Partitioning of transpiratory water loss of the desert scorpion, Hadrurus arizonensis (Iuridae)

Terrestrial arthropods lose body water to the environment mainly through transpiration. The aim of this study was to determine the fraction of respiratory losses from total transpiratory water loss in scorpions, as relatively high respiratory losses would indicate a fitness benefit from regulation of gas-exchange rate under stressful desiccating conditions. We measured metabolic rates and water-loss rates of Hadrurus arizonensis (Iuridae) at a range of ecologically-relevant temperatures. Calculation of respiratory water losses was based on increased metabolic and water-loss rates during nocturnal activity (assuming no change in cuticular resistance at a given constant experimental temperature). Respiratory losses accounted for 9.0 ± 1.7% of total transpiratory losses at 25 °C, doubled to 17.9 ± 1.8% at 30 °C and increased to 31.0 ± 2.0% at 35 °C (n = 5, 15 and 15, respectively). Furthermore, the relative importance of respiratory transpiration is likely to be higher at temperatures above 35 °C, which have been recorded even within the burrows of H. arizonensis. Measurements of cuticular lipid melting points do not provide evidence for increased cuticular resistance to water loss at higher temperatures. However, the relatively high fraction of respiratory water losses reported here for H. arizonensis supports the notion of respiratory regulation as an evolved mechanism for conserving scorpion body water stores under stressful conditions.     

南蝠对鸟的捕食及其对昆虫的选择

2005年11月和2006年5、7、9月在贵州兴义研究了南蝠(Iaio)的食性。通过对南蝠粪便分析,发现7、9和11月份,鸟的残留羽毛在粪便中占很大比例,尤其是在11月份,鸟的羽毛占了食物组成的82%(体积百分比,下同),结果证实南蝠是一种食鸟蝙蝠。但在5月份的粪便中未发现鸟毛,而鞘翅目所占比例很大(85%);7和9月份,鸟的羽毛和鞘翅目残遗物所占的比例相当(7月份分别为44.6%和48.7%;9月份分别为51.1%和43.4%)。5、7、9、11月份南蝠取食鸟类的比例逐渐增加,而对鞘翅目的取食则逐渐减少。除取食鞘翅目外,南蝠还捕食鳞翅目、半翅目、直翅目和膜翅目等昆虫。对比捕食区内潜在的食物,发现南蝠对部分昆虫表现出明显的选择性,说明南蝠为选择性捕食者。     

The relative importance of respiratory water loss in scorpions is correlated with species habitat type and activity pattern

Scorpions exhibit some of the lowest recorded water loss rates compared with those of other terrestrial arthropods of similar body size. Evaporative water loss (EWL) includes cuticular transpiration and respiratory water loss (RWL) from gas exchange surfaces, that is, book lung lamellae. Estimated fractions of cuticular and respiratory losses currently available from the literature show considerable variation, at least partly as a result of differences in methodology. This study reports RWL rates and their relative importance in scorpions from two families (Buthidae and Scorpionidae), including both xeric and mesic species (or subspecies). Two of the included Buthidae were surface-dwelling species, and another inhabits empty burrows of other terrestrial arthropods. This experimental design enabled correlating RWL importance with scorpion phylogeny, habitat type, and/or homing behavior. Buthidae species exhibited significantly lower EWL rates compared with those of Scorpionidae, whereas effects of habitat type and homing behavior were not significant. Resting RWL rates were not significantly affected by scorpion phylogeny, but rates for the xeric species (totaling ~10% of EWL rates at 30°C) were significantly lower compared with those of mesic species. These lower RWL values were correlated with significantly lower H(2)O/CO(2) emission rates in xeric species. The experimental setup and ~24-h duration of each individual recording allowed estimating the effect of interspecific variation in activity on RWL proportions. The high respiratory losses in active hydrated Scorpio maurus fuscus, totaling 30% of EWL, suggest that behavioral discretion in this species is a more likely mechanism for body water conservation under stressful conditions when compared with the responses of other studied species.     

