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Anthropophony is a prominent component of soundscapes worldwide and is known to impact biota. While responses to anthropophony in terrestrial and marine animals have been relatively well-studied, there is still a lack of knowledge regarding freshwater animals. In fact, freshwater taxa are among the possibly most threatened groups, and unveiling the reasons for their threat is crucial. We investigated the effect of low-frequency sounds -usually associated with anthropophony- on the stridulation of Krizousacorixa femorata, a common water bug in Mexico City. Using aerial recordings, we estimated the Normalized Difference Soundscape Index (NDSI), which is the most commonly used index to measure anthropophony, to characterize soundscapes in six city sites throughout the year. Additionally, from underwater recordings in the same sites, we obtained the peak frequency (Pf) of the stridulations, as it is the frequency with the highest energy and, therefore, the one that can travel the farthest and can be identified even in the presence of overlapping sounds. Finally, we evaluated the relationships between soundscapes and Pf through a mixed linear model. There was a negative correlation between NDSI and Pf, indicating higher-pitched stridulations at sites with dominant anthropophony. While we cannot rule out other factors contributing to stridulation variation, we remain uncertain about how low-frequency sounds impact freshwater ecosystems and the intricate relationship between soundscapes and aquatic life in urban settings. Implications for insect conservation: There is a correlation between anthropophony and variations in the stridulation of aquatic bugs. This highlights the possibility of sound pollution on freshwater systems, emphasizing the need for assessment to better understand and prevent potential harm to aquatic insects. [ABSTRACT FROM AUTHOR]

Circadian rhythms are ubiquitous in nature and endogenous circadian clocks drive the daily expression of many fitness-related behaviors. However, little is known about whether such traits are targets of selection imposed by natural enemies. In Hawaiian populations of the nocturnally active Pacific field cricket (Teleogryllus oceanicus) , males sing to attract mates, yet sexually selected singing rhythms are also subject to natural selection from the acoustically orienting and deadly parasitoid fly, Ormia ochracea. Here, we use T. oceanicus to test whether singing rhythms are endogenous and scheduled by circadian clocks, making them possible targets of selection imposed by flies. We also develop a novel audio-to-circadian analysis pipeline, capable of extracting useful parameters from which to train machine learning algorithms and process large quantities of audio data. Singing rhythms fulfilled all criteria for endogenous circadian clock control, including being driven by photoschedule, self-sustained periodicity of approximately 24 h, and being robust to variation in temperature. Furthermore, singing rhythms varied across individuals, which might suggest genetic variation on which natural and sexual selection pressures can act. Sexual signals and ornaments are well-known targets of selection by natural enemies, but our findings indicate that the circadian timing of those traits' expression may also determine fitness. [ABSTRACT FROM AUTHOR]

Sound production in Passandridae is discovered and the involved structures are described and illustrated using scanning electron microscopy (SEM), revealing a single type of stridulatory apparatus. The phylogenetic significance of this newly described mechanism is discussed based on a finely detailed analysis of representatives from 8 of 9 passandrid genera as well as from five closely related families, which allows hypothesizing the presence of a prosterno-coxal stridulatory apparatus as a unique synapomorphy of the clade comprising all passandrid genera except Aulonosoma Motschulsky. A note on the sound generation mechanism and behaviour is also provided. [ABSTRACT FROM AUTHOR]

Belohina inexpectata Paulian, 1958, the only known representative of Belohinidae (Coleoptera: Scarabaeoidea) and a Madagascan endemic, is redescribed based on recently collected material. Some remarks are provided on its unusual morphology and in particular its mouthparts, with recessed mandibles and membranous epipharynx, its antennae with a V-shaped sensory area and its capsule-like aedeagus, with a regular, unrotated position at rest and the presence of "parameroids". Data on its life history are also provided, including evidence of stridulation. Finally, its phylogenetic position is briefly discussed based on a molecular analysis, which points towards a sister-group relationship with the genus Orubesa (Dynamopodidae), with both taxa together being sister to Hybosoridae. [ABSTRACT FROM AUTHOR]

Silk and hawk moth caterpillars produce a variety of defence sounds described as clicking, chirping, whistling, and vocalising. Such diversity provides opportunity to test hypotheses on the functions and evolution of insect defence sounds using comparative analyses. A key step to conducting comparative analyses is to categorise different phenotypes. Here, we describe mandible sounds of 20 species of late instar Bombycoidea caterpillars and establish objective criteria for differentiating between sound-producing mechanisms. First, we assess how the two mandibular mechanisms – clicking and chirping – differ from one another using two reference species: Antheraea polyphemus (clicker) and Saturnia pyri (chirper). In these references, clicks are produced by ridged and serrated mandibles and have short duration units with few pulses, whereas chirps are produced by scalloped mandibles and have longer duration units with more pulses. Second, we characterise acoustic and morphological traits of 18 additional species. These are categorised as clickers (13 species), chirpers (4 species), or other (1 species) using diagnostic features identified from the reference species. Third, these categorisations are tested using a predictive logistic regression model. The results of this study contribute to our understanding of acoustically mediated defences in caterpillars and provide necessary criteria for conducting further comparative studies. [ABSTRACT FROM AUTHOR]

