Phenotypically plastic responses to environmental variation are more complex than life history theory predicts.

For insects that exhibit wing polyphenic development, abiotic and biotic signals dictate the adult wing morphology of the insect in an adaptive manner such that in stressful environments the formation of a flight-capable morph is favored and in low-stress environments, a flightless morph is favored. While there is a relatively large amount known about the environmental cues that dictate morph formation in wing polyphenic hemipterans like planthoppers and aphids, whether those cues dictate the same morphs in non-hemipteran (i.e., cricket) wing polyphenic species has not been explicitly investigated. To experimentally test the generality of environmental cue determination of wing polyphenism across taxa with diverse life histories, in this study, we tested the importance of food quantity, parasitic infection, and tactile cues on wing morph determination in the wing polyphenic sand field cricket, Gryllus firmus. Our results also show that certain stress cues, such as severe diet quantity limitation and parasitic infection, actually led to an increase in the production of flightless morph. Based on these findings, our results suggest that physiological and genetic constraints are important to an organism's ability to respond to environmental variation in an adaptive manner beyond simple life history trade-offs.

Bimodality of auditory receptors in bush-crickets. Сontinued discussion. It's time to experiment.

Continuation of the discussion on the sensitivity of the chordotonal sensilla of the tympanal organ of bush-crickets to vibratory stimuli. We have previously shown that individual receptors registered directly in the tympanal organ perceive vibrations along with sound stimuli. In addition, scolopidia of the crista acustica possess mixed sensitivity, too, as well as receptors of the intermediate organ. The authors of the comment offered their opinion concerning our applied methods as well as our obtained results. In particular, they noted the dissimilarity of our data from the previously obtained data (the 1970s-1990s), mainly in the laboratory of Prof. K. Kalmring, who assumed that only low-frequency receptors, in particular receptors of the intermediate organ, possess mixed sensitivity. At the same time, receptor activity was recorded in the tympanal nerve without morphological identification of receptors (with the exception of one stained neuron in the prothoracic ganglion). We carried out a series of experiments using the method of K. Kalmring and found that it is possible to register several receptors in the tympanal nerve with different reactions during one experiment: to sound only, also both to vibration stimuli and sound. In the latter case, we dealt with low-threshold receptors, which responded to ultrasound, and this with high probability belonged to the crista acustica. Similar data were previously obtained on the bush-cricket Decticus verrucivorus. In this publication, we explain the methodological features of our work and suggest that the loss of sensitivity to vibrations at the level of the tympanal nerve by some auditory receptors may be due to the ephaptic and/or chemical interaction of the tympanal organ receptors with vibroreceptors of the subgenual or other organs. To verify this hypothesis, it is necessary to conduct additional studies, such as physiological, morphological, and immunohistochemical, along the entire vibroacoustic afferent tract, that is, from the peripheral part to the first switches to the corresponding interneurons.

Differential impacts of ionizing radiation on a sexually dimorphic trait in male and female Acheta domesticus.

PURPOSE: In many Orthopteran species, including crickets, forewings exhibit substantial sexual dimorphism driven by sexual selection. In the cricket, Acheta domesticus, females are the 'choosy' sex and males exhibit multiple sexual signals to attract and successfully mate. Male forewings have highly specialized structures critical for acoustic signaling and mating. In contrast, female forewings currently serve no known purpose in this flightless species. Forewings also differ morphologically with male forewings containing complex acoustic producing and resonating regions and females lacking any defined structures. Due to their importance to mating as well as their structural complexity, impacts of environmental stress that target cricket forewing development may therefore have more severe consequences in males than females. Here, we investigate the sensitivity of a sexually dimorphic trait, forewing morphology, to an early life environmental stressor. MATERIALS AND METHODS: We applied ionizing radiation (0--27.8 Gy) as a stressor as dose can be precisely applied as well as its relevance in both environmental contamination and use in the Sterile Insect Technique. RESULTS: A canonical variate analysis indicated that wing shape was significantly altered in males at all doses; .58 Gy, 2.3 Gy, 4.6 Gy, 16.2 Gy, and 23.2 Gy. In females, shape was significantly altered at 27.8 Gy and 23.2 Gy groups and to a lesser extent at .58 Gy and 16.2 Gy. Linear regression analysis of centroid size indicated a dose dependent decline in wing size in both sexes, with males exhibiting more decline. Fluctuating asymmetry, a measure of environmental sensitivity, revealed that males were more sensitive to shape changes due to stress than females. This difference in sensitivity is likely due to the complexity of male forewings. CONCLUSION: These results expand understanding of sex dimorphism in stress responses and sensitivity to ionizing radiation.