Gas exchange of Agropyron desertorum: diurnal patterns and responses to water vapor gradient and temperature

Summary The response of leaf gas exchange to environmental variables were measured at different levels of drought stress for Agropyron desertorum, a naturalized perennial bunchgrass of the semiarid shrub steppes of western North America. Leaf conductance (stomatal plus boundary layer) was more sensitive to changes in water vapor gradient than to changes in leaf temperature. Assimilation was sensitive to both temperature and vapor gradient, and also appeared to be affected by conductance and high transpiration rates. The magnitudes of both assimilation and conductance decreased with increased drought conditions. Diurnal patterns of gas exchange were measured during 3 growing seasons. For a typical spring day with moderate leaf temperature and vapor gradient, diurnal patterns were similar for plants at different levels of soil water availability. Assimilation was relatively constant during most of the day, but conductance decreased during the afternoon. Total daily carbon gain was decreased to a lesser extent than daily water loss as soil water was depleted. Consequently, the ratio of daily carbon gain to daily water loss, i.e. daily water use efficiency, increased with decreased soil water content for diurnals under spring conditions. Diurnal patterns of assimilation for a typical summer day with high leaf temperature and vapor gradient differend from those for a spring day. An afternoon decrease in assimilation was typical during a summer day. Daily carbon gain, water use, and water use efficiency for summer diurnals decreased only under severe drought conditions. Almost complete recovery of assimilation and conductance occurred if leaf microclimate was ameliorated during the afternoon of either spring or summer diurnals. Thus, conditions responsible for a midday depression in assimilation during a single day did not have persistent effects on leaf gas exchange. Daily carbon gain of a typical summer day was restricted by leaf microclimate during the afternoon, but daily water use efficiency was not relatively increased by the amelioration of leaf microclimate.     

Heat and mosquitoes cause breeding failures and adult mortality in an Arctic-nesting seabird

We report on variation in rates of egg loss among Brünnich's Guillemot Uria lomvia breeding at Coats Island, northern Hudson Bay, in 1997–1999, and on several cases of adult mortality during incubation in the same years. Common factors in the dates of peak egg loss and adult mortality were high maximum daily temperatures and the presence of high numbers of mosquitoes in the area. Mortality was confined to breeding sites close to the edge of the colony, where mosquito parasitism was highest, and to those sites exposed to afternoon sunshine. High temperatures that occurred on days without mosquitoes were not associated with high egg losses or with adult mortality. Hence, it appears that a combination of heat and mosquitoes was necessary to bring about observed mortality and egg losses. The dates of first appearance and peak abundance of mosquitoes at Coats Island have advanced since the mid-1980s, perhaps in response to ongoing climate change. The effects on breeding Brünnich's Guillemots suggest that the birds have not had time to adjust their behaviour to the resulting changes in the timing of peak mosquito parasitism.     

Utilizable water in leaves of 8 arid species as derived from pressure-volume curves and chlorophyll fluorescence

The water-storage properties of leaves from 8 co-occurring arid species, ranging from 4 to 36 in turgid weight/dry weight ratio, were studied. Total water content at saturation varied from 75 to 97%, with 65–93% of this utilizable when bound water (B) was subtracted, and 72–93% when water content at a critical level of optimal fluorescence (F_c) was subtracted. F_c represented the turning point from slight to substantial impairment of chlorophyll fluorescence, and either coincided with B (two species) or was slightly below B (6 species). An incipient level of fluorescence was also recognized, corresponding to the lowest water content before any effect on maximum variable fluorescence/maximum fluorescence could be detected. This lay closer to B than to water content at turgor loss point (TLP), rendering TLP of no significance in dictating the fraction of stored water utilizable (UWC). Under laboratory conditions, turgid branchlets of the 8 species were estimated to take from 1.5 days to 15 weeks to reach F_c. The rate of water loss was almost completely explained by variations in leaf thickness. Under field conditions in mid-spring, UWC at F_c on a harvest weight basis ranged from 51 to 87% predawn and from 45 to 86% by early afternoon (EA). The UWC of plants severed from their root systems 6 weeks earlier ranged from 0 to 63% during the EA. Overall, two groups of species could be recognized: thick-leaved species whose UWC is high and varies little during the day and which use their stored water conservatively and have limited reliance on their root system for replenishment after winter; and thinner leaved species whose UWC is moderate and fluctuates daily, and whose stored water falls rapidly unless replenished continuously from the soil.     