The evolution of the calling songs in Gomphocerinae was evaluated via estimating a phylogenetic signal of the song characters and an ancestral character state reconstruction. Analyses of the calling songs in 80 palearctic gomphocerine species allowed us to define 24 characters describing the temporal pattern of the sound and the stridulatory leg‐movement pattern. The ancestral song of Gomphocerinae was shown to consist of numerous short echemes lasting on average 0.9 s; each echeme comprised only one syllable produced by movements of only one leg. The next step of the song evolution could be producing longer echemes or longer echeme‐sequence. Later, echeme duration again decreased, but this was accompanied by increasing of echeme or syllable complexity. The characters describing the echeme structure were found to be conservative in their evolution. By contrast, most characters of the syllable temporal structure were shown to be relatively labile and more likely under natural or sexual selection. Our study shows that the song evolution in Gomphocerinae implied not only increasing but also decreasing complexity of the syllable temporal structure. [ABSTRACT FROM AUTHOR]

Katydids produce sound for signaling and communication by stridulation of the tegmina. Unlike crickets, most katydids are known to sing at ultrasonic frequencies. This has drawn interest in the investigation of the biophysics of ultrasonic sound production, detection, evolution, and ecology (including predator-prey interactions) of these katydids. However, most of these studies are based on species from the Neotropics, while little is known about katydid species from the hyperdiverse region of Southeast Asia. To address this, a concerted effort to document, record, and describe the calling songs of Southeast Asian katydids, especially species that call at ultrasonic frequencies, was made. A study spanning two years (2018-2020) in the Malay Peninsula (Singapore and Malaysia), Borneo (Brunei Darussalam and Sabah), and the Philippines revealed previously unknown calls of 24 katydid species from four subfamilies. The calling songs of Southeast Asian katydid species are highly diversified in terms of time and frequency. Call structure can range from isolated syllables (e.g., Holochlora), continuous trills (e.g., Axylus philippinus), to short pulse-trains (e.g., Euanisous teuthroides) and complex echemes (e.g., Conocephalus spp.), with 87.5% of species having ultrasonic peak frequencies and 12.5% being considered extreme ultrasonic callers (peak frequency >40 kHz). The call spectrum ranges from tonal (e.g., spectral entropy is 6.8 in Casigneta sp. 2) to resonant (entropy is 8.8 in Conocephalus cognatus). Of the 24 species whose calls are described here, we imaged and described the soundproducing structures of 18. This study provides a preliminary overview of the acoustic diversity of katydids in Southeast Asia, and the authors hope to inspire further investigation into the bioacoustics of little-known katydids from these areas. Amassing a database of calling songs and soundproducing organ illustrations from different species is important to address taxonomic impediments while advancing our knowledge about the bioacoustics of Southeast Asian katydids. [ABSTRACT FROM AUTHOR]

Intra- and interspecific communication is crucial to fitness via its role in facilitating mating, territoriality and defence. Yet, the evolution of animal communication systems is puzzling—how do they originate and change over time? Studying stridulatory morphology provides a tractable opportunity to deduce the origin and diversification of a communication mechanism. Stridulation occurs when two sclerotized structures rub together to produce vibratory and acoustic (vibroacoustic) signals, such as a cricket ‘chirp’. We investigated the evolution of stridulatory mechanisms in the superfamily Coreoidea (Hemiptera: Heteroptera), a group of insects known for elaborate male fighting behaviours and enlarged hindlegs. We surveyed a large sampling of taxa and used a phylogenomic dataset to investigate the evolution of stridulatory mechanisms. We identified four mechanisms, with at least five evolutionary gains. One mechanism, occurring only in male Harmostini (Rhopalidae), is described for the first time. Some stridulatory mechanisms appear to be non-homoplastic apomorphies within Rhopalidae, while others are homoplastic or potentially homoplastic within Coreidae and Alydidae, respectively. We detected no losses of these mechanisms once evolved, suggesting they are adaptive. Our work sets the stage for further behavioural, evolutionary and ecological studies to better understand the context in which these traits evolve and change.

The Cestrophorini are small katydids of Ecuador’s montane rainforest bearing a prominent awl-shaped fastigium verticis. They are unusual among Conocephalinae in lacking pre-tympanic ear chambers: their eardrums are exposed on their fore tibiae. There are presently two genera, Cestrophorus Redtenbacher, 1891 and Acanthacara Scudder, 1869. Awl-head habitat includes both climax forest and anthropogenically disturbed areas (e.g., pastures, roadsides) on lower slopes in the drainage of the volcanoes Aliso, Chiles and Tungurahua. At night, males perch on low vegetation and stridulate to attract females. To three extant species, we add a further seven, two in Cestrophorus and five in Acanthacara. Male calling songs were recorded and analyzed for all three Cestrophorus species and for three of the Acanthacara spp. We describe and discuss the waveforms of their sinusoid and transient sound pulses in time and frequency domains. [ABSTRACT FROM AUTHOR]

