Publications (16)20.01 Total impact
-
Article: Larval food plants can regulate the cabbage moth, Mamestra brassicae population
[show abstract] [hide abstract]
ABSTRACT: The effect of different food plants on various parameters of development and hibernation in the cabbage moth, Mamestra brassicae L. (Lepidoptera Noctuidae), a serious polyphagous pest, was tested. Brassica oleracea, Brassica napus, Beta vulgaris, Allium cepa and Pisum sativum, differed in their influence on larval development rate, on body mass, mass loss and mortality and on the intensity of pupal diapause. When the larvae were fed on A. cepa, B. vulgaris and particularly on P. sativum, larval development was longer, mortality was higher and pupae had a smaller body mass with diapause not deeply engaged, leading to death during hibernation. Therefore, P. sativum may be used to exhaust the resources of M. brassicae until local outbreaks perish. This study provides strategic information for establishing integrated pest management for cropping systems and for predicting the population dynamics of the cabbage moth.Bulletin of Insectology 01/2013; · 0.59 Impact Factor -
Article: Effects of Fastac 50 EC on bumble bee Bombus terrestris L. respiration: DGE disappearance does not lead to increasing water loss.
[show abstract] [hide abstract]
ABSTRACT: Sublethal effects of pesticides in insects can be observed through physiological changes, which are commonly estimated by metabolic rate and respiratory patterns, more precisely by the patterns of discontinuous gas-exchange (DGE) cycles. The aim of the present research was to study the effect of some low concentrations of Fastac 50 EC on the cycles of CO(2) release and respiratory water loss rates (WLR) in bumble bee Bombus terrestris L. foragers. Bumble bees were dipped into 0.004% and 0.002% Fastac 50 EC solution. Flow-through respirometry was used to record the respiration and WLR 3h before and after the treatment. The respirometry was combined with infrared actography to enable simultaneous recording of abdominal movements. Our results show that Fastac 50 EC has an after-effect on bumble bee respiratory rhythms and muscle activity but does not affect WLR. Treatment with 0.004% Fastac 50 EC solution resulted in disappearance of the respiration cycles; also the lifespan of treated bumble bees was significantly shorter. Treatment with 0.002% Fastac 50 EC solution had no significant effect on respiration patterns or longevity. We found no evidence for the DGE cycles functioning as a water saving mechanism.Journal of insect physiology 09/2012; 58(11):1469-76. · 2.24 Impact Factor -
Article: Oxygen convective uptakes in gas exchange cycles in early diapause pupae of Pieris brassicae.
[show abstract] [hide abstract]
ABSTRACT: Oxygen convective uptakes in gas exchange cycles were directly recorded in early diapause pupae of Pieris brassicae L. (Lepidoptera; Pieridae) by means of O2 coulometric respirometry. This method was combined with flow-through CO2 respirometry, the two systems being switchable one to the other. During recording with both systems, measurements were also taken with infrared actography. The pupae displayed short discontinuous gas exchange cycles lasting 40-70 min. No true C phase was found by flow-through measurements; instead, flutter opening of the spiracles with discrete convective O2 uptakes began shortly after the O phase whereas CO2 release was suppressed by the inward directed passive suction ventilation. The F phase was characterized by a series of small CO2 bursts (flutter events). Between these bursts, novel sub-phase `miniflutter' was observed, which consisted of six to 10 miniature inspirations without any CO2 emission. During the flow-through measurements, oxygen convective uptakes were indirectly recorded by the infrared actograph as sudden extensions (lengthening) of the abdominal segments at each spiracular microopening.Journal of Experimental Biology 09/2011; 214(Pt 17):2816-22. · 3.00 Impact Factor -
Article: Gas exchange patterns of Pterostichus niger (Carabidae) in dry and moist air
[show abstract] [hide abstract]
