential role in learning to avoid aposematic prey has never been studied. We tested the effect of social learning on the acquisition of avoidance of aposematic insect prey (firebug Pyrrhocoris apterus; Heteroptera) in juvenile, hand-reared great tits (Parus major). Behaviour towards aposematic prey was compared between two groups of birds: (1) the observers that were, prior to encounter with firebugs, allowed to watch the experienced conspecific demonstrator repeatedly refuse to attack the prey, and (2) the control birds that lacked this opportunity. Observing an experienced demonstrator was not sufficient for learning complete avoidance, because birds from both groups attacked at least the first firebug they had encountered in avoidance training. However, the opportunity to observe the avoidance behaviour of another bird significantly increased the rate of subsequent individual learning of observers in comparison with control birds. Social learning also decreased mortality of firebugs killed by the birds during the avoidance learning. Socially enhanced learning to avoid aposematic prey might be a mechanism important especially for naive juvenile birds learning from their parents, but it could also enhance learning in adults from their more experienced flock mates. Because social learning of avoidance may also lead to decreased mortality of aposematic prey, its effect should be taken into account in scenarios considering evolution and maintenance of prey warning signals.

Beneficial effect of adipokinetic hormone on neuromuscular paralysis in insect body elicited by braconid wasp venom

The effect of Habrobracon hebetor venom and the role of the adipokinetic hormone (AKH) in poisoned adult females of the firebug Pyrrhocoris apterus were studied 24 and 48h after treatments. Venom application elicited total neuromuscular paralysis in firebugs, but the co-application of venom and Pyrap-AKH significantly reduced paralysis (up to 3.2 times) compared to the application of venom only. Although the mechanisms of their action are unknown, both agents might affect neuromuscular junctions. Venom application significantly increased the expression of both P. apterus Akh genes (Pyrap-Akh 5.4 times and Peram-Cah-II 3.6 times), as well as the level of AKHs in the central nervous system (2.5 times) and haemolymph (3.0 times). In the haemolymph, increased AKH levels might have led to the mobilization of stored lipids, which increased 1.9 times, while the level of free carbohydrates remained unchanged. Total metabolism, monitored by carbon dioxide production, significantly declined in paralysed P. apterus individuals (1.4 times and 1.9 times, 24 and 48h after the treatment, respectively), probably because of a malfunction of the muscular system. The results suggest an active role of AKH in the defence mechanism against the stress elicited by neuromuscular paralysis, and the possible involvement of this hormone in neuronal/neuromuscular signalling.

Adipokinetic hormone activities in insect body infected by entomopathogenic nematode

The role of adipokinetic hormone (AKH) in the firebug Pyrrhocoris apterus adults infected by the entomopathogenic nematode (EPN) Steinernema carpocapsae was examined in this study. It was found that co-application of EPN and AKH enhanced firebug mortality about 2.5 times within 24h (from 20 to 51% in EPN vs. EPN+AKH treatments), and resulted in metabolism intensification, as carbon dioxide production in firebugs increased about 2.1 and 1.6times compared to control- and EPN-treated insects, respectively. Accordingly, firebugs with reduced expression of AKH receptors showed a significantly lower mortality (by 1.6 to 2.9-folds), and lower general metabolism after EPN+AKH treatments. In addition, EPN application increased Akh gene expression in the corpora cardiaca (1.6times), AKH level in the corpora cardiaca (1.3times) and haemolymph (1.7times), and lipid and carbohydrate amounts in the haemolymph. Thus, the outcomes of the present study demonstrate involvement of AKH into the anti-stress reaction elicited by the nematobacterial infection. The exact mechanism by which AKH acts is unknown, but results suggested that the increase of metabolism and nutrient amounts in haemolymph might play a role.

Molecular characterization, tissue distribution, and ultrastructural localization of adipokinetic hormones in the CNS of the firebug Pyrrhocoris apterus (Heteroptera, Insecta)

Adipokinetic hormones (AKHs) are a group of insect metabolic neurohormones, synthesized and released from an endocrine retrocerebral gland, the corpus cardiacum (CC). Small amounts of AKH have also been identified in the brain, although their role in this organ is not clear. To address this gap in the knowledge about insect brain biology, we studied the nucleotide sequence, tissue distribution, and subcellular localization of AKHs in the brain and CC of the firebug Pyrrhocoris apterus. This insect expresses two AKHs; the octapeptides Pyrap-AKH and Peram-CAH-II, the presence of which was documented in the both studied organs. In situ hybridization and quantitative reverse-transcription (q-RT)-PCR revealed the expression of the genes encoding for both AKHs not only in the CC, but also in brain. Electron microscopy analysis of the brain revealed the presence of these hormones in specialized secretory granules localized predominantly in the cellular bodies of neurons. The hormones might be transported from the granules into the axons, where they could play a role in neuronal signaling. Under acute stress induced by the injection of 3μmol KCl, the level of AKHs in the brain increased to a greater extent than that in the CC. These results might indicate an enhanced role of brain-derived AKHs in defence reaction under acute stress situations.

