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Twelve selected cultivated or wild solanaceae (Solanum dulcamara, Solanum nigrum, Solanum villosum, Solanum lycopersicum, Solanum muricatum, Solanum melongena, Datura innoxia, Datura metel, Physalis spp., Capsicum annuum, Nicotiana alata, and Petunia spp.) (all species Solanales: Solanaceae) were tested as potential alternative host plants against Solanum tuberosum for a local population of the Colorado potato beetle Leptinotarsa decemlineata Say (CPB) in Estonia. Some CPB populations in America and southern Europe accept most of these plants. However, geographically isolated populations of beetles can differ in their acceptance of new host plants. Migrants from the southern Europe supplement Estonian beetle population regularly, so individuals may differ in their host plant preferences. S. melongena and S. dulcamara were well accepted by the beetles, Lycopersicum spp. (Solanales: Solanaceae) and N. alata were intermediate, and S. villosum and S. nigrum were least accepted. The beetles rejected S. muricatum, Physalis spp., C. annuum, Petunia spp., and D. metel. First-instar larvae completed a full life cycle only on S. dulcamara, N. alata, S. lycopesicum, S. melongena, although their development rate was slower, mortality was higher and emerging adults were underweight relative to those that fed on S. tuberosum. The fourth-instar larvae were less sensitive in relation to food. We found that S. dulcamara as a native plant could provide resources for CPB during early and late season. At the same time, the cultivated S. melongena would be suitable plant species for further testing as dead-end crop for integrated pest management.

We compare standard metabolic rate (VCO₂) and gas exchange patterns in the Colorado potato beetle (Leptinotarsa decemlineata Say) in winter diapause (i.e. lasting only one overwintering period) with those of beetles in prolonged diapause (i.e. diapause lasting 2 or 3 years). The length of diapause is estimated by the behaviour of the beetles: burrowing into soil as a sign of the beginning of diapause and emergence from the soil as the ending of diapause. Measurement with a flow‐through carbon dioxide (CO₂) infrared gas analyzer reveals that most beetles in winter or prolonged diapause display distinct discontinuous gas exchange cycles at 23 °C. Beetles with cyclic gas exchange and continuous breathing do not survive the winter. Beetles in prolonged diapause are characterized by a three‐ to five‐fold lower standard metabolic rates, longer discontinuous gas exchange periods and shorter CO₂ releases (open phase) than those in winter diapause.

Agelastica alni L. (Coleoptera: Chrysomelidae) is a common beetle pest of alder trees (Alnus incana L.) in forests and parks across Estonia. The supercooling ability and capacity to survive low temperature exposure changes temporally. Relatively high unimodal supercooling point (SCP) levels (with a mean value of -6 to -8°C) were characteristic of the beetles in September during their diapause induction period, in April when the beetles had terminated their diapause development and in May when they started to reproduce. During their deep diapause period the SCPs of beetles had a bimodal distribution. Some beetles decreased their SCPs to -14 to -19°C while others retained a high SCP value of -6 to -8°C. Most vulnerable to low temperature were overwintered active beetles in May; after 1 h exposure their LTemp50 (median lethal temperature) was -6.3°C. In September with the onset of diapause tolerance of beetles started to increase, LTemp50 = -7.7°C. Beetles were most cold tolerant during their deep diapause period with LTemp50 < -12.0°C. A. alni beetles use one of two different strategies for overwintering, some are freeze-tolerant while others are freeze-avoidant. The freeze-avoidant beetles with low SCP (-12 to -15°C) acquired greater cold tolerance than those with higher SCP (-6 to -8°C), with LTemp50 = -13.7°C and LTemp50 = -11°C, respectively.

