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The insect gut is colonized by microbes that confer a myriad of beneficial services to the host, including nutritional support, immune enhancement, and even influence behavior. Insect gut microbes show dynamic changes due to the gut compartments, sex, and seasonal and geographic influences. Crickets are omnivorous hemimetabolous insects that have sex-specific roles, such as males producing chirping sounds for communication and exhibiting fighting behavior. However, limited information is available on their gut bacterial communities, hampering studies on functional compartmentalization of the gut and sex-specific roles of the gut microbiota in omnivorous insects. Here, we report a metagenomic analysis of the gut bacteriome of the field cricket Teleogryllus occipitalis using 16S rRNA V3-V4 amplicon sequencing to identify sex- and compartment-dependent influences on its diversity and function. The structure of the gut microbiota is strongly influenced by their gut compartments rather than sex. The species richness and diversity analyses revealed large difference in the bacterial communities between the gut compartments while minor differences were observed between the sexes. Analysis of relative abundance and predicted functions revealed that nitrogen- and oxygen-dependent metabolism and amino acid turnover were subjected to functional compartmentalization in the gut. Comparisons between the sexes revealed differences in the gut microbiota, reflecting efficiency in energy use, including glycolytic and carbohydrate metabolism, suggesting a possible involvement in egg production in females. This study provides insights into the gut compartment dependent and sex-specific roles of host-gut symbiont interactions in crickets and the industrial production of crickets. [ABSTRACT FROM AUTHOR]

Previous studies on sex differences in behaviour have largely focused on differences in average behaviours between sexes. However, males and females can diverge not only in average behaviours but also in the direction of behavioural correlations at the individual level (i.e. behavioural syndromes). Behavioural syndromes, with their potential to constrain the independent evolution of behaviours, may play a role in shaping sex‐specific responses to selection and contributing to the development of sex differences in behaviour. Despite the pivotal role of behavioural syndromes in the evolution of sexual dimorphism in behaviour, robust empirical evidence of sex differences in behavioural syndromes based on repeated measurements of behaviours is scarce. In this study, we conducted repeated measurements of activity and aggression in male and female field crickets Teleogryllus emma, providing evidence of sex differences in the existence of behavioural syndromes. Males exhibited a significantly positive behavioural syndrome between activity and aggression, whereas females, in contrast, did not show any aggressive behaviour, resulting in the absence of such a syndrome. The sex differences in the existence of the activity‐aggression behavioural syndromes in this species could be attributed to differences in selection. Selection favouring more active and aggressive males may have shaped a positive activity‐aggression behavioural syndrome in males, whereas the absence of selection favouring female aggression may have resulted in the absence of aggression and the related behavioural syndrome in females. However, given the plasticity of behaviour with changes in age or the environment, further research is needed to explore how sex differences in the existence of activity‐aggression behavioural syndromes change across contexts. Furthermore, understanding the genetic underpinning of sex differences in a behavioural syndrome would be pivotal to assess the role of behavioural syndromes in the evolution of sexual dimorphism in behaviours. [ABSTRACT FROM AUTHOR]

Although many theoretical models of male sexual trait evolution assume that sexual selection is countered by natural selection, direct empirical tests of this assumption are relatively uncommon. Cuticular hydrocarbons (CHCs) are known to play an important role not only in restricting evaporative water loss but also in sexual signalling in most terrestrial arthropods. Insects adjusting their CHC layer for optimal desiccation resistance is often thought to come at the expense of successful sexual attraction, suggesting that natural and sexual selection are in opposition for this trait. In this study, we sampled the CHCs of male black field crickets (Teleogryllus commodus) using solid‐phase microextraction and then either measured their evaporative water loss or mating success. We then used multivariate selection analysis to quantify the strength and form of natural and sexual selection targeting male CHCs. Both natural and sexual selection imposed significant linear and stabilizing selection on male CHCs, although for very different combinations. Natural selection largely favoured an increase in the total abundance of CHCs, especially those with a longer chain length. In contrast, mating success peaked at a lower total abundance of CHCs and declined as CHC abundance increased. However, mating success did improve with an increase in a number of specific CHC components that also increased evaporative water loss. Importantly, this resulted in the combination of male CHCs favoured by natural selection and sexual selection being strongly opposing. Our findings suggest that the balance between natural and sexual selection is likely to play an important role in the evolution of male CHCs in T. commodus and may help explain why CHCs are so divergent across populations and species. [ABSTRACT FROM AUTHOR]

