Scavenging in Antarctica: Intense variation between sites and seasons in shallow benthic necrophagy

The response of scavengers to a feeding cue at Adelaide Island, West Antarctic Peninsula was investigated using a baited video camera system. Fourteen experimental deployments, each lasting 72 h were conducted at two contrasting sites during the winter and summer of 2005. The rate of bait consumption varied between sites but not between seasons, and was low in comparison with studies at lower latitudes and greater depths. At the Hangar Cove site, the nemertean Parborlasia corrugatus was out-competed at the bait and displaced by the lysianassid amphipod Cheirmedon femoratus during winter. However, C. femoratus did not feed on the bait during summer, allowing P. corrugatus to monopolise the feeding opportunity. At the South Cove site the asteroid Odontaster validus dominated the bait in both seasons but sporadic feeding by the nototheniid fish Notothenia coriiceps considerably affected consumption rates during two of the six deployments. Scavengers were attracted to the bait in very high numbers and opportunistic necrophagy seems to be a successful strategy in an environment that is intensely disturbed by ice.     

Thermoregulation of nutrient-restricted hair ewes subjected to heat stress during late pregnancy

In summers with severe hot environmental temperatures, thermoregulation is expected to be critical during the last third of gestation of hair ewes, and this effect can be overstated by suboptimal feeding conditions. Twenty-four multiparous hair sheep ewes with approximately 100 d of pregnancy were randomly assigned to two treatments to evaluate the effects of nutritional restriction (NR) during late gestation on some serum metabolites, physiological variables, and thyroid hormone concentrations under intense heat load (maximum temperature 42–45 °C). Treatments were as follows: (1) control, ewes fed free choice wheat straw plus a concentrate at a rate of 500 g/d, and (2) nutritionally-restricted (NR) ewes, which were offered wheat straw only ad libitum. Body weight of NR ewes dropped 5.1 kg (P<0.05), while control ewes gained 4.7 kg during the study period. Rectal temperature was not affected (P>0.05) by feeding regime either in the morning or afternoon hours. Respiration rate was greater (P<0.05) in control ewes (20 and 40 breaths/min higher in the day and night, respectively) on d 130 and 145 of pregnancy compared to NR ewes. Skin temperatures during the morning and afternoon were affected (P<0.05) by feeding regime at d 130 and 145 of pregnancy. In the morning, NR ewes presented greater (P<0.05) head and rump temperature at day 145 of gestation, and lower (P<0.05) udder temperatures at d 130 and 145 than control ewes. In the afternoon, skin temperatures of NR ewes were higher (P<0.05) in head and right flank on d 130 and 145 of pregnancy, and in udder at day 145 compared to control ewes. Serum glucose was higher (P<0.05) in NR ewes than control animals at day 145 of pregnancy. Serum cholesterol, triglyceride and thyroid hormones were not affected by nutritional restriction. Overall, it was found that nutritionally restricted ewes were less affected by intense heat loads than well-fed ewes, apparently due to the lower metabolic heat produced by this underfed animals. Also, it was apparent that the lower respiration rate of NR ewes was compensated by a greater body surface temperature.     

Diurnal activity rhythms of the subterranean termiteAnacanthotermes vagans (Hagen) under laboratory and field conditions of the Kuwait desert

Daily foraging activity ofAnacanthotermes vagans was tested using toilet paper rolls as bait. The highest activity was recorded at midnight and during the hours of the early morning in both summer and winter seasons. In spring the time of highest activity was reversed to take place at midday, afternoon and early evening. Aktograph records in the laboratory demonstrated that individual workers are active most of the day and not naturally entrianed by photoperiods. Daily activity of groups of 10 workers was not statistically different from that of individual workers.     