Studies on chevron crickets: Morphological redescription of Chilean red cricket Cratomelus armatus Blanchard, 1851 (Orthoptera: Anostostomatidae).

An updated diagnosis for Cratomelus is provided, accompanied by a key to the identification of species. Cratomelus armatus is redescribed, including the genital structures, which were unknown until now, being a significant contribution to the morphological differentiation of this taxon of chevron crickets, giving additional data that will allow the future to differentiate them from the other anostostomatids of the world.

The mechanics of acoustic signal evolution in field crickets.

Field crickets (Family Gryllidae, Subfamily Gryllinae) typically produce tonal calls with carrier frequencies in the range 3-8 kHz. In this study, we explored the use of a finite element model (FEM) of the stridulatory apparatus of a field cricket, Gryllus bimaculatus, based on experimental measurements of resonator geometry and mechanical properties, to predict the measured call carrier frequencies of eight other field cricket species, ranging between 3 and 7 kHz. The model allowed accurate predictions of carrier frequencies for all eight species to within a few hundred hertz from morphological measurements of their resonators. We then used the model to explore the plausible evolutionary design space for field cricket call carrier frequency along the axes of resonator size and thickness, and mapped the locations of the nine experimentally measured species in this design space. Although the nine species spanned the evolutionarily conserved spectrum of carrier frequency and body size in field crickets, they were clustered in a small region of the available design space. We then explored the reasons for this apparent evolutionary constraint on field cricket carrier frequencies at both the lower and higher limit. We found that body size and sound radiation efficiency were the main constraints at the lower limits, whereas the energetics of stridulation using the clockwork mechanism may pose a constraint at higher frequencies.

One new species of Homogryllacris Liu, 2007 from China with comments on the characters of mitochondrial genome (Orthoptera: Gryllacrididae; Gryllacridini).

This paper reported on new species from China which differs from other species of Homogryllacris in being without styli of male subgenital plate. The nearly complete mitochondrial genome (mitogenome), except control region, of the new species Homogryllacris parcibrevipenna was sequenced and analyzed. This partial mitogenome was 15509 bp in length and encoded 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and 2 ribosomal RNA unit genes. The gene arrangement and contents were consistent with other members of the Gryllacrididae. All the PCGs were started with the standard ATN codons except ND1 with TTG; and most of PCGs were terminated with a complete stop codon (TAA/TAG). Most tRNAs could be folded into the typical cloverleaf secondary structures, while tRNASer1 lacked a DHU stem. This data could enrich the genome information available for Gryllacrididae and facilitate phylogenetic studies of related insects. All the material were deposited in the Museum of Guangxi Normal University.

Studies on Neotropical crickets: A new Anurogryllina genus (Orthoptera: Gryllidae: Gryllinae).

Andeogryllus n. gen. including two new species from the inter-Andean slopes and valleys of the Magdalena and Cauca rivers of Colombia are described. This new genus is similar to Zebragryllus in their habitus, differed by not have white stripes on the body or antennae and by a modified pseudoepiphallic sclerite. The genus Atsigryllus (Atsigryllae group) is located in the subtribe Anurogryllina, highlighting the secondary reduction of the median lobe. An updated key is provided for the genera of the subtribe Anurogryllina and the species of the new genus.

Studies on Neotropical crickets: New species and notes on the classification of Field Crickets genera Anurogryllus and Gryllus (Orthoptera: Gryllidae: Gryllinae).

In this contribution to the American Field and Short-tail crickets, two new species from the continental and insular area of Colombia are described. Anurogryllus (Urogryllus) edithsantosum n. sp. from the Meta department, is more related to some Caribbean species, and its genital structure fits the morphological current definition of the subgenus Urogryllus, although it has pseudepiphallic median lophi covered with hairs, as it happens in the species of the subgenus Pilosogryllus. The same way, Gryllus (Gryllus) providiensis n. sp. from Providencia Island, San Andres Archipelago is described, this new species has thick hairs on the pronotum as Gryllus (Gryllus) assimilis (widely distributed in America), as well as the color pattern of the cephalic capsule; but the new species is smaller in size, and has a particular organization in the harp veins of the tegmina, which only resembles Gryllus (Gryllus) marchena from the Galapagos Archipelago (Ecuador), from which it differs markedly in its morphology. Finally, the status of the Gryllus species, distributed in Latin America and the Caribbean, is reviewed, and it is recorded which species have acoustic records, and from here we start with the review of this peculiar genus in Latin America.

