Introduction Many organisms have an endogenous timekeeper

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nitidula emahrt sich vor allem von Samen und Grdsern, Aiolopus fhalassi''nus ist
pofyphag und tendenziell krduterfressend. FOr Ruspolia nitidula legen die Beobachtungen nahe, daB die Art jahreszeitlich wechselnd die ndhrstoffreichsten Nahrungsressourcen ausbeutet. Schilf wird nur in jungem Zustand gefressen, wdhrend spdter Grassamen die Hauptnahrung darstellen.
Danksagung
Ein Teil der Beobachtungen erfolgte im Rahmen von Untersuchungen fUr die Bezirksstelle f0r Naturschutz und Landschaftspflege Karlsruhe und fUr das Bayerische Landesamt fiir Umweltschutz, denen fUr die M6glichkeit zur Ver6ffentlichung gedankt sei.
Reinhold Treiber
lm Westengarten 12
79241 lhringen
e-mail : [email protected]
Literatur
GorrscHALK, E. (1993): Sukzession auf neu angelegten Rebb6schungen im Kaiserstuhl am
Beispiel der Heuschrecken. Diplomarbeit Fak. f. Biologie, Univ. Freiburg; 65 S.
(unver6ff.).
lNGRrScH, & KOHLER (1998): Die Heuschrecken Mitteleuropas. Neue Brehm-Bucherei Bd. 629.
460 S. Magdeburg.
lNGRrScH, S. (1 976): Vergleichende Untersuchungen zum Nahrungsspektrum
mifteleuropdischer Laubheuschrecken (Saltatoria: Tettigoniidae). Entomol. Z" 20:217224; Stuttgart.
R. & ALBRECHT, M. (1996): Die GroBe Schiefkopfschrecke (Raspo/la nifdula Scopolt,
1786) neu f0r Bayern und Wiederfund f0r Deutschland (Orthoptera, Saltatoria).
Nachrbl. bayer. Entomol . 45(314). 60-72. M0nchen.
TREIBER, R. (1998):
f
-78
BIOLOGIE
nduction of song activity in Oecanthus pellucens (Scoeou, 1763)
(Gryllidae, Oecanthinae)
Manfred Alban Ffeifer
Zusammenfassung
Gesangsausfdsung beim Weinhiihnchen (Oecanthus pellucens)
Verfasser
TRETBER,
ARTICULATA 2001 16(1t21:75
Der Autor gibt Hinweise darauf, dass bei Oecanthus pellucens Gesang ausschlieBlich durch Dunkelheit ausgeldst wird. Die Art scheint nicht eine bestimmte
Zeit wdhrend der Nacht zu bevorzugen, eine Steuerung der Gesangsaktivitdit
durch eine biologische Uhr ist daher nicht anzunehmen. Gesang beginnt unterhalb einer bestimmten Lichtintensitdt, welche normalervveise mit dem Dimmerungseinbruch erreicht wird, und endet am ndchsten Morgen, sofern Nachts nicht
eine Minimaltemperatur unterschritten wird. Die Art singt auch tagsUber, wenn
durch starke Bewcilkung die Lichtintensitdt reduziert ist.
Summary
The author gives evidence that song activity in Oecanthus pellucens is induced
only by a scotophase. Because it has no preference for a certain time during the
natural scotophase the species has no need for a biological clock for the
regulation of its song activity at all. Song activity is starting just below a certain
light intensity - which is normally reached at dusk - and is ending at dawn or
when temperature falls at night below a certain threshold. The species may sing
during the day when clouds reduce light intensity.
Introduction
Chorthippusvagans. In: DETzEL, P. (1998): Die Heuschrecken Baden-
W0rttembergs.
WANCURA, R. & DErzEL, P. (1998): Aiolopus thalassinus. In: DErzEL, P. (1 998): Die Heuschre-
cken Baden-W0rttembergs.
