Dinocras Cephalotes Research Articles

Sensory pathway in aquatic basal polyneoptera: Antennal sensilla and brain morphology in stoneflies

Aquatic insects represent a great portion of Arthropod diversity and the major fauna in inland waters. The sensory biology and neuroanatomy of these insects are, however, poorly investigated. This research aims to describe the antennal sensilla of nymphs of the stonefly Dinocras cephalotes using scanning electron microscopy and comparing them with the adult sensilla. Besides, central antennal pathways in nymphs and adults are investigated by neuron mass-tracing with tetramethylrhodamine, and their brain structures are visualized with an anti-synapsin antibody. No dramatic changes occur in the antennal sensilla during nymphal development, while antennal sensilla profoundly change from nymphs to adults when switching from an aquatic to an aerial lifestyle. However, similar brain structures are used in nymphs and adults to process diverging sensory information, perceived through different sensilla in water and air. These data provide valuable insights into the evolution of aquatic heterometabolous insects, maintaining a functional sensory system throughout development, including a distinct adaptation of the peripheral olfactory systems during the transition from detection of water-soluble chemicals to volatile compounds in the air. From a conservation biology perspective, the present data contribute to a better knowledge of the biology of stoneflies, which are very important bioindicators in rivers.

The complete mitochondrial genome of a stonefly species, Neoperlops gressitti (Plecoptera: Pelidae)

The small genus Neoperlops only contains four species over the whole world now, and the mitochondrial genome of the genus Neoperlops is still a gap. Here, we report the complete mitochondrial genome of Neoperlops gressitti representing the rare perlid stonefly genus Neoperlops. The circular mitochondrial genome is 15,699 bp in length, which consisting of A (33.30%), G (12.5%), T (29.7%), and C (24.6%), and it is composed of 22 tRNA genes, 13 protein-coding genes (PCGs), two rRNA genes, and a control region like the other published stonefly. In all PCGs, eleven genes initial with the typical start codon ATN, the rest of the two genes (ND1, ND2) with TTG. All PCGs stop with TAG/TAA, except COIII, ND5 use incomplete T—as stop codon. Besides, the phylogenetic result based on the nucleotide of the 13 PCGs and two rRNA genes by using Bayesian (BI) method supports the sister relationship between N. gressitti and Dinocras cephalotes. The complete mitogenome of N. gressitti can provide genetics data to further explore the taxonomic status of Pelidae.

The effects of pastoral intensification on the feeding interactions of generalist predators in streams.

Land‐use change can alter trophic interactions with wide‐ranging functional consequences, yet the consequences for aquatic food webs have been little studied. In part, this may reflect the challenges of resolving the diets of aquatic organisms using classical gut contents analysis, especially for soft‐bodied prey. We used next‐generation sequencing to resolve prey use in nearly 400 individuals of two predatory invertebrates (the Caddisfly, Rhyacophila dorsalis, and the Stonefly Dinocras cephalotes) in streams draining land with increasingly intensive livestock farming. Rhyacophila dorsalis occurred in all streams, whereas D. cephalotes was restricted to low intensities, allowing us to test whether: (i) apparent sensitivity to agriculture in the latter species reflects a more specialized diet and (ii) diet in R. dorsalis varied between sites with and without D. cephalotes. DNA was extracted from dissected gut contents, amplified without blocking probes and sequenced using Ion Torrent technology. Both predators were generalists, consuming 30 prey taxa with a preference for taxa that were abundant in all streams or that increased with intensification. Where both predators were present, their diets were nearly identical, and R. dorsalis's diet was virtually unchanged in the absence of D. cephalotes. The loss of D. cephalotes from more intensive sites was probably due to physicochemical stressors, such as sedimentation, rather than to dietary specialization, although wider biotic factors (e.g., competition with other predatory taxa) could not be excluded. This study provides a uniquely detailed description of predator diets along a land‐use intensity gradient, offering new insights into how anthropogenic stressors affect stream communities.

