The stimulation of territorial singing in house crickets (Acheta domesticus)

Summary The chirp rate in a territorial male cricket can be increased by playing chirps from a tape recorder. The increase is independent of the cricket's chirp rate before stimulation as long as the highest possible chirp rates are not yet reached (Figs. 5, 6, 8), but the size of the increase depends on the chirp rate of the stimulus used. After the end of stimulation the chirp rate returns exponentially to its previous level with a half Me of about 20 seconds.A momentarily silent cricket is more likely to start chirping at the beginning of stimulation and less so after a few minutes of stimulation than would be expected without stimulation. The chirp rate reached in these cases is higher the sooner the cricket starts chirping during stimulation (Figs. 9, 10, 11). These regularities can easily be deduced by allowing the chirp activity to have negative values if no chirps occur (see discussion).

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Zusammenfassung Spielt man einem zirpenden territorialen Heimchen das Zirpen eines Artgenossen vor, so kann sich seine Zirp-Rate steigern. Solange höchst mögliche Zirp-Raten noch nicht erreicht sind, ist dieser Zuwachs unabhängig von der Zirp-Rate vor dem Vorspielen. Der Betrag dieses Zuwachses hängt aber von der Zirp-Rate des verwendeten Reizgesanges ab. Nach Ende des Vorspielens dieses Gesanges kehrt die Zirp-Rate des Heimchens exponentiell mit einer Halbwertzeit von etwa 20 sec auf ihr früheres Niveau zurück.Ein momentan schweigendes Heimchen beginnt mit größerer Wahrscheinlichkeit zu Beginn des Reizgesanges und mit geringerer Wahrscheinlichkeit zu späteren Zeitpunkten zu zirpen, als man ohne Vorspiel des Reizgesanges erwartet. In diesen Fällen erreicht die Zirp-Rate höhere Werte, je früher das Heimchen zu zirpen beginnt. Diese Zusammenhänge lassen sich leicht herleiten, wenn man negative Werte für die Zirpaktivität zuläßt, wenn das Zirpen selbst nicht auftritt.

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The Deutsche Forschungsgemeinschaft loaned part of the electronic apparatus used in these studies and the Volkswagen-Stiftung granted funds for further electronic equipment.     

Susceptibility of North-American and European crickets to Acheta domesticus densovirus (AdDNV) and associated epizootics

The European house cricket, Acheta domesticus L., is highly susceptible to A. domesticus densovirus (AdDNV). Commercial rearings of crickets in Europe are frequently decimated by this pathogen. Mortality was predominant in the last larval stage and young adults. Infected A. domesticus were smaller, less active, did not jump as high, and the adult females seldom lived more than 10-14 days. The most obvious pathological change was the completely empty digestive caecae. Infected tissues included adipose tissue, midgut, epidermis, and Malpighian tubules. Sudden AdDNV epizootics have decimated commercial mass rearings in widely separated parts of North America since the autumn of 2009. Facilities that are producing disease-free crickets have avoided the importation of crickets and other non-cricket species (or nonliving material). Five isolates from different areas in North America contained identical sequences as did AdDNV present in non-cricket species collected from these facilities. The North American AdDNVs differed slightly from sequences of European AdDNV isolates obtained in 1977, 2004, 2006, 2007 and 2009 and an American isolate from 1988. The substitution rate of the 1977 AdDNV 5 kb genome was about two nucleotides per year, about half of the substitutions being synonymous. The American and European AdDNV strains are estimated to have diverged in 2006. The lepidopterans Spodoptera littoralis and Galleria mellonella could not be infected with AdDNV. The Jamaican cricket, Gryllus assimilis, and the European field cricket, Gryllus bimaculatus, were also found to be resistant to AdDNV.     