Abstract Previous studies on sex differences in behaviour have largely focused on differences in average behaviours between sexes. However, males and females can diverge not only in average behaviours but also in the direction of behavioural correlations at the individual level (i.e. behavioural syndromes). Behavioural syndromes, with their potential to constrain the independent evolution of behaviours, may play a role in shaping sex‐specific responses to selection and contributing to the development of sex differences in behaviour. Despite the pivotal role of behavioural syndromes in the evolution of sexual dimorphism in behaviour, robust empirical evidence of sex differences in behavioural syndromes based on repeated measurements of behaviours is scarce. In this study, we conducted repeated measurements of activity and aggression in male and female field crickets Teleogryllus emma, providing evidence of sex differences in the existence of behavioural syndromes. Males exhibited a significantly positive behavioural syndrome between activity and aggression, whereas females, in contrast, did not show any aggressive behaviour, resulting in the absence of such a syndrome. The sex differences in the existence of the activity‐aggression behavioural syndromes in this species could be attributed to differences in selection. Selection favouring more active and aggressive males may have shaped a positive activity‐aggression behavioural syndrome in males, whereas the absence of selection favouring female aggression may have resulted in the absence of aggression and the related behavioural syndrome in females. However, given the plasticity of behaviour with changes in age or the environment, further research is needed to explore how sex differences in the existence of activity‐aggression behavioural syndromes change across contexts. Furthermore, understanding the genetic underpinning of sex differences in a behavioural syndrome would be pivotal to assess the role of behavioural syndromes in the evolution of sexual dimorphism in behaviours.

Many organisms are capable of growing faster than they do. Restrained growth rate has functionally been explained by negative effects on lifespan of accelerated growth. However, the underlying mechanisms remain elusive. Telomere attrition has been proposed as a causal agent and has been mostly studied in endothermic vertebrates. We established that telomeres exist as chromosomal‐ends in a model insect, the field cricket Gryllus campestris, using terminal restriction fragment and Bal 31 methods. Telomeres comprised TTAGGn repeats of 38 kb on average, more than four times longer than the telomeres of human infants. Bal 31 assays confirmed that telomeric repeats were located at the chromosome‐ends. We tested whether rapid growth between day 1, day 65, day 85, and day 125 is achieved at the expense of telomere length by comparing nymphs reared at 23°C with their siblings reared at 28°C, which grew three times faster in the initial 65 days. Surprisingly, neither temperature treatment nor age affected average telomere length. Concomitantly, the broad sense heritability of telomere length was remarkably high at ~100%. Despite high heritability, the evolvability (a mean‐standardized measure of genetic variance) was low relative to that of body mass. We discuss our findings in the context of telomere evolution. Some important features of vertebrate telomere biology are evident in an insect species dating back to the Triassic. The apparent lack of an effect of growth rate on telomere length is puzzling, suggesting strong telomere length maintenance during the growth phase. Whether such maintenance of telomere length is adaptive remains elusive and requires further study investigating the links with fitness in the wild. [ABSTRACT FROM AUTHOR]

Sexual signals may be acquired or lost over evolutionary time, and are tempered in their exaggeration by natural selection. In the Pacific field cricket, Teleogryllus oceanicus, a mutation ("flatwing") causing loss of the sexual signal, the song, spread in