Hypostomus is the most diverse genus within Loricariidae. These catfish species exhibit a very conservative morphology with relatively few external characteristics that differ between different species. In consequence, there is a challenge to understand the distinction of species of this genus. This study aims to describe the sounds produced by ten species of Hypostomus from Araguari River and Paraopeba River (Minas Gerais, Brazil), to examine whether acoustic features could be used to distinguish between the species, and to understand the corresponding sound production mechanisms. The fish were recorded making sounds by holding them in hand underwater, in a glass tank on the river shore next to where they had been caught. All ten species produced sounds, and no effect of body size on acoustic features was observed. Furthermore, the species could not be distinguished using acoustic features. Likewise, all the studied species exhibited similar bony ridges on the dorsal processes of the pectoral spine. Since the sounds produced by the fish do not seem to exhibit interspecific specificity, they do not appear to have a role in behaviours requiring conspecific recognition, such as reproduction. Sound production may have an alarm, distress, or acoustic aposematism function warning predators of the presence of pectoral spines, which have an anti‐predatory function in this clade. [ABSTRACT FROM AUTHOR]

The genera Holocnemus Simon, 1873 and Crossopriza Simon, 1893 are revised. Together with Stygopholcus Kratochvíl, 1932 (revised recently) and the newly described genus Maghreba gen. nov., they constitute the spotted-leg clade within the northern clade of Smeringopinae. Males and females in this group are characterized by dark marks on the leg femora and tibiae. The native area of the spotted-leg clade ranges from northern Africa and the Mediterranean to Central Asia and NW India. A morphological cladistic analysis suggests that Holocnemus is paraphyletic while Crossopriza is monophyletic, but morphology seems only partly adequate to resolve phylogenetic relationships convincingly. The genus Holocnemus includes four species, all of which are redescribed: H. pluchei (Scopoli, 1763); H. reini (C. Koch, 1873) comb. nov. (transferred from Pholcus); H. caudatus (Dufour, 1820); and H. hispanicus Wiehle, 1933. The genus Maghreba gen. nov. includes eight species from NW Africa: M. aurouxi (Barrientos, 2019) gen. et comb. nov. (transferred from Holocnemus; redescribed, female newly described) and seven newly described species. The genus Crossopriza includes six previously described species (of which five are redescribed), and 18 newly described species. The Madagascan C. nigrescens Millot, 1946 is synonymized with C. lyoni (Blackwall, 1867). All new species are described on the basis of both sexes.

Ecoacoustics is increasingly being used to monitor species populations and to estimate biodiversity in marine ecosystems, but the underwater soundscapes of freshwater environments remain largely unexplored in this respect. Few studies exist concerning the acoustic diversity of ponds, but because aquatic plants and many arthropods such as Coleoptera and Hemiptera are known to produce sound, there is potential to use ecoacoustic techniques to monitor changes in biodiversity and conservation value.This pilot study compares the underwater soundscapes of recently restored open‐canopy ponds and unmanaged highly terrestrialized ponds situated in an arable agricultural landscape of North Norfolk, UK, in order to assess the benefits of farmland pond restoration.Daytime sound recordings were made for 10 min in each pond and analysed primarily for arthropod stridulations. In addition, six commonly used acoustic indices were calculated to assess the soundscape biodiversity between the unmanaged and the restored ponds. The stridulations of three diving beetle species (Dytiscidae) were recorded in tank studies to assess the potential for individual species recognition from underwater sound capture.Sound‐type richness and abundance, as estimated by visually and aurally identifying arthropod stridulation from spectrograms, were significantly higher in the restored open‐canopy ponds compared with the unmanaged terrestrialized ponds. In addition, the acoustic indices 'acoustic complexity' and 'biodiversity index' were significantly higher in restored open‐canopy ponds than in unmanaged terrestrialized ponds.The three dytiscid water beetle species recorded in a tank were found to produce distinctive and recognizable sounds, indicating potential to create an audio reference library that could be used for automatic acoustic monitoring of freshwater arthropods.Pond soundscapes are rich in biological information and this study suggests that, with further development, automated passive ecoacoustic monitoring could be an effective non‐invasive technique for assessing pond conservation value and pond restoration and management success. [ABSTRACT FROM AUTHOR]

The social parasitic beetle Paussus favieri (Coleoptera, Carabidae, Paussini) performs different types of stridulations, which selectively mimic those emitted by different ant castes of its host Pheidole pallidula (Hymenoptera, Formicidae, Myrmicinae). However, the significance of this acoustical mimicry for the success of the parasitic strategy and the behaviors elicited in the host ants by stridulations was unknown. We reared Paussus favieri in Pheidole pallidula colonies and filmed their interacting behaviors. We analyzed in slow motion the behavior of ants near a stridulating beetle. We analyzed separately trains of pulse (Pa + Pb, produced by repeated rubbings) and single pulse (Pc, produced by a single rubbing) of stridulations, clearly recognizable from the shaking up and down of the beetle hind legs, and associated them with different ant responses. The full repertoire of sounds produced by P. favieri elicited benevolent responses both in workers and soldiers. We found that different signals elicit different (sometimes multiple) behaviors in ants, with different frequency in the two ant castes. However, Pc (alone or in conjunction with other types of pulses) appears to be the type of acoustic signal mostly responsible for all recorded behaviors. These results indicate that the acoustic channel plays a pivotal role in the host–parasite interaction. Finding that a parasite uses the acoustical channel so intensively, and in such a complicated way to trigger ant behaviors, indicates that acoustic signals may be more important in ant societies than commonly recognized. [ABSTRACT FROM AUTHOR]

