Calling,Courtship, and Condition in the Fall Field Cricket,Gryllus pennsylvanicus

Theoretically, sexual signals should provide honest information about mating benefits and many sexually reproducing species use honest signals when signalling to potential mates. Male crickets produce two types of acoustic mating signals: a long-distance mate attraction call and a short-range courtship call. We tested whether wild-caught fall field cricket (Gryllus pennsylvanicus) males in high condition (high residual mass or large body size) produce higher effort calls (in support of the honest signalling hypothesis). We also tested an alternative hypothesis, whether low condition males produce higher effort calls (in support of the terminal investment hypothesis). Several components of long-distance mate attraction calls honestly reflected male body size, with larger males producing louder mate attraction calls at lower carrier frequencies. Long-distance mate attraction chirp rate dishonestly signalled body size, with small males producing faster chirp rates. Short-range courtship calls dishonestly reflected male residual mass, as chirp rate and pulse rate were best explained by a curvilinear function of residual mass. By producing long-distance mate attraction calls and courtship calls with similar or higher effort compared to high condition males, low condition males (low residual mass or small body size) may increase their effort in current reproductive success at the expense of their future reproductive success, suggesting that not all sexual signals are honest.     

Relationship Between Condition,Aggression, Signaling,Courtship, and Egg Laying in the Field Cricket,Gryllus assimilis

Sexual selection theory suggests males in good condition should be more successful than males in poor condition when competing with rivals for territories and mates. Understanding how condition influences the interplay between aggression, mate attraction, and courtship displays could help explain why variation is maintained in traits that confer fitness. Using laboratory‐reared Jamaican field crickets, Gryllus assimilis, we found that fine‐scale temporal components of mate attraction signals were positively correlated with body condition (residual body mass) and body size; signaling effort was positively correlated with both body condition and fine‐scale temporal signaling components; aggression was positively correlated with signaling effort; number of eggs laid was positively correlated with female body size, male body condition and aggression. Together our correlative study suggests that variation in body condition and size may drive some of the variation in cricket mate attraction signaling and aggression. Given condition and body size are influenced by foraging ability, nutrient availability and the organism’s ability to uptake and retain these essential nutrients could explain some of the persistent variation in fitness conferring traits.     

Processing of Song Signals in the Cricket and its Hormonal Control

SYNOPSIS. Phonotaxis by female crickets to the calling songof males, is an important model for investigating the neuralbasis of auditory behavior. Recent advances make it possibleto explain some components of this behavior and its hormonalcontrol, at the level of identified neurons and molecular expressionwithin those neurons Tonotopically arranged afferents from the cricket's ear, projectto local and intersegmental prothoracic interneurons. Bilateralprocessing of signals and some temporal-pattern specific processingoccurs in the prothoracic ganglion and influences acoustic informationthat is sent to the brain via ascending interneurons that aredemonstrably involved in phonotaxis. High, low and band- passinterneurons in the brain continue temporal pattern processingwhich matches the selectivity of phonotaxis and may be filtersfor recognition of the calling song. Neurons descending fromthe brain and prothoracic ganglion, direct multimodal signals(including auditory) to more posterior regions, possibly theleg motor neurons that are responsible for phonotaxis Age-related changes or artificially induced changes in JuvenileHormone III levels regulate the threshold for phonotaxis inAcheta domesticus, by varying the threshold of LI, a prothoracicascending interneuron that is necessary for phonotaxis to lowintensity calling songs. Results from in situ hybridizationsuggest that this might be accomplished, in part, by controllingthe levels of nicotinic acetylcholine receptor-like mRNA expressedin LI, presumably by increasing its neurotransmitter receptordensity. L3 is a prothoracic ascending interneuron that exhibitsbandselective response properties to the syllable period ofthe calling song. L3's response is age and JHIII related, andis correlated to phonotactic selectivity. These changes in L3might be accomplished, at least in part by JHIII regulatingthe expression of nicotinic acetylcholine receptor-like mRNAin L3     

No Effect of Body Size on the Frequency of Calling and Courtship Song in the Two-Spotted Cricket,Gryllus bimaculatus

The relationship between body size and vocalization parameters has been studied in many animal species. In insect species, however, the effect of body size on song frequency has remained unclear. Here we analyzed the effect of body size on the frequency spectra of mating songs produced by the two-spotted cricket, Gryllus bimaculatus. We recorded the calling songs and courtship songs of male crickets of different body sizes. The calling songs contained a frequency component that peaked at 5.7 kHz. On the other hand, courtship songs contained two frequency components that peaked at 5.8 and 14.7 kHz. The dominant frequency of each component in both the calling and courtship songs was constant regardless of body size. The size of the harp and mirror regions in the cricket forewings, which are the acoustic sources of the songs, correlated positively with body size. These findings suggest that the frequency contents of both the calling and courtship songs of the cricket are unaffected by whole body, harp, or mirror size.     