Simple Summary: Farming edible insects such as field crickets (Gryllus bimaculatus), called the Mediterranean cricket, is increasingly being adapted for more commercial purposes. Adapting the mass cricket-rearing conditions for field cricket production, we found crickets had a typical growth rate and capacity for conversion of ingested feed into body mass. The efficiency of the deposition of major nutrients (inorganic matter, protein, fat, fiber, and carbohydrate) in the field crickets from the ingested feed is possible to be measured under mass cricket-rearing conditions. The feed intake and mortality rate for cricket rearing should be considered for calculating major nutrient conversion efficiency as increased mortality rate resulted in higher conversion efficiency. Currently, there is an increased interest in mass producing edible insects, e.g., field crickets (Gryllus bimaculatus), due to their market value and sustainable development. The current study aimed to measure the production performance of field crickets and to quantify the major nutrient deposition rate using a new approach for a nutrient conversion efficiency calculation for the field crickets under mass-rearing conditions. The field crickets were reared under mass-rearing conditions in the rearing crates and fed with a commercial cricket feed. Measurements for daily feed offered, final body weight, and dead cricket quantity were carried out during the feeding trial period. There were three production rounds with the same procedure for farmed cricket management. The samples of diet, adult crickets, and dead crickets were collected and then analyzed for chemical analysis of macronutrients. The production performance and nutrient conversion efficiency were calculated and then compared with applicable earlier reports for both field and house (Acheta domesticus) crickets. The production performance for the studied field crickets under mass-rearing conditions had final a body weight, an average daily gain (ADG), a feed conversion ratio (FCR), and a survival rate of 0.95 g, 23.20 mg/day, 2.94 and 88.51%, respectively. The field crickets had nutrient conversion efficiency for dry matter (DM), ash, crude protein (CP), crude fat (EE), crude fiber (CF), and nitrogen-free extract (NFE) of 13.26, 8.03, 28.95, 88.94, 34.87, and 1.85, respectively, with an adjusted nutrient conversion efficiency of 14.85, 8.99, 32.37, 99.17, 38.95, and 2.10, respectively. Thus, the production of field crickets could be performed under mass-rearing conditions, and the nutrient conversion efficiency for both adjusted and non-adjusted values could be measured. [ABSTRACT FROM AUTHOR]

The effects of mating experience on male mating behavior are mediated by four factors: mating cost, such as resource depletion, perception of mating opportunities, self-perception of attractiveness, and female quality. For example, encountering females might increase male expectations of prospective mating opportunities, while copulation increases self-perception of attractiveness in males. To determine the relative importance of these factors, the effect of mating on the two components of reproductive effort (courtship and fighting effort) in Gryllus bimaculatus was examined. Calling activity before and after encountering females was measured, and copulation success was recorded. Subsequently, the intensity and outcome of male–male fighting behavior was recorded. Female encounter increased calling activity irrespective of copulation, thereby indicating that the perception of mating opportunities is important factor for the males. Changes in courtship effort of males were larger and fighting success was lower when they were previously paired with relatively heavier females. These results indicate that male reproductive effort is also affected by quality of previous mating partners. [ABSTRACT FROM AUTHOR]

Among-individual differences in behavior are now a widely studied research-focus within the field of behavioral ecology. Furthermore, elements of an animal's internal state, such as energy or fat reserves, and infection status can have large impacts on behaviors. Despite this, we still know little regarding how state may affect behavioral variation. Recent exposure to pathogens may have a particularly large impact on behavioral expression given that it likely activates costly immune pathways, potentially forcing organism to make behavioral tradeoffs. In this study we investigate how recent exposure to a common bacterial pathogen, Serratia marcescens, affects both the mean behavioral expression and the among-individual differences (i.e. variation) in boldness behavior in the field cricket, Gryllus integer. We find that recent pathogen exposure does not affect mean behavioral expression of the treatment groups, but instead affects behavioral variation and repeatability. Specifically, bacterial exposure drove large among-individual variation, resulting in high levels of repeatability in some aspects of boldness (willingness to emerge into a novel environment), but not others (latency to become active in novel environment), compared to non-infected crickets. Interestingly, sham injection resulted in a universal lack of among-individual differences. Our results highlight the sensitivity of among-individual variance and repeatability estimates to ecological and environmental factors that individuals face throughout their lives.