Studies on Raspy Crickets: A new Andean Hyperbaenini genus (Orthoptera: Gryllacrididae: Hyperbaeninae).

Mikrohyperbaenus n. gen. is the first Andean genus for the tribe Hyperbaenini, the other genera such as Hyperbaenus and Dibelona inhabit the low and humid lands of South America. The new genus is distinguished by the structure of the male terminalia and the apex of the labial and maxillary palps, which are unusually naked or without the cuticle, that covers the other body segments. Mikrohyperbaenus n. gen. is a monotypic genus, found in the surroundings of the Zapatoca municipality, Santander, Colombia, a territory inhabited in the past by the Guane indigenous people, for which the new species Mikrohyperbaenus guane n. gen. et n. sp. is dedicated to that particular Pre-columbian indigenous people.

Report of a new genus Majialandrevus, with a new species M. dingguo from Western Yunnan, China (Orthoptera: Gryllidae: Landrevinae).

We reported a new genus Majialandrevus from Western Yunnan, China. The new genus differs from other genera in having the following combination of characters: short forewings, male genitalia with blunt distal parts of posterolateral epiphallic lobes, absence of medial lobes of epiphallus and ectoparamere being membranous. The type specimens are deposited in the Museum of Biology, East China Normal University (ECNU).

A narrow ear canal reduces sound velocity to create additional acoustic inputs in a microscale insect ear.

Located in the forelegs, katydid ears are unique among arthropods in having outer, middle, and inner components, analogous to the mammalian ear. Unlike mammals, sound is received externally via two tympanic membranes in each ear and internally via a narrow ear canal (EC) derived from the respiratory tracheal system. Inside the EC, sound travels slower than in free air, causing temporal and pressure differences between external and internal inputs. The delay was suspected to arise as a consequence of the narrowing EC geometry. If true, a reduction in sound velocity should persist independently of the gas composition in the EC (e.g., air, [Formula: see text]). Integrating laser Doppler vibrometry, microcomputed tomography, and numerical analysis on precise three-dimensional geometries of each experimental animal EC, we demonstrate that the narrowing radius of the EC is the main factor reducing sound velocity. Both experimental and numerical data also show that sound velocity is reduced further when excess [Formula: see text] fills the EC. Likewise, the EC bifurcates at the tympanal level (one branch for each tympanic membrane), creating two additional narrow internal sound paths and imposing different sound velocities for each tympanic membrane. Therefore, external and internal inputs total to four sound paths for each ear (only one for the human ear). Research paths and implication of findings in avian directional hearing are discussed.

Colonization of different biomes drove the diversification of the Neotropical Eidmanacris crickets (Insecta: Orthoptera: Grylloidea: Phalangopsidae).

The phylogeny of the cricket genus Eidmanacris is used to analyse its historical distribution and diversification in three South American biomes: Atlantic Forest, Cerrado, and Chiquitano Dry Forest. A morphological phylogeny with all the 29 species of Eidmanacris and the Geographically explicit Event Model (GEM) is used to explain their colonization and diversification through three different biomes and their ancestral habitats and distributional areas. We analysed ecologically-significant characters, such as body size and metanotal characters, to test whether if morphology, habitat, or behaviour are connected. The relations of these features with the colonisation of wetter or drier biomes based on the distributional area, phylogeny and diversity of the genus were also tested. The results show that the ancestral distribution of the genus was the Atlantic Forest, and that biome occupancy, habitat, size, and mating behaviour evolved congruently through the phylogeny, drawing a coherent pattern of changes through Eidmanacris evolution toward the colonisation of drier biomes. Our results indicate that gallery forests could play a key role in the distribution and diversification of Eidmanacris species.

Isophya sonora, a new bush-cricket species from Eastern Black Sea region of Turkey (Orthoptera: Tettigoniidae; Phaneropterinae).