Field Cricket Species Differences in the Temporal Patterns of Long-Distance Mate Attraction Signals

We quantify variation in the temporal components of long‐distance mate attraction signals produced by a North American field cricket, Gryllus rubens Scudder. Total signaling time, trilling bout duration, and hourly bout number exhibit high repeatability within individuals. Extensive variation exists across individuals: some males never signal while others signal for several hours each night; of the signalers, average trilling bout duration ranges from <1 min to well over an hour; some males produce only one trilling bout in an evening while others produce three bouts every 2 h. Body size, weight, wing morphology, and condition do not appear to explain the variation. We compare the temporal signaling components of G. rubens with its sister species, G. texensis. Although G. rubens produce slightly more trills per hour with slightly shorter trilling bout durations, the temporal components of these long‐distance mate attraction signals are surprisingly similar across species.     

Courtship Behavior in the Hawaiian Cricket Laupala cerasina: Males Provide Spermless Spermatophores as Nuptial Gifts

The role of sexual selection in the crickets (family Gryllidae) is well known but new forms of courtship behavior continue to be discovered. Here we describe the elaborate mating behavior of the Hawaiian endemic Laupala cerasina (subfamily Trigonidiinae) on the basis of both laboratory and field observations. We found that courtship and mating involve multiple copulations during which repeated spermatophores are transferred. Initial copulations involved the transfer of relatively small ‘microspermatophores’. The final copulation results in the transfer of a considerably larger ‘macrospermatophore’. We tested and rejected the hypothesis that the number of spermatophore transfers results in greater offspring sired by a given male. Matings involving only microspermatophores resulted in no offspring, whereas most matings involving micros and a macrospermatophore, or a macrospermatophore only, produced offspring. A direct examination of the contents of the microspermatophore revealed an absence of sperm, whereas examination of the macrospermatophore revealed the presence of sperm. Given that females consume the spermless microspermatophores, we conclude that the microspermatophores are a form of nuptial feeding of females by males. We discuss possible hypotheses to explain this unusual courtship system.     

Ontogeny of the cricket Phaeophilacris bredoides Kaltenbach (Orthoptera, Gryllidae)

Development of Phaeophilacris bredoides Kalt. was studied under stable laboratory conditions: temperature of 26°C, air humidity 60%, and 12L: 12D photoperiod (Knyazev, 1985). The life cycle of Ph. bredoides includes four stages: egg, pronymph, nymph, and adult. The duration of embryonic development is 28 days. The nymphal ontogeny lasts 230 days and consists of 25 instars. The duration of nymphal instars (days) is: 1st—16, 2nd—6, 3rd—8, 4th—10, 5th—10, 6th—15, 7th—10, 8th—8, 9th—9, 10th—11, 11th—11, 12th—8, 13th—9, 14th—10, 15th—7, 16th—9, 17th—7, 18th—7, 19th—7, 20th—10, 21st—11, 22nd—7, 23rd—9, 24th—6, and 25th—9. The duration of adult life is 126 days in males and 125 days in females. Three periods were distinguished in the imaginal ontogeny of males and females: pre-reproductive, reproductive, and post-reproductive. The pre-reproductive period begins with the molt to the adult and ends with the onset of reproductive behavior in males and with the first copulation in females. Its duration is 4 (3–6) days in males and 5 (2–7) days in females. The reproductive period in males starts with the onset of reproductive behavior on the 4th (3rd–6th) day and lasts 119 (98–135) days. In females it begins when they start responding to males’ courtship behavior and lasts 116 (97–133) days. The female reproductive period includes two alternating phases: copulation and egg-laying. The egg-laying phase is initiated by successful copulation. The post-reproductive period in females starts when oviposition ceases and in males, when their reproductive behavior disappears. This period lasts about 3 (2–3) days in males and 4 (2–7) days in females, until the insect dies.     

