A circadian rhythm influencing foraging behaviour in the saw‐toothed grain beetle Oryzaephilus surinamensisBELL, C. H.; KERSLAKE, P. R.
doi: 10.1111/j.1365-3032.1986.tb00384.xpmid: N/A
ABSTRACT. Adults of Oryzaephilus surinamensis (L.) (Coleoptera, Silvanidae) placed in an open arena containing a refuge showed a cyclic pattern of activity in light, dark (LD) cycles when food in the form of damaged wheat grains was placed in the arena outside the refuge. Placing food in the refuge reduced cyclic change and lowered the general activity of the beetles. Batches of fifty insects conditioned in LD 9:15 h or 15:9 h at 25°C, 65% r.h., and transferred to continuous darkness (DD) at the end of a photophase, showed a circadian rhythm of foraging activity of periodicity near 24 h. Those transferred to continuous light at the end of a scotophase showed a 6 h delay in the onset of the next peak of activity, but subsequent peaks, although damped, revealed a periodicity near that in DD. The mean number of beetles wandering in the arena ranged from about eight in LD 15:9 h with all food in the refuge to about twenty‐one in LD 9:15 h with all food in the arena.
The time course of dark adaptation in the bee: a phototactic and electrophysiological investigationKINDERMANN, UTE; HERTEL, HORST
doi: 10.1111/j.1365-3032.1986.tb00387.xpmid: N/A
ABSTRACT. The time course of dark adaptation in Apis melifera L. was investigated by analyses of phototactic behaviour and electroretinogram (ERG). The behavioural results give a function for dark adaptation showing that in the dark after strong light adaptation the sensitivity increases exponentially with a time constant of 3 min. The sensitivity changes c. 2.4 log units during the time span of 5–720 s. The electrophysiological results indicate a smaller change in sensitivity at the level of the photoreceptors. Within a time span between 20 and 720 s the sensitivity increases during dark adaptation by a factor of 4.3 on a linear scale.
The timing of larval wandering and puparium formation in the flesh‐fly Sarcophaga argyrostomaRICHARD, D. S.; SAUNDERS, D. S.; EGAN, V. M.; THOMSON, R. C. K.
doi: 10.1111/j.1365-3032.1986.tb00390.xpmid: N/A
ABSTRACT. In mixed‐age cultures of the flesh‐fly, Sarcophaga argyrostoma (Robineau‐Desvoidy), the initiation of larval wandering (exodus behaviour) occurs as a gated circadian rhythm. In light‐dark (LD) cycles, most of this activity occurs in the dark, except in very short nights, or in certain phase relationships between the rhythm and light cycle. When transferred from series of LD cycles into continuous darkness (DD), cultures show a weakly persistent free‐running rhythm with a period of about 21 h. However, after transfer of first instar larvae from continuous light (LL) to DD, no such rhythm is observed. In contrast to larval exodus, formation of the puparia occurs at any stage of the LD cycle. The physiological mechanisms underlying this gated exodus behaviour, and its possible selective advantages, are discussed.
Modification of the courtship song by visual stimuli in the grasshopper Gomphocerus rufus (Acrididae)RIEDE, KLAUS
doi: 10.1111/j.1365-3032.1986.tb00391.xpmid: N/A
ABSTRACT. Males of Gomphocerus rufus L. perform a courtship song consisting of repetitive units, each of which is composed of three subunits (S1, S2, S3). S1 is characterized mainly by slow and fast head rolling; S2 and S3 are distinguished by different types of leg‐stridulation. These movements and the associated sounds were recorded during presentation of visual stimuli, either linear displacement of a living female or optomotor stimuli generated by a striped drum. Females moved artificially through the binocular visual field of a courting male with a velocity of 1 cm/s or more are mounted by the male from any subunit S1, S2 or S3, although under natural conditions mounting occurs only from S2. Thus above a critical velocity the courtship programme can be modified. Rotation of a striped drum about the yaw axis of the male during the slow S1 induces asymmetrical leg position, following movements of the head, and prolongation of S1. During S2 the male is especially sensitive to optomotor stimuli and responds with marked changes in body position. In S3 the intensity of the song is reduced, and its duration shortened. Fast drum movements interrupt the courtship programme. Rotation of the drum about the roll axis elicits optomotor head turning that interferes with the head rolling of S1. The fast phase of S1 and the frequency of head‐rolling during S1 cannot be modified by optomotor stimulation. The results can be interpreted by assuming certain interactions between three central nervous elements: a calling‐song generator, a head‐rolling generator, and an optomotor centre.
Effects of temperature and light on calling in the tiger moth Holomelina lamae (Freeman) (Lepidoptera: Arctiidae)SCHAL, COBY; CARDÉ, RING T.
doi: 10.1111/j.1365-3032.1986.tb00392.xpmid: N/A
ABSTRACT. In Holomelina lamae Freeman daily eclosion of adults is gated, with males emerging before females. By advancing the onset of photophase and by delaying the onset of scotophase, it was demonstrated that lights‐on acts as the main phase‐setting cue for calling. Few females call on the day they eclose. Calling is initiated c. 9 h after the onset of photophase in 2‐day‐old females, and shifts to earlier times in older females. The duration of calling also increases with age. That calling is controlled by an endogenous circadian clock is indicated by its persistence in continuous light (LL) and dark (DD). In LL calling is dampened rapidly, but a single scotophase re‐entrains the rhythm. Decreases in temperature advance the onset of calling and the mean hour of calling, while increases in temperature delay both. However, the magnitudes of such phase‐shifts depended upon hour of the photoperiod. Moreover, cooling and heating appears to exert both transient and long‐term effects on the calling rhythm. An 8 h period at a reduced temperature in LL induces calling in females whose calling is dampened, and entrains the calling rhythm. Females maintained in DD from second instar larvae to the adult stage exhibit a circadian calling rhythm set by eclosion.
Development and relationships of locomotor, feeding, and oxygen consumption rhythms in house cricketsWOODRING, J. P.; CLIFFORD, CRAIG W.
doi: 10.1111/j.1365-3032.1986.tb00393.xpmid: N/A
ABSTRACT. Locomotor, feeding, drinking, and oxygen consumption rhythms in adult virgin Acheta domesticus L. all appear to peak in the first half of the scotophase, be entrained cophasically by a LD 14:10 h cycle, have a lights‐off Zeitgeber and persist in LL with a πc. 25 h for the locomotor rhythm and c. 23 h for the oxygen consumption rhythm. There is no evidence of these rhythms in last instar larvae. The onset of the locomotor rhythm requires 3 days at 30°C but 5–7 days at 25–28°C after the final ecdysis in virgins, indicating a temperature related development of the locomotor rhythm. Oxygen consumption rhythms are lacking in 2‐day‐old virgins but present in 8‐day‐old virgins. Feeding rhythms can be recorded in virgins as young as 2 days (before locomotor rhythm developed). Both oxygen consumption and locomotor rhythms persist during starvation. The results suggest that a central brain oscillator drives both feeding and locomotor rhythms independently, but that the oxygen consumption rhythm is derived from the metabolic demands associated with the other rhythms.