Variation in development time can affect life‐history traits that contribute to fitness. In Gryllus vocalis, a non‐diapausing cricket with variable development time, we used a path analysis approach to determine the causative relationships between parental age, offspring development time and offspring life‐history traits. Our best‐supported path model included both the effects of parental age and offspring development time on offspring morphological traits. This result suggests that offspring traits are influenced by both variation in acquisition of resources and trade‐offs between traits. We found that crickets with longer development times became larger adults with better phenoloxidase‐based immunity. This is consistent with the hypothesis that crickets must make a trade‐off between developing quickly to avoid predation before reproduction and attaining better immunity and a larger adult body size that provides advantages in male–male competition, mate choice and female fecundity. Slower‐developing crickets were also more likely to be short‐winged (unable to disperse by flight). Parental age has opposing direct and indirect effects on the body size of daughters, but when both the direct and indirect effects of parental age are taken into account, younger parents had smaller sons and daughters. This pattern may be attributable to a parental trade‐off between the number and size of eggs produced with younger parents producing more eggs with fewer resources per egg. The relationships between variables in the life‐history traits of sons and daughters were similar, suggesting that parental age and development time had similar causative effects on male and female life‐history traits. [ABSTRACT FROM AUTHOR]

Sexual displays can be energetically taxing, power-limited tests of endurance that favour the vigorous. Therefore, these displays may reliably indicate the ability to pay the energetic costs of sustained motor performance. Field cricket calling song involves the repeated mechanical movement of wings to produce pulses of sound grouped into species-specific chirp patterns, often sustained for long periods across nights. We quantified variation and repeatability of cricket calling song phenotypes and determined how age and body size impacted this variation. All our experiments involved tightly controlled signalling environments, but there was a great deal of interindividual variation in behaviour. Although there were species differences, most traits associated with signalling vigour exhibited mean level declines with age and conditional repeatability (individual∗age interactions). These results suggest that males differing in quality may differ in their ability to buffer themselves against age-related changes in signalling vigour. Furthermore, the repeatability of calling traits itself changed with age, declining slightly in some species but increasing in others. We also challenged motor performance by altering dietary carbohydrate and protein; we predicted that increased carbohydrate would enhance signalling vigour and increased protein would decrease it. Although diet influenced the probability of calling and time spent calling in a predictable manner, these effects were not profound. Our findings confirm the scope for sexual selection to act on motor performance and point to ways in which constraints and trade-offs may yield variation within and among species in how vigour is signalled. • Calling in crickets involves repeated mechanical wing movements (performance). • Individuals differed in calling vigour and in changes in vigour with age. • Although diet predictably influenced calling vigour, the effects were small. • Trade-offs may yield variation between vigour and other fitness-enhancing traits. [ABSTRACT FROM AUTHOR]

Insect meals are potential alternatives to fishmeal because they contain high protein, have short life cycle and can be farmed. Fishmeal is a sole ingredient of the standard feed for the production of mono‐sex tilapia fry. Attempts have been made to avoid or reduce fishmeal use exploring alternatives. The present study tested field cricket (Gryllus bimaculatus) meal (FCM) replacing fishmeal (FM) at the rates of 0, 20, 40, 60, 80 and 100% to evaluate the effects on sex‐reversal efficiency, survival, growth and feed utilization. Six diets with similar levels of crude protein (55.7 ± 0.2%) were formulated and fed to Nile tilapia fry (8.0 ± 0.1 mg) stocked in 18 aquaria (100 L) at the density of 300 each. They were fed five times a day for 21 days as per the standard protocol. They were also nursed additional 63 days. Results showed that replacement of fishmeal by FCM did not affect the efficiency of conversion, the percentage of males remained high (range 97.2%–98.6%) regardless of the replacement rate. During sex reversal, when the replacement of fishmeal increased from 20% to 80%, growth, survival and feed utilization indicators continue to improve. However, 100% replacement of fishmeal by FCM reduced the growth and survival. Broken line analysis showed that 80% replacement of fishmeal resulted in highest survival during sex reversal and 85% replacement during the first nursing and no effects on second nursing. The highest biomass gains, apparent digestibility and feed conversion efficiencies were obtained at 80% replacement for all the phases. Replacement of 80% fishmeal by FCM increased 9% cost of the SRT diet and 12% of the nursing diet based on the current prices in Thailand. [ABSTRACT FROM AUTHOR]