Role of adipokinetic hormone in stimulation of salivary gland activities: The fire bug Pyrrhocoris apterus L. (Heteroptera) as a model species

The effect of adipokinetic hormone (Pyrap-AKH) in stimulating the function of insect salivary glands (SGs) in extra-oral digestive processes was studied in the firebug, Pyrrhocoris apterus L. (Heteroptera). The analyses were performed on samples of SGs and extracts of linden seeds, a natural source of the bug’s food. The SGs from 3-day old P. apterus females (when the food ingestion culminates), primarily contained polygalacturonase (PG) enzyme activity, whereas the level of lipase, peptidase, amylase and α-glucosidase was negligible. The transcription of PG mRNA and enzymatic activity were significantly increased in SGs after Pyrap-AKH treatment. The piercing and sucking of linden seeds by the bugs stimulated the intrinsic enzymatic cocktail of seeds (lipase, peptidase, amylase, glucosidase), and moreover the activity of these enzymes was significantly enhanced when the seeds were fed on by the Pyrap-AKH treated bugs. Similarly, a significant increase in PG activity was recorded in linden seeds fed on by hormonally-treated bugs or when injected by SG extract from hormonally treated ones as compared to untreated controls. The mechanism of AKH action in SGs is unknown, but likely involves cAMP (and excludes cGMP) as a second messenger, since the content of this compound doubled in SGs after Pyrap-AKH treatment. This new and as yet undescribed function of AKH in SGs is compared with the effect of this hormone on digestive processes in the midgut elucidated earlier.

The responses of Central European avian predators to an allopatric aposematic true bug

A mimicry ring of red-and-black pentatomorph true bugs in Central Europe had been proposed to occur based on avoidance of its mutually non-relative members, which was confirmed based on responses of avian predators. We compared the responses of two species of European insectivorous passerines (great tit Parus major, blue tit Cyanistes caeruleus) to a typical member of the proposed ring (red firebug Pyrrhocoris apterus) and to a similarly coloured south Asian species of true bugs (red cotton bug Dysdercus cingulatus) to test if the allopatric species will be included in the proposed ring. Additionally, individuals of both bug species with colour signals artificially removed were offered to birds to assess the effect of chemical protection per se. Birds attacked the unmodified red cotton bugs more often than the red firebugs, which suggests that the birds did not include the red cotton bug in the proposed mimetic ring. Red cotton bugs were eaten by a greater number of birds than were the brown-painted red firebugs at first encounter. However, the birds quickly learned to avoid all visually unprotected bugs, suggesting that the red cotton bug possesses an effective chemical protection.

Complete genome sequence of Coriobacterium glomerans type strain (PW2(T)) from the midgut of Pyrrhocoris apterus L. (red soldier bug).

Coriobacterium glomerans Haas and König 1988, is the only species of the genus Coriobacterium, family Coriobacteriaceae, order Coriobacteriales, phylum Actinobacteria. The bacterium thrives as an endosymbiont of pyrrhocorid bugs, i.e. the red fire bug Pyrrhocoris apterus L. The rationale for sequencing the genome of strain PW2T is its endosymbiotic life style which is rare among members of Actinobacteria. Here we describe the features of this symbiont, together with the complete genome sequence and its annotation. This is the first complete genome sequence of a member of the genus Coriobacterium and the sixth member of the order Coriobacteriales for which complete genome sequences are now available. The 2,115,681 bp long single replicon genome with its 1,804 protein-coding and 54 RNA genes is part of the Genomic Encyclopedia of Bacteria and Archaea project.

Do long- and short-winged adult females of the bug Pyrrhocoris apterus (Heteroptera: Pyrrhocoridae) differ in lifespan and reproductive capacity?

In the present study we tested whether long-winged (macropterous) and short-winged (brachypterous) adult females of the firebug Pyrrhocoris apterus (L.) differ in their reproductive capacity and length of life. The following seven physiological markers were measured in these females: lengths of the pre-oviposition period (pre-OP), inter-ovipositon period (inter-OP) and post-oviposition period (post-OP), and the mean number of eggs per batch, total number of eggs, mean total number of egg batches laid and lifespan of the females. The results showed that macropterous and brachypterous females significantly differed in the length of the pre-OP, which was significantly shorter in brachypterous (7.95 ± 1.75 days) than in macropterous females (26.84 ± 9.86 days), but there was no significant difference between the lengths of the inter-OP in brachypterous (4.00-8.79 days) and macropterous (3.00-9.89 days) females. In contrast the length of the post-OP was significantly longer in brachypterous (48.23 ± 30.95 days) than in macropterous females (35.02 ± 17.32 days). Except for the 2nd and 3rd egg batches there was no significant difference between the average numbers of eggs in the other egg batches laid by females of the two wing morphs. Total number of eggs laid by macropterous females during their whole lifespan was not significantly lower (326.47 ± 155.65 eggs) than by brachypterous females (382.82 ± 207.52 eggs), but associated with the lower number of egg batches laid by macropterous (13) than by brachypterous females (19). However, there was no significant difference in the longevity of brachypterous (95.43 ± 41.21 days) and macropterous (93.40 ± 21.18 days) females. The relationship of these results to the reproductive arrest, inactivity of the endocrine gland, corpus allatum, and different levels of adipokinetic hormone in macropterous females is discussed.