Effect of Time of Day on Aerobic Contribution to the 30‐s Wingate Test Performance

The purpose of this study was to evaluate the effects of time of day on aerobic contribution during high‐intensity exercise. A group of 11 male physical education students performed a Wingate test against a resistance of 0.087 kg · kg^?1 body mass. Two different times of day were chosen, corresponding to the minimum (06:00 h) and the maximum (18:00 h) levels of power. Oxygen uptake (V˙O₂) was recorded breath by breath during the test (30 sec). Blood lactate concentrations were measured at rest, just after the Wingate test, and again 5 min later. Oral temperature was measured before each test and on six separate occasions at 02:00, 06:00, 10:00, 14:00, 18:00, and 22:00 h. A significant circadian rhythm was found in body temperature with a circadian acrophase at 18:16±00:25 h as determined by cosinor analysis. Peak power (P_peak), mean power (P_mean), total work done, and V˙O₂ increased significantly from morning to afternoon during the Wingate Test. As a consequence, aerobic contribution recorded during the test increased from morning to afternoon. However, no difference in blood lactate concentrations was observed from morning to afternoon. Furthermore, power decrease was greater in the morning than afternoon. Altogether, these results indicate that the time‐of‐day effect on performances during the Wingate test is mainly due to better aerobic participation in energy production during the test in the afternoon than in the morning.     

Field oviposition rates and egg load dynamics of pollen beetles (Meligethes aeneus Fab.) (Colepotera: Nitidulidae)

Abstract 1 Egg loads from field collected pollen beetles (Meligethes aeneus Fab., Coleoptera: Nitidulidae) were determined by dissecting beetles caught at the beginning and end of the putative daily oviposition period. Field collected beetles were offered Brassica napus (L.) plants in cages for 8 (morning and early afternoon), 16 (overnight), and 24 h to ascertain the number of eggs laid during these time periods. 2 Most eggs were laid in the morning and early afternoon. The proportion of gravid females was higher at the beginning of the oviposition period than at the end. Most females in the morning carried two eggs, whereas one egg was more common in the afternoon. 3 We hypothesized that the number of eggs laid during the oviposition period would be equivalent to the difference between egg loads at the beginning and end of oviposition. This was not the case; differences in egg loads were significantly lower than number of eggs laid. However, the number of eggs laid was equivalent to the egg load at the beginning of the oviposition period, suggesting that eggs available in the morning are laid during the following day. 4 Population estimates of daily oviposition rates, approximately 0.7 eggs per beetle and day, were close to estimates from laboratory studies when the proportion of gravid females was taken into consideration.     

Variation in the airborne fungal spore population of the Tuscarawas Valley II

For years the medical profession has recognized a relationship between fungal airspora and the incitement of respiratory allergies. An evaluation of outdoor fungal airspora on an eastern Ohio campus during June 1988 revealed significant differences in quality and quantity with respect to microenvironments. Type of vegetation, diurnal periodicities, and daily weather conditions affected the airspora at each site. Shaded lawns within groves and windbreaks, unshaded lawns, and asphalt-covered parking lots presented varying dynamics for fungal spore liberation. Unshaded lawns produced airspora most abundantly during morning and least abundantly during afternoon. Arboreal sites produced airspora most prolifically at midday. A deciduous sycamore grove produced fewer afternoon airspora than evergreen pine and arborvitae stands. Evening airspora at all vegetated sites increased after experiencing afternoon troughs. Frequently encountered molds included Cladosporium spp., brightly pigmented sterile mycelia, and Alternaria spp.     

Daily variation in body core temperature using radio-telemetry in aluminium industry shift-workers

The aim of this study was to investigate the diurnal variation in core temperature in aluminium shift-workers exposed to hot ambient conditions. Core temperature was continuously recorded via an ingestible radio-telemetry thermistor in 29 shift-workers. Data from the morning, afternoon and night shifts were aggregated for each participant to obtain 24-h recordings during work duties. Complete data were obtained from 10 participants. Results showed that body core temperatures recorded in the afternoon (from 12:00 h to 20:00 h) were significantly higher (P<0.05) than in the late evening, night and early morning (from 21:00 h to 08:00 h). In addition, core temperature displayed a circadian variation with a mesor of 37.45 (±0.19) °C, an amplitude of 0.23 (±0.12) °C and an acrophase at 16:36 h (±3:37 h). The peak values of core temperature recorded at each hour of the day on the work site followed the same pattern with an acrophase in the early afternoon. In summary, our data showed that shift-workers present higher core temperatures in the afternoon than in the morning or during the night. In addition, it was not the work duration but the hour-of-day that triggered the variation in core temperature. This result partly explains previous observations that workers under heat stress have a higher probability of heat illness during daytime shifts than during the night shift, and suggests that special care should be given to the afternoon shift and to the end of the morning shift.     