Antennal responses to volatile organic compounds in a stonefly

Notwithstanding their long antennae, especially in the adult stage, Plecoptera represent a poorly studied group as regards their sensory structures and their ability to perceive olfactory stimuli is so far totally unknown. A recent investigation on the antenna of Dinocras cephalotes revealed two kinds of putative olfactory sensilla (multiporous single walled sensilla and digitated double walled sensilla). The present electrophysiological study (electroantennography, EAG), in which male and female antennae of D. cephalotes (Plecoptera, Perlidae) have been stimulated with a set of generic odours belonging to different functional groups, shows that Plecoptera can perceive olfactory cues through their antennal sensilla. Indeed, although many chemicals did not elicit any response, high EAG activity has been recorded in response to pentanoic acid, propanal, butyric acid, propionic acid, isoamylamine and ammonia. The response was very similar in both sexes even if propanal elicited a response only in males. EAG dose-responses curves in both males and females showed that EAG responses were similar in males and females and generally increased in amplitude with increasing doses of the chemicals. Behavioural, neuroanatomical and molecular investigations on Plecoptera olfaction, could be particularly interesting not only to increase the knowledge of the adult stonefly behaviour but also to better understand the adaptation of the olfactory sensory system in aquatic insects moving from land to water.

A comparison between the adult antennal sensilla of the cavernicolous stonefly Protonemura gevi and other epigean Protonemura species (Plecoptera: Nemouridae) in a biological context

SummaryIn the present paper we study the antennal sensilla of the unusual hypogean stonefly Protonemura gevi Tierno de Figueroa & López-Rodríguez, 2010 (Plecoptera: Nemouridae), comparing them with those of two epigean species of the genus Protonemura, P. alcazaba (Aubert, 1954) and P. meyeri (Pictet, 1842), with the aim to describe possible peculiarities. No differences exist in the types and morphology of antennal sensilla among the studied species and neither between sexes. The types of sensilla identified are long aporous trichoid sensilla with a tactile function, uniporous gustatory sensilla chaetica, multiporous sensilla basiconica (porous pegs) and sensilla coeloconica (digitated pegs), with a supposed olfactory function, and domes probably hosting aporous thermohygroreceptive pegs. These sensilla are very similar to those observed in other Plecoptera families and described in detail in Dinocras cephalotes (Curtis, 1827), thus suggesting a quite conserved sensory function for the antenna in the whole order, as it happens in other aquatic insects, such as Ephemeroptera and Odonata.

Antennal sensilla of the stonefly Dinocras cephalotes (Plecoptera: Perlidae)

Plecoptera, one of the most primitive groups of Neoptera, are important aquatic insects usually employed as bioindicators of high water quality. Notwithstanding the well-developed antennae of the adult, its sensory abilities are so far not well known. The present paper describes at ultrastructural level under scanning and transmission electron microscopy the antennal sensilla of the adult stonefly Dinocras cephalotes (Plecoptera, Perlidae). Adult males and females show a filiform antenna constituted of a scape, a pedicel and a flagellum composed of very numerous segments with no clear sexual dimorphism in the number and distribution of the antennal sensilla. The most represented sensilla are sensilla trichodea, with different length, whose internal structure reveal their mechanosensory function, sensilla chaetica, with an apical pore, with an internal structure revealing a typical gustatory function, porous pegs representing single-walled olfactory sensilla, digitated pegs with hollow cuticular spoke channels representing double-walled olfactory sensilla, pegs in pits for which we hypothesize a thermo-hygrosensory function. The diversity of described sensilla is discussed in relation to known biological aspects of the studied species. This opens new perspectives in the study of the behavior of these aquatic insects during their adult stage.

Stoneflies (Plecoptera) of the Javorníky Mts (Czech Republic)

Abstract The investigation of three streams in the Moravian part of the Javorníky Mts in 2003 and 2006–2009 brings the first records of Plecoptera in these mountains. A total of 28 species and were found (30 % of the recent fauna of the Czech Republic), among which species of the upper parts of streams predominate. This result corresponds to the nature of the habitat on which researches have been carried out. One endangered species (Leuctra cf. major), two vulnerable species (Dinocras cephalotes, Perla marginata) and one near threatened species (Leuctra quadrimaculata) were recorded. Comparing the recorded species to those of the neighbouring mountains, it can be assumed that the fauna of stoneflies of the Javorníky Mts may contain more than 40 species and can form a continuous transition between the Moravskoslezské Beskydy Mts and the Bílé Karpaty Mts (including the Vizovická vrchovina Highlands).

