Susceptibility of Culicoides species biting midges to deltamethrin‐treated nets as determined under laboratory and field conditions in the Balearic Islands,Spain

Culicoides Latreille (Diptera: Ceratopogonidae) are vectors of several arboviruses, including bluetongue virus (BTV) and African horse sickness virus (AHSV), which cause diseases in, respectively, sheep and cattle, and horses, and have economic repercussions mainly as a result of trade restrictions. Insecticides can be used to reduce vector populations and hence the spread of disease. Despite the economic importance of these diseases, relatively few studies have evaluated the efficacy of commercially available insecticides and the effectiveness of treated nets against Culicoides species. The aim of the present study was to evaluate the insecticidal effect of commercially available polyethylene nets (ZeroVector^®) treated with deltamethrin (4.4 g/kg ± 15%) on Culicoides species. Laboratory and field trials were conducted in Culicoides populations collected in Majorca in the Balearic Islands, Spain. The present study shows that deltamethrin‐treated nets provoke high and rapid mortality (90–100%) in Culicoides midges under laboratory conditions and increase mortality by 13% when deployed in the field.     

The effect of ambient temperature on infrared thermographic images of joints in the distal forelimbs of healthy racehorses

The aim of the study was to describe the dependence on ambient temperature of distal joint temperature at the forelimbs of racehorses. The study also investigated the influence of differing ambient temperatures on the temperature difference between joints: this was measured ipsilaterally (i.e. between the carpal and fetlock joints along each forelimb) and contralaterally (i.e. between the same joints of the left and right forelimbs). Sixty-four healthy racehorses were monitored over 10 months. At each session, three thermographic images were taken of the dorsal, lateral and medial aspects of the distal forelimbs. Temperature measurements were made from regions of interest (ROIs) covering the carpal and fetlock joints. There was a strong correlation between ambient temperature and absolute joint temperature at all ROIs. The study also observed a moderate correlation between ambient temperature and the ipsilateral temperature differences between joints when measured from the medial and lateral aspects. No significant correlation was noted when measured dorsally. The mean contralateral temperature differences between joints were all close to 0 °C. The data support previous reports that the temperature distribution between the forelimbs of the healthy equine is generally symmetric, although some horses differ markedly from the average findings.     

Locomotor activity and body temperature rhythms in the Mahali mole-rat (C. h. mahali): The effect of light and ambient temperature variations

African mole-rats (family: Bathyergidae) are strictly subterranean mammals that reside in extensive networks of underground tunnels. They are rarely, if ever, exposed to light and experience muted temperature ranges. Despite these constant conditions, the presence of a functional circadian clock capable of entraining to external light cues has been reported for a number of species. In this study, we examine a social mole-rat species, Cryptomys hottentotus mahali, to determine if it possesses a functional circadian clock that is capable of perceiving light and ambient temperature cycles, and can integrate these cues into circadian rhythms of locomotor activity and core body temperature. Eight male and eight female, non-reproductive individuals were subjected to six cycles of varying light and temperature regimes. The majority of the individuals displayed daily rhythms of locomotor activity and body temperature that are synchronised to the external light and temperature cycles. Furthermore, endogenous rhythms of both locomotor activity and core body temperature were displayed under constant conditions. Thus, we can conclude that C. h. mahali possesses a functional circadian clock that can integrate external light and temperature cues into circadian rhythms of locomotor activity and core-body temperature.     

MELODIE: a whole-farm model to study the dynamics of nutrients in dairy and pig farms with crops

In regions of intensive pig and dairy farming, nutrient losses to the environment at farm level are a source of concern for water and air quality. Dynamic models are useful tools to evaluate the effects of production strategies on nutrient flows and losses to the environment. This paper presents the development of a new whole-farm model upscaling dynamic models developed at the field or animal scale. The model, called MELODIE, is based on an original structure with interacting biotechnical and decisional modules. Indeed, it is supported by an ontology of production systems and the associated programming platform DIESE. The biotechnical module simulates the nutrient flows in the different animal, soil and crops and manure sub-models. The decision module relies on an annual optimization of cropping and spreading allocation plans, and on the flexible execution of activity plans for each simulated year. These plans are examined every day by an operational management sub-model and their application is context dependent. As a result, MELODIE dynamically simulates the flows of carbon, nitrogen, phosphorus, copper, zinc and water within the whole farm over the short and long-term considering both the farming system and its adaptation to climatic conditions. Therefore, it is possible to study both the spatial and temporal heterogeneity of the environmental risks, and to test changes of practices and innovative scenarios. This is illustrated with one example of simulation plan on dairy farms to interpret the Nitrogen farm-gate budget indicator. It shows that this indicator is able to reflect small differences in Nitrogen losses between different systems, but it can only be interpreted using a mobile average, not on a yearly basis. This example illustrates how MELODIE could be used to study the dynamic behaviour of the system and the dynamic of nutrient flows. Finally, MELODIE can also be used for comprehensive multi-criterion assessments, and it also constitutes a generic and evolving framework for virtual experimentation on animal farming systems.     