Many organisms have an endogenous timekeeper which regulates their
activities. In insects this endogenous timekeeper is a so called insect clock. This
insect clock mostly follows
a
circadian rhythm which
is
calibrated by the
alternation of day and night. ln Saltatoria the activities in many species follow a
circadian rhythm but there are exceptions. For example in Sclsfocerca gregana
no circadian rhythm in locomotion activity was found (Oonnueo 1966). As
singing in Saltatoria is an essential activity most species have a preferential time
for song activity (FtscHER et al. 1996). For example Metrbpten roeseliiand M.
bicolor have higher song activities in the first half of a day (FtscHen et al. 1996).
But most known is from light trapping in night flying moth the preference of some
species for coming at different hours to the light
Saltatoria, like all insects, are poikilothermal animals and they need a minimum
air temperature for song activitity or - in diurnal species - sunshine to raise their
body temperature by solar radiation. ln Teftigonia viidissima was found that the
ARTfCULATA 2001 16
(n)
ARTTCULATA 2001
rql/2)
FP7
E:6
species prefer singing in warm evenings but is the temperature low the species
already sing in the afternoon (NrELsoN & DRErsrG 1970).
E:E
Oecanthus pellucens adult emerge from the end of July to the beginning of
August. On warm days males start singing around sunset and song is performed
until late night. When temperature remains above a certain threshold (Snruoen
1995:12 "C) the species may continue singing till dawn (Fig. 1).
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Methods and results
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Field observations
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Surprisingly males may even sing during the day. Sander (1995) reports, that in
summer, O. pellucens starts singing at dusk, but that in autumn the species often
starts singing in the afternoon. DETZEL (1998) also observed singing males on
cloudy days. Even on a sunny day I located a singing male in thick bushes while
individuals in adjacent grassland were not singing. I also found singing males in
the early afternoon when sunlight intensity was strongly reduced by thunder
ox(!
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Observation during the total solar eclipse on the 11'n of August 1999 in SouthWest Germany
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used the rare opportunity of a total solar eclipse for investigating the song
activity of O. pellucens in the nature reserve'Monbijou' near Zweibriicken in the
South-West of Rhineland-Palatinate. O. pellucens began singing soon after 8pm
at the day prior to the eclipse (Fig. 1), and continued singing until dawn. The
eclipse lasted from 11:10 until 13:54 Central European Summertime, and the
period of the total eclipse from 12:30 until 12:32. During this 2 minute period of
intense darkening only males were heard singing.
Capture experiments
In my flat in Bobenheim-Roxheim I kept some individuals of the species - which I
caught in and around the town - in 1% I pickled cucumber jars. At night they
started singing in the same timescale as individuals in nature. As soon as I
switched an artificial light on they stopped. When the artificial light was switched
off they started singing again within a few minutes.
ln an other experiment I covered the jar with dark woollen sheets so that the
crickets were subjected to darkness during the day. Within less than five minutes
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ARTfCULATA 2001 16
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Discussion
ARTICULATA 2001
The observations in the field and during the solar eclipse show that
o.
only sings below a certain level of light intensity. Especially in the capture
experiment I could give evidence that song activity is rapidly triggered by
diminishing light intensity and is switched off immediately in bright light. The
immediate reaction to the exogenous factor light implies that song activity itself is
not induced by an endogenous biological clock as it is generally assumed for
saltatorian insects (lNGRtscH & Koeulen 1998, p234).
species which prefer a certain time of day for song activity - such as Metioptera
bicolor - may need a biological clock for orientation to the time of day. Also this I
call in question because this diurnal active species stopped singing for the span
of reduced fight intensity during the solar eclipse (PFEIFER in prep.). o. pellucens
starts singing below a certain light intensity and continues throughout the nlght
until the temperature declines to below a certain threshold or until the beginning
of the next photoperiod at dawn. Explanation of this behaviour requires no
recourse to
a
t6 (1 t2l:79
KURZMITTEILUNG
pellucens
biological clock, but can be explained purely by response to
prevailing light intensity.