Gas exchange patterns in the ladybird beetle, Adalia bipunctata (L.) (Coleoptera: Coccinellidae), were investigated using an infrared gaseous analyser (IRGA) and a coulometric O2 respirometer (manometric–volumetric system). Before testing, the beetles were kept either in dry (dehydrated) or moist (hydrated) conditions for 1 day. Their subsequent gas exchange patterns did not depend on their state of humidity but rather were controlled by the humidity of the insect chamber during gas exchange measurement. If this chamber contained dry air, the beetles exhibited CO2 release by burst, which we interpreted as cyclic gas exchange (CGE) with inter-burst periods, but if the chamber was switched to contain moist air, then cyclic CO2 release was soon abandoned and a pattern of continuous gas exchange appeared. Measurements with the coulometric respirometer in moist air showed that continuous gas exchange was often associated with weak abdominal pulsations, which we interpreted as active ventilation. Their metabolic rate was lower during gas exchange cycles than during continuous gas exchange. We revealed that in the ladybird beetle metabolic rate increased in moist air when the gas exchange pattern transitioned from cyclic to continuous.

The great web-spinning pine-sawfly Acantholyda posticalis Mats. (Hymenoptera: Pamphiliidae) is one of the major defoliating insects of pine forests. Mass outbreaks of this species have occurred in Scots pine (Pinus sylvestris L.) stands in Central Europe and in the southern parts of Eastern Europe and Siberia. Recently, the outbreak range has shifted northward and new outbreaks have been recorded in Estonia and Finland. The dynamics of the supercooling capability of pre-imaginal stages of A. posticalis (eonymphs, pronymphs, pupae) collected from the soil in a pine forest on the Island of Saaremaa, Estonia, were determined. The supercooling points (SCP) of overwintering eonymphs and pronymphs changed during the winter, although there were no significant differences between the mean SCPs of either larval stage on any measuring date. The mean SCPs decreased from October (−8 to −10 °C) to January and March (−15 to −17 °C) and increased once again in May (−9 to −11 °C). The average SCP of pupae was considerably higher (−5.3 °C). Overwintering larvae in the soil are potentially covered by an insulating layer of forest litter, moss and snow, thus avoiding direct exposure to low temperatures. Cold-hardiness in both overwintering larval stages of A. posticalis is sufficient for successful survival during winter in the northern Baltic region. At present, outbreaks of A. posticalis in higher latitudes are concentrated in milder maritime regions near the coast of the Baltic Sea, although these may expand in the future as a result of climate warming, with the sawfly possibly becoming a serious pest of pine forests of northern Europe.

Before its establishment in Estonia at the beginning of the twenty-first century, the Colorado potato beetle Leptinotarsa decemlineata Say was a notifiable quarantine pest for many years. In high-latitude environments it encounters strong evolutionary pressure to adapt to low temperatures due to high overwintering mortality and periodic influx of new individuals from more southern populations. Our study focused on gathering evidence for such a range shift leading to the formation of a permanent local population. The phenology and overwintering success of beetles was investigated from 2008 to 2015. Depending on weather conditions in the different years, the overwintered beetles emerged from the soil from the beginning of May to mid-June. Over 700 degree days accumulated in 2010, 2011, 2013 and 2014 exceeding the limit needed for development of two generations. However, food supply and temperature distribution in the growing period enabled development of the second complete generation only in 2010 a...

Vegetation rehabilitation of harvested peat fields is globally important because it facilitates the restoration of natural biodiversity. The objective of this study was to determine the occurrence of mosses, lichens and arthropods in blueberry plantations of differing age on an abandoned peat production area. In the experiment, two lichen and five moss species were detected in total. By contrast, only one species, a moss, was found on a non-vegetated, abandoned peat area. Although the total number of lichens and mosses was not high, it varied significantly according to lowbush blueberry age. It was higher in 5–7-year old plantations with no significant differences with a natural, drained bog. As plant cover by cultivated blueberry plants increased up to 99% in the 13-year plantation, the presence of non-vascular plants diminished. The total number of arthropods depended on the age of the blueberry plantation and was lowest in the non-vegetated, abandoned peat area. Plantation age influenced arthropod abundance in both experimental years. More beneficial or neutral arthropods were found in bog and 6- and 7-year old plantations, while phytophagous arthropods predominated in older plots. Dominating beneficial arthropod groups in both years were Araneidae, Thomisidae, Lycosidae, Collembola, Formicidae and Carabidae. The growing of lowbush blueberry may become one option for the vegetation restoration of abandoned peatlands and the plant cover it provides serves as a suitable habitat for various arthropods.