High water-loss rates and rapid dehydration in the burying beetle, Nicrophorus marginatus

Abstract.  During the summer months, there is a high mortality of burying beetle (Coleoptera: Silphidae) species in pitfall traps containing dry soil. The present study investigated the possibility that the burying beetle Nicrophorus marginatus is highly susceptible to death from desiccation. In the laboratory, adult beetles lose 1–5% body mass per hour in low humidity conditions (25–30% relative humidity), depending on temperature. This rate of water-loss results in a 50% mortality within 7–16 h at temperatures between 16 and 28 °C. Nicrophorus marginatus produces oral and anal defensive secretions when disturbed but these secretions do not significantly contribute to the high rate of water loss. Beetles readily drink and thus beetles with access to water or in high humidity conditions suffer near zero mortality. For comparison, the similarly sized mesic bess beetle (Coleoptera: Passalidae), Odontotaenius disjunctus , and a large nocturnal tiger beetle (Coleoptera: Cicindelidae), Amblychila cylindriformis , are exposed to dehydrating conditions. Nicrophorus marginatus have higher rates of water-loss (by 26% and 79%, respectively). It is predicted that the diurnal N. marginatus uses behavioural mechanisms to avoid lethal water loss. In the field, N. marginatus displays a strong bimodal activity pattern, avoiding the hottest hours of the day. The significance of these findings is that N. marginatus defies normal predictions of association between water-loss rates and habitat type, and has extended its range into apparently unfavourable habitats despite high water-loss rates. In addition, the results suggest that researchers should provide moisture when studying burying beetles, including the endangered American burying beetle ( Nicrophorus americanus ).     

Arthropod prey of shelterbelt-associated birds: linking faecal samples with biological control of agricultural pests

Abstract  The value of insectivorous birds as agents for biological control of arthropod pests has been little studied, especially in Australia. This paper reports on the extent to which arthropods from various pest and non-pest taxa feature in the diets of birds captured in farm shelterbelts in central western New South Wales. The parameters examined were the types of arthropod fragments in bird faeces and percentage volume and frequency of occurrence of each component. The faecal data were compared with samples of the arthropod fauna trapped in shelterbelts during the period the birds were captured. In 26 of 29 faecal samples, arthropod fragments were the predominant components, the most common being from Coleoptera, Hymenoptera (especially Formicidae), Orthoptera and Araneae. The recognisable pest taxa in faecal samples were Scarabaeidae and wingless grasshopper Phaulacridium vittatum (Sjöstedt) (Orthoptera: Acrididae). The results indicate that the native bird species common in farm shelterbelts preyed on a range of arthropod taxa including several that are pests of crops and pastures. Accordingly, conservation of birds in farmlands could contribute to suppression of arthropod pests.     