Currently, there is an increased interest in mass producing edible insects, e.g., field crickets (Gryllus bimaculatus), due to their market value and sustainable development. The current study aimed to measure the production performance of field crickets and to quantify the major nutrient deposition rate using a new approach for a nutrient conversion efficiency calculation for the field crickets under mass-rearing conditions. The field crickets were reared under mass-rearing conditions in the rearing crates and fed with a commercial cricket feed. Measurements for daily feed offered, final body weight, and dead cricket quantity were carried out during the feeding trial period. There were three production rounds with the same procedure for farmed cricket management. The samples of diet, adult crickets, and dead crickets were collected and then analyzed for chemical analysis of macronutrients. The production performance and nutrient conversion efficiency were calculated and then compared with applicable earlier reports for both field and house (Acheta domesticus) crickets. The production performance for the studied field crickets under mass-rearing conditions had final a body weight, an average daily gain (ADG), a feed conversion ratio (FCR), and a survival rate of 0.95 g, 23.20 mg/day, 2.94 and 88.51%, respectively. The field crickets had nutrient conversion efficiency for dry matter (DM), ash, crude protein (CP), crude fat (EE), crude fiber (CF), and nitrogen-free extract (NFE) of 13.26, 8.03, 28.95, 88.94, 34.87, and 1.85, respectively, with an adjusted nutrient conversion efficiency of 14.85, 8.99, 32.37, 99.17, 38.95, and 2.10, respectively. Thus, the production of field crickets could be performed under mass-rearing conditions, and the nutrient conversion efficiency for both adjusted and non-adjusted values could be measured.

Female crickets can potentially gain both direct and indirect benefits from mating multiple times with different males. Most studies have only examined the effects of small numbers of matings, although female crickets are capable of mating many times. The goal of this paper is to examine the direct and indirect benefits of mating large numbers of times for female reproductive success. In a previous experiment, female Gryllus vocalis were found to gain diminishing direct benefits from mating large numbers of times. In this study I attempt to determine whether mating large numbers of times yields similar diminishing returns on female indirect benefits. Virgin female Gryllus vocalis crickets were assigned to mate five, ten or 15 times with either the same or different males. Females that mated more times gained direct benefits in terms of laying more eggs and more fertilized eggs. Females that mated with different males rather than mating repeatedly with the same male did not have higher offspring hatching success, a result that is contrary to other published results comparing female reproductive success with repeated versus different partners. These results suggest that females that mate large numbers of times fail to gain additional genetic benefits from doing so.

Male same-sex sexual behaviour (SSB), where males court or attempt to mate with other males, is common among animal taxa. Recent studies have examined its fitness costs and benefits in attempts to understand its evolutionary maintenance, but the evolutionary consequences of SSB are less commonly considered. One potential impact of SSB might be to facilitate the evolution of traits associated with less sexually dimorphic males, such as alternative reproductive tactics, by diverting costly aggression from other males. To test this, we capitalized on the recent rapid spread of a silent male morph of the field cricket, Teleogryllus oceanicus , which is unable to produce characteristic male acoustic signals, benefits from satellite mating behaviour and has feminized appearance and cuticular hydrocarbon profiles. We tested the prediction that interactions involving these nonsignalling, less sexually dimorphic male morphs would show heightened rates of SSB, which could reduce the strength of male–male competition and permit greater access to females. We found no evidence that SSB was more common in trials involving silent males. Instead, SSB was predicted by courtship of females presented during a pretrial treatment. Our results provide evidence supporting the view that SSB represents a spillover of sexually selected courtship behaviour in a nonadaptive context, but do not support a strong role for SSB in the evolution of less ornamented males in this system. • Male same-sex sexual behaviour (SSB) is related to mistaken identity in crickets. • The incidence of SSB was not affected by silent alternative reproductive morphs. • SSB was more likely to be expressed by males that had previously courted females. • No evidence SSB promoted the spread of a less sexually dimorphic male morph. [ABSTRACT FROM AUTHOR]

