Changes in the behavior of the female short-tailed cricket,Anurogryllus muticus (De Geer) (Orthoptera: Gryllidae) following mating

InAnurogryllus muticus females, mating stimulates burrow construction, burrow provisioning, feeding, egg production, and egg-laying. Since mating often occurs before the ovaries are fully developed, the time span between mating and oviposition is used for increased food intake and the accumulation of nutrient reserves in the fatbody. Oviposition triggers maternal care of eggs and emerging hatchlings, and blocks egg consumption. Hatchling behavior is investigated. When hatchlings eat eggs, they prefer newly laid over older, embryonic eggs.     

Courtship song, male agonistic encounters, and female mate choice in the house cricket,Acheta domesticus (Orthoptera: Gryllidae)

Whether female crickets choose among males based on characteristics of the courtship song is uncertain, but in many species, males not producing courtship song do not mate. In the house cricket,Acheta domesticus, we examined whether a female chose or rejected a male based on his size, latency to chirp, latency to produce courtship song, or rate of the high-frequency pulse of courtship song (“court rate”). We confirmed that females mated only with males that produced courtship song, but we found no evidence that the other factors we measured affected a female’s decision to mate. In addition, we investigated whether the outcome of male agonistic encounters affected the subsequent production of courtship song. In one experiment, we observed courtship and mating behavior when a single female was placed with a pair of males following a 10-min interaction period between the two males. Winners of male agonistic encounters had higher mating success. However, winners and losers of agonistic encounters were not different in their likelihood or latency to produce courtship song or in the number of times they were disrupted by the other male in the pair. In a second experiment, we allowed two males to interact for a 10-min period, but following this interaction period, we placed a female with each male separately and observed courtship and mating behavior. The mating success of winners and losers was not different under these circumstances, and we found no differences between winners and losers in any subsequent courtship or mating behavior examined. We conclude that winning agonistic encounters influences a male’s mating success in ways other than his production of courtship song and this effect is lost when winning and losing males are separated and each is given an opportunity to mate.     

A new species of Cephalobium (Rhabditida,Cephalobiidae), a parasite of Anurogryllus muticus (De Geer) (Orthoptera,Gryllidae) in Argentina

Cephalobium odontolateralis n. sp. (Nematoda, Cephalobiidae) is described and illustrated from the nymphs of Anurogryllus muticus (De Geer) (Orthoptera, Gryllidae) from Buenos Aires province, Argentina. It is characterized by a lateral large tooth in the stoma and by the arrangement and number of the genital papillae in the male; there are 6 pairs of postanal papillae, but none is preanal.     

Female mating behavior in the field cricket,Gryllus pennsylvanicus (Orthoptera: Gryllidae) at different operational sex ratios

The influence of operational sex ratio on the mating behavior of female field crickets,Gryllus pennsylvanicus, was investigated. Females were predicted to be more discriminating under conditions of high mate availability and show less selectivity when males were rare. Such selectivity was indicated in this study with the proportion of courtships leading to a mating changing with sex ratio. Females accepted almost 70% of all courtships at the female-biased sex ratio, but only about half of all courtships were successful at even or male-biased sex ratios. Females moved least at the female-biased sex ratio. There was also a trend for females to be guarded more under male-biased conditions. Female weight did not influence any of the behaviors examined.     

Habitat requirements for the conservation of wood cricket (Nemobius sylvestris) (Orthoptera: Gryllidae) on the Isle of Wight, UK

In the UK, wood cricket (Nemobius sylvestris) is a ‘Species of Conservation Concern’, being restricted to only three areas in southern England. Little information is available on the specific habitat requirements of this species. In 2006, a field investigation within three woodlands on the Isle of Wight was undertaken to identify its habitat preferences. Factors positively influencing wood cricket presence within woodlands included the presence of a well-developed leaf litter layer, relatively low ground vegetation cover and height, low canopy cover and relatively short distances between individual populations. Regression models identified the degree of isolation and variables describing vegetation structure as the main predictors for wood cricket presence within woodland fragments. The results of this study indicate the preference of wood cricket for open wooded edges. Conservation efforts for this species should focus on continuation of regular management activities aimed at providing permanent open edge habitat within woodlands, to maintain viable populations.     