No direct or indirect benefits to cryptic female choice in house crickets (Acheta domesticus)

Cryptic female choice in crickets occurs through the prematureremoval of a male's spermatophore after copulation, which terminatessperm transfer. Although it is known that this behavior candirectly influence the paternity of offspring, its effects onfemale fitness have not been directly assessed. We tested thehypothesis that spermatophore removal by female house crickets(Acheta domesticus) confers fitness benefits on females, byrandomly assigning mates to females but permitting some femalesto freely remove spermatophores after mating (cryptic-choicetreatment) while forcing others to accept complete ejaculates(no-choice treatment). Although there was about a two-fold differencein the volume of ejaculate received by females of the two treatments,there were no significant differences in female longevity, reproductiveoutput, or offspring quality, as measured by offspring massand developmental time. Although differential spermatophoreremoval by females imposes strong sexual selection on males,the absence of a clear treatment effect suggests that femalesobtain no direct or indirect genetic benefits through theirpostcopulatory mating preferences.     

The role of chemoreception in sex recognition by male crickets: Acheta domesticus and Teleogryllus oceanicus

ABSTRACT. Contact chemoreception is important in female recognition by Teleogryllus oceanicus (Le Guillou) males. Antennal contact of female conspecifics, body regions, detached antennae and conditioned substrate elicited mostly courtship responses including courtship songs. Aggressive acts were produced only in response to male conspecifics. Male body regions, detached antennae and conditioned substrate elicited very few courtship or aggressive acts and no songs. This suggests that one or several communication modes, in addition to chemical communication, are necessary to elicit aggressive responses. Acheta domesticus (L.) males cannot rely upon chemical cues for recognition of either sex. Responses to conspecifics suggest that A. domesticus males produce aggressive acts immediately after antennal contact with either sex. Aggressive response to males usually persists, but response to females often switches to courtship. Responses to body regions, detached antennae, and conditioned substrate were few, with courtship and aggressive responses elicited by both male- and female-generated stimuli. The importance of contact chemoreception in cricket communication is suggested by (1) failure of hexane-washed antennae to elicit aggressive or courtship acts, and (2) males spending more time in contact with body regions and conditioned substrates than with corresponding controls. Lack of response to male or female odour-laden air suggests that chemical signals are used by males only if directly contacted. Chemical and other signals supplement the obvious use of acoustic signals for intra- and intersexual communication in these crickets. The importance of multimodal communication in sex recognition is discussed.     

Prolonged response to calling songs by the L3 auditory interneuron in female crickets (Acheta domesticus): intracellular evaluation

The L3 auditory interneuron in female Acheta domesticus, produces two different responses to the male calling song: an immediate response and a prolonged response. The prolonged response exhibited spiking activity and a correlated prolonged depolarization, both of which are clearly seen in intracellular recordings. The morphology revealed by intracellular staining was clearly the L3 neuron. The amplitude of the prolonged depolarization associated with the prolonged response increased with increases in sound intensity, resulting in increased spiking rates. Both depolarization and sound presentation increased the spiking rate and the slope of pre-potentials (thus leading to spiking threshold more quickly). Injecting hyperpolarizing current had the expected opposite effect. The effects of positive current injection and sound presentation were additive, resulting in spiking rates that were approximately double the rates in response to sound alone. Short postsynaptic potentials (PSPs), whose duration ranged from 15-60 ms, which may lead to action potentials were also observed in all recordings and summated with the prolonged depolarization, increasing the probability of spiking.     

Apparent inhibition of in vitro juvenile hormone biosynthesis by the corpus cardiacum of adult crickets (Gryllus bimaculatus and Acheta domesticus) is due to juvenile hormone esterase