Impacts of introduced common wasps (Vespula vulgaris) on experimentally placed mealworms in a New Zealand beech forest

An introduced social wasp Vespula vulgaris may compete with native birds for honeydew and invertebrates in New Zealand forests. Experimentally hidden mealworms (Tenebrio molitor) persisted longer at two sites following wasp poisoning that at two sites where wasps were not poisoned. Mealworms persisted longer in the morning than in the afternoon within all study sites. An unusually low mealworm removal rate during a morning trial before wasp poisoning heavily influences the results of this experiment but we have no ecological reason to ignore it. Wasps may therefore be having a heavy impact on invertebrate abundance on very short time scales (within a day following dawn emergence). They may also remove cached food items that would otherwise be retrieved by the South Island robin (Petroica australis australis) during cold or dark feeding conditions.     

A COMPARISON OF THE IMMEDIATE EFFECTS OF MODERATE EXERCISE IN THE EARLY MORNING AND LATE AFTERNOON ON CORE TEMPERATURE AND CUTANEOUS THERMOREGULATORY MECHANISMS

Twelve healthy male subjects each undertook two bouts of moderate exercise (70% VO₂max for 30 minutes) in the morning (08:00) and late afternoon (18:00) at least 4 days apart. Measurements were made of heart rate, core (rectal) temperature, sternum skin temperature, and forearm skin blood flow during baseline conditions, during the bout of exercise, and throughout a 30-minute recovery period. Comparisons were made of the changes of heart rate, temperature, and skin blood flow produced by the exercise at the two times of day. Student t tests indicated that baseline values for core temperature (37.15°C ±. 06°C vs. 36.77°C ± 0.06°C) and sternum temperature (33.60°C ± 0.29°C vs. 32.70°C ± 0.38°C) were significantly (p <. 05) higher in the late afternoon than the early morning. Two-way analysis of variance (ANOVA) indicated that the increases in core and sternum temperatures during exercise were significantly less (p =. 0039 and. 0421, respectively) during the afternoon bout of exercise compared with the morning, even though the work loads, as determined by changes in heart rate, were not significantly different (p =. 798) at the two times of testing. There were also tendencies for resting forearm skin blood flow to be higher in the afternoon than in the morning and for exercise to produce a more rapid rise in this variable in the afternoon. The possible mechanisms producing these responses to exercise are discussed in terms of those that are responsible for the normal circadian rhythm of core temperature. It is concluded that the body's ability to remove a heat load is less in the early morning, when the circadian system is in a “heat gain” mode, than in the late afternoon, when heat gain and “heat loss” modes are balanced more evenly. (Chronobiology International, 17(2), 197–207, 2000)     

A new tent trap for monitoring the daily activity of Aedes aegypti and Aedes albopictus

In this study, we designed a new tent trap; the BioDiVector (BDV) tent trap, consisting of two rectangular tents that use human bait without endangering the technical personnel. The daily activity pattern of Aedes aegypti and Aedes albopictus in intra, peri, and extradomiciliary sites was studied in an endemic area of dengue in southern Mexico by using the BDV tent trap. Totals of 3,128 individuals of Ae. aegypti and 833 Ae. albopictus were captured. More Ae. aegypti males than females were caught, while the opposite was true with Ae. albopictus. The activity of both mosquito species was affected by the interaction between the collection site and time of day. In general, more individuals of both mosquito species were captured at the extradomicillary sites than at the peri and intradomicillary sites. Mosquitoes showed two peaks of activity, one in the morning and the other in the afternoon, but in general this only occurred at the extradomicillary sites, whereas no peak of activity was observed at the intra and peridomicillary sites. Overall, Ae. aegypti had a higher indirect biting rate than Ae. albopictus. Finally, due to its efficiency, simplicity, and low cost, we suggest the use of this innovative tool for entomological surveillance, bionomics and vector incrimination studies in geographical areas where dengue and other arboviruses are present.     