The cold tolerance of different seasonal groups (pre-diapause, diapauses and post-diapause) of Colorado potato beetle (Leptinotarsa decemlineata Say) was assessed by exposing them either to a constant temperature of –3°C for 48 to 624 h, or to –3, −4, −5, −6 or −7 °C for a constant 24 h. Cold survival was affected by the length of exposure, by the temperature rates and by seasonality. The least cold-tolerant were pre-diapause beetles in August with a mean lethal temperature (Ltemp50) of −4.4°C for 24 h exposure and with a lethal time (Ltime50) of 106.8 h at −3°C. Cold tolerance was significantly higher in the diapause group in January and in the post-diapause group in March; it did not differ significantly between these groups of beetle for 24 h exposure, the lethal temperature being −5.8°C for both groups. Seasonality had a greater influence on survival of these groups after longer exposure to constant mild sub-zero temperature (−3°C); in diapause group, all the beetles survived 624 h exposure, but in post-diapause group the survival limit decreased to 216 h and lethal time was 153.9 h. Colorado potato beetle eggs tolerated 24 h exposure to sub-zero temperatures from −3°C to −5°C or longer exposure at −3°C for 72 h without a reduction in hatchability. The mean lethal time for 50% mortality of eggs was 76.5 h and mean lethal temperature was −5.8°C. Thus, we conclude that night frosts common in northern regions do not damage Colorado potato beetle adults or eggs to the extent that might threaten the survival of the population.

Gas exchange is studied in diapausing pupae of Mamestra brassicae L., whose larvae are reared under identical conditions. The release of CO2 gas is recorded with infrared gaseous analyzers. Oxygen convective uptake into the tracheae and oxygen consumption rates are recorded by means of a constant-volume coulometric respirometer. Outputs from both of these respirometry systems are combined with infrared actographs. All 3-month-old pupae of M. brassicae display a pattern of discontinuous gas exchange (DGE) cycles of CO2 gas release by bursts, although the lengths of these cycles varies between individuals. Some pupae exhibit long DGE cycles of at least 20 h in duration, with negligible CO2 gas release during interburst periods, and there is presumed to be a convective gas exchange at this time. As a result of a partial vacuum inside the tracheae, a large oxygen convective uptake always occurs at the start of the spiracular opening phase. Other pupae have short DGE cycles of less than 3 h in duration, with elevated CO2 gas release during the interburst period, when gas exchange is predominantly diffusive. The spiracular open phase in these pupae consists of frequent separate convective bursts of CO2 gas release, with the opening–closing rhythms of the spiracles, which are considered as O phase fluttering. The pupae with long DGE cycles exhibit extremely low metabolic rates and very low total water loss rates, whereas those with short DGE cycles have higher metabolic and total water loss rates. The pupae with long DGE cycles live approximately twice as long as those with short cycles; thus, the present study demonstrates that long DGE cycles confer a fitness benefit on pupae as a result of a lower metabolic rate associated with water economy, conferring on them a longer life.

Flea beetles are significant insect pests of cruciferous oilseed crops in northern Europe. A two-year small-scale field experiment was performed to determine the species complex and abundance of flea beetles (Chrysomelidae: Alticinae) associated with eight cruciferous oilseed plants: Brassica juncea (L.) Czern., Brassica napus L. var. oleifera subvar. annua, Brassica nigra (L.) Koch, Brassica rapa L. var. oleifera subvar. annua, Camelina sativa (L.) Crantz, Eruca sativa Mill., Raphanus sativus L. spp. oleifera (DC) Metzg. and Sinapis alba L. Their relative attractiveness to flea beetles was compared to assess their potential for use within a trap crop system for spring oilseed rape. Adults of six species of flea beetles were found on the test plants. Phyllotreta undulata Kutsch. was the most abundant species followed by Phyllotreta nigripes (Fabr.), Phyllotreta nemorum L. and Phyllotreta vittata (=striolata) (Fabr.), while Phyllotreta atra (Fabr.) and Chaetocnema concinna Marsh. were occasionally present....