The Importance of Acoustic Signals in Multimodal Courtship Behavior in Drosophila virilis,D. lummei and D. littoralis

The courtship rituals of Drosophila include an exchange of several signals with different modalities, chemical, visual, acoustic and tactile stimuli, between sexes. Using a video recording method, we studied the role of acoustic communication in courtship behavior in three species of the Drosophila virilis group, D. virilis, D. lummei and two populations of D. littoralis. Five series of experiments were performed: tests with intact flies (control), tests with mute flies (wingless males or females), and tests with deaf flies (aristaless males or females). We distinguished the two situations: either a female did not hear a male or vice versa, males did not hear females. When females did not hear males, the reduction in the copulation number was found in D. virilis and both populations of D. littoralis, but not in D. lummei. When males did not hear females, the reduction in the copulation number was only found in D. littoralis. The ablation of the male aristae in D. virilis and D. lummei even increased the mating success as compared to the control, which may be explained by the ‘sensory overload’ hypothesis. The changes in courtship temporal structure usually included the delayed onset of the main courtship elements (tapping, licking, and singing), and the variation in their duration and the total time of courtship. These effects were, however, more substantial in D. virilis and both populations of D. littoralis than in D. lummei. Thus, the effect of blocking the acoustic channel was different in the three species regardless of their phylogenetic relationship, and the role of acoustic communication in courtship behavior seemed to increase in the order D. lummei – D. virilis – D. littoralis.

     

Previous Motor Experience Enhances Courtship Behavior in Male Cricket <Emphasis Type=Italic>Gryllus bimaculatus</Emphasis>

In crickets Gryllus bimaculatus, flight has been shown to be able to promote aggressive encounters between males and to suppress escape behavior. The aim of this study was to examine the influence of flight on male behavior in male–female interactions. We found that flown males demonstrate enhanced courtship behavior. The latency of calling song was significantly shorter, while the relative total duration of singing as well as the duration of singing episodes longer in flown males than in the control. Mating rate was also significantly higher in the experimental group containing flown males. The results suggest that, in addition to previously reported effects on aggressiveness and escape, flying has a profound accelerating effect on male courtship behavior.     

Cave breeding by African Penguins near the northern extreme of their range: Sylvia Hill,Namibia

Only three mainland sites are known among the total 27 breeding colonies of the African Penguin, Spheniscus demersus: two in South Africa and one in Namibia. The latter is a unique cave site near the northern extreme of the species' range on the edge of the Namib Desert. To determine the colony size, long-term viability and any difference in breeding ecology relative to more southern sites we combined data from previous visits to the site with four visits in 2001. We found that about 240 to 300 birds use the Sylvia Hill cave, and about 90 nests are active with a laying peak in January. Eggs are laid on top of guano mounds not in burrows as is usual for this species. Smaller clutches (1.68 eggs/nest) but larger broods (x = 1.31 chicks/nest) were apparent in this colony than those farther south. Larger mean clutches farther south suggest a latitudinal trend in clutch size for Namibia's penguins. We found no evidence for a population decline over 17 years, and thus no evidence that birds at the periphery of their range moved southwards into core areas. We conclude that the colony is healthy and thriving despite a general decline in penguin numbers in southern Africa.     

Hickmania Troglodytes, the Tasmanian Cave Spider, and its Potential Role in Cave Management

Cave faunas – which often contain a high representation of spiders – are subject to increasing pressure from the effects of epigean habitat degradation and recreational caving activities. Hickmania troglodytes is a prominent member of the Tasmanian cave fauna, a spider of phylogenetic, zoogeographic and ecological importance, but about which little has previously been known. Long-term monitoring has revealed many unusual life-cycle characteristics in this species, most of which occur over long periods of time and are dependent upon environmental stability. The species presents a potentially useful tool in the management and monitoring of cave fauna and karst, as it is large, conspicuous, numerous, ubiquitous, sedentary, functionally significant and potentially sensitive to various sources of disturbance. H. troglodytes may provide a visible and obvious measure of disturbance in and around cave entrances, and may also prove useful in detecting broader scale impacts affecting the entire cave. Many promising developments are being made in terms of cave management in Tasmania, but other issues are less well addressed and still need to be resolved. With further research, the use of indicator or sentinel species may prove to be well suited to the less complex and often sparsely populated subterranean environment, and may play an important role within larger management strategies for cave fauna and karst.     