Acoustic communication in the trilling field cricket,Gryllus rubens (Orthoptera: Gryllidae)

Male field crickets produce calling songs that are used for attracting conspecific females for mating. Acoustic communication was studied in the trilling field cricket, Gryllus rubens.A trilled calling song consists of a continuous train of sound pulses, each of which was repeated at a stereotyped rate. Singing males were recorded at different temperatures. The pulse period of the calling song decreased with increasing temperature; there was less effect of temperature on pulse duration. Female phonotaxis was studied on a noncompensating, spherical treadmill. In two-stimulus (choice) playback experiments, females preferred the conspecific trilled song over the chirped calling song of a sympatric species, Gryllus fultoni.This preference persisted even when the song of G. fultoniwas 6 dB louder. Females also discriminated between synthetic trills having different pulse periods; females chose trills with the conspecific pulse period over trills having lower and higher pulse periods.     

Learning and solar orientation in the mole cricket Gryllotalpa gryllotalpa (Orthoptera: Gryllidae)

The ecologically efficient escape direction assumed by Gryllotalpa gryllotalpais learned by the larvae after they leave the maternal nest. Nonetheless, larvae hatched in the laboratory are innately capable of using the sun to maintain a set escape direction. The species can also modify the set point of its sun compass to conform to topographical changes encountered during its wanderings.     

Development of microsatellite markers for the wood cricket, Nemobius sylvestris (Orthoptera: Gryllidae)

Thirty-four novel microsatellite markers developed for wood cricket (Nemobius sylvestris) were tested and optimized. Twenty-five microsatellite loci were polymorphic, exhibiting between two and nine alleles. Observed heterozygosities ranged from 0.038 to 0.925. The microsatellites were also tested in a species belonging to another genus of the Gryllidae family (Gryllus bimaculatus). Two markers produced clear banding patterns with the expected product size. These markers will be used to study the effects of forest fragmentation on genetic connectivity using wood cricket as a model species.     

Detailed developmental morphology of the spermatophore of the Mediterranean field cricket, Gryllus bimaculatus (De Geer) (Orthoptera: Gryllidae)

The detailed developmental morphology of the spermatophore of a cricket (Gryllus bimaculatus, De Geer) is described for the first time. A specific behavioural reference point is identified from which time developmental processes proceed in a more or less robotic manner. The structures previously identified as forming part of the fully formed spermatophore, that is, the ampulla, the sperm tube and the attachment plate are all identified in detail during their development. Interestingly the attachment plate material is extruded as an amorphous mass from the ejaculatory duct prior to its insertion into the dorsal pouch, the sperm do not enter the sperm sac until the end of spermatophore formation, and the sperm tube itself is formed from a flattened layer of material which rolls up into a tube and involves the use of a die mechanism.     

The influence of female age on phonotaxis during single and multiple song presentations in the field cricket,Gryllus integer (Orthoptera: Gryllidae)

The influence of age on variation in female phonontaxis in the field cricket,Gryllus integer, was investigated using a Kugel treadmill-type device. Synthetic male calling songs, with different pulse rates, were presented in both single-stimulus and three-stimulus designs. Females were either 11–14 or 25–28 days postecdysis. Females varied in motivation, or the degree of reproductive effort they exhibited, but only in single-stimulus trials: older females achieved higher scores than younger females. Females varied in selectivity, or the extent to which they discriminated among potential mates, in both presentation designs. All females discriminated against atypical pulse rates. In multiple-stimulus trials with normal range pulse rates, younger females were discriminatory; older females were not. Mated females showed reduced phonotaxis and selectivity irrespective of mating interval.     

the effect of pair formation on diel calling patterns in two cricket species,Gryllus veletis andGryllodes sigillatus (Orthoptera: Gryllidae)

After pair formation, male crickets should reduce calling to minimize the risks to males of attracting predators and/or rivals. We tested this hypothesis in two cricket species, one in which males exhibit a high mating propensity (Gryllus veletis)and another in which the mating propensity of males is constrained by the manufacture of elaborate, bipartite spermatophores (Gryllodes sigillatus).Calling durations of male G. veletisdeclined precipitously after the introduction of females but remained unchanged in G. sigillatus.We attribute the asymmetric effect of female proximity on male calling to differences in the mating propensity of males of the two species. Male G. veletisabstain from further calling in favor of repeated matings with the same female. Male G. sigillatusprobably lack the opportunity to mate repeatedly with the same female and, thus, resume calling shortly after mating to increase their probability of attracting additional mates.     