Interacting effects of temperature and density on individual growth performance in a wild population of brown trout

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The effect of temperature on growth and early maturation in a wild population of Atlantic salmon parr

Atlantic salmon Salmo salar parr exposed to heated water effluent were larger than parr living upstream of the discharge. There was no effect, however, of temperature on the incidence of male parr maturation, despite the link between growth and maturation found in other studies. Mature parr upstream of the effluent were smaller than mature parr downstream of it, suggesting a higher size threshold for maturation in those parr exposed to the heated water. The small distance between upstream and downstream sampling sites probably precluded genetic differences between the parr, thus implying an environmental influence on the threshold size above which male parr matured.     

The influence of a parasite community on the dynamics of a host population: a longitudinal study on willow ptarmigan and their parasites

Despite the fact that most host populations are infected by a community of different parasite species, the majority of empirical studies have focused on the interaction between the host and a single parasite species. Here, we explore the hypothesis that host population dynamics are affected both by single parasite species and by the whole parasite community. We monitored population density and breeding productivity of two populations of willow ptarmigan ( Lagopus lagopus ) in northern Norway for 8 and 11 years, respectively, and sampled eukaryotic endoparasites. We found that increasing abundances of the cestode Hymenolepis microps was associated with increased breeding mortality and reduced annual growth rate of the host population in both areas, and reduced host body mass and body condition in the area where such data were available. In one of the areas, the abundance of the nematode Trichostrongylus tenuis was associated with reductions in host body mass, body condition and breeding mortality and the filaroid nematode Splendidofilaria papillocerca was negatively related to host population growth rates. The parasite community was also negatively related to host fitness parameters, suggesting an additional community effect on host body mass and breeding mortality, although none of the parasites had a significant impact on their own. The prevalence of parasites with very different taxonomical origins tended to covary within years, suggesting that variability in the parasite community was not random, but governed by changes in host susceptibility or environmental conditions that affected exposure to parasites in general. Other variables including climate, plant production and rodent densities were not associated with the recorded demographic changes in the host population.     

The effect of different primary producers on Hydrobia ulvae population dynamics: a case study in a temperate intertidal estuary

The effect of macroalgal blooms and the consequent disappearance of Zostera noltii meadows on Hydrobia ulvae population dynamics and production was studied in the Mondego estuary based on data obtained from January 1993 to September 1995. Sampling was carried out at a non-eutrophicated area, covered with Z. noltii, and also at an eutrophicated area, where seasonal Enteromorpha spp. blooms occur.Stable populations represented by individuals of all age classes were found only at the Z. noltii meadows throughout the study period. On the contrary, at the eutrophicated area, during most of the time, solely juveniles were present, with adults appearing only during the macroalgal bloom (>1.5 mm width).During the algal bloom (e.g. 1993), H. ulvae population density was clearly higher in the eutrophicated area due to the combined effect of stronger benthic recruitments (99% of veliger larvae newly recruited) and dispersion of juveniles proceeding from the Z. noltii meadows to this area. On the other hand, in the absence of macroalgae (spring of 1994), 98.9% of veliger larvae was recruited in the Z. noltii meadows. Therefore, H. ulvae seems to respond rapidly to macroalgal dynamics and its presence at the eutrophicated area depends on the existence of green macroalgae.H. ulvae presented the same benthic recruitment pattern at the two sampling areas, with new cohorts being produced in March, June, July and September. Depending on the time of the year in which the recruitment took place, cohorts showed different growth rhythms. However, after 12 months they reached a similar size.A three-generation life cycle involving a short-lived (16 months), fast growing spring generation, a medium growing (17-19 months) summer generation and a longer-lived (20 months) slower growing generation that overwinters is identified.As a general trend, productivity and mean population standing biomass were higher at the Z. noltii meadows, during the entire study, except for a short period, during the macroalgal bloom, when production was higher at the eutrophicated area. On the contrary, P/B? ratios were higher at the eutrophicated area. According to our results, H. ulvae population structure and yearly productivity are clearly affected by eutrophication, namely by the dynamics of macroalgal blooms.In the long run, we may infer that, following the disappearance of the Z. noltii meadows, due to eutrophication, H. ulvae would also tend to disappear, since reproductive adults were almost exclusively found in this area.     