Courtship inhibition pheromone in desert locusts,Schistocerca gregaria

Male desert locusts in the gregarious phase release phenylacetonitrile (PAN) on becoming sexually mature. It has been assumed that this chemical is responsible for aggregation of adult desert locusts. However, PAN has repellent characteristics and is involved in sexual behavior. Mature males release PAN as a volatile to serve as a kind of olfactory concealment during mating and to prevent competing males from homosexual encounters. We conclude that PAN is a courtship-inhibiting pheromone exclusively used under crowded conditions in dense populations when high sperm competition occurs among desert locust males. By chemically enhancing their mate guarding, gregarious males improve the protection of their mate from rivals and ensure their reproductive success.     

Vibratory Communication in the Jumping Spider Phidippus clarus: Substrate‐borne Courtship Signals are Important for Male Mating Success

Recently, work has shown that multimodal communication is common throughout the animal kingdom but the function of multimodal signals is still poorly understood. Phidippus clarus are jumping spiders in which males produce multimodal (visual and vibrational) signals in both male–male (aggressive) and male–female (courtship) contexts. The P. clarus mating system is complex, with sex ratios and the level of male competition changing over the course of the breeding season. Vibrational signal components have been shown to function in male aggressive contests but their role in courtship has not been investigated. Here, we performed an experiment to test the role of vibrational signaling in courtship by observing mating success for males that were experimentally muted. We show that vibratory courtship signals, and in particular signaling rate, is an important component of mating success and potentially a target of female choice. While the ability to produce vibratory signals significantly increased mating success, some muted males were still able to successfully mate. In these trials, signaling rate also predicted mating success suggesting that redundant signal components may compensate for errors and perturbations in signal transmission or that vibratory signals function to enhance the efficacy of visual signals.     

Stratigraphy, U-Th chronology, and paleoenvironments at Gladysvale Cave: insights into the climatic control of South African hominin-bearing cave deposits

Gladysvale Cave is one of the few Plio-Pleistocene hominin-bearing cave sites in South Africa that contains a well-stratified cave fill with clastic sediments interspersed with flowstones. The clastic sediments can be divided into units based on the presence of intercalated flowstones, forming flowstone bounded units (FBU). Ten MC-ICP-MS uranium-series dates on several flowstone horizons in the Gladysvale Internal Deposit fan indicate deposition from the late mid-Pleistocene ( approximately 570 ka) to Holocene ( approximately 7 ka) during limited periods of higher effective moisture. Clastic sedimentation occurred during the interceding, presumably more arid, periods. This sequence is not consistent with earlier models for South African caves that simply assumed interglacial sedimentation and glacial erosion. (13)C/(12)C data suggest that flowstone tended to form during periods with higher proportions of C(3) plants in the local vegetation, while clastic sediments reflect higher proportions of C(4) grasses, although this is not always the case. We argue that flowstones are precipitated during periods of higher effective precipitation and restricted cave entrances, while clastic sediments accumulated during periods with more open vegetation. The sedimentary fill of the fossiliferous deposits are, therefore, highly episodic in nature, with large periods of time unlikely to be represented. This has serious implications for the other hominin-bearing caves close by, as these deposits are likely to be similarly episodic. This is especially pertinent when addressing extinction events and reconstructions of paleoenvironments, as large periods of time may be unrecorded. The Gladysvale Cave fill sediments may serve as a climatically forced chronostratigraphic model for these less well-stratified and well-dated Plio-Pleistocene sites.     

The Influence of Weapon Asymmetry on Male-Male Competition Success in a Sexually Dimorphic Insect,the African King Cricket Libanasidus vittatus (Orthoptera: Anostostomatidae)

Journal of Insect Behavior -     

Family Effects on Antipredator Behavior in the Field Cricket, Gryllus Integer

Most animals have antipredator mechanisms. These may include a variety of behaviors. One such behavior is “freezing”, i.e. becoming immobile in response to a predator. This paper is focused on freezing behavior in a species of field cricket, Gryllus integer. We studied this behavior in both nymphs and adults, and looked for family effects, as well as the effects of sex. Our research shows that there are no family effects in nymphs, but there are family effects in adults. No sex differences occur between the sexes at either stage of development. Because all of the crickets were reared under identical conditions in the laboratory, such family effects are likely due to genetic effects, maternal effects, or both.     