Sexual dimorphism in cuticular hydrocarbons of the Australian field cricket Teleogryllus oceanicus (Orthoptera: Gryllidae)

Sexual dimorphism is presumed to reflect adaptive divergence in response to selection favouring different optimal character states in the two sexes. Here, we analyse patterns of sexual dimorphism in the cuticular hydrocarbons of the Australian field cricket Teleogryllus oceanicus using gas chromatography. Ten of the 25 peaks found in our chromatographs, differed in their relative abundance between the sexes. The presence of sexual dimorphism in T. oceanicus is discussed in reference to a review of sexual dimorphism in cuticular hydrocarbons of other insects. We found that this trait has been examined in 103 species across seven different orders. Seventy-six of these species (73%) displayed sex specificity of cuticular hydrocarbons, the presence/absence of which does not appear to be directly linked to phylogeny. The occurrence of sexual dimorphism in cuticular hydrocarbons of some but not other species, and the extent of variation within genera, suggest that this divergence has been driven primarily by sexual selection.     

The function of mate guarding in a field cricket (Orthoptera: Gryllidae;Teleogryllus natalensis otte and cade)

Three hypotheses relating to the function of postcopulatory mate guarding were tested for the cricketTeleogryllus natalensis. The hypothesis that guarding allows the male to remain with the female for repeated matings was rejected. This was because the mean intercopulatory interval for maleT. natalensis was found to be nearly twice as long as the mean duration of guarding. Nor do the results provide evidence to support the hypothesis that guarding functions to prevent copulation attempts by rival males (the rival exclusion hypothesis): the presence of a rival male was found to have no significant effect on the duration of spermatophore attachment for either guarded or unguarded females. The results do, however, support a third hypothesis, namely, that guarding functions to prevent the female from removing the spermatophore ampulla before complete sperm transfer. As predicted by this hypothesis, the presence of a guarding male was found to have a significant positive effect on the duration of spermatophore attachment. Further support for this hypothesis was provided by the fact that there was a significant positive correlation between the duration of mate guarding and the duration of spermatophore attachment.     

Inter- and intraspecific variation in nightly calling duration in field crickets,Gryllus integer andG. rubens (Orthoptera: Gryllidae)

The time that male field crickets spend calling was measured electronically in the laboratory to examine nightly calling duration from different species and populations. Male Gryllus integerfrom Davis, CA, and Las Cruces, NM, called approximately 7 h per 24 h, whereas male G. integerfrom San Antonio and Austin, TX, and Norman, OK, and male G. rubensfrom McAlester, OK, and Arkadelphia, AR, called approximately 3 h per 24 h. Variation in duration of calling is discussed in terms of the energetic costs of producing song and selection against calling by acoustically orienting parasites and predators. Duration of calling was also studied infield-collected male G. integer.Males were first observed in field populations and then collected. Those males observed calling in the field later called significantly more in the laboratory than males observed showing non-calling, satellite behavior. Flying G. integercollected under lights were intermediate in their calling duration to calling and satellite males. These data are discussed in terms of the heritability of nightly calling song duration infield crickets.     