Desiccation resistance and water balance in southern African keratin beetles (Coleoptera, Trogidae): the influence of body size and habitat

Desiccation resistance and water balance were examined in the adults of seven trogid species, which differed both in body size and in the habitats from which they were collected. Body water contents (51–58% fresh mass) and desiccation rates at 27 °C (0.00026–0.00093 g h⁻¹) in these species were very similar to those of unrelated, similar-sized beetles from arid habitats. The keratin beetles differed markedly from many other adult Coleoptera by virtue of their very high haemolymph osmolality and inability to regulate haemolymph osmolality, and to catabolise lipids for water production, during desiccation. Like most other insects, the xeric trogid species had lower rates of water loss and longer survival times than trogids from mesic areas. This was due both to lower rates of water loss and to the larger body size of species from the more arid areas. Because absolute body water content was higher in large beetles than in small ones, larger body size conferred higher desiccation resistance on the very large Kalahari desert species. This suggests that there may be strong selection for large body size in such insects from arid areas. Most ecological and ecophysiological investigations of geographical variation in body size, and the species-body size distribution, have focused on temperature and metabolic rate as explanatory variables. This study suggests that attention should also be given to desiccation resistance. Accepted: 29 September 1997     

Revisiting water loss in insects: a large scale view

Desiccation resistance in insects has long been thought to covary with environmental water availability, and to involve changes in both cuticular and respiratory transpiration. Here, we adopt a large-scale approach to address both issues. Water loss rate and precipitation are positively related at global scales. A significant proportion (68%) of the interspecific variation in water loss rate is explained at the genus level or above. The relationship between metabolic rate and water loss rate differs substantially between mesic and xeric species. While these variables covary as a consequence of their independent covariation with body mass in mesic species, this is not the case in xeric species. In the latter, there is a strong relationship between the residuals of the water loss rate-body mass and metabolic rate-body mass relationships, and water loss rate is much reduced. Moreover, because metabolic rate does not differ significantly between xeric and mesic species of a similar size, respiratory transpiration constitutes a greater proportion of total water loss in xeric than in mesic species of a similar size. This implies that respiratory transpiration and the extent to which it can be modified must be of considerable importance in xeric insect species, although finer scale studies suggest otherwise.     

Long-Term Storage of Infective Microsporidian Spores in Liquid Nitrogen

Thirty-one species of microsporidia, isolated from insects and stored in liquid nitrogen for up to 25 yr, were infectious when removed from liquid nitrogen. The natural hosts of all of these microsporidia were terrestrial insects, representing six different insect orders: Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, and Orthoptera. All microsporidia from terrestrial insects that were tested survived storage in liquid nitrogen, while Nosema algerae , a microsporidium from aquatic mosquito hosts did not survive freezing in liquid nitrogen. A Nosema species from the alfalfa weevil, Hypera postica , lost some infectivity in a water storage medium after 25 yr in liquid nitrogen. Liquid nitrogen storage of microsporidian spores in 50% and 100% glycerol media reduced loss of infectivity and is recommended for extended storage of microsporidia from terrestrial insect hosts.     

Assessment of errors associated with harbour seal (Phoca vitulina) faecal sampling

Six harbour seals, ages 4–8 years, were held as pairs in a 10 times 20 times 2 m tank filled with sea water, and on 60 occasions were fed a meal of a specific species of fish or cephalopod of known size. The tank was drained periodically, and harbour seal faeces were collected on a 0.5 mm sieve. Number and size of otoliths and beaks found in faeces were determined. Fifty-eight percent of 670 fish and 37% of 36 cephalopods fed to harbour seals were represented by their otoliths or beaks in faeces. Estimated number of prey consumed was determined from the greatest number of left or right otoliths or upper or lower beaks collected in faeces. Estimated length ofprey was determined from measurements of otoliths and beaks recovered in the tank and relationships of otolith and beak measurements to prey length. Estimated number of fish eaten was not significantly different among pairs of harbour seals, but was different among species of fishes. Only 24–35% of fish species with small otoliths were represented in faeces, whereas more robust otoliths from other species were less apt to be completely dissolved. Estimated length of fishes was significantly less than lengths of fishes fed to harbour seals in 39 (76.5%) of 51 trials. Cephalopod beaks were not affected by passage through the harbour seal digestive tract. Amount of otolith dissolution was not related to species of fish; estimated fish length was underestimated by an average 27.5%. Although some (7.4%) of the otoliths were collected within 100 h after the fish were ingested, more than 90% were recovered within 24 h after the fish was eaten. Correction factors were developed which will allow researchers to estimate more reliably number and size of fish and cephalopod prey eaten by harbour seals.     