We have established for the first time that Colorado potato beetle (CPB) (Leptinotarsa decemlineata Say) (Coleoptera: Chrysomelidae) produced a distinct second generation in 2010 in Estonia. This species has a history, in Estonia, of less than 50 years. Due to their great ability to adapt to variable environmental conditions, the beetles spread very quickly throughout the country and established a permanent population in the 1980s. Before 2010, CPB has been predominantly univoltine. The occurrence of the second generation was the result of rare coincidence of extremely favourable weather as the cumulative degree days (DD) of 927 exceeded the sum needed for two full generations. Constantly high temperatures from the beginning of May caused the formation of summer generation adults already by the end of July and the long day photoperiod, as well the availability of fresh food, kept the beetles in reproductive mode preventing the onset of diapause. Summer beetles continued to oviposit up to the second half o...

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 respira- tion, 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 char- acterized by continuous pumping and almost regular periods of activity. RMR increased significantly after treatment with a pyre- throid.

The opening-closing rhythms of the subelytral cavity and associated gas exchange patterns were monitored in diapausing Leptinotarsa decemlineata beetles. Measurements were made by means of a flow-through CO2 analyser and a coulometric respirometer. Under the elytra of these beetles there is a more or less tightly enclosed space, the subelytral cavity (SEC). When the cavity was tightly closed, air pressure inside was sub-atmospheric, due to oxygen uptake into the tracheae by the beetle. In about half of the beetles regular opening-closing rhythms of the SEC were observed visually and also recorded; these beetles displayed a discontinuous gas exchange (DGE) pattern. The SEC opened at the start of the CO2 burst and was immediately closed. On opening a rapid passive suction inflow of atmospheric air into the SEC occurred, recorded coulometrically as a sharp upward peak. As the CO2 burst lasted beyond the closure of the SEC, we suggest that most of the CO2 was expelled through the mesothoracic spiracles. In the other half of the beetles the SEC was continually semi-open, and cyclic gas exchange (CGE) was exhibited. The locking mechanisms and structures between the elytra and between the elytra and the body were examined under a stereomicroscope and by means of micro-photography. We concluded that at least some of the L. decemlineata diapausing beetles were able to close their subelytral cavity tightly, and that the cavity then served as a water saving device.

Oilseed rape (Brassica napus) is a valuable crop, attacked by several insect pests, of which the pollen beetle (Meligethes aeneus) is one of the most widespread and important in Europe. The relative attractiveness for the pollen beetle of Brassica nigra, Eruca sativa and Raphanus sativus was compared with that of spring oilseed rape, to assess the potential of these plant species as trap crops for the pest. At early growth stages, B. nigra and R. sativus were more attractive to over-wintered adult pollen beetles than B. napus. At the bud and flowering stages, B. nigra was the most attractive while E. sativa was the least attractive. At flowering, B. nigra was more attractive for oviposition than the other species. Thus, of the species tested, B. nigra has the most potential as a prospective trap crop to protect spring oilseed rape before flowering when it is at its most vulnerable developmental phase, due to its faster development and its acceptability both for feeding and oviposition to overwintered pollen beetle adults. Raphanus sativus was accepted both for feeding and oviposition, but pollen beetle larvae failed to develop in its flowers; it therefore has the potential for use as a dead-end crop. At the end of the growing season, both E. sativa and R. sativus, as late-flowering species, attracted the new generation of pollen beetles and thereby have potential to extend the effectiveness of a trap-cropping system at this time.