Abstract. The emission of distress stridulation is a common defense mechanism among insects, including species from the order Hymenoptera (ants, bees and wasps). Wasps from the family Mutillidae (also known as velvet ants) emit audible distress stridulations when attacked. While species-specific variation in the acoustic properties of velvet ants stridulation has been described, one common theme across species is the absence of ultrasonic frequency components (> 20 kHz). We recorded and analyzed the distress stridulation emitted by females of three species of Chilean endemic velvet ants, popularly known as panda ants: Euspinolia chilensis (Spinola, 1851), E. militaris (Mickel, 1938) and Reedomutilla gayi (Spinola, 1851). In general, the stridulation emitted by R. gayi is similar to the distress signal of other velvet ant species described to date. In contrast, the distress signals of both Euspinolia species differ from previously reported Mutillidae stridulations, including the presence of high-frequency spectral components, reaching the ultrasonic range. Due to the scarce information on the natural predators of South American velvet ant species, the defensive significance of distress stridulation having ultrasonic components remains unknown, however, its potential role against reptile and rodent predators is discussed and its potential role as intra-specific communication is suggested.

Bark and ambrosia beetles and pinhole borers (Coleoptera: Curculionidae: Scolytinae and Platypodinae) are two subfamilies of weevils that use acoustic communication within plant tissue. These insects transmit and detect sound in a medium that is neither air nor water and they are among the smallest animals with sound-producing organs. Nevertheless, their sound production is sorely understudied, mostly due to the difficulties associated with acoustically monitoring individuals inside plants. We analysed the stridulatory sounds from 55 bark and ambrosia beetle species within 15 subtribes collected in four countries, making this the largest acoustic dataset of these taxa to date. We characterised and compared the amplitude and spectro-temporal parameters of the distress airborne signals produced by the beetles, in conjunction with phenology and life history data. Sound production was present in 33% of the collected species, of which 60% of these sounds had not been previously reported. Depending on species, either both sexes stridulated or only one. Some species had calls with different acoustic morphotypes (one, two, or three notes), and when both sexes stridulated, sounds generally differed. Our data suggest that type of mating system and size play an important role in determining the acoustic communicatory capacity of most species. [ABSTRACT FROM AUTHOR]

The biology and seasonal phenology of Aacanthocnema dobsoni (Froggatt) were studied at a single site in Victoria over a 2 year period between 2013 and 2015. This species is monophagous on the dioecious host, Allocasuarina verticillata (Lam.) L. Johnson (Casuarinaceae). Laboratory studies found that females attained reproductive maturity 24 h post‐eclosion, lived for 28.6 ± 2.8 (mean ± SE) days and laid 182 ± 23 (mean ± SE) eggs each. Egg development was most rapid at 26 °C, ceased below 7 °C and above 33 °C; hatching required 188 degree‐days. Nymphs could not be reared to adulthood on excised host branchlets maintained under controlled conditions, so no developmental data were obtained for these life stages. Seasonal phenology data revealed pronounced developmental asynchrony, i.e. with overlapping generations and multiple life stages occurring simultaneously. Three generations per year were observed, and there was no evidence of either developmental (egg and nymph) or reproductive diapause. A 4 day heat wave in January 2014 drastically reduced psyllid abundance at the study site and the size of the adults that eclosed from the surviving nymphs. These smaller adults produced substrate‐borne vibrational signals with altered characteristics, i.e. with significantly higher intensities and power. The altered signals might have facilitated communication over longer distances and increased mate finding opportunities when populations were low. The abundance of adults had recovered to preheat wave levels 3 months after the heat wave. High fecundity, multivoltinism and effective mate attraction signalling are life history traits that may mitigate against localised extinction of populations as a consequence of extreme weather events. [ABSTRACT FROM AUTHOR]

Crickets are mainly nocturnal species known for the loud, persistent, chirping sounds many of their species make. Cricket chirping, or stridulation, is produced when the insect rubs together stridulatory organs located on the forewings. Stridulation is a form of intraspecific acoustic communication used by males to entice females. However, predators and parasitic insects may exploit their singing, using it to find their cricket prey. Consequently, crickets cease chirping when they sense sound frequency vibrations nearby, indicating that a predator is nearby. In this experiment, the cricket species Acheta domesticus (Linnaeus)(Orthoptera:Gryllidae) was used to test stridulation frequency differences based on exposure to different music genres. Crickets were exposed to either silence (control), hip hop, jazz, country, or classical music. During this music exposure period, the number of chirps was counted for one minute. Stridulation frequency was 83.3 chirps per minute for the control setting, 65 chirps per minute for classical music, 61.3 chirps per minute for country music, 54 chirps per minute for jazz music, and 41 chirps per minute for hip hop music. Causative factors for this trend may be due to neurological characteristics of the cricket. A major auditory sensory neuron, Ascending Neuron 1 (AN1), is excited by both highfrequency sounds and self-generated chirps. We conclude that music genres dominated by highfrequency sounds, such as hip hop and jazz, stimulate AN1, causing increased auditory information to be sent to the brain, leading to decreased stridulation as crickets interpret this information as the presence of a possible threat. [ABSTRACT FROM AUTHOR]