南充高坪机场土壤及草丛动物群落特征和鸟类的关系

机场鸟类是机场安全的重大隐患,减少机场附近鸟类数量是机场安全至关重要的一环.2007年4～12月,对南充高坪机场3种生境土壤动物和草丛动物群落组成、数量和季节性变化特征进行了初步的研究.调查共获得土壤动物25类,其中蜱螨目、原尾目、线虫纲为土壤动物群落优势类群,占年总捕获量的71.88%;常见类群有弹尾目、线蚓科、腹足纲、膜翅目、双翅目、鞘翅目、蚯蚓、蜘蛛目,直翅目9类,占总捕获量的22.84%.地表草丛动物21类,其中半翅目、蜘蛛目、双翅目、腹足纲为地表草丛动物的优势类群,占年捕获量的65.7%;常见类群有直翅目、鞘翅目、同翅目、膜翅目、鳞翅目、革翅目、弹尾目7类,占总捕获量的31.2%.将土壤动物群落、草丛动物群落与肉食性鸟类进行相关分析,结果显示土壤动物群落变化与肉食性鸟类群落之间有一定关系;草丛动物数量与肉食性数量鸟类呈现一定正相关性,机场肉食性鸟类数量与直翅目数量呈显著的正相关关系(r=0.910,P=0.032).结合机场区域鸟类食性观察、分析,直翅目、腹足纲动物是机场肉食性鸟类数量的主要捕食对象,通过定期割草、消除腐草和杂物、喷洒农药控制地表草丛动物是减少机场区域肉食性鸟类数量的有效方法和途径.     

Broken bridges: The isolation of Kilimanjaro's ecosystem

Biodiversity studies of global change mainly focus on direct impacts such as losses in species numbers or ecosystem functions. In this study, we focus on the long‐term effects of recent land‐cover conversion and subsequent ecological isolation of Kilimanjaro on biodiversity in a paleobiogeographical context, linking our findings with the long‐standing question whether colonization of African mountains mainly depended on long‐distance dispersal, or whether gradual migration has been possible through habitat bridges under colder climates. For this, we used Orthoptera as bioindicators, whose patterns of endemism and habitat demands we studied on about 500 vegetation plots on Kilimanjaro and Mt. Meru (Tanzania) since 1996. Land‐cover changes in the same area were revealed using a supervised classification of Landsat images from 1976 to 2000. In 1976, there was a corridor of submontane forest vegetation linking Kilimanjaro with Mt. Meru, replaced by human settlements and agriculture after 2000. Until recently, this submontane forest bridge facilitated the dispersal of forest animals, illustrated by the large number of endemic submontane forest Orthoptera shared by both mountains. Furthermore, the occurrence of common montane endemics suggests the existence of a former forest corridor with montane vegetation during much earlier times under climatic conditions 2–7°C cooler and 400–1,700 mm wetter than today. Based on the endemicity patterns of forest Orthoptera, negative consequences are predicted due to the effects of isolation, in particular for larger forest animals. Kilimanjaro is becoming an increasingly isolated ecosystem with far reaching consequences for diversity and endemism. Forest bridges between East African mountains acted as important migratory corridors and are not only a prehistoric phenomenon during periods with other climatic conditions but also disappeared in some places recently due to increasing and direct anthropogenic impact.     