Characterization of arylalkylamine N-acetyltransferase (AANAT) activities and action spectrum for suppression in the band-legged cricket, Dianemobius nigrofasciatus (Orthoptera: Gryllidae)

Arylalkylamine N-acetyltransferase (AANAT), constituting a large family of enzymes, catalyzes the transacetylation from acetyl-CoA to monoamine substrates, although homology among species is not very high. AANAT in vertebrates is photosensitive and mediates circadian regulation. Here, we analyzed AANAT of the cricket, Dianemobius nigrofasciatus. The central nervous system contained AANAT activity. The optimum pHs were 6.0 (a minor peak) and 10.5 (a major peak) with crude enzyme solution. We analyzed the kinetics at pH 10.5 using the sample containing collective AANAT activities, which we term AANAT. Lineweaver-Burk plot and secondary plot yielded a K_m for tryptamine as substrate of 0.42 µM, and a V_max of 9.39 nmol/mg protein/min. The apparent K_m for acetyl-CoA was 59.9 µM and the V_max was 8.14 nmol/mg protein/min. AANAT of D. nigrofasciatus was light-sensitive. The activity was higher at night-time than at day-time as in vertebrates. To investigate most effective wavelengths on AANAT activity, a series of monochromatic lights was applied (350, 400, 450, 500, 550, 600 and 650 nm). AANAT showed the highest sensitivity to around 450 nm and 550 nm. 450 nm light was more effective than 550 nm light. Therefore, the most effective light affecting AANAT activity is blue light, which corresponds to the absorption spectrum of blue wave (BW)-opsin.     

Electrophysiology of the visual system in the cricket Gryllus firmus (Orthoptera: Gryllidae): Spectral sensitivity of the compound eyes

The electroretinographic spectral sensitivity of the cricket compound eyes shows the presence of two receptor types, a dominant one at 520 nm and another in the near-u.v. (λ_max 355 ± 5 nm) under dark- and intense chromatic adaptation conditions (Fig. 3). The waveform of the electrical responses elicited by short-wavelength stimuli differ from those elicited by long wavelength stimuli (Fig. 1).     

Reproductive biology and function of multiple mating in the mating system of a tree cricket,Truljalia hibinonis (Orthoptera: Podoscritinae)

A tree cricket,Truljalia hibinonis, is known to show a novel sperm removal during copulation. The pattern of copulations and ovipositions showed that the sperm removal functioned to increase reproductive success for sperm removing males. The sperm removal by males evolves under the system in which female accept multiple mating. The possible benefits of multiple mating for females are examined. Multiple mating did not seem to be necessary for avoiding sperm depletion, because females stored huge number of sperm in their sperm storage organ after finishing oviposition. The ingestion of metanotal secretion during copulation also had no effect on increasing fecundity and egg size. However, mating experience may have a positive effect on increasing fecundity slightly, though there were no differences between once- and twice-mated females. The other possible benefits for each male and female are discussed.     

The effect of age at mating on the rate of egg laying in the cricket, Teleogryllus commodus

As female crickets, Teleogryllus commodus (Walker) age there is a progressive change in their ability to produce eggs as indicated by the number deposited. Virgin females lay very few eggs (11/week) when only one week old, but the number increases to an average value of 160/week by the age 3, 5 or 7 weeks post imago. There is essentially no change in the number of eggs oviposited when very young (1 week old) or senescent (7 weeks old) females are mated, but there is a dramatic increase in the long term production of eggs when females are mated at middle age (3 and 5 weeks old). The results are correlated with previously published data from this species on the JH III titres of virgin females and females mated at different ages.

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Zusammenfassung Das Altern von T. commodus-Weibchen bringt eine fortschreitende Veränderung in ihrer Eiproduktion mit sich, die sich in der Anzahl von abgelegten Eiern ausdrückt. Während 1 Woche-alte, unbegattete Weibchen wenige Eier (11/Woche) ablegen, steigt ihre Zahl im Alter von 3, 5 oder 7 Wochen auf eine Durchschnittswert von 160/Woche an. Eine Begattung von jungfräulichen Weibchen im Alter von 1 Woche oder 7 Wochen ändert die Anzahl der abgelegten Eier nicht, wogegen sich bei 3–5 Wochen alten Weibchen zu einem dramatischen Anstieg in der langfristigen Eiproduktion führt. Die Ergebnisse sind mit früher publizierten Daten an T. commodus korreliert, die unterschiedliche JH III Titer in unbegatteten und begatteten Weibchen aufzeigten.