Phloem Translocation and Heat-induced Callose Formation in Field-grown Gossypium hirsutum L

Phloem translocation rates in field-grown cotton (Gossypium hirsutum L.) dropped from morning to afternoon and continued to decline toward evening, except that recovery occurred following the hottest afternoon when the maximum temperature was 44 C. Water deficits increased from morning to evening, and severity of deficits generally were proportional to daytime heating. Water stress contributed toward reducing translocation but was not always the governing factor. Callose breakdown appeared to be slower than heat-induced synthesis, and in the evening callose still reflected the influence of high afternoon temperatures. Translocation was considerably reduced when about 50% or more of the hypocotyl sieve plates had large amounts of callose. While heat-induced callose may have reduced translocation because of sieve plate pore constriction, temperatures of 39 to 44 C appeared to inhibit an additional component of translocation as well, possibly in the leaf blade.     

帽儿山地区落叶松人工林CO2通量特征及对林分碳收支的影响

2008年,采用涡度协方差法测定了黑龙江省尚志市帽儿山地区落叶松人工林的CO₂通量,并于生长季(5—10月)不同月份测定了落叶松叶片光合日变化.结果表明: 不同时间段环境因子变化对落叶松人工林净生态系统交换量的影响存在差异,下午(12:00—24:00) 的净生态系统交换量对其饱和蒸汽压亏缺的变化反应较上午(0:00—12:00)迟钝;上午光能利用效率为0.6284 mol·mol^-1,是下午的1.14倍;随温度上升,上午净生态系统交换量的增幅是下午的1.5倍(气温>15 ℃).这种差异使落叶松林净碳交换量的88%在上午完成,而下午仅完成净碳交换量的12％;上、下午生态系统生产力分别占全天的60%和40%,上午叶片的光合能力为下午的3倍.落叶松人工林全年净生态系统交换量在263～264 g C·m^-2,生态系统呼吸在718～725 g C·m^-2,总初级生产力在981～989 g C·m^-2.     

Aggressive Behavior and Territoriality in the Olive Fruit Fly,Bactrocera oleae (Rossi) (Diptera: Tephritidae): Role of Residence and Time of Day

Bactrocera oleae is a worldwide olive fruit pest. In late afternoon males form swarms on the windward side of trees. Within the swarm, each male occupies a leaf and aggressively excludes male conspecifics before starting courtship displays. Females display aggressive interactions each other too, particularly when they are in close proximity of oviposition sites. In this research, the aggressive behavior displayed by both sexes was quantified. Aggressions were composed by wing waving, fast running towards the opponent, pouncing and boxing on the head and thorax of the foe. High-speed videos highlighted that the parameters characterizing the aggressions did not strongly differ between sexes and between residents and intruders. Resident flies won more combats, both in male-male and female-female aggressive interactions. In both sexes, aggressions were more frequent in the late morning than in the afternoon. Among males, aggressions could be functional to maintain single leaf territories in which each fly can perform courtship displays. Through aggressions females could gain and maintain single oviposition sites. Lastly, by favorable fight outcomes B. oleae could also get access to food sources on olive leaves and fruits.     

Environmental and genetic components of stomatal behavior in two genotypes of upland cotton

Two parental lines of Upland cotton (Gossypium hirsutum L.) plus their reciprocal F₁, F₂, and backcross populations were field-tested for environmental and genetic components of leaf diffusive resistance. Leaf resistance was measured with a diffusion porometer three times each day during 6 days in August. A large, consistent environmental component was present during the morning, afternoon, and evening, but the genetic component appeared mainly during the afternoon. Leaf water potential indicated that afternoon was the period of highest water stress. Genetic analyses revealed that leaf resistance was associated with both additive and dominance genetic variances, with an estimated narrow sense heritability of 25%. High leaf resistance was completely dominant to low resistance.     