ABSTRACT: Gas exchange patterns of adult male Pterostichus niger Schaller after hydration (i.e. given access to food and water) are compared in dry air [5–7% relative humidity (RH)] and moist air (90–97% RH) by means of flow-through CO2 respirometry combined with infrared probe actography. Of thirty beetles examined, slightly more than 50% showed continuous gas exchange and are not considered further. Of the remaining beetles, the majority (approximately 71%) display a pattern of cyclic gas exchange in both dry and moist air (i.e. CO2 gas is released in bursts, with a low level of CO2 release during the interburst periods). A minority of the beetles (four out of 30) are found to exhibit discontinuous gas exchange in both dry and moist air; this is characterized by three clearly separated states of the spiracles: closed (C), flutter (F) and open (O) phases. The pattern of cyclic gas exchange is associated with weak abdominal pulsations. After switching from moist to dry air, a small modulation of the discontinuous gas exchange cycles (maximum mean CO2 production rate) occurs, providing no clear support for the hygric theory of discontinuous gas exchange in this species (i.e. that it serves to restrict respiratory water loss).Physiological Entomology 12/2010; 36(1):62 - 67. · 1.33 Impact Factor -
Article: Diversity in gas exchange and muscular activity patterns in insects studied by a respirometer‐actograph
[show abstract] [hide abstract]
ABSTRACT: Different events in insect gas exchange and muscular activity are described by a new system of automatic respirometers, a differential electrolytic microrespirometer-actograph. This is very sensitive to volumetric changes caused by insect respiration and/or body movements. In this system, oxygen generation and its regulation are combined in the same current circuit. According to this principle, the oxygen consumed by the insect is continuously replaced by equal amounts of electrolytically produced oxygen. This simple laboratory-made apparatus records simultaneously metabolic rate, the cyclicity of external gas exchange, rhythms of muscular ventilating and the pattern of other body movements, including abdominal pulsations not observable with the naked eye. The respirometer-actograph described here is applicable also to the recording of the respiration of other terrestrial arthropods or other living organisms or tissues.Physiological Entomology 10/2008; 24(2):150 - 157. · 1.33 Impact Factor -
Article: Periodic muscular activity and its possible functions in pupae of Tenebrio molitor
[show abstract] [hide abstract]
ABSTRACT: During pupal development, Tenebrio molitor L. show regular periods of rhythmic muscular contractions and associated body movements. These periods of activity last 2.5-5.8 min and are more frequent in newly ecdysed pupae (c. 3h-1). They become less frequent (c. 1.5 h-1) when the basal metabolism reaches its lowest level. In the pharate adult stage the clear pattern of muscular activity disappears.Muscular activity is temperature-dependent and is commonly absent below 20d̀C. Muscular activity did not disturb the cyclic output of CO2, which is characteristic of metamorphosis. The heart shows characteristic periods (1–3 min) of activity during pupal development. The frequency of these heart pulsation periods depends on metabolic rate. Heart pumping was correlated mostly with muscular contractions. Therefore we suggest that the main physiological function of muscular activity is to support circulation.Physiological Entomology 03/2008; 19(3):216 - 222. · 1.33 Impact Factor -
Article: Effects of Neem EC on gas exchange, tracheal ventilation, and water loss in diapausing pupae of Pieris brassicae
[show abstract] [hide abstract]
ABSTRACT: Effects of Neem EC (The Indian Neem Tree CompanyTM, 1% azadirachtin) on gas exchange cycles, tracheal ventilation, and water loss in diapausing pupae of the large white butterfly, Pieris brassicae L. (Lepidoptera: Pieridae), were studied using a constant volume respirometer combined with an infrared probe actograph. The non-treated pupae displayed discontinuous gas exchange cycles (DGC) with a trend coinciding with the bursts of carbon dioxide (CO2) release, active tracheal ventilation, and the heartbeat periods. Two independent forms of tracheal ventilation were observed, relatively vigorous abdominal shaking movements and weak abdominal pulsations. The ability to respond to mechanical excitation with abdominal movements was entirely lost on the 2nd day after treatments with Neem EC, and also a reduced tendency to use a DGC was observed. During 2–3 days after treatments, the DGCs and gas exchange microcycles were entirely lost, as was active ventilation. Before treatments, body mass loss, that is, water loss, was 0.6–0.9 mg g−1 day−1. After the treatments, water loss increased to 3–5 mg g−1 day−1. The pupae remained alive for 10–15 days after the treatments and died after having lost about 50% of their initial body mass. The absence of heartbeats measured during at least 4–5 h was the main criterion for ascertaining death of pupae. The results suggested that respiratory failures, that is, the loss of cyclic gas exchange, evoked by Neem EC were the primary cause of lethal desiccation. Thus, the hypothesis that the cyclic gas exchange is an adaptation for restricting water losses in insects was supported.Entomologia Experimentalis et Applicata 01/2008; 126(2):165 - 173. · 1.53 Impact Factor -