Studies on Proteolytic Enzyme of the Cricket,Gryllulus taiwanemma Ohmachi

A protease was isolated from the alimentary canal of crickets. This cricket protease was purified by ammonium sulfate, rivanol and acetone fractionations, and DEAE-cellulose and CM-cellulose (Ca-form) column chromatographies. The optimum temperature was 50°C and the optimum pH was 8.0. For preservation, the enzyme was most stable at pH 3.0. Aluminum had the best stabilizing action with no drops of enzyme activity after 24 hours of dialysis. The cricket protease was specific for the synthetic substrate, α-benzoyl-l-arginine amide. Cricket protease had a K_m. 10³ of 2.8 which is similar to that of trypsin, 1.2. The Ea was 3,770 while that of trypsin was 14,960 using α-benzoyl-l-arginine amide as the substrate. Although cricket protease has the same substrate specificity and similar optimum pH and pH-stability as trypsin, it differed in metal requirements to obtain activity. Certain metals are essential for cricket protease activity.     

Courtship Behavior of the Cumberland Plateau Woodland Salamander,Plethodon kentucki (Amphibia: Plethodontidae), with a Review of Courtship in the Genus Plethodon

Complete catalogs of courtship behavior are available for only seven of the 42 currently recognized species of Plethodon. Additional detailed studies of courtship behavior in Plethodon species are needed to analyze the evolution of courtship behavior in this genus. We investigated the courtship behavior of the Cumberland Plateau woodland salamander (Plethodon kentucki) and compared it to previous accounts of courtship in other Plethodon species. In the laboratory, we videotaped the complete courtship of 30 different P. kentucki pairs, which included 46 tail-straddling walks that resulted in spermatophore deposition. From a transition matrix of observed motor patterns, we constructed a flow diagram of significant motor-pattern transitions during courtship. In general, the courtship behavior of this species is very similar to that of other large eastern Plethodon; however, there are some notable differences. Prior to the tail-straddling walk, the male transfers courtship pheromone from his mental gland to the female's nasolabial grooves (via mental-gland tapping and ‘chin-to-chin’ behavior patterns) more frequently than in other Plethodon. In most courtships, the female initiates contact leading to the tail-straddling walk. Males exhibit a greater propensity to deposit multiple spermatophores per courtship (two deposited in 33% of courtships, three deposited in 10% of courtships, X = 1.53 spermatophores per courtship) than males of other plethodontids. Mean size of the spermatophore is smaller than in other large eastern Plethodon. Overall, the courtship behavior of this species is most similar to that of P. jordani.     

Timing of Environmental Enrichment Affects Memory in the House Cricket,Acheta domesticus

Learning appears to be ubiquitous among animals, as it plays a key role in many behaviors including foraging and reproduction. Although there is some genetic basis for differences in learning ability and memory retention, environment also plays an important role, as it does for any other trait. For example, adult animals maintained in enriched housing conditions learn faster and remember tasks for longer than animals maintained in impoverished conditions. Such plasticity in adult learning ability has often been linked to plasticity in the brain, and studies aimed at understanding the mechanisms, stimuli, and consequences of adult behavioral and brain plasticity are numerous. However, the role of experiences during post-embryonic development in shaping plasticity in adult learning ability and memory retention remain relatively unexplored. Using the house cricket (Acheta domesticus) as a model organism, we developed a protocol to allow the odor preference of a large number of crickets to be tested in a short period of time. We then used this new protocol to examine how enrichment or impoverishment at two developmental stages (either the last nymphal instar or young adult) affected adult memory. Our results show that regardless of nymphal rearing conditions, crickets that experienced an enriched rearing condition as young adults performed better on a memory task than individuals that experienced an impoverished condition. Older adult crickets (more than 1 week post adult molt) did not demonstrate differences in memory of the odor task, regardless of rearing condition as a young adult. Our results suggest that environmentally-induced plasticity in memory may be restricted to the young adult stage.