Rainer Rupprecht

Das Trommeln der Plecopteren

Summary1.Not only the males of the drumming stoneflies drum, but also the females.2.The drumming of the males serves for recognizing and finding the females, which answer this drumming only in an uncoupled state.3.The male drums first, afterwards the female answers at once. With Capnia, Perla and Dinocras only the males are in search for the females, which remain sitting on their places, whereas with Isoperla both (male and female) look for each other and drum when they meet each other.4.After the first coupling the females do not drum any longer and they begin laying eggs, which they otherwise keep for days and weeks.5.If the coupled females by chance are found again by a male, they may prevent further couplings by an attitude which is typical of the refusal (Fig. 5).6.The knocks caused by drumming are produced by the up and down swinging of the abdomen.7.The transference of the vibrations caused by the drumming exclusively takes place by the vibration of base, not by any sounds.8.Each investigated species of the stoneflies drums with a frequency and duration only characteristic of this one species.9.The specification and variability of the drum signals, as well as the way they drum were controlled and confirmed by drumming knocks which were artificially produced and varied.10.The subgenual organ — one of the possible sense-organs for the reception — was proved to be the perceiving sense-organ by experiments which eleminated or stimulated certain parts of the body.11.The males of Capnia bifrons find their way to the females by observing the increasing intensity of the drum knocks, the males of Perla marginata — which usually sit on stems — find their way by the devision of before and behind as well as by right and left hand side (of seperation of leaves).12.For the calculation of the speed of the expansion of the vibration on plants there is destined the modulus of elasticity and torsion of Phalaris arundinacea L. (Gramineae).Zusammenfassung1.Bei den trommelnden Perliden trommeln nicht nur die Männchen, sondern auch die Weibchen.2.Das Trommeln der Männchen dient der Erkennung und Auffindung der Weibchen, die nur im unbegatteten Zustand das Trommeln erwidern.3.Das Männchen trommelt immer zuerst, das Weibchen antwortet sofort danach. Bei Capnia, Perla und Dinocras sucht nur das Männchen, das Weibchen bleibt auf seinem Platz sitzen, während bei Isoperla sich beide Geschlechter gegenseitig suchen und beim Zusammentreffen trommeln.4.Nach der ersten Kopulation trommeln die Weibchen nicht mehr und beginnen mit dem Legen von Eiern, die sie sonst über Tage und Wochen zurückhalten.5.Werden die begatteten Weibehen zufällig von einem Männehen wiedergefunden, so können sie weitere Kopulationen durch eine charakteristische Verweigerungsstellung verhindern (Abb. 5).6.Die Trommelstöße werden durch Auf- und Abschwingen des Abdomens hervorgebracht.7.Die Übertragung der durch Trommelstöße ausgelösten Vibrationen erfolgt ausschließlich durch den Untergrund, nicht durch Schall.8.Jede der untersuchten Perlidenarten trommelt mit einer für sie charakteristischen Frequenz und Dauer.9.Die Spezifität und Variabilität der Trommelsignale sowie deren Vortragsweisen wurden durch künstlich erzeugte und variierte Trommelstöße überprüft und bestätigt.10.Von den als Rezeptor möglichen Sinnesorganen wurde durch Ausschaltungsund lokale Reizungsversuche das Subgenualorgan als perzipierendes Sinnesorgan nachgewiesen.11.Die Männchen von Capnia bifrons orientieren sich bei der Suche der Weibchen nach steigenden Intensitäten der Trommelstöße, die Männchen von Perla marginata, die meist an Stengeln sitzen, durch die Unterscheidung von vorne und hinten, sowie von rechts und links bei Blattabzweigungen.12.Für die Berechnung der Ausbreitungsgeschwindigkeit von Erschütterungen auf Pflanzen wird der Elastizitäts- und Torsionsmodul von Phalaris arundinacea L. bestimmt.

Die Kommunikation von Sialis (Megaloptera) durch Vibrationssignale

Abstract A newly discovered system of communication used by Sialidae while mating is described here. By means of this system males and unmated females of Sialis lutaria and S. fuliginosa are able to find each other and to communicate. Three kinds of signals are to be distinguished: (a) Rhythmic vibrations of the abdomen (♂+♀) allow mutual approach and recognition of species and sex; (2) prolonged, unstructed vibrations (♂ only), and (3) tapping of abdomen and wings on the ground is used by ♂♂ of S. lutaria as feedback for ♀♀ after their approach and by ♂♂ and ♀♀ of S. fuliginosa in the first step of their approach. The vibrations caused by movements of the abdomen are passed on via legs on to the ground and transmitted there only. The receptor is located within the legs. Observations in nature are being tested by experiments in the laboratory.

Drumming signals of Danish Plecoptera

Abstract The drumming signals of 4 species of Plecoptera collected in Denmark are reported. Danish Capnia bifrons drum about 15 times longer and more slowly than specimens from the Taunus Mountains, central Germany (d= 1.4 sec, as compared to 0.09 sec; f=6 and 80 knocks/sec, respectively). The drumming signals of Danish Isoperla grammatica differ only in duration (d = 0.5 sec.) from signals of German specimens (d = 1.0 sec). Drumming of Amphinemura sulcicollis was analyzed for the first time. Its signal is divided into two compounds lasting 0.1 and 0.4 sec, respectively. Frequency decreases from 49 to 31 knocks/sec. At 20°C, Taeniopteryx nebulosa drums for 1.6 sec, with a frequency of 5.5 knocks/sec. However, their drumming pattern varies largely with temperature.