Article: COLD-HARDENING OF THE GROUND BEETLE CARABUS GRANULATUS L.(COLEOPTERA, CARABIDAE)
[show abstract] [hide abstract]
ABSTRACT: Cold-hardiness is the ability of insects to survive low temperatures, with or without freezing. Supercooling point (SCP) is the temperature at which spontaneous freezing occurs. The aim of present research was to study seasonal cold adaptation dynamics of the ground beetle Carabus granulatus L. (Coleoptera, Carabidae). Seasonal changes in mean SCP values in C. Gra-nulatus were determined as follows: −4.4 o C (in January 2007), −5.3 o C (in May 2007), −6.3 o C (in September 2007) and −5.6 o C (in February 2008). The tests showed weak supercooling ability of this species and according to Hawes and Bale (2007) classification C. granulatus belongs to freeze-tolerant cryotype.01/2008; 957:428-432. -
Article: Rhythms of passive and active ventilation, and circulation recorded in diapausing pupae of Mamestra brassicae using constant volume respirometry
[show abstract] [hide abstract]
ABSTRACT: Abstract The periodically occurring convective inflow of air into the tracheal system, or passive suction ventilation, together with the cyclic bursts of release of CO2 and active ventilation, is recorded in diapausing pupae of Mamestra brassicae. A constant volume respirometer combined with an opto-cardiograph-actograph is used. In all pupae with a metabolic rate of 0.025–0.054 mL g−1 h−1, the bouts of almost imperceptible abdominal contractions are recorded during the bursts of carbon dioxide release and this mode of active ventilation is qualified as extracardiac haemocoelic pulsations. The pupae whose metabolic rate is 0.052–0.075 mL−1 g−1 h−1 show more vigorous abdominal contractions. The results demonstrate that, in diapausing pupae, characterized with low metabolic rates, both passive suction ventilation, referred to also as passive suction inspiration, and active ventilation occurs. In approximately 50% of the pupae, each gas exchange microcycle during the interburst periods begins with a miniature PSI followed by a microburst of CO2 release; in approximately 30% of the individuals, passive suction inspirations occur separately from CO2 microbursts; in the remaining pupae, miniature ones without microbursts of CO2 are recorded. A typical event is heartbeat reversion: in longer periods, the heart peristalses are directed forward (anterograde of heartbeat) and, in shorter periods, the heart peristalses are directed backward (retrograde of heartbeat). At 0 °C, the cyclic release of CO2 and miniature passive suction inspirations during the interburst periods are preserved at lower frequencies but active ventilation is lost.Physiological Entomology 05/2007; 32(3):246 - 252. · 1.33 Impact Factor -
Article: Respiration rhythms and heartbeats of diapausing Colorado potato beetles, Leptinotarsa decemlineata, at low temperatures
[show abstract] [hide abstract]
ABSTRACT: Discontinuous gas exchange cycles (DGCs), active muscular ventilation, microcycles of repetitive openings, and heartbeats of diapausing adult Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), were studied at low temperatures (0, 5, and 10 °C) using an electrolytic respirometer combined with an infrared actograph. The DGC of the adult constriction-flutter-open type was the main respiration mode in fully quiescent beetles at temperatures from 5 to 10 °C. The CO2 bursts were actively ventilated at temperatures above 5 °C. During the flutter period, a series of microcycles appeared, but no muscular contractions associated with the microcycles were detected. We identified this respiration mode as discontinuous suction ventilation.The hydration condition of the beetles did not influence the frequency of the gas exchange cycles, but dehydrated beetles showed significantly longer flutter periods and shorter ventilation periods than hydrated beetles. The heartbeat frequencies were influenced by both temperature and hydration status.We conclude from the results that DGCs are used at rest in adult L. decemlineata under various environmental conditions and also at low temperatures. Our results showed that DGCs are the main respiration mode of resting adult Colorado potato beetle irrespective of its hydration state and temperature. Our method resolves O2 uptake and subsequent CO2 release in flutter and ventilation periods and shows that diffusion is replaced by convection to reduce water loss in adult beetles.Entomologia Experimentalis et Applicata 12/2005; 118(1):21 - 31. · 1.53 Impact Factor -