When measuring the in vitro JH III-biosynthesis by corpora allata (CA) from adult female crickets in the presence of corpora cardiaca (CC), the amount of JH III in the medium decreased in a dose dependent manner. The CC of a 4-day-old female Gryllus bimaculatus contain 42 pmol.pair CC⁻¹ Grb-AKH, 0.62 pmol.pair CC⁻¹ octopamine, and a JH-esterase activity of 9.8 pmol JH.h⁻¹.pair CC⁻¹. Comparable values for Acheta domesticus are 21 pmol.pair CC⁻¹ Grb-AKH, 0.53 pmol.pair CC⁻¹ octopamine, and 6.5 pmolJH.h⁻¹.pair CC⁻¹ of JH-esterase activity. Even if the entire octopamine content of the CC were released into the medium, the concentration would be below the 10⁻⁵ M threshold for octopamine inhibition of JH synthesis. An in vitro AKH inhibition of JH III synthesis was observed, but only at a relatively high concentration (10⁻⁵ M). If the entire AKH content (10⁻⁶ M) of the CC were released into the medium, the AKH concentration would approach JH synthesis inhibiting levels. However, the rate of release of AKH in vitro was very low, and, therefore, AKH from the CC could not affect JH synthesis. In contrast, a specific JH-esterase, released by isolated CC into the medium, was sufficiently high in both cricket species to account for the observed decrease in JH III present. OTFP-sulfone (10⁻⁵ M) restored apparent JH synthesis of the CA to the control level. There was no reduction in the amount of JH released when CA were incubated with heat treated CC. The CA themselves contained almost no JH-esterase activity. © 1997 Wiley-Liss, Inc.     

Temperature and the energetics of development in the house cricket (Acheta domesticus)

The influence of rearing temperature on the energetics of development was investigated in house crickets (Acheta domesticus). Crickets raised at 25 degrees C grew slower (0.51 mg d(-1), dry mass basis) and took longer to develop (119 d) but obtained a greater adult body mass (61 mg, dry mass) than crickets reared at 28 degrees C (0.99 mg d(-1), 49 d, 48 mg). Total metabolic energy consumed during development at 25 degrees C (1351 J) was twice that at 28 degrees C (580 J) primarily because of the longer development period, and as a consequence the specific net cost of growth was much greater for crickets reared at 25 degrees C (22.1 kJ g(-1)) than 28 degrees C (11.9 kJ g(-1)).     

Modulation of syllable period‐selective phonotaxis by prothoracic neurones in crickets (Acheta domesticus): juvenile hormone,picrotoxin and photoinactivation of the ON1 neurones

Abstract In response to model calling songs (CSs), the phonotaxis of female Acheta domesticus ranges from being very selective to unselective. Within 15 min of nanoinjecting juvenile hormone III (JHIII) or picrotoxin (PTX) into the prothoracic ganglion, females become more selective for syllable period (SP) than in pre‐tests. Controls for JHIII experiments, including nanoinjection of acetone into the prothoracic ganglion or nanoinjection of JHIII into the metathoracic ganglion, do not influence selectivity. Similarly, nanoinjection of saline into the prothoracic ganglion and nanoinjection of PTX outside of the prothoracic ganglion does not change the overall selectivity of the female’s phonotaxis. These results indicate that circuits in the prothoracic ganglion modulate the SP‐selectivity of phonotaxis. Photoinactivating both of the ON1 prothoracic auditory interneurones in old females that were previously unselective for SP also results in greater SP‐selectivity during phonotaxis. Evidence suggesting that ON1 has this effect via its inhibitory input to L3 (another prothoracic auditory neurone) includes: photoinactivation of one ON1 neurone causes angular errors in the female’s orientation to CSs at 85 dB (above the threshold of the L3), stimulation with 60 dB CSs (above the threshold of ON1 but below the threshold of L3) does not induce errors in angular orientation, inactivation of ON1 in old crickets results in greater angular errors (85 dB stimulus) than it does when ON1 is inactivated in young females, and photoinactivation of ON1 increases the firing rate of the L3 neurone.     

Tritium labelling and cytochemistry of extra DNA in Acheta

Females of Acheta domesticus were injected with H³-thymidine and H³-uridine at various stages of development in order to study DNA and RNA synthesis in the DNA body present in the oocytes. Staining with alkaline fast green, azure B and the Feulgen reaction were employed as cytochemical tests. The following main results were obtained.