The effects of mass and age on standard metabolic rate in house crickets

Abstract. This study employed flow-through respirometry to measure the oxygen consumption rates (VO₂) of inactive male house crickets, Acheta domesticus L. (Orthoptera: Gryllidae), and to quantify the effects of body mass and adult age on standard metabolic rate (SMR). The Vo₂ increased with male body mass at a rate similar to that found in other studies of insect aerobic metabolism. The data reported in this study are combined with published data from other species of Orthoptera to generate a consensus allometric relationship between SMR and body mass for the Order. In general, the Orthoptera expend 2–3 times the energy per unit of body mass when inactive as compared to other arthropods, such as tenebrionid beetles, ants and spiders. Possible explanations for this substantial difference are discussed. By contrast to body mass, mass-specific Vo₂ decreased with increasing male age. This age effect has previously been reported for mammals but is not well established for insects, and its implications for the preference of cricket females for older mates is discussed. As energy expended for metabolic maintenance comprises 78% of a male cricket's daily energy budget, changes in SMR may have a substantial effect on the energy available for reproduction.     

Post-prandial urine loss and its relation to ecology in brown long-eared (Plecotus auritus) and Daubenton's (Myotis daubentoni) bats (Chiroptera: Vespertilionidae)

Urine loss, over the first 12 hours after feeding, was positively and linearly dependent on food consumption in water-denied, brown long-eared bats ( Plecotus auritus ) and also in water-denied and water-provided, Daubenton's bats ( Myotis daubentoni ). The slope of the relationship (food-dependent urine loss) (363 μ 1 g dry mass food⁻¹, S.D.=±70, n=19 ) was not significantly different between the two species but predicted urine loss at zero food consumption (food-independent urine loss) was significantly lower in P. auritus (0.048 μl.min⁻¹, S.D. =±0.015, n= 12) than in M. duubentoni (0.217 μl min⁻¹ S.D. =±0.040, n = 7 ). The same results were apparent if the data for M. daubentoni were restricted to water-deprived animals only. Of total urine loss, 46% occurred in the first hour after feeding in M. daubentoni compared with only 20% in P. auritus . We suggest that the differences between the two species in the pattern of postprandial urine loss reflect their relative association with open water when foraging and roosting in the wild. In the course of the water-denied experiment, M. duubentoni lost 15% of pre-fed body mass and showed signs of severe dehydration, while P. auritus only lost 6% and did not. However, urine loss only accounted for 8–10% of body mass loss. A water budget model for wild P. auritus in the summer was developed and suggested that if bats did not drink, approximately 19% of water loss would be attributable to faecal water loss, 18–20% to urine loss, and 59–62% of intake would be available to support evaporation and reproductive losses.     

Changes in leaf hydraulics and stomatal conductance following drought stress and irrigation in Ceratonia siliqua (Carob tree)

Changes in leaf hydraulic conductance (K) were measured using the vacuum chamber technique during dehydration and rehydration of potted plants of Ceratonia siliqua . K of whole, compound leaves as well as that of rachides and leaflets decreased by 20–30% at leaf water potentials (Ψ_L) of −1.5 and −2.0 MPa, i.e. at Ψ_L values commonly recorded in field-growing plants of the species. Higher K losses (up to 50%) were measured for leaves at Ψ_L of −2.5 and −3.0 MPa, i.e. near or beyond the leaf turgor loss point. Leaves of plants rehydrated while in the dark for 30 min, 90 min and 12 h recovered from K loss with characteristic times and to extents inversely proportional to the initial water stress applied. Leaf conductance to water vapour of plants dehydrated to decreasing Ψ_L and rehydrated at low transpiration was inversely related to loss of K, thus suggesting that leaf vein embolism and refilling (and related changes in leaf hydraulics) may play a significant role in the stomatal response.     