Article: Cyclic release of carbon dioxide accompanied by abdominal telescoping movements in forager ants of Formica polyctena (Hymenoptera, Formicidae)
[show abstract] [hide abstract]
ABSTRACT: Discontinuous gas exchange and abdominal telescoping movements were investigated in intact forager ants of Formica polyctena Förster. For simultaneous recording of discontinuous gas exchange and abdominal movements, an electrolytic differential microrespirometer was combined with an infrared-optical device using an infrared-sensor diode commonly applied as a cardiograph in insect studies. The air in the insect chamber was saturated with water vapour, and an ant was contacted with a sliver of wet filter paper. Accordingly, the ants used in the experiments were regarded as being hydrated. The enforced immobility of the ant in the respirometry chamber (0.15 mL volume) induced continuous struggling during the first hours of measurement but, after 3–4 h, the activity periods alternated with quiescent periods when regular cycles of discontinuous gas exchange (8.97 mHz) were displayed. After remaining in the chamber for a day, the ants showed such cycles (8.15 mHz) without any interruption by periods of activity. The cyclic release of carbon dioxide (burst) was accompanied by a bout of telescoping movements of the abdominal segments (rapid contractions and slow relaxations), which were interpreted as active ventilation. The irregular and rare abdominal contractions, recorded during the interburst periods on the first day of measurements, were regarded as a symptom of stress because these disappeared on the second day. In approximately 20% of foragers, the telescoping movements during the interburst periods were characterized by very rapid (0.09 s) protractions and slow retractions of the abdominal segments, obviously acting as inspiration movements. The results do not support the hypothesis that discontinuous gas exchange is an adaptation for conserving water in ants.Physiological Entomology 05/2004; 29(2):152 - 158. · 1.33 Impact Factor -
Article: Abdominal movements, heartbeats and gas exchange in pupae of the Colorado potato beetle, Leptinotarsa decemlineata
[show abstract] [hide abstract]
ABSTRACT: The rhythms of abdominal movements, heartbeats and gas exchange in the pupae of Leptiontarsa decemlineata (Say) were recorded simultaneously using an electrolytic respirometer and infrared gas analyser, both combined with contact thermography.Abdominal pulsations and heartbeat occurred periodically with little variance among individuals. The abdominal pulsations and heartbeat pauses varied individually within large limits, with the frequency of abdominal pulsations being six to seven times lower than that of the heart pulses.A proportion of the pupae (20%) showed discontinuous gas exchange with large, actively ventilated CO2 bursts, whereas others (≈ 25%) exhibited continuous regular microcycles (flutter) with abrupt intake of air into the tracheae before discrete microbursts of carbon dioxide. The abdominal pulsations exerted only a minor influence on ventilation during the microcycles.More than 90% of the bursts of abdominal movement coincided with a series of forward directed heartbeats, but interspersed between the bouts of abdominal movement commonly two to three heartbeat pulses were observed that were not associated with abdominal movements. A period of abdominal movement associated with a heartbeat pulse was commonly initiated by one or two vigorous strokes of abdominal rotation.Physiological Entomology 12/2001; 25(2):151 - 158. · 1.33 Impact Factor -
Article: Body movements and their role as triggers of heartbeats in pupae of the Colorado potato beetle Leptinotarsa decemlineata
[show abstract] [hide abstract]