A comparison of modelled and actual distributions of eleven benthic macroinvertebrate species in a Central European mountain catchment

Species distribution Modelling (SDM) constitutes a useful tool to predict the distribution of freshwater species based on selected habitat variables. Model performance (goodness-of-fit) expressed as coefficient of determination is straightforward to judge on SDM quality but does not sufficiently address predictive success. Hence, predictive performance (e.g. AUC) accounts for the correctness of predicted species occurrences. In this study, we compared the model and predictive performance of SDMs on eleven macroinvertebrate taxa in a mountain catchment, with emphasis on species prevalence. SDMs were based on two regression methods using broad-scale environmental predictors (land use, instream habitat quality). We applied a cross-validation and a field validation approach using newly sampled field data. Opposed to other species, SDMs showed acceptable performance (pseudo-R2 > 0.3) for the stonefly Dinocras cephalotes and the caddisflies Silo piceus and Silo pallipes. Model performance was neither positively nor linearly correlated with predictive accuracy. The comparison of cross- and field validation revealed an overestimation of the discriminatory power of cross-validated models. SDMs of less prevalent species tend to over-predict absences rather than presences. Consequently, model performance is decoupled from predictive performance. The validation results suggest the use of new field data providing a more reliable benchmark for SDM assessment.

Life cycle, nymphal feeding and secondary production of Dinocras cephalotes (Plecoptera) in a Mediterranean river

Summary. Some aspects of the life history of a population of Dinocras cephalotes inhabiting a Mediterranean river in Southern Spain were studied over a year (2012–2013). The life cycle of this population seems to be semivoltine, of approximately two years of duration, and with an asynchronous egg hatching period. The comparison of these data with those of an unpublished study carried out in the same population almost a decade before (2004–2005) shows the existence of no differences between years. The nymphal feeding study revealed that the main prey of these organisms are Chironomidae, Psychomyiidae and Baetidae, but some of them, usually the smallest, also had non-animal matter in their guts, mainly detritus, coarse particulate organic matter and algae. So, an onthogenetic shift in feeding was detected. This feeding confirms broadly what was already reported in previous studies in the same and other populations. Finally, and for the first time for this species, the secondary production was estimated. Due to differences in hatching, and so development, among nymphs, annual secondary production was calculated both assuming a CPI of 20 months and a CPI of 14 months. In both cases this value was relatively high, 2854.46 and 4077.80 mg DW m–2 year–1, respectively. These results were compared with those of other predators, and particularly with a stonefly predator with a similar life cycle and from a nearby temporal river.

Physiological strategies contributing to the coexistence of two predatory species of stoneflies: Dinocras cephalotes and Perla bipunctata

Our study focuses on the oxidative state of two aquatic insects of the order Plecoptera belonging to the family Perlidae, namely Dinocras cephalotes (Curtis, 1827) and Perla bipunctata Pictet, 1833. These species are widely distributed throughout the Western Palearctic region and coexist in the stream where individuals for this study come from. We highlight the physiological strategies of these two different predator species of stoneflies, showing a higher accumulation of lipid reserves in P. bipunctata, higher glucose levels in the body tissues of D. cephalotes and a higher capacity of the antioxidant enzymes in P. bipunctata, what provides it a protection against oxidation of lipids, which are greater in this species. This leads to a similar oxidative state in both species. Based on these results is discussed how two close related species developing a very similar ecological role in the same habitat can achieve a similar fitness with differences in their physiological strategies.

Genetic diversity and dispersal potential of the stoneflyDinocras cephalotesin a central European low mountain range

AbstractAquatic insects are widely used as indicator taxa to assess the ecological state of streams and to evaluate the success of stream restoration projects. Information on intraspecific genetic diversity and population connectivity is often lacking for such indicator taxa. However, these parameters are of critical importance for restoration plans and conservation management because: 1) species sometimes consist of several cryptic species and 2) species can recolonize only those restored habitats within a reachable distance from their source populations. Gene flow generally cannot be observed directly, and molecular markers provide a reasonable alternative to assess the dispersal potential and evaluate species’ genetic diversity. We investigated the genetic diversity and dispersal potential of the predatory stonefly Dinocras cephalotes using 323 specimens from 29 populations in the Sauerland, a low mountain range in Germany. We used a 658 base pair (bp) fragment of the mitochondrial cytochrome c oxidase...

Adult feeding habits of three Perloidea species (Plecoptera: Perlidae and Chloroperlidae)

The gut content composition of three species of the superfamily Perloidea, Marthamea selysii (Pictet, 1842), Dinocras cephalotes (Curtis, 1827), and Siphonoperla torrentium (Pictet, 1842), from northwestern Spain is analyzed and described. The quantity of food found in all adults of M. selysii and D. cephalotes was very low. Spores of fungi and pollen of angiosperms were the most abundant components in the diet of M. selysii. Pollen of angiosperms, followed by fungal spores, detritus, and animal matter were the most abundant components in the diet of both sexes of D. cephalotes. The adult diet of both sexes of S. torrentium consists mainly of pollen and agrees with data of the previous studies on this same species in other areas. Our results also show that the consumption of animal matter could be a way to get a nutritional complement and is more common than previously considered in adult stoneflies. The obtained data support the hypothesis that adult feeding is less important for large stoneflies (as M. selysii and D. cephalotes) than for other smaller Perloidea (as S. torrentium), but feeding habits in these large Plecoptera could not be as negligible as previously supposed.