Herein I describe Isophya sonora sp. nov. a new bush-cricket species from Trabzon, Northeastern part of Turkey (Black Sea Region). The species is characterized by the shape of the markedly convergent fastigium, distinctly broadened pronotum at metazona, elongate tegmina and large mirror area of left tegmen in the male. The bioacoustic characteristics, and the shape and number of the teeth of stridulatory organs are also different compared to closely related species. The new species is clearly a member of I. zernovi species-group allied with I. bivittata. Both the bioacoustics, and the morphological data, demonstrate the relationships between species of the I. zernovi species-group are as follows: (I. bicarinata + (I. zernovi + I. horon)) + (I. sonora sp. n. + I. bivittata?))) + (I. karadenizensis + I. autumnalis)))).

A Novel Head Capsule Labial Gland Lobe in the Black Field Cricket (Orthoptera: Gryllidae).

We describe a pair of labial gland lobes on either side of the retrocerebral complex in the head of the Australian black field cricket, Teleogryllus commodus Walker. As the retrocerebral complex includes the corpora cardiaca and corpora allata, hormones secreted by these glands can be absorbed by these lobes. These lobes of the labial gland are connected to the thoracic lobes via a relatively long duct that enters the main duct draining the thoracic lobes. Measurement of the flow rate of dye from head to thorax in the ducts is rapid, suggesting that these glands may serve as a transport system into the thoracic region. Both serotonin and adipokinetic hormone are shown to be present in the lobes near the retrocerebral complex and the ducts of the thoracic lobes, but whether this connection between the head and thorax acts as a hormone transporter is still unclear.

Impact of low sperm competition on male reproductive trait allometries in a bush-cricket.

BACKGROUND: Studying reproductive trait allometries can help to understand optimal male investment strategies under sexual selection. In promiscuous mating systems, studies across several taxa suggest that testes allometry is usually positive, presumably due to strong selection on sperm numbers through intense sperm competition. Here, we investigated testes allometry in a bush-cricket species, Metaplastes ornatus, in which females mate promiscuously, but where sperm removal behaviour by males likely drastically reduces realised sperm competition level. RESULTS: As hypothesised, we found evidence for negative testes allometry and hence a fundamentally different male investment strategy compared to species under intense sperm competition. In addition, the mean relative testes size of M. ornatus was small compared to other species of bush-crickets. Surprisingly, the spermatophore gland, a potential alternative trait that males could invest in instead of testes, also did not show positive allometry, but was approximately isometric. We further observed the expected pattern of negative allometry for the male morphological structure responsible for sperm removal in this species, the subgenital plate, supporting the one-size-fits-all hypothesis for intromittent genitalia. CONCLUSION: Our findings suggest that the evolution of sperm removal behaviour in M. ornatus was a key adaptation for avoiding sperm competition, with important consequences for reproductive trait allometries. Nevertheless, they also imply that it does not pay for larger males to invest disproportionately in nuptial gift production in this species.

Structure, mechanics and material properties of claw cuticle from mole cricket Gryllotalpaorientalis.

Powerful shovel-like forelimbs with special shape, structure and biological materials enable mole cricket to digging efficiently. During digging, the tip of the claw needs to wedge into the soil, and the base needs to withstand considerable anti-shear force. In this study, we analysed the structural characteristics, material composition and mechanical properties of the claw teeth using scanning electron microscopy, plasma atomic emission spectroscopy, nanoindentation and finite element analysis. The results show that the tips of claw teeth have a dense and homogeneous structure and a higher hardness and contents of Mn and Zn compared with the base. The structure of the base of claw teeth has an obvious laminar structure and higher fracture resistance. Moreover, it is speculated from the simulation results that basal position of the claw teeth is tough enough to withstand high stress, and the presence of the ribs effectively improves the mechanical stability and load-bearing capacity of the teeth during excavation. The results of this study can provide inspiration for the design of efficient mechanical components and agricultural implements.

Phylo-comparative analyses reveal the dual role of drift and selection in reproductive character displacement.

When incipient species meet in secondary contact, natural selection can rapidly reduce costly reproductive interactions by directly targeting reproductive traits. This process, called reproductive character displacement (RCD), leaves a characteristic pattern of geographic variation where divergence of traits between species is greater in sympatry than allopatry. However, because other forces can also cause similar patterns, care must be given in separating pattern from process. Here we show how the phylo-comparative method together with genomic data can be used to evaluate evolutionary processes at the population level in closely related species. Using this framework, we test the role of RCD in speciation of two cricket species endemic to Anatolian mountains by quantifying patterns of character displacement, rates of evolution and adaptive divergence. Our results show differing patterns of character displacement between species for reproductive vs. non-reproductive characters and strong patterns of asymmetric divergence. We demonstrate diversification results from rapid divergence of reproductive traits towards multiple optima under the dual influence of strong drift and selection. These results present the first solid evidence for RCD in Anatolian mountains, quantify the amount of drift and selection necessary for RCD to lead to speciation, and demonstrate the utility of phylo-comparative methods for quantifying evolutionary parameters at the population level.