Feeding, nutrient flow, and digestive enzyme release in the giant milkweed bug, Oncopeltus fasciatus

Abstract.  The giant milkweed bug, Oncopeltus fasciatus , is an intermittent feeder, spending most of its time in compact groups away from the food, with feeding bouts lasting 30–60 min. They macerate a small area of the seed with their stylets, secreting large amounts of saliva (which suspends and emulsifies the seed tissue), and quickly suck the emulsion into the gut. Therefore, little digestive activity occurs in the seed tissue. Freshly ingested food in the first gut region (V1) consists of 50% water, 46% lipid, 5% protein, and 1% soluble carbohydrates. The junction of the midgut and hindgut lacks a lumen in the larvae stages, and a 3 μL large oil drop (> 85% triacylglycerides) accumulates in the third gut region (V3). Approximately 24 h after the imaginal moult, this large volume of oil and faeces is defecated, and thereafter an oily faeces is defecated several times daily. It is postulated that the delayed egestion in larvae protects them against suffocation due to self-soiling with oily faeces. Serine proteases are absent in the gut and, instead, a cystein proteinase, inhibited by E64, is present (gut pH 6.0). High lipase activity was found throughout the gut, but only limited amylase activities. Basal levels of all three enzymes occurred throughout the gut, but at lower levels in starved bugs. Salivary gland extracts contain a cysteine proteinase and a lipase, but no amylase.     

Plasma Corticosterone, Motor Activity and Metabolic Circadian Patterns in Streptozotocin-Induced Diabetic Rats

Experiments were conducted in male rats to study the effects of streptozotocin-induced diabetes on circadian rhythms of (a) plasma corticosterone concentrations; (b) motor activity; and (c) metabolic patterns. Animals were entrained to LD cycles of 12: 12 hr and fed ad libitum.

A daily rhythm of plasma corticosterone concentrations was found in controls animals with peak levels at 2400 hr and low values during the remaining hours. This rhythm was statistically confirmed by the cosinor method and had an amplitude of 3.37μg/100 ml and the acrophase at 100 hr. A loss of the normal circadian variation was observed in diabetic animals, with a nadir at the onset of light period and high values throughout the remaining hours; cosinor analysis of these data showed no circadian rhythm, delete and a higher mean level than controls.

As expected, normal rats presented most of their motor activity during the dark period with 80+ of total daily activity; the cosinor method demonstrated a circadian rhythm with an amplitude of 60+ of the mean level and the acrophase at 0852 hr. Both diabetic and control rats showed a similar activity during the light phase, but diabetic animals had less activity than controls during the night and their percentage of total daily activity was similar in both phases of the LD cycle (50+ for each one). With the cosinor method we were able to show the persistence of a circadian rhythm in the motor activity of diabetic rats, but with a mesor and amplitude lower than in controls (amplitude rested at 60+ of the mean level) and its acrophase advanced to 0148 hr.

The metabolic activity pattern of diabetic rats also changed: whereas controls showed a greater metabolic activity during the night (70+ food; 82+ water; 54+ urine; 67+ faeces), diabetics did not show differences between both phases of the LD cycle. Water ingested and urine excreted by the diabetic group were higher than normal during light and dark periods; food consumed and faeces excreted were higher than controls only in the light phase.

These data suggest that alterations in circadian rhythms of plasma corticosterone and motor activity are consecutive to the loss of the feeding circadian pattern, due to polyphagia and polydipsia showed by these animals, which need to extend intakes during the light and dark phases.     

Arthropods in diet of Little Bustards Tetrax tetrax during the breeding season in western France

Capsule Seasonal, age- and sex-related variations in the diet were studied during March to October.

Aims To determine which arthropod orders contributed most during the laying–rearing period and those important in determining breeding success of the species in an intensive agricultural habitat.

Methods Faeces (n = 388, 345 g) and three gut samples were dissected to determine which arthropod orders contributed most to the diet, especially during the laying–rearing period.

Results Coleoptera were the most numerous prey followed by Orthoptera, Dermaptera and Hymenoptera. No difference was observed in the diet of adult males and females. Although adults ate arthropods throughout the breeding season, plant material contributed 97–99% of faecal contents by weight in each month. Chicks, however, only ate arthropods, notably Coleoptera and Orthoptera, at least until 2–3 weeks old.

Conclusion Increasing arthropod availability would be a useful management tool for maintaining endangered Little Bustard populations by potentially increasing chick survival.