Author:
Manfred Alban Pfeifer
AnebosstraBe 4
D 67240 Bobenheim-Roxheim
lmagines von Chorthippus mollis (CHAReENTIEn, 1825) und
Gomphocerippus rufus (Llt.tueus, 1758) am 15. Dezember 2000
Gabriel Hermann
In den Mittagsstunden des 15.12.2000 herrschte im baden-wurttembergischen
Aichtal (15 km sUdl. Stuttgart) teils sonnige, aber kuhle und windige Witterung
vor. Da im Verlauf des Herbstes bis dato weder stdrkere Fr6ste noch ldnger andauernde Schneelagen aufgetreten waren und der November 2000 im Vergleich
zum langjiihrigen Mittel auBergew6hnlich warm blieb, wurde der Versuch unternommen, auf einem sUdexponierten Magerrasen noch Feldheuschrecken aufzufinden. Zwischen voll besonnter Nadelstreu einer dlteren Waldkiefer (Pinus sylvestns) fanden sich schlieRlich sechs Weibchen und ein singendes Mdnnchen
der Roten Keulenschrecke (Gomphocerippus rufus) sowie ein Weibchen des
Verkannten GrashUpfers (Chorthippus mollis). An der Fundstelle wurden bodennah Temperaturen knapp unter 15"C gemessen. Beide Arten Zihlen im betreffenden Gebiet zu den hiiufigsten Feldheuschrecken und erreichen hier im Spiithohe bis sehr
sommer mit unterschiedlichen Vorkommensschwerpunkten
-
-
hohe Abundanzen.
References
FUr G. rufus waren iihnliche Phdnologie-Daten bereits bekannt. Derzrl (1998,
schriftl. Mitt. SMErrAu) gibt fUr Baden-WUrttemberg als spdtestes Nachweisdatum von fmagines den 14.12. an. Adulte Ch. mollis-lndividuen sind in diesem
Bundesland dagegen offenbar noch nicht im Monat Dezember gefunden worden
(vgl. Phainogramm in BRnNot& GorrscHALK 1998).
It.
DETZEL, P. (1998): Die Heuschrecken Baden-Wtirtembergs. 580 S. (Ulmer), Stuttgart
FrscHER, P.F.; ScHueeRr, H.; FENN, S. & ScHULz, U. (1996): Diurnal song activity in grassland
Orthoptera. - Acta Oecologia 17(5): 345-364.
s. & KoHLER, G. (1998): Die Heuschrecken Mitteleuropas.460 s. (westarp-wiss.),
Magdeburg;
lNGRrscH,
NTELSoN, E. T. & DRErsrc, H. (1970): The behavior of stridulation in
Behaviour 37: 205-251
orthoptera Ensifera.
Arbeitsgruppe fUr Tierdkologie und Planung
.
ODHIAMBo, T.R. (1966): The metabolic effects of the corpus allatum hormone in the male desert
locust. ll. Spontaneous locomotoractivity. J. exp. Biol.45: 51-63.
PFETFER, M. A. (in prep.): Beobachtungen des Gesangs von Langfuhlerschrecken (Ensifera)
wahrend der totalen Sonnenfinstemis am 1 1 . August 1999 in der Pfalz - Hinweise auf
eine exogene Steuerung des Gesangsverhaltens.
SANDER, U. (1995): Neue Erkenntnisse iiber Verbreitung und Bestandssituation des Weinhdhn-
chens oecanfhus pellucens (scopoLr, 1763) (Gryllidae, oecanthinae) im ndrdlichen
Rheinland-Pfalz und in Nordrhein-Westfalen. - Articulata 1995 10(1): 73-Bg.
ARTICULATA 2OO1 16
Verfasser:
Gabriel Hermann
(I2I
Johann-StrauB-Str. 22
D 70794 Filderstadt
Literatur
Gor-rscHALr,E.: Chorthippus mollis (CHARPENTIER, 1825). - In: DETZEL, P. (199e):
Die Heuschrecken Baden-W0rftembergs. - 580 S. (Ulmer), Stuftgart.
BRANDT, D.,
- In: DETZEL, P. (1998): Die
- 580 S. (Ulmer), Stuftgart.
DErzEL, P. (1998): Gomphoceippus rufus (L|NMEUS, 1758).
Heuschrecken Baden-Wiirttembergs.
ARTICULATA 2OO1
16(1 12\
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