Testing the role of trait reversal in evolutionary diversification using song loss in wild crickets.

The mechanisms underlying rapid macroevolution are controversial. One largely untested hypothesis that could inform this debate is that evolutionary reversals might release variation in vestigial traits, which then facilitates subsequent diversification. We evaluated this idea by testing key predictions about vestigial traits arising from sexual trait reversal in wild field crickets. In Hawaiian Teleogryllus oceanicus, the recent genetic loss of sound-producing and -amplifying structures on male wings eliminates their acoustic signals. Silence protects these "flatwing" males from an acoustically orienting parasitoid and appears to have evolved independently more than once. Here, we report that flatwing males show enhanced variation in vestigial resonator morphology under varied genetic backgrounds. Using laser Doppler vibrometry, we found that these vestigial sound-producing wing features resonate at highly variable acoustic frequencies well outside the normal range for this species. These results satisfy two important criteria for a mechanism driving rapid evolutionary diversification: Sexual signal loss was accompanied by a release of vestigial morphological variants, and these could facilitate the rapid evolution of novel signal values. Widespread secondary trait losses have been inferred from fossil and phylogenetic evidence across numerous taxa, and our results suggest that such reversals could play a role in shaping historical patterns of diversification.

Low-frequency vibration transmission and mechanosensory detection in the legs of cave crickets.

Vibrational communication is common in insects and often includes signals with prominent frequency components below 200 Hz, but the sensory adaptations for their detection are scarcely investigated. We performed an integrative study of the subgenual organ complex in Troglophilus cave crickets (Orthoptera: Rhaphidophoridae), a mechanosensory system of three scolopidial organs in the proximal tibia, for mechanical, anatomical and physiological aspects revealing matches to low frequency vibration detection. Microcomputed tomography shows that a part of the subgenual organ sensilla and especially the accessory organ posteriorly in this complex are placed closely underneath the cuticle, a position suited to evoke responses to low-frequency vibration via changes in the cuticular strain. Laser-Doppler vibrometry shows that in a narrow low-frequency range the posterior tibial surface reacts stronger to low frequency sinusoidal vibrations than the anterior tibial surface. This finding suggests that the posterior location of sensilla in tight connection to the cuticle, especially in the accessory organ, is adapted to improve detectability of low-frequency vibration signals. By electrophysiological recordings we identify a scolopidial receptor type tuned to 50-300 Hz vibrations, which projects into the central mechanosensory region specialised for processing low-frequency vibratory inputs, and most likely originates from the accessory organ or the posterior subgenual organ. Our findings contribute to understanding of the mechanical and neuronal basis of low-frequency vibration detection in insect legs and their highly differentiated sensory systems.

Sex and life history shape the strength of cellular and humoral immune responses in a wing dimorphic cricket.

Immune function is a complex collection of responses that often trade-off with one another and with other life history traits, because of the high costs of mounting and maintaining immune responses. Animals, even those from the same populations, may emphasize different aspects of immune function depending on their habitat and phenotype. For example, host population density mediates the threat from density-dependent parasites. Animals at high densities may emphasize fast-acting humoral responses, while those at low densities may favor slower, but more specific, cellular responses. However, these predictions may be dependent on other life history traits, like sex, which is associated with variation in many immune responses. We used wing dimorphic Gryllus firmus crickets to test humoral responses, measured by lysozyme and phenoloxidase activities, and cellular immune responses, measured by encapsulation, between morphs and sex. We found that both morphs and sexes differed in aspects of immune function. Long wing morphs had stronger encapsulation responses than short winged morphs. Additionally, females exhibited higher PO activity than males, and by contrast, males had higher lysozyme activity than females. Our study suggests that G. firmus morphs prioritize different immune responses that may reflect a balancing between the costs of immunity and differing pathogen threats. Male and female crickets exhibit differences in humoral immune responses that may reflect their different life history demands.