Information is acquired through cognitive processes and is essential for enhanced fitness in many animal species. However, little is known about intraspecific variation in cognitive performance, or about phenotypic correlates of this variation, especially in invertebrates. Here we quantified individual variation in spatial learning, exploration, boldness and thigmotaxis (wall hugging) in female Texas field crickets, Gryllus texensis. We trained females to locate a food reward (dish baited with food) located in one arm of a radial arm maze, followed by a cognitive test (probe) trial where no food reward was present. Our results suggest that female crickets could learn and remember the food location, as latency to find the reward dish, distance travelled, number of complete arm entries and number of errors made prior to finding the reward dish all declined with training trials and during the cognitive test trial. Furthermore, females performed equally well on all cognitive measures during the cognitive test trial and the last training trial, suggesting they did not rely on olfactory cues to locate the correct dish during the cognitive test trial. Individual variation in cognitive measures during the test trial were significantly negatively correlated with thigmotaxis during the trial, but were not correlated with body size, latency to leave the novel maze's acclimation zone or the percentage of the novel maze explored during initial exploration of the maze. Our findings suggest individuals with reduced thigmotaxis either (1) are better at learning a spatial task and/or (2) rely more heavily on vision than olfaction. These results contribute to the growing literature examining links between personality and cognition, and highlight the importance of quantifying correlated aspects of the phenotype when assessing individual variation in cognitive performance in a cognitive test. Highlights • We trained 56 female Gryllus texensis to locate food in one arm of a radial arm maze. • Females needed to spend 48 h in the maze prior to training to learn the food location. • Performance in the test trial was not related to boldness, exploration or body mass. • Low thigmotaxis individuals were more accurate during the test trial. • Variation in performance may stem from different cognitive abilities or strategies. [ABSTRACT FROM AUTHOR]

To address the hypothesis that male acoustic sexual advertisement signals, in addition to chemical signals, might be indicators of aggressiveness, we examined the relationship between levels of aggression/dominance status and acoustic sexual advertisement signals in the field cricket Gryllus integer. Males were paired in aggression trials and recorded the night before and night after the trial. This allowed us to test whether aggression is inherently linked to song phenotypes, or whether aggressive interactions cause males to alter their songs. We found that dominant (winning) males signaled with higher energy, amplitude, and power the night after winning an aggressive encounter, but we could not detect any differences before the encounter. Time spent calling and the number of calling bouts were apparently unrelated to aggression, whereas winning males increased their bout lengths after winning, and losing males decreased their bout lengths after losing.

The nutritional values of the field cricket (Gryllus assimilis (Fabricius, 1775)) were analysed for dry matter using infrared scales, crude protein using Kjeldahl method, fat by Soxhlet method and fatty acid composition using GC-MS. The average dry matter content of analysed insect was 22.6 %, content of crude protein was 55.6 %, fat content was 11.8 %. The analysis of the fatty acid profile shows that the most abundant fatty acids were C18:2, C16:0 and C18:1 and the atherogenic index was 0.55. Microbial analyses were also part of the research, with evaluation of the total content of bacteria (3.3.106 CFU g-1), coli form bacteria (3.5.104 CFU g-1) and lactic acid bacteria (5.8.106 CFU g-1) and of yeasts and moulds (4.4.105 CFU g-1). For the high content of lipids and proteins edible insects could be a good alternative future source of crude protein and fat. EFSA also deals with obtaining sufficient data about the nutritional value and safety of consuming edible insects. [ABSTRACT FROM AUTHOR]

Researchers examining how nutrition impacts fitness traits usually examine one nutrient at a time, ignoring potential interactions. When researchers simultaneously examine multiple nutrients, their studies often focus on adults, ignoring potential changes in nutritional needs that occur during the transition between juvenile and adult stages. To address these issues, we quantified how dietary nutrient balance (relative amounts of protein and carbohydrate) during development and into adulthood influenced life history and sexually selected traits using male Jamaican field crickets, Gryllus assimilis . Our findings revealed that male crickets developed significantly faster and grew larger when they were reared on a protein-rich diet, but their average daily time spent signalling for mates was significantly higher when they were reared on a carbohydrate-rich diet. Furthermore, while the probability of signalling and daily time spent signalling increased with age, time spent signalling for mates tended to increase at a higher rate with age when males consumed a carbohydrate-rich diet in adulthood. Together our findings suggest that traits may differ in their nutrient requirements, resulting in diet influencing a possible trade-off between traits across different life stages. The ability to locate and consume foods rich in protein during development should impact adult male fitness, as protein availability results in larger males, and larger males typically produce more attractive signals and are preferred by females. Conversely, the ability to locate and consume foods rich in carbohydrate should also impact a male's fitness, as males signal with higher effort when fed carbohydrate-rich diets, and higher signalling effort can directly impact a male's ability to attract a female. [ABSTRACT FROM AUTHOR]