The complete mitochondrial genome of the stonefly Dinocras cephalotes (Plecoptera, Perlidae)

The complete mitochondrial genome of the perlid stonefly Dinocras cephalotes (Curtis, 1827) was sequenced using a combined 454 and Sanger sequencing approach using the known sequence of Pteronarcys princeps Banks, 1907 (Pteronarcyidae), to identify homologous 454 reads. The genome is 15,666 bp in length and includes 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes and a control region. Gene order resembles that of basal arthropods. The base composition of the genome is A (33.5%), T (29.0%), C (24.4%) and G (13.1%). This is the second published mitogenome for the order Plecoptera and will be useful in future phylogenetic analysis.

Digestive enzyme activity and trophic behavior in two predator aquatic insects (Plecoptera, Perlidae). A comparative study

Plecoptera (Perlidae) are among the major macroinvertebrate predators in stream ecosystems and one of the insect families with lower tolerance to environmental alterations, being usually employed as bioindicators of high water ecological quality. The differences in the trophic roles of the coexisting species have been exclusively studied from their gut contents, while no data are available on the comparative digestive capacity. In the present paper, we make a comparative study of the activity of several digestive enzymes, namely proteases (at different pH), amylase, lipase, trypsin and chymotrypsin, in two species of stoneflies, Perla bipunctata and Dinocras cephalotes, which cohabit in the same stream. The study of digestive enzyme activity together with the analysis of gut contents can contribute to a better understanding of the ecology of these aquatic insects and their role in freshwater food webs. Thus, our results show that the two studied predator species inhabiting in the same stream present specializations on their feeding behaviors, facilitating their coexistence, and also differences in their capacity of use the resources. One of the main findings of this study is that D. cephalotes is able to assimilate a wider trophic resource spectrum and this could be one of the reasons why this species has a wider global distribution in all its geographical range.

Can Oxygen Set Thermal Limits in an Insect and Drive Gigantism?

BackgroundThermal limits may arise through a mismatch between oxygen supply and demand in a range of animal taxa. Whilst this oxygen limitation hypothesis is supported by data from a range of marine fish and invertebrates, its generality remains contentious. In particular, it is unclear whether oxygen limitation determines thermal extremes in tracheated arthropods, where oxygen limitation may be unlikely due to the efficiency and plasticity of tracheal systems in supplying oxygen directly to metabolically active tissues. Although terrestrial taxa with open tracheal systems may not be prone to oxygen limitation, species may be affected during other life-history stages, particularly if these rely on diffusion into closed tracheal systems. Furthermore, a central role for oxygen limitation in insects is envisaged within a parallel line of research focussing on insect gigantism in the late Palaeozoic.Methodology/Principal FindingsHere we examine thermal maxima in the aquatic life stages of an insect at normoxia, hypoxia (14 kPa) and hyperoxia (36 kPa). We demonstrate that upper thermal limits do indeed respond to external oxygen supply in the aquatic life stages of the stonefly Dinocras cephalotes, suggesting that the critical thermal limits of such aquatic larvae are set by oxygen limitation. This could result from impeded oxygen delivery, or limited oxygen regulatory capacity, both of which have implications for our understanding of the limits to insect body size and how these are influenced by atmospheric oxygen levels.Conclusions/SignificanceThese findings extend the generality of the hypothesis of oxygen limitation of thermal tolerance, suggest that oxygen constraints on body size may be stronger in aquatic environments, and that oxygen toxicity may have actively selected for gigantism in the aquatic stages of Carboniferous arthropods.