Stridulatory signals are involved in conspecific interactions between bark beetles (Coleoptera: Curculionidae, Scolytinae). In this study, we compared the qualitative profiles of acoustic signals in three species from the genus Polygraphus Er. Sympatry can be periodically observed in two of them –P. proximus and P. subopacus. Sporadically they occur on the same plants. P. nigrielytris colonize distinctly different host plant species; however, on the island of Sakhalin it inhabits the same biotopes. The purpose of the study is to identify species-specific parameters and the extent of differences in stridulatory signals of these species. Airborne signals produced during the contact of males of the same species were experimentally recorded. Among tested parameters of stridulatory signals, as the most species-specific were noted: chirp duration, number of tooth-strikes per chirp, and intertooth-strike interval.

Sexual selection is a major evolutionary process, shaping organisms in terms of success in competition for access to mates and their gametes. The study of sexual selection has provided rich empirical and theoretical literature addressing the ecological and evolutionary causes and consequences of competition for gametes. However, there remains a bias towards individual, species-specific studies, whilst broader, cross-species comparisons looking for wider-ranging patterns in sexual selection remain uncommon. For instance, we are still some ways from understanding why particular kinds of traits tend to evolve under sexual selection, and under what circumstances. Here we consider sexual selection in the Heteroptera, a sub-order of the Hemiptera, or true bugs. The latter is the largest of the hemimetabolous insect orders, whilst the Heteroptera itself comprises some 40,000-plus described species. We focus on four key sexual signaling modes found in the Heteroptera: chemical signals, acoustic signaling via stridulation, vibrational (substrate) signaling, and finally tactile signaling (antennation). We compare how these modes vary across broad habitat types and provide a review of each type of signal. We ask how we might move towards a more predictive theory of sexual selection, that links mechanisms and targets of sexual selection to various ecologies.

Hygrobiidae, or squeak beetles, originated in the Triassic-Jurassic and exhibit a relictual distribution in the Palaearctic, Oriental and Australasian regions. Hygrobiids are well known for their sound-producing abilities, although studies of their bioacoustics remain limited. Here we describe sound producing organs and bioacoustics of the Palaearctic Hygrobia hermanni (Fabricius, 1775). Plectra and pars stridens were examined in both sexes, and sound characteristics analysed. Despite small differences between male and female last abdominal ventrites, plectra were identical. Pars stridens, however, differed subtly, tooth ridges being wider in females. Calls of both sexes were harmonic, with peak frequency at 6.1 kHz, and secondary peak at 10.9 kHz; males exhibiting longer inter-chirp intervals. Calls changed with time in the laboratory, this possibly condition-related effect being more apparent in males. The differences found between sexes suggest that sound production in squeak beetles may function in intraspecific communication, in addition to being an antipredator device. [ABSTRACT FROM AUTHOR]

Blue catfish Ictalurus furcatus, the largest catfish in North America and an invasive species in Chesapeake Bay estuaries, has experienced explosive population growth, negatively impacting native species. They have strong pectoral spines that can be locked and rubbed against the pectoral girdle to produce stridulation sounds although sound production during behavioral interactions is unstudied. We examined agonistic behavior in juveniles by allowing individuals to establish a territory and introducing an intruder. Big (43–50 cm total length) and small (36–41 cm) fish were paired within and across size ranges. Territory was considered established when a fish remained in its shelter for over an hour. Fish typically entered the shelter head first and maintained that orientation. They used a variety of agonistic behaviors in shelter defense including aggressive contact, caudal sweeping, and standoff but not the production of stridulation sounds. Individuals often utilized different behaviors indicating less stereotypy than in many fishes, and there were differences in incidence of behaviors between big and small fish. Residents and larger fish did not always win, perhaps due to juvenile status and low fitness consequences of territorial possession. [ABSTRACT FROM AUTHOR]

Stridulatory signals are involved in conspecific interactions between bark beetles (Coleoptera: Curculionidae, Scolytinae). In this study, we compared the qualitative profiles of acoustic signals in three species from the genus Polygraphus Er. Sympatry can be periodically observed in two of them -P. proximus and P. subopacus. Sporadically they occur on the same plants. P. nigrielytris colonize distinctly different host plant species; however, on the island of Sakhalin it inhabits the same biotopes. The purpose of the study is to identify species-specific parameters and the extent of differences in stridulatory signals of these species. Airborne signals produced during the contact of males of the same species were experimentally recorded. Among tested parameters of stridulatory signals, as the most species-specific were noted: chirp duration, number of tooth-strikes per chirp, and intertooth-strike interval. [ABSTRACT FROM AUTHOR]

Leafcutter ants communicate with the substrate-borne component of the vibratory emission produced by stridulation. Stridulatory signals in the genus Atta have been described in different behavioural contexts, such as foraging, alarm signalling and collective nest building. Stridulatory vibrations are employed to recruit nestmates, which can localize the source of vibration, but there is little information about the underlying mechanisms. Our experiments reveal that time-of-arrival delays of the vibrational signals are used for tropotactic orientation in Atta sexdens. The detected time delays are in the same range as the time delays detected by termites. Chemical communication is also of great importance in foraging organization, and signals of different modalities may be combined in promoting the organization of collective foraging. Here we show that the tropotactic orientation to vibrational signals interacts with chemical communication signals.