Supercooling point (SCP) and cold-hardiness of the pollen beetle Meligethes aeneus (Fabricius) (Coleoptera: Nitidulidae) were investigated. Mature eggs from the oviduct were supercooled on average to -28.0 °C and from oilseed rape buds to -24.4 °C; first instars were supercooled to -21.0 °C and second instars to -16.8 °C. Despite their high supercooling ability, none of the eggs survived 24 h exposure to -2.5 °C. The supercooling ability of adults varied significantly among feeding and non-feeding beetles: high SCPs prevailed during the whole warm period, being about -12 °C; low values of SCP of -20 °C dominated in non-feeding beetles. In spring and autumn, beetles displayed the same acclimation efficiency: after 1 week of exposure at 2.0 °C with no access to food their SCPs were depressed equally by about 3 °C. Meligethes aeneus beetles have a different response to low temperatures depending on the season. The lowest tolerance was found in reproductively active beetles after emergence from overwintering sites; the time needed to kill 50% of individuals (Ltime 50 ) was 56.2 h at -7 °C and the lower lethal temperature needed to kill 50% (Ltemp so ) after 24 h exposure was -8.6 °C. Cold hardiness increased from midsummer to midwinter; Ltime so was 80 h in August, 182.8 h in September, and 418.1 h in January. Lethal temperature after 24 h exposure was -9.1 °C in August and -9.8 °C in September. In February, after diapause, the beetles started to loose their cold tolerance, and Ltemp 50 was slightly increased to -9.5 °C. Hibernating beetles tolerated long exposure at -7 °C well, but mortality was high after short exposure if the temperature dropped below -9 °C for 24 h. Despite the season, the beetles died at temperatures well above their mean SCP; consequently, SCP is not a suitable index for cold hardiness of M. aeneus.

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).

The striped flea beetle, Phyllotreta undulata Kutschera (Coleoptera: Chrysomelidae), is a pest of cruciferous crops. It overwinters as an adult. During winter in northern European countries, such as Estonia, it is subject to sometimes severe temperatures that may fluctuate daily, over the season, and between seasons. The objective of this study was to investigate factors that affect its cold hardiness. In a series of five experiments, the effects of food plant, starvation, and acclimatization on the beetles’ ability to supercool and survive exposure to sub-zero temperatures was investigated. The supercooling points (SCP) of overwintered beetles field-collected from white mustard and Indian mustard differed from those caught from white cabbage and oilseed rape, but these differences disappeared after a 4-day period of starvation at room temperature, indicating that gut content probably influences the potential to supercool. The duration and temperature of acclimation affected SCP in overwintered beetles. The decrease in SCP was more rapid at 22 � C than at 0 � C, probably because of faster dehydration and gut evacuation at the higher temperature. Acclimation at 0 � C for a week increased the ability of overwintered beetles to survive subzero temperatures, lowering both SCP and lower lethal temperature (LLT50). Some pre-freeze mortality occurred; SCP and LLT50 were correlated but the latter was a constant 3 � C higher than the former. The SCP of field-collected pre-winter beetles decreased gradually during the autumn. It also decreased when field-collected pre-winter beetles were acclimated at 0 � C in the laboratory, attaining its lowest level after 18 days. Phyllotreta undulata is well-adapted to unstable and sometimes severe winter conditions; its high potential to supercool enhances its cold hardiness and ability to survive short periods at sub-zero temperatures although it cannot survive freezing of its body fluids.

Effects of Neem EC (The Indian Neem Tree Company TM , 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 (CO 2 ) 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.

The periodically occurring convective inflow of air into the tracheal system, or passive suction ventilation, together with the cyclic bursts of release of CO 2 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 imper- ceptible 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 CO 2 release; in approxi- mately 30% of the individuals, passive suction inspirations occur separately from CO 2 microbursts; in the remaining pupae, miniature ones without microbursts of CO 2 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 CO 2 and miniature passive suction inspirations during the inter- burst periods are preserved at lower frequencies but active ventilation is lost.

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 suc- ceeding 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 , respec- tively. 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 day 1 . 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.

Cold-hardiness can be measured by supercooling points – the temperature at which spontaneous freezing occurs. Seasonal changes in supercooling point were assessed in field-collected predacious carabid beetle species: Carabus granulatus L., Pterostichus oblongopunctatus L. and Platynus assimilis Payk. (Coleoptera: Carabidae). Supercooling ability of these beetles changed seasonally. The tested carabid beetles proved to belong to freeze-avoiding cryotype.

SUMMARY 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.