Comparative Proteomic Analysis of Hemocyanins inDinocras cephalotesandPerla marginata(Plecoptera)

Hemocyanins are large oligomeric respiratory proteins found in many arthropods and mollusks. The overall expression of hemocyanin mRNA, revealed by studies on Plecoptera hemocyanin sequencing, has raised the question of whether the protein is expressed or not. In fact, the presence of expressed hemocyanin has only been reported in the literature for one species, Perla marginata (Panzer, 1799). In this paper, we report the presence of hemocyanin and hexamerin proteins in Dinocras cephalotes (Curtis, 1827), a species closely related to P. marginata. To assess the presence of hemocyanin, we used a reproducible and highly sensitive method based on liquid chromatography tandem mass spectrometry. We conclude that regardless of its putative function (respiratory, immune defense, storage protein), the hemocyanin is actually expressed in species in which its mRNA is present.

Do all stoneflies nymphs have respiratory proteins? Further data on the presence of hemocyanin in the larval stages of plecoptera species

Contrary to what was assumed regarding the presence of respiratory proteins in insects, a functional hemocyanin was recently found in larvae and adults of the stoneflies species Perla marginata, whereas in the close species Perla grandis, hemocyanin functionality was deduced from sequence data. In order to verify if the presence of this ancient trait is widespread within the order and to investigate why stoneflies have maintained it, we have extended the search for hemocyanin to species of other Plecoptera families. In particular, we assessed the presence of hemocyanin in the larval stage of nine Plecoptera species, belonging to six of the seven families of the European stonefly-fauna, and analyzed its potential functionality as deduced by sequence data. We cloned and sequenced the corresponding cDNAs and studied their expression with RT-PCR technique. Moreover, we performed homology studies using the deduced amino acid sequences. On the basis of our analysis, we hypothesized a functional role of the hemocyanin only for two species: Dinocras cephalotes and Isoperla grammatica (Perloidea). In all the investigated Nemouroidea and in Siphonoperla torrentium (Perloidea), this protein may have been lost. Larval size, life-cycle length, trophic role and environmental induction are discussed as possible explanations of these different physiological requirements.

Trophic Behavior of Two Perlidae Species (Insecta, Plecoptera) in a River in Southern Spain

AbstractTwo Perlidae species, Dinocras cephalotes and Perla bipunctata, were studied in a river in Spain with the objectives of: a) describing their diets; b) detecting differences between size classes; c) analyzing niche breadth; and d) assessing the degree of niche overlap between both species and size classes. Dinocras cephalotes and Perla bipunctata nymphs fed mainly on Baetidae and immature Chironomidae. We did not detect significant differences in the quantity of ingested detritus, algae, and leaf pieces. Niche breadth was very low, although both species presented a high niche overlap. P. bipunctata seems to select some prey items throughout its nymphal development, whereas D. cephalotes augments its diet with other prey items as it grows. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Diet of Dinocras cephalotes and Perla marginata (Plecoptera: Perlidae) in an Apennine stream (northwestern Italy)

AbstractThe feeding habits of nymphs of Perla marginata (Panzer) and Dinocras cephalotes (Curtis) were investigated in the Rio Orbarina (northwestern Italy). These species are among the largest European carnivorous freshwater invertebrates and they play an important role in the trophic structure of small, fishless Apennine streams. We examined the gut contents of 60 P. marginata and 60 D. cephalotes nymphs to characterize the diets and evaluate possible feeding differences between the species. In both of these predaceous stoneflies, the diet included vegetable detritus, mainly in the smaller instars. Both species showed trophic preferences, since only a few taxa constituted most of the ingested prey items, independently of their availability in the substratum. Interestingly, there were no clear differences in prey selection between nymphs of the two species.

Short-term physiological responses to a severe acid stress in three macroinvertebrate species: A comparative study

The present study focuses on the sensitivity among freshwater invertebrate species to acidic stress. Three common macroinvertebrate species in the Vosges Mountains (North-Eastern France), Gammarus fossarum (Amphipoda), Hydropsyche pellucidula (Trichoptera) and Dinocras cephalotes (Plecoptera) were exposed for 24, 72 and 120 h to natural acidified water (pH = 4.73 ± 0.08, [Ca 2+] = 39.1 ± 0.6 μmol l −1, [Al tot] = 28.4 ± 1 μmol l −1). Short-term exposure to acid stress caused significant decreases both in survival rate and haemolymph ions ([Cl −] and [Na +]). The relative sensitivity to a natural acidic stress slightly differed among the species and was in the following order: G. fossarum, as the most sensitive, then H. pellucidula and D. cephalotes. Results of this study confirm the interest of in situ tests to assess the toxicity of short-term acid exposure. Finally, our results reinforce the hypothesis that transient acidification can offset the recovery of sensitive species of macroinvertebrates in streams chemically recovering from acidification either through liming or declining deposition.