Indicator models of sexual selection predict that sexually selected trait elaboration should covary positively with condition. However, nutrition might influence the expression of multiple traits, where high-quality diets may result in positive trait correlations and low-quality diets in trade-offs. Although previous studies have examined how diet quantity or single nutrients, such as protein, carbohydrate and phosphorus, influence sexual traits, few have examined how dietary nutrient balance affects sexual trait expression. We therefore investigated how dietary protein:carbohydrate ratio and percentage of phosphorus influence the relationship between investment in mate attraction signalling and aggression. We fought groups of six adult male Gryllus veletis crickets, each consuming a unique diet, while recording their prefight and postfight signalling parameters. We found no evidence that diet influenced aggression or prefight signalling, with the exception that high-phosphorus diets had a negative influence on several signalling effort parameters. Body size was an important predictor of aggressive behaviour and most signalling parameters, suggesting that developmental diet may have a greater influence on these sexual traits. Several prefight signalling parameters were weakly related to aggression, suggesting that signalling may advertise competitive abilities. Males consuming high-carbohydrate and equal protein:carbohydrate diets experienced changes in signalling parameters that represented an overall increase in signalling effort following aggressive contests compared to males consuming high-protein diets, suggesting that dietary effects on signalling may only become apparent following periods of highly energetic activity. Changes in signalling following aggressive contests were also related to aggression levels modulated by dietary phosphorus content, such that only males consuming low-phosphorus diets were able to invest heavily in signalling after investing heavily in aggression. Our findings highlight the importance of research on the interplay between multiple sexually selected traits, and how dietary nutrient balance influences these relationships. [ABSTRACT FROM AUTHOR]

Male mate choice is an often neglected aspect of sexual selection studies. While theory predicts that females should exhibit mate choice due to their comparatively greater investment in gametes, males may also exhibit mate choice for a variety of reasons, including seeking mates with greater fecundity. Furthermore, males may exhibit discriminant or indiscriminate mate choice as a function of their own intrinsic characteristics, such as body size or condition. Here we experimentally evaluated male Jamaican field cricket, Gryllus assimilis , mating preferences using randomly selected females and determined how both male and female morphology (body size and residual mass) and male signalling behaviour influence male mate preference. Results show that male crickets exhibit mating preferences, with larger males tending to exhibit more consistent mate preferences than smaller males. Contrary to predictions, males did not prefer larger or relatively heavier females, suggesting that males may not be basing their choosiness on these proxy measures of female fecundity. Our findings highlight the need for continued research on male mate choice and identifying the intrinsic characteristics of both sexes that drive them. [ABSTRACT FROM AUTHOR]

An individuals' experience with conspecific signaling during development can lead to variation in their mating signals and behavior later in life. It is unclear whether experience with sexual signals also alters receivers' fitness through changes in investment in offspring. Male field crickets attract mates using a long-distance calling song. To determine how developmental experience with calling song quality and quantity alters mating responsiveness and fitness, we raised juvenile female Teleogryllus oceanicus in five acoustic environments. These environments mimicked two mate quantities (high and low) crossed with two mate qualities (high and low), and a silent control. At adulthood, we measured females' responsiveness in phonotaxis trials. Following phonotaxis, females were offered opportunities to mate and lay eggs. We measured egg number and proportion hatching as components of fitness and reproductive investment. Corroborating previous research in this system, female crickets raised in silence approached a broadcast calling song nearly 45% faster than their counterparts reared hearing a high-quantity/high-quality combination of calling song. Additionally, females adjusted other aspects of phonotaxis behavior in response to the quantity, but not quality of song. We found no evidence that females adjusted mating rates or investment in offspring. Regardless of acoustic experience, females laid equivalent numbers of eggs that had equivalent hatching success. Our results show that female mating behavior responds to juvenile experience mimicking a lack of mating opportunities, but is less responsive to variation in mate quality. Furthermore, reproductive investment may be less plastic than mating behavior. Significance statement: Social experience can inform organisms about current environmental conditions and lead to changes in behavior. Existing work suggests that field crickets in the genus Teleogryllus change their mating behavior in response to acoustic environments that mimic varied mate availabilities and qualities. However, we do not know if females alter their investment in offspring under similar circumstances. Variable investment could speed evolutionary change when combined with behavioral plasticity. We found that although female mating behavior is sensitive to variation in acoustic experience, reproductive investment is not. The number of eggs laid and the percent hatching did not depend on acoustic experience. We discuss evolutionary explanations for these patterns, including the possibility that investment is less plastic than mating behavior. [ABSTRACT FROM AUTHOR]