Die bauchblase von Nemurella picteti klapalek (Insecta, Plecoptera)

Summary1.The vesicle of Nemurella is a protrusion on the ventral side of the 9th abdominal segment. It is found only in males.2.Fine-structure investigation shows mechanoreceptive hairs on the ventral and the lateral sides of the vesicle.3.At the base of each hair is a bipolar sensory cell and three enveloping cells. Below the basis of the tubular body a supporting rib of the cuticular sheath protrudes inwards. This rib might serve to prevent a downward movement of the tubular body on stimulation.4.The morphology of the hair and their uniform arrangement on the ventral side of the vesicle in longitudinal direction are in keeping with the observation that the vesicle is used for drumming.5.The drumming of a representative of the Nemouridae family is described here for the first time: the males knock at short impulse-rates whose frequency gradually increases from 10 to 50 cycle/sec; the females answer with signals whose frequency rises from 20 to 47 cycle/sec.6.There are two theories on to the function of the vesicle:a)it helps to explore or to check the signal-conductibility of the ground and/orb)it helps to centre the knocking movement and facilitates maintenance of an exact frequency of the signal on uneven ground.Zusammenfassung1.Die Bauchblase von Nemurella ist eine mediane Ausbuchtung des 9. Abdominalsternums. Sie kommt nur bei den ♂♂ vor.2.Ventral und lateral sitzen nach den elektronenmikroskopischen Untersuchungen mechanorezeptorische Sinneshaare.3.Zu jedem Haar gehören eine bipolare Sinneszelle und jeweils drei Hüllzellen. Unterhalb der Basis des Tubularkörpers ragt eine Verstärkungsrippe der cuticularen Scheide nach innen. Diese dürfte dazu dienen, bei Reizung ein Ausweichen des Tubularkorpers nach unten zu verhindern.4.Die Morphologie der Haare und ihre einheitliche Anordnung auf der Ventralseite in Längsrichtung der Bauchblase stimmen überein mit der Beobachtung, daß die Bauchblase zum Trommeln verwendet wird.5.Das Trommeln eines Vertreters der Familie Nemouridae wird erstmals beschrieben: die ♂♂ klopfen mit kurzen Schlagfolgen, deren Frequenz von 10–50 Hz ansteigt; die ♀♀ antworten mit Signalen, deren Frequenz von 20 auf 47 Hz erhöht wird.6.Für die Funktion der Bauchblase werden zwei Möglichkeiten angenommen: sie dient der Überprüfung des Untergrundes auf dessen Leitfähigkeit des Signals und/oder der Schlagzentrierung der Bewegung für eine genaue Frequenzeinhaltung auf unebenem Untergrund.

Attempts to re-colonise water insects in German brooks

Attempts were made to reintroduce water insects (five stonefly species and one mayfly species) into several third order streams in Rhineland-Palatine and Hessen, Germany. All these streams had been strongly affected by waste water and rubbish and had lost most of their macroinvertebrates. As a consequence of the installation of several purification plants in the past three decades, water quality has improved. Since no stoneflies returned, 700–1300 eggs of three different species (Isoperla goertzi, I. oxylepis, and I. grammatica) were exposed in the Selz brook (1997). In February 1998 a few larvae and in 1999 about 10,000 eggs of Perla marginata were added in the Walluf brook, and in 1998, 500 larvae of Oligoneuriella rhenana each in the Ruwer, Alf and Elz brooks. After 10 years, I found only one single larva of Perla marginata in the Walluf brook. In the laboratory, the total number of eggs produced per female could be determined by rearing. On that basis coupled with the assumption of about 3% survival chances for the embryonic and larval development and of about 50% survival chances for the adult females, it was calculated that at least two females of I. goertzi, eight females of I. oxylepis and seven females of I. grammatica were required to found a new and sustainable population.

Drumming Signals of Japanese Calineuria Species (Plecoptera: Perlidae)

The drumming signals of two Japanese stonefly species are here described for the first time. Both species belong to the same genus Calineuria but the signals differ clearly as to the method used in the production of the first part of the signal, as to the tapping frequency and the duration of the whole signal.

Drumming signals within the family Taeniopterygidae (Plecoptera)

Drumming signals of the 11 species of Palaearctic Taeniopterygidae are described for the first time based on the study of populations from nine different European countries from Spain to Russia. In this way, a contribution is made to our knowledge of the constancy respectively the divergence of signals typical for the species distributed over a very wide area. Communication patterns of the family under varying temperatures were analysed. The dependence on temperature indicates that the adults of this family are cold stenothermic insects. Within the genus Brachyptera (Newport, 1851), the call signal of males is significantly different from their response signal (duration and drumming frequency). The marked modulation of the drumming frequency, e.g., of B. risi (Morton, 1896) and B. seticornis (Klapálek, 1902) is reached by a modulation of the amplitude of abdominal movements. Based on the study of the drumming signals, Taeniopteryx auberti (Kis and Sowa, 1964) is proposed as a subspecies of T. hubaulti (Aubert, 1946). Actual intensity of the drumming signals of T. auberti was measured. Taeniopteryx hubaulti is recorded for the first time outside the Alps.