Strident lobsters of the Palinuridae family emit sounds in the presence of predators that can be used in the acoustic monitoring of such species. This study aims to identify sound emission and describe the structures of sound mechanism in red (Panulirus meripurpuratus) and green (Panulirus laevicauda) Brazilian spiny lobsters. The lobsters were collected in the environment, and recordings were performed in laboratory tanks with submerged hydrophones. The animals were stimulated to emit sound by the presence of an artificial octopus in the tank. The sounds emitted by the lobsters were analyzed by means of the waveform, and the structures involved (plectrum and file) were observed using scanning electron microscopy (SEM). Both species emitted a rasp sound composed of several pulses, with a rate varying from 125 to 265 pulses per second. The SEM showed that the file is similar between the species and it is covered by microscopic plates (shingles) measuring between 12.6 and 12.9 μm of medial–lateral width and 6.2 μm and 7.1 μm of anteroposterior length. This analysis also revealed for the first time the presence of pores (< 1 μm in diameter) with vestiges of cuticular setae in-between the shingles, which could be involved in the mechanosensory control of sound production in lobsters. The results of this study corroborate the morphological pattern of sound emission structure described for other lobsters of the genus Panulirus. [ABSTRACT FROM AUTHOR]

Theraphosid spiders are repleted with cuticular structures that evolved into distinct morphologies and developed different functions. The stridulatory apparatus present in the subfamily Theraphosinae is composed by a group of setae and opposed organs (ridged surface) that emit sound through friction. Only sixteen genera of Theraphosinae spiders were reported with stridulatory setae: Acanthoscurria , Aguapanela, Brachypelma, Citharacanthus, Cyrtopholis , Grammostola , Hemirrhagus, Lasiodora , Longilyra , Nhandu, Theraphosa, Pamphobeteus, Phormictopus, Proshapalopus, Pterinopelma and Vitalius. Besides these stridulating setae, other cuticular structures have been traditionally used in Theraphosinae taxonomy: the plumose scopula on the lateral faces of femora I and IV. However, the ultrastructure of these setae and scopulae was never studied in detail. Here, we analyzed the diversity of cuticular structures on coxae, trochanters and femora of Theraphosinae spiders using SEM. Beside the description of plumose and claviform stridulating setae on femora, we established five distinct variations of stridulatory setae found on coxae and trochanters and report their presence for the genus Megaphobema , Crassicrus and Cotztetlana for the first time. [ABSTRACT FROM AUTHOR]

Social parasitism represents a particular type of agonistic interaction in which a parasite exploits an entire society instead of a single organism. One fascinating form of social parasitism in ants is the “inquilinism”, in which a typically worker-less parasitic queen coexists with the resident queen in the host colony and produces sexual offspring. To bypass the recognition system of host colonies, inquilines have evolved a repertoire of deceiving strategies. We tested the level of integration of the inquiline Myrmica karavajevi within the host colonies of M. scabrinodis and we investigated the mechanisms of chemical and vibroacoustic deception used by the parasite. M. karavajevi is integrated into the ant colony to such an extent that, in rescue experiments, the parasite pupae were saved prior to the host’s brood. M. karavajevi gynes perfectly imitated the cuticular hydrocarbon profiles of M. scabrinodis queens and the parasite vibroacoustic signals resembled those emitted by the host queens eliciting the same levels of attention in the host workers during playback experiments. Our results suggest that M. karavajevi has evolved ultimate deception strategies to reach the highest social status in the colony hierarchy, encouraging the use of a combined molecular and behavioural approach when studying host–parasite interactions.

Circadian rhythms are ubiquitous in nature and endogenous circadian clocks drive the daily expression of many fitness-related behaviors. However, little is known about whether such traits are targets of selection imposed by natural enemies. In Hawaiian populations of the nocturnally active Pacific field cricket ( Teleogryllus oceanicus) , males sing to attract mates, yet sexually selected singing rhythms are also subject to natural selection from the acoustically orienting and deadly parasitoid fly, Ormia ochracea . Here, we use T. oceanicus to test whether singing rhythms are endogenous and scheduled by circadian clocks, making them possible targets of selection imposed by flies. We also develop a novel audio-to-circadian analysis pipeline, capable of extracting useful parameters from which to train machine learning algorithms and process large quantities of audio data. Singing rhythms fulfilled all criteria for endogenous circadian clock control, including being driven by photoschedule, self-sustained periodicity of approximately 24 h, and being robust to variation in temperature. Furthermore, singing rhythms varied across individuals, which might suggest genetic variation on which natural and sexual selection pressures can act. Sexual signals and ornaments are well-known targets of selection by natural enemies, but our findings indicate that the circadian timing of those traits' expression may also determine fitness., Competing Interests: The authors declare no competing interests., (© The Author(s) 2023. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology.)

