Discontinuous gas exchange (DGE) is the main (23 individuals) breathing mode in resting adult Platynus assimilis. Few of the beetles tested (13 individuals) displayed a pattern of cyclic gas exchange or CGE. The burst of CO2 release in DGE and CGE was always accompanied by abdominal pumping (active ventilation or V). Seven individuals displayed a pattern of continuous respiration, characterized by regular abdominal pumping. Resting metabolic rate (RMR) in continuously breathing beetles was higher than in those using DGE and CGE. After treatment with sub-lethal doses of alpha-cypermethrin DGE ceased. Treated beetles were characterized by continuous pumping and almost regular periods of activity. RMR increased significantly after treatment with a pyrethroid., Irja Kivimägi ... [et al.]., and Obsahuje seznam literatury
Rhythmic body movements, cyclic gas exchange and heart activity were studied at low temperature (mostly at 5°C) in bumblebee Bombus terrestris foragers. Simultaneous measurements by means of an electrolytic respirometer combined with an optical system by infrared radiation, revealed a co-ordination between discontinuous gas exchange cycles and body rhythmic movements. No distinct correlation was found between intermittent heart activity and body movements. The carbon dioxide bursts were actively ventilated by abdominal vigorous pumping movements. These bursts followed each other with intervals of 25-30 minutes.
The periods of heart activity regularly alternated with heart pauses. The frequency of the heartbeat was similar to that of the weak abdominal pulsations (0.2-0.25 Hz) which were imperceptible with the naked eye. All bumblebees displayed abdominal pulsations which were independent of vigorous pumping movements. In bumblebee B. terrestris foragers haemolymph oscillation was assumed at 5°C, as is known in the honeybee and some other Bombus species.
Rhythms in abdominal pumping, heartbeats and discontinuous gas exchange cycles (DGCs) of CFV subtype (closed, flutter and ventilation periods) in adults of pine weevil Hylobius abietis were simultaneously recorded using an electrolytic microrespirometer and an infrared (IR) cardiograph or IR actograph (IRA). The cyclic release of carbon dioxide was associated with active ventilation (V phase) provided by vigorous abdominal pumping movements due to contractions of tonic longitudinal and transversal abdominal muscles, which are visible to the naked eye. On the IRA-recordings, the abdominal pumping signals are superimposed on the heartbeat spikes. The relative amplitude of the abdominal pumping signals on these recordings is more than 10 times greater than that of the heart beats. Visual observations showed that the subelytral cavity appeared to be closed during the release of carbon dioxide and open at other times. The flutter (F) of the CFV cycle is characterised by active miniature inspirations or ventilations before the V period. The miniature ventilation movements were imperceptible to the naked eye, but were recorded on the respirometer-actigraph as clear spikes. In addition, movements of the tip of the abdomen, of between 10-20 mm were seen under a stereomicroscope at a magnification of 40×. Some cycles were categorized as (C)FV cycles, when the C period disappears into the end of the V period. Abdominal pumping and miniature inspirations were clearly synchronized with the CFV cycles. Abdominal pumping movements, miniature inspirations or ventilations and heartbeats in adult H. abietis were distinguishable when recordings of the electrolytic microrespirometer-actograph and IRA were made in parallel. These three events were recognized by their different amplitudes and frequencies. It is presumed that abdominal pumping and miniature inspirations in adult H. abietis are obligatory rhythmic movements of different function and origin.
Using an opto-cardiograph combined with an infrared gas analyzer regular bouts of abdominal contractions were recorded from last instar larva of Bombus terrestris. The rate of CO2 release was about 0.7 ml g-1 h-1. The bouts of contractions were of two types: weak extracardiac pulsations and vigorous pumping. The frequencies of pulsations and pumping were 25-35 per min and 8-12 per min, respectively. Bouts of extracardiac pulsations and abdominal pumping were independent of each other and sometimes overlapped. Cardiac contractions (heartbeats) were continuous (57-63 pulses/min). This study suggests that the periodically occurring abdominal contractions play an essential role in respiration and/or in haemolymph circulation in larvae of B. terrestris.
The relations between the patterns of discontinuous gas exchange cycles (DGCs) and water loss were investigated in non-chilled diapausing pupae of the white cabbage butterfly Pieris brassicae kept at room temperature (22-24°C) in Petri dishes. An electrolytic respirometer, combined with an infrared (IR) actographic device was used for the simultaneous recordings of metabolic rate, cyclic release of carbon dioxide (bursts), passive suction inspirations (PSIs) and body movements. The patterns of cyclic gas exchange in four- and five-month-old non-chilled diapausing pupae varied individually to a considerable extent. About 40% of the pupae displayed long DGCs lasting 1-3 h, while the interburst periods were characterised by rare and almost regular large PSIs succeeding at intervals of 1-4 min. Nearly 30% of the pupae exhibited short DGCs lasting 3-5 min, while between the bursts there occurred unclear frequent gas exchange microcycles. Standard metabolic rate (SMR) did not reveal significant differences between long DGCs and short DGCs ranging from 32-56 (mean 47.6 ± 4.6) ml O2 g-1 h-1, and 28-61 (mean 44.95 ± 5.3) ml O2 g-1 h-1, respectively. The mentioned levels of SMR were characteristic of diapausing pupae.
Water loss in pupae with long DGCs was determined gravimetrically to be 0.29 ± 0.1 mg g-1 day1. At the same time, water loss in pupae that showed only short DGCs and irregular microcycles was 1.73 ± 0.31 mg g-1 day-1, which was significantly higher than in individuals characterised by long DGCs. We suggest that water loss in the non-chilled diapausing pupae may depend significantly on the patterns of cyclic gas exchange: long cycles and rare but deep PSIs exerted a marked water conserving effect.
Adults of Colorado potato beetle Leptinotarsa decemlineata are very active at room temperature, and their almost continuous struggling in the respirometer prevents the measurements of the patterns of gas exchange, body movements and heartbeat. The tonic immobility of beetles was evoked by light flashes and by shaking as external stimuli. The immediate reaction to these stimuli was the reflexive closing of the spiracles and the cessation of CO2 release for some minutes, which was followed by a large burst of this gas. The state of the evoked tonic immobility did not influence heartbeat and abdominal pulsations, but the periodically -occurring abdominal-thoracic pumping movements stopped for 2-5 minutes. During the periods of pumping ventilation the metabolic rate was increased about two times.The state of tonic immobility evoked by light flashes lasted 2-6 minutes, but when shaking was applied as a stimulus complete immobility was about two times longer.