1. The DNA body appears in the oogonia at interphase as a Feulgen positive spherical structure 2 microns in diameter and is seen in subsequent mitotic divisions as a slightly smaller structure of variable shape. H³-thymidine autoradiography discloses that the DNA present in this body is synthesised at a different time from the chromosomal DNA.
2. At interphase and during the early prophase of meiosis the DNA body increases in size becoming a large Feulgen positive sphere 6 microns in diameter. Small nucleoli are present within this body. The DNA of the body is complexed with histone as revealed by alkaline fast green staining. H³-thymidine labelling discloses that it is at these stages that the bulk of the DNA synthesis takes place in the body.
3. Every oocyte contains a DNA body, and no body of comparable size or shape seems to be present in the male meiotic prophase.
4. At pachytene and diplotene the DNA body acquires the appearance of a “puff”. Two zones can be distinguished inside the DNA body: (1) an inner core of DNA and an outer shell of RNA. The inner core is Feulgen positive and stains light green with azure B, the outer shell is Feulgen negative and stains purple-violet with azure B, as does the cytoplasm. From the inner DNA core many Feulgen positive fibrils radiate into the outer RNA shell. These fibrils appear unstained or slightly greenish with Azure B, forming a transparent network in a purple-violet background. This gives the body the typical appearance of a “puff”. H³-uridine incorporation reveals that the RNA synthesis occurs in the outer RNA shell of the body and in the chromosomes. RNase treatment removes the H³-uridine incorporated into these regions.
5. At the end of diplotene the DNA body starts to disintegrate. The DNA core breaks up into minor components and the outer RNA zone also begins to disintegrate. By late diplotene the whole body has vanished, releasing DNA, histone and RNA into the nucleus. Subsequently the nuclear envelope disintegrates as it regularly does at the end of prophase of meiosis.
6. The simplest interpretation of the above results is that the DNA body represents hundreds of copies of the genes of the nucleolar organizing region.

     

Proteine in der Frühentwicklung der Grille (Acheta domesticus,Orthoptera)

Zusammenfassung Aus Grilleneiern wurden verschiedene Proteingemische gewonnen durch: Homogenisierung, Ultrabeschallung, fraktionierte Zentrifugation, Essigsäureextraktion und Säulenchromatographie an Hydroxyapatit. Die nach Acetonfällung in 8 M Harnstoff gelösten Proteine wurden durch SDS-Polyacrylamidelektrophorese aufgetrennt und densitometrisch analysiert. In Grilleneiern ließen sich durch Inkubation in¹⁴CO₂ Proteine radioaktiv markieren. Die Markierungsrate einzelner Proteinfraktionen wurde als Radioaktivität eluierter Gelfraktionen oder im Autoradiogramm von Gelscheiben gemessen. Die Verteilung der radioaktiv markierten Proteine im Elektropherogramm entsprach nicht dem Muster der gefärbten Proteinbanden und unterschied sich in charakteristischer Weise in den geprüften Stadien: Furchung (Omnipotenz), Keimanlage (Determination) und Keimstreif (Primäre Differenzierung).

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Proteins in early development of the cricket (Acheta domesticus, Orthoptera)

Summary Proteins in homogenates of yolk-rich cricket eggs were fractionated by sonication, differential centrifugation, acetic acid-extraction and column chromatography on hydroxyapatite and separated by SDS-polyacrylamide electrophoresis in 8 M urea. Radioactivity was introduced by incubating the eggs, which are impermeable to labeled amino acids, in a¹⁴CO₂-atmosphere.¹⁴C-label in protein extracts was resistant to hot TCA-extraction and was proved to be mainly in glutamic acid and aspartic acid. The profiles of radioactivity across the electropherogram as analysed by gel-fractionation and scintillation counting or by radioautography were found to be distinct from the pattern of stained protein-bands. During early development characteristic changes in the patterns of radioactive proteins occurred at the three stages tested: cleavage (omnipotency), germ-disc (determination) and germ-band (primary differentiation).