In a sexual context, it is expected that females base their choice of mate on the behaviours that males perform during courtship, as such behaviours are associated with the male's mate quality. Stridulation is one form of female communication in arthropods, for example, spiders. In spiders, stridulation during sexual interactions is relatively common in some groups but mainly restricted to males. In the pholcid spider Holocnemus pluchei (Pholcidae), both sexes have stridulatory organs. The aims of the present work were to: (a) determine possible differences in the frequency of occurrence of stridulation between females during inter‐sexual interactions, (b) establish female consistency in stridulation along repeated interactions and (c) analyse if female stridulation is associated with certain male behaviours during pre‐copulatory courtship and with male size. Female H. pluchei showed highly repeatable differences in their frequency of stridulation across consecutive encounters with males (ICC = 0.64). However, only a modest level of repeatability was detected in total time females spent stridulating across trials (ICC = 0.19). Females' mean stridulatory behaviour did not change across ten consecutive trials spread across 20 days, and their behaviour was apparently unaffected by male persistence of copulatory attempted and/or size. These results imply that the frequency of female stridulatory behaviour is a trait that is highly characteristic of each individual. Finally, our work opens the door to determine whether behavioural consistency manifests in other ecological contexts and their functional implications. [ABSTRACT FROM AUTHOR]

Highlights • Accelerometer is an efficient tool to monitor the acoustic behaviour of P. elephas. • Low accelerometer sample frequencies don't influence detection of acoustic events. • Low accelerometer sample frequencies increase the error on pulses estimation. • Accelerometer data let to separate acoustic from behavioural events of P. elephas. Abstract The European spiny lobster Palinurus elephas emits sound ("rasp"), moving the base of their antennas, as response to the presence of predator and for interspecific communication. During the last decade, three-axial accelerometers have been used to mainly describe diel activity patterns, circadian rhythms and rate of energy consumption of different lobster species, but these devices can also record sound emission in terms of mechanical vibration of carapace. In order to evaluate the efficiency of accelerometers in recording sound production (rasp events and number of pulses inside each rasp) and in discriminating of that from other behavioural events, accelerometers were used in combination with hydrophone and during mesocosm free ranging conditions. Three-axial accelerometers were able to detect sound production events in P. elephas. All the rasp events (n = 405) recorded with hydrophones were also detected by the accelerometers considering its data sampled at different frequency (from 800 Hz to 12 Hz). However, the detection of the number of pulses within each rasp sound decreased with sampling frequency of accelerometer data (median of predictive error for 800 Hz = 0.33; median of predictive error for 12 Hz = 0.65). During mesocosm free condition, three behavioural categories were identified: walk, tail flip, and rasp, the last with averaged (15.16 ± 3.52 m/s2) and maximum (29.49 ± 9.37 m/s2) values of acceleration significantly higher than the other two. Findings from this study prove that accelerometers register only lobster body vibrations providing a clear signal that is not distorted by other noises in the environment. They also allowed to identify rasps for each tagged lobster, something not possible using hydrophones in both, aquaria or natural habitat. Accelerometer resulted an useful tool to detect behaviours even with low mobility species. Moreover, the possibility to couple accelerometer and other biologging techniques would help to improve our understanding of the behaviour of a large range of free-living species. [ABSTRACT FROM AUTHOR]

Many insects vary their song patterns to communicate different messages, but the underlying biomechanisms are often poorly understood. Here, we report on the mechanics of sound production and variation in an elytro-tergal stridulator, male Dendroctonus valens bark beetles. Using ablation experiments coupled with high-speed video and audio recordings, we show that: (1) chirps are produced using a stridulatory file on the left elytron (forewing) and a protrusion (plectrum) on the seventh abdominal segment; (2) chirps are produced by 'spring stridulation', a catch-and-release mechanism whereby the plectrum catches on a file tooth and, upon release, springs forward along the file; and (3) variability in chirp types is caused by introducing multiple catch-and-release events along the file to create regular interruptions. These results provide experimental evidence for the mechanics of elytro-tergal stridulation, and provide insight into how an insect can incorporate variability into its acoustic repertoire using a spring-loaded mechanism. [ABSTRACT FROM AUTHOR]