A Behaviorally-Explicit Approach for Delivering Vaccine Baits to Mesopredators to Control Epizootics in Fragmented Landscapes

Despite the widespread use of aerial baiting to manage epizootics among free-ranging populations, particularly in rabies management, bait acceptance and seroconversion rates often are lower than required to eliminate spread of disease. Our objectives in this study, therefore, were to evaluate the performance of stratified bait distribution models derived from resource selection functions (RSF) on uptake of placebo rabies baits by raccoons (Procyon lotor) and Virginia opossums (Didelphis virginiana), as well as the probability of bait uptake as a function of proximity to bait distribution areas in fragmented agricultural ecosystems. Among 478 raccoons and 108 opossums evaluated for presence of Rhodamine B (RB) across 8 sites, only 26% of raccoons and 20% of opossums exhibited marking consistent with bait consumption 14–24 days post-baiting. The effective area treated, based on 90% kernel density estimators of marked individuals, ranged from 99–240 ha larger than bait distribution zones, with RB marked individuals captured up to 753m beyond the bait zone. Despite incorporation of RSF data into bait distribution models, no differences in uptake rates were observed between treatment and control sites. These data likely reflect the underlying constraints imposed by the loss and fragmentation of habitat on animal movement in heterogeneous landscapes, forcing individuals to optimize movements at coarse (i.e., patch-level) rather than fine spatial scales in highly fragmented environments. Our data also confirm that the probability of bait acceptance decreases with increasing distance from bait zone interiors, even within the zone itself. Thus, although bait acceptance was confirmed beyond bait zone boundaries, the proportion of vaccinated individuals may comprise a small minority of the population at increasing distances from baiting interiors. These data suggest focal baiting creates a buffered area of treated individuals around bait zones or bait stations, but repeated treatments may be needed to achieve sufficient uptake to eradicate disease.     

Enhanced Photosynthesis and Stomatal Conductance of Pima Cotton (Gossypium barbadense L.) Bred for Increased Yield

Yield of Pima cotton (Gossypium barbadense L.) has tripled over the last 40 years with the development of new cultivars. Six genetic lines representing successive stages in the breeding process (one primitive noncultivated accession, four cultivars with release dates from 1949 to 1983, and one unreleased breeding line) were grown in a greenhouse, and their gas exchange properties were compared. Among the cultivated types, genetic advances were closely associated with increasing single-leaf photosynthetic rate (A) and stomatal conductance (g_s), especially in the morning. The A and g_s of the primitive line approached those of the cultivated types early in the morning, but were much lower for the rest of the day. In both morning and afternoon, A was correlated with g_s across genotypes but was not correlated with leaf thickness, concentrations of chlorophyll or starch, or intercellular CO₂ concentration (c_i). In the oldest cultivar, the relationship of A to c_i did not change between morning and afternoon. In the two most recent lines, the slopes of the A:c_i curves at limiting c_i exceeded that of the oldest cultivar by 25 to 50% in the morning, but the differences were much smaller in the afternoon. The maximum A of the newer lines at high c_i exceeded that of the oldest cultivar only in the morning. Breeding for increasing yield has enhanced the photosynthetic capacity and stomatal conductance of Pima cotton and altered the diurnal regulation of photosynthesis.     

Temporal Variation in Cleanerfish and Client Behaviour: Does It Reflect Ectoparasite Availability?