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Wir danken der Deutschen Forschungsgemeinschaft für die Unterstützung dieser Arbeit durch ein Ausbildungsstipendium (G. W.) und Sachbeihilfen.     

Prolonged response to calling songs by the L3 auditory interneuron in female crickets (Acheta domesticus): possible roles in regulating phonotactic threshold and selectiveness for call carrier frequency

L3, an auditory interneuron in the prothoracic ganglion of female crickets (Acheta domesticus) exhibited two kinds of responses to models of the male's calling song (CS): a previously described, phasically encoded immediate response; a more tonically encoded prolonged response. The onset of the prolonged response required 3-8 sec of stimulation to reach its maximum spiking rate and 6-20 sec to decay once the calling song ceased. It did not encode the syllables of the chirp. The prolonged response was sharply selective for the 4-5 kHz carrier frequency of the male's calling songs and its threshold tuning matched the threshold tuning of phonotaxis, while the immediate response of the same neuron was broadly tuned to a wide range of carrier frequencies. The thresholds for the prolonged response covaried with the changing phonotactic thresholds of 2- and 5-day-old females. Treatment of females with juvenile hormone reduced the thresholds for both phonotaxis and the prolonged response by equivalent amounts. Of the 3 types of responses to CSs provided by the ascending L1 and L3 auditory interneurons, the threshold for L3's prolonged response, on average, best matched the same females phonotactic threshold. The prolonged response was stimulated by inputs from both ears while L3's immediate response was driven only from its axon-ipsilateral ear. The prolonged response was not selective for either the CS's syllable period or chirp rate.     

A Glimpse into the Microbiota of Marketed Ready-to-Eat Crickets ( Acheta domesticus )

The present study was aimed to get an insight into the bacterial biota of ready-to-eat small crickets (Acheta domesticus) already marketed in the European Union. 16S rRNA gene of the DNAs extracted from thirty-two samples of ready-to-eat crickets commercialized by 4 European Union producers located in Austria, Belgium, France and the Netherlands (2 batches per producer) was analyzed by Polymerase Chain Reaction–Denaturing Gradient Gel Electrophoresis (PCR–DGGE). The species belonging to the genera Hespellia, Ruminococcus and Clostridium were detected in samples from Austria, while those from genera Lysobacter, Staphylococcus and Clostridium were detected in samples from Belgium. Moreover, samples from France were characterized by Staphylococcus, Pseudomonas, and Hydrogenophilus genera. Finally, the genera Staphylococcus, Hydrogenophilus, Clostridium and Ruminococcus were identified in the samples produced in the Netherlands. When insects are intended for commercialization, rearing, processing and handling could affect the presence of the occurring microbial species. Hence, to assure a safe product, the need for a full standardization of production technologies, including feed supply as well as rearing and processing practices, is recommended.     

Cyclic guanosine 3'-5'-monphosphate. High levels in the male accessory gland of Acheta domesticus and related crickets.

Guanosine 3',5'-monophosphate (cyclic GMP) was found in the accessory gland of reproductively mature male house crickets (Acheta domesticus (L.)) up to the exceptionally high level of 500 pmol/mg protein (10(-4) mol/kg wet weight). The identity of cricket cyclic GMP was confirmed by enzymatic and spectral analysis. A survey of 10 closely related species of Orthoptera indicated that high levels of cyclic GMP in the accessory gland occur in the subfamily Gryllinae, to which A. domesticus belongs. In these crickets, cyclic GMP in the accessory gland increases together with protein content during two weeks after the final molt. Levels are not augmented by dissection, and are independent of the presence of sperm in the seminal vesicles and of the production of spermatophores by the gland. The function of cyclic GMP in the accessory gland is not yet understood.