Invasion of Polygraphus proximus (Blandford) has caused an extensive destruction in the aboriginal forest ecosystems of South Siberia. The goal of this study was to better understand the acoustic communication of P. proximus by analyzing the beetles' sound-production mechanisms and comparing sounds produced during different behaviors. Comparisons applied waveform analysis and quantitation of temporal parameters such as syllable, chirp duration, interchirp interval, number of tooth-strike per chirp, strike rate, and the duration of intervals between strikes. We recorded the acoustic signals of the bark beetle in three behavioral contexts: stress (handling), rivalry (male–male interactions), and courtship (male–female interactions). Acoustic signals produced during stress, rivalry behavior, and courtship chirps have very similar waveforms but are distinguishable according to temporal parameters (e.g. number of strikes in chirps and duration of intervals between them). During courtship, males produce two types of chirps. The first type was produced in all three contexts. The second chirp type was registered only in male–female interactions just before copulation. Precopulation signals produced by rubbing of the tibia against the elytral margin were registered for the first time in a bark beetle. The role of the precopulation signal was the clearest. The established modulations of signals in stress trials in comparison with the similar courtship and rivalry chirps are apparently due to effects of insect body movement against restraint. We hypothesize that the chirp temporal parameters in courtship and rivalry may be used by the sender to reveal his presence or physical characteristics to a receiver (female or rival male). [ABSTRACT FROM AUTHOR]

Asian genera and species of the plant bug tribe Hallodapini are reviewed. The present classification system is based particularly on detailed morphology and function of the stridulatory device and concealed habitat preference. Our recent efforts successfully demonstrated that the stridulatory devices of the forewing edge and dorsal metafemur are doubtlessly used for intraspecific communication (at least for courtship behavior). Based on the stridulatory structures and additional characters, Cleotomiris Schuh, 1995, Cleotomiroides Schuh, 1984, Hallodapus Fieber, 1858 and Wygomiris Schuh, 1984, are re-diagnosed and discussed; Alloeomimella Yasunaga & Duwal gen. nov. is proposed to accommodate Alloeomimus muiri Schuh, 1984 and a new combination, Alloeomimella muiri (Schuh) comb. nov., is accordingly established. Six new species are further described: Cleotomiroides ishikawachui Yasunaga & Duwal sp. nov. (Indonesia: Java); Hallodapus jingfui Yasunaga & Duwal sp. nov. (Taiwan); H. spinosus Yasunaga & Duwal sp. nov. (Thailand); H. susurratus Yasunaga & Duwal sp. nov. (Thailand); Wygomiris paveli sp. nov. (Taiwan); and W. phormictes sp. nov. (Taiwan). The male of Wygomiris nanae Yasunaga, 2012 is reported for the first time. A teratological form found on the antennae in two Wygomiris species is also documented. [ABSTRACT FROM AUTHOR]

Pupae of numerous Papilionidae and Nymphalidae produce twitter sounds when wriggling in response to mechanical stimulation. The structural basis comprises distinct pairs of sound-producing organs (SPOs) located at intersegmental membranes of the abdomen. They differ—as the twitters do—in sampled taxa of Papilioninae, Epicaliini, and Heliconiini. The opposing sculptured cuticular sound plates (SPs) of each SPO appear structurally the same but are actually mirror-images of each other. Results suggest that sounds are not generated by stridulation (friction of a file and a scraper) but when these inversely sculptured and interlocking surfaces separate during pupal wriggling, representing a stick-slip mechanism. Twitter sounds comprise series of short broadband pulses with the main energy in the frequency range 3–13 kHz; they can be heard by humans but extend into ultrasonic frequencies up to 100 kHz. [ABSTRACT FROM AUTHOR]

Male katydids produce mating calls by stridulation using specialized structures on the forewings. The right wing (RW) bears a scraper connected to a drum-like cell known as the mirror and a left wing (LW) that overlaps the RW and bears a serrated vein on the ventral side, the stridulatory file. Sound is generated with the scraper sweeping across the file, producing vibrations that are amplified by the mirror. Using this sound generator, katydids exploit a range of song carrier frequencies (CF) unsurpassed by any other insect group, with species singing as low as 600 Hz and others as high as 150 kHz. Sound generator size has been shown to scale negatively with CF, but such observations derive from studies based on few species, without phylogenetic control, and/or using only the RW mirror length. We carried out a phylogenetic comparative analysis involving 94 species of katydids to study the relationship between LW and RW components of the sound generator and the CF of the male's mating call, while taking into account body size and phylogenetic relationships. The results showed that CF negatively scaled with all morphological measures, but was most strongly related to components of the sound generation system (file, LW and RW mirrors). Interestingly, the LW mirror (reduced and nonfunctional) predicted CF more accurately than the RW mirror, and body size is not a reliable CF predictor. Mathematical models were verified on known species for predicting CF in species for which sound is unknown (e.g. fossils or museum specimens). [ABSTRACT FROM AUTHOR]

The Afrotropical subgenus Phornus Paulian, 1948 of the genus Orphnus MacLeay, 1819 is revised and currently comprises six species. Four new species are described: Orphnus renaudi sp. nov., Orphnus valeriae sp. nov., Orphnus ferrierei sp. nov. and Orphnus parastrangulatus sp. nov. The subgenus is characterized by the coarse stridulatory field, sclerotized plate on the second abdominal sternite near plectrum, absence of the pronotal lateral processes in males, rounded apices of the parameres and endophallus without armature, although some of these characters differ in O. giganteus Paulian, 1948. Symphysocery is reported for the first time for members of the Orphninae. In O. giganteus, the majority of specimens have malformed antennomeres. Four of the six species of Phornus are brachypterous and all species except for O. giganteus are known only from males. A key to Phornus species and a map of their localities are provided.