We tested the importance of ectoparasites as the proximate cause of cleaning interactions by comparing the activity of Caribbean cleaning gobies (Elacatinus evelynae) and of their clients during three daily periods (early morning, midday, and late afternoon) in which ectoparasite availability varied naturally. Emergence from the benthos of gnathiid isopod larvae, the main target of cleaning goby predation, was higher at night, when cleaners were inactive, than during the day. As a result, overall ectoparasite loads on client fish tended to be higher in the morning. Inspection bouts by cleaning gobies were longest in the morning, but also at midday when ectoparasite availability on clients was lower. Client fish were observed at cleaning stations most often in the afternoon, when they harboured few ectoparasites, but they were more likely to adopt incitation poses, which increase the likelihood of being cleaned, in the morning than later in the day. Most cleaner and client behaviours therefore did not change predictably in response to natural diurnal variation in ectoparasite availability. Our study suggests that the ultimate and proximate causes of cleaning behaviour need not necessarily coincide.     

Behavioural functions of grooming in male Aedes albopictus (Diptera: Culicidae), the Asian tiger mosquito

Flight, walking and resting behaviours of male Aedes albopictus (Skuse) were observed in a flight cage. These behaviours were also associated with repetitive acts of grooming. The effects of sugar meal and period of the day on the total duration, the frequency and the duration of each individual grooming behaviour were studied. Fed or unfed males were individually released in a transparent plastic flight cage and direct visual observations using Observer software were carried out for 2?h during the morning and 2?h in the afternoon. There was no significant difference in the grooming behaviour between morning and afternoon observations. Fed male mosquitoes groomed longer than unfed males. The sugar meal seemed an important influencing factor of the grooming behaviour by giving more energy and making different parts of the mosquito sticky. The functions of grooming behaviour are discussed in regard to other behaviours such as mating, copulation, sensory detection and flight.     

Time-of-Day Effect on Cardiac Responses to Progressive Exercise

This study was designed to examine time-of-day effects on markers of cardiac functional capacity during a standard progressive cycle exercise test. Fourteen healthy, untrained young males (mean?±?SD: 17.9?±?0.7 yrs of age) performed identical maximal cycle tests in the morning (08:00–11:00?h) and late afternoon (16:00–19:00?h) in random order. Cardiac variables were measured at rest, submaximal exercise, and maximal exercise by standard echocardiographic techniques. No differences in morning and afternoon testing values at rest or during exercise were observed for oxygen uptake, heart rate, cardiac output, or markers of systolic and diastolic myocardial function. Values at peak exercise for Vo₂ at morning and afternoon testing were 3.20?±?0.49 and 3.24?±?0.55?L min^?1, respectively, for heart rate 190?±?11 and 188?±?15?bpm, and for cardiac output 19.5?±?2.8 and 19.8?±?3.5?L min^?1. Coefficients of variation for morning and afternoon values for these variables were similar to those previously published for test-retest reproducibility. This study failed to demonstrate evidence for significant time-of-day variation in Vo₂max or cardiac function during standard progressive exercise testing in adolescent males. (Author correspondence: thomas.rowland@bhs.org)     

Factors affecting the thermal behavior of the sand lizard Liolaemus wiegmannii in natural and modified grasslands of temperate coastal dunes from Argentina

The present study describes and compares the thermal behavior of individuals of Liolaemus wiegmannii, inhabiting patches of natural grassland and modified patches with exotic trees of Acacia longifolia, by analyzing the factors affecting its behavior. Thermal behavior of L. wiegmannii was assessed by radiotracking 22 adult individuals in a coastal dune area from Argentina. In order to account for individual responses we analyzed the factors affecting thermal behavior using Generalized Linear Mixed Models. Thermal behavior of L. wiegmannii was mainly affected by the time of day and the substrate temperature. The individuals basking on bare sand in the morning shifted to filtered sunlight during midday and to the shade of clump and erect stems and herbs during the afternoon. The individuals buried in sand when the substrate temperature was low and the wind speed was high. The use of sub-shrubs and shrubs could not be explained solely by thermal factors. In natural L. wiegmannii regulated its body temperature by shuttling between microhabitats that provided them with different levels of exposure to sunlight during the day. However, in modified patches individuals varied in the choice of plants used as shaded places to mitigate high microenvironmental temperatures and they were also more exposed to full shaded sites and less to warm sand to bask, which could have negative consequences for its thermal biology.