ABSTRACT: Rhythmic body movements and their role as triggers of intermittent heartbeats were studied in pupae of Leptinotarsa decemlineata Say. Heartbeats and body movements were recorded simultaneously by means of an optical method (infra-red cardiography) combined with respirometry. IR-cardiography allows heartbeats and body movements to be distinguished on the basis of their different rates (40–80 min−1 and 4–8 min−1, respectively) and amplitude.In the mid-interecdysial period, abdominal movements in the pupae were always accompanied by heart activity beginning after the first 5–12 abdominal strokes. Simultaneous periods of abdominal movements and heartbeats lasted 2–5 min, while the intervening pause ranged from 40 to 72 min at 24°C.Experiments of forced heart activity showed that a slight external tactile stimulus (prodding once with a single hair), applied prior to an expected heartbeat bout, evoked abdominal movements followed soon afterwards by contractions of the dorsal vessel. Repeated prodding with a hair evoked body rotating movements (1–3 strokes) at any time with heartbeats starting at the first movement.We surmise that rhythmic body movements play an active role in the triggering of heart activity in pupae according to the principle of cardiac reflex response. This is a possible mechanism for synchronizing periods of heart activity with periods of rhythmic body movements. Haemolymph circulation in pupae is favoured when heartbeat bouts are accompanied by active body movements.Physiological Entomology 05/2001; 26(2):158 - 164. · 1.33 Impact Factor -
Article: Calorimetric investigations on physiological stress in Tenebrio molitor (Coleoptera, Tenebrionidae) pupae
[show abstract] [hide abstract]
ABSTRACT: Individual variation in the susceptibility to handling stress (mechanical irritation) in laboratory-reared pupae of yellow mealworm, Tenebrio molitor, was studied by means of simple thermocouple twin set-up calorimeters.The stress condition was characterised by disturbances in normal rhythms of gas exchange and body stereotyped movements well distinguishable from calorimetric recordings. Recovering time from stress, induced by the device, was 10–15 min.In every newly established population, a portion of pupal individuals (13–15%) was highly sensitive to handling and these pupae lost significantly more water than the pupae exhibiting no symptoms of stress.Thermochimica Acta. -
Article: Discontinuous gas exchange cycles and active ventilation in pupae of the bumblebee Bombus terrestris
[show abstract] [hide abstract]
ABSTRACT: Discontinuous release of CO2 (bursts) or discontinuous gas exchange cycles (DGC), metabolic rate (MR) and ventilation movements were simultaneously recorded from the pupae of the bumblebee Bombus terrestris by means of an electrolytic respirometer and an infrared gas analyser (IRGA) combined with an infrared actograph (IRA). After recovering from stress, the early stage pupae showed irregular continuous respiration, mid-stage pupae displayed regular DGC. The bursts of CO2 release tended to coincide with abdominal contractions. In late stage pupae all bursts of CO2 were associated with active ventilation. During interburst periods, spikes appeared on the respirograms interpreted as micro-cycles of passive suction ventilation (PSV). After removal from their cocoons, the pupae exhibited frequent periods of muscular activity due to stress. Water loss of pupae inside cocoons was significantly less than that from pupae without cocoons.http://dx.doi.org/10.1051/apido:2005045. -
Article: Metabolic cost of ventilating movements in pupae of Tenebrio molitor and Galleria mellonella studied by direct calorimetry
[show abstract] [hide abstract]
ABSTRACT: The energetic cost of periodically occurring rhythmic body movements in pupae of the mealworm Tenebrio molitor and the wax moth Galleria mellonella was estimated by the use of direct calorimetry. The motions affect tracheal ventilation and/or accelerate hemolymph circulation.The contribution of muscular activity to the total specific heat production rate in 46 to 52 h old pupae of Tenebrio molitor and Galleria mellonella was 1.24% and 0.9%, respectively. The energetic cost of stereotyped body motions serving diverse functions formed a negligible part (less than 3%) of the total energy consumed during pupal development.Thermochimica Acta 276:41-47. · 1.80 Impact Factor
Top co-authors
Top Journals
Institutions
-
2007–2011
-
Estonian University of Life Sciences
- • Department of Plant Protection
- • Institute of Agricultural and Environmental Sciences
Tartu, Tartumaa, Estonia
-