Despite the ever increasing interest in animal personalities, i.e. among-individual variation in behavior, there are still several gaps in our understanding of how experiences during ontogeny influence the expression of behavior in adulthood. Immune challenges during ontogeny have been proposed to drive feedback loops between investment in immune function and personality type. In this study we investigate the effects of an early immune challenge, in the form of an introduced bacterial pathogen, on the development of personality in field crickets. Our results indicate that early pathogen exposure does not influence life history characteristics, immune response, or mean level of boldness behavior. Instead, early immune challenge affects the presence of personality later in the adult stage. Specifically, immune challenged individuals lack repeatability in some aspects of boldness behavior, indicating that among-individual variation is not present, while non-immune challenged individuals remain repeatable in their boldness behavior. This study joins a slowly growing body of literature indicating that experiences during ontogeny can have large influences on the among-individual differences in behaviors, thus affecting the presence of personality as adults.

Field cricket species are ideal model organisms for the study of sexual selection because cricket calling songs, used to attract mating partners, are pronouncedly sexually dimorphic. However, few studies have focused on other sexually dimorphic traits of field crickets. The horn-headed cricket, Loxoblemmus doenitzi, exhibits exaggerated sexual dimorphism in head shape: males have flat heads with triangular horns, while females lack horns. This study examines the relationship between horn length, male calling efforts and diet quality. Horn length was not found to be significantly correlated with calling efforts. When diet was manipulated for late-stage nymphs, calling efforts in the group with poor-quality diet treatment was significantly lower than that of crickets in the group with high-quality diet treatment. However, horn length was not affected by diet quality. The implication of these results in the context of the evolution of multiple signals and sexual dimorphism is discussed. [ABSTRACT FROM AUTHOR]

Male field crickets generate calls to attract distant females through tegminal stridulation: the rubbing together of the overlying right wing which bears a file of cuticular teeth against the underlying left wing which carries a sclerotized scraper. During stridulation, specialized areas of membrane on both wings are set into oscillating vibrations to produce acoustic radiation. The location of females is unknown to the calling males and thus increasing effective signal range in all directions will maximize transmission effectiveness. However, producing an omnidirectional sound field of high sound pressure levels may be problematic due to the mechanical asymmetry found in this sound generation system. Mechanical asymmetry occurs by the right wing coming to partially cover the left wing during the closing stroke phase of stridulation. As such, it is hypothesized that the sound field on the left-wing side of the animal will contain lower sound pressure components than on the right-wing side as a result of this coverage. This hypothesis was tested using a novel method to accurately record a high-resolution, three dimensional mapping of sound pressure levels around restrained Gryllus bimaculatus field crickets singing under pharmacological stimulation. The results indicate that a bilateral asymmetry is present across individuals, with greater amplitude components present in the right-wing side of the animal. Individual variation in sound pressure to either the right-or left-wing side is also observed. However, statistically significant differences in bilateral sound field asymmetry as presented here may not affect signalling in the field. [ABSTRACT FROM AUTHOR]

Multivariate female preference functions for male sexual signals have rarely been investigated, especially in a comparative context among sister species. Here we examined male signal and female preference co-variation in three closely related, but allopatric species of Gryllus crickets and quantified male song traits as well as female preferences. We show that males differ conspicuously in either one of two relatively static song traits, carrier frequency or pulse rate; female preference functions for these traits also differed, and would in combination enhance species discrimination. In contrast, the relatively dynamic song traits, chirp rate and chirp duty cycle, show minimal divergence among species and relatively greater conservation of female preference functions. Notably, among species we demonstrate similar mechanistic rules for the integration of pulse and chirp time scales, despite divergence in pulse rate preferences. As these are allopatric taxa, selection for species recognition per se is unlikely. More likely sexual selection combined with conserved properties of preference filters enabled divergent coevolution of male song and female preferences. [ABSTRACT FROM AUTHOR]