The demographic impact of extreme events: stochastic weather drives survival and population dynamics in a long-lived seabird

1. Most scenarios for future climate change predict increased variability and thus increased frequency of extreme weather events. To predict impacts of climate change on wild populations, we need to understand whether this translates into increased variability in demographic parameters, which would lead to reduced population growth rates even without a change in mean parameter values. This requires robust estimates of temporal process variance, for example in survival, and identification of weather covariates linked to interannual variability. 2. The European shag Phalacrocorax aristotelis (L.) shows unusually large variability in population size, and large-scale mortality events have been linked to winter gales. We estimated first-year, second-year and adult survival based on 43 years of ringing and dead recovery data from the Isle of May, Scotland, using recent methods to quantify temporal process variance and identify aspects of winter weather linked to survival. 3. Survival was highly variable for all age groups, and for second-year and adult birds process variance declined strongly when the most extreme year was excluded. Survival in these age groups was low in winters with strong onshore winds and high rainfall. Variation in first-year survival was not related to winter weather, and process variance, although high, was less affected by extreme years. A stochastic population model showed that increasing process variance in survival would lead to reduced population growth rate and increasing probability of extinction. 4. As in other cormorants, shag plumage is only partially waterproof, presumably an adaptation to highly efficient underwater foraging. We speculate that this adaptation may make individuals vulnerable to rough winter weather, leading to boom-and-bust dynamics, where rapid population growth under favourable conditions allows recovery from periodic large-scale weather-related mortality. 5. Given that extreme weather events are predicted to become more frequent, species such as shags that are vulnerable to such events are likely to exhibit stronger reductions in population growth than would be expected from changes in mean climate. Vulnerability to extreme events thus needs to be accounted for when predicting the ecological impacts of climate change.     

The effect of temperature on the size and population density of dinoflagellates in larvae of the reef coral Porites astreoides

Abstract. Pre-settlement events play an important role in determining larval success in marine invertebrates with bentho-pelagic life histories, yet the consequences of these events typically are not well understood. The purpose of this study was to examine the pre-settlement impacts of different seawater temperatures on the size and population density of dinoflagellate symbionts in brooded larvae of the Caribbean coral Porites astreoides. Larvae were collected from P. astreoides at 14–20 m depth on Conch Reef (Florida) in June 2002, and incubated for 24 h at 15 temperatures spanning the range 25.1°–30.0°C in mean increments of 0.4±0.1°C (±SD). The most striking feature of the larval responses was the magnitude of change in both parameters across this 5°C temperature range within 24 h. In general, larvae were largest and had the highest population densities of Symbiodinium sp. between 26.4°–27.7°C, and were smallest and had the lowest population densities at 25.8°C and 28.8°C. Larval size and symbiont population density were elevated slightly (relative to the minimal values) at the temperature extremes of 25.1°C and 30°C. These data demonstrate that coral larvae are highly sensitive to seawater temperature during their pelagic phase, and respond through changes in size and the population densities of Symbiodinium sp. to ecologically relevant temperature signals within 24 h. The extent to which these changes are biologically meaningful will depend on the duration and frequency of exposure of coral larvae to spatio-temporal variability in seawater temperature, and whether the responses have cascading effects on larval success and their entry to the post-settlement and recruitment phase.     

The interacting effects of food,spring temperature,and global climate cycles on population dynamics of a migratory songbird

Although long‐distance migratory songbirds are widely believed to be at risk from warming temperature trends, species capable of attempting more than one brood in a breeding season could benefit from extended breeding seasons in warmer springs. To evaluate local and global factors affecting population dynamics of the black‐throated blue warbler (Setophaga caerulescens), a double‐brooded long‐distance migrant, we used Pradel models to analyze 25 years of mark–recapture data collected in New Hampshire, USA. We assessed the effects of spring temperature (local weather) and the El Niño Southern Oscillation index (a global climate cycle), as well as predator abundance, insect biomass, and local conspecific density on population growth in the subsequent year. Local and global climatic conditions affected warbler populations in different ways. We found that warbler population growth was lower following El Niño years (which have been linked to poor survival in the wintering grounds and low fledging weights in the breeding grounds) than La Niña years. At a local scale, populations increased following years with warm springs and abundant late‐season food, but were unaffected by spring temperature following years when food was scarce. These results indicate that the warming temperature trends might have a positive effect on recruitment and population growth of black‐throated blue warblers if food abundance is sustained in breeding areas. In contrast, potential intensification of future El Niño events could negatively impact vital rates and populations of this species.     

大气CO2浓度和温度互作对水稻生长发育的影响

大气二氧化碳(CO_2)浓度和温度的增加是全球气候变化的两个最主要特征。目前空气中的CO_2浓度已从1800年的不到280μmol/mol上升到391μmol/mol,预测本世纪末最高将增至936μmol/mol。伴随CO_2及其它温室气体增强的温室效应,相比1980—1999年,2100年之前全球地表平均气温将增高1.5—4.0℃。水稻是人类最重要的食物来源,为全球半数以上人口提供营养。在介绍CO_2浓度和温度增高试验平台的基础上,系统总结了CO_2浓度和气温这两个重要的环境因子特别是两者的交互互作对水稻影响的实验进展,内容包括光合作用、生育进程、分蘖发生、物质生产、籽粒产量、受精过程、碳氮代谢、稻米品质以及水稻/杂草竞争等方面。结果表明,作为光合作用的底物,大气CO_2浓度增高对水稻生产力的直接影响通常是有益的;相反,气温升高及其与CO_2的互作对水稻各生长过程的影响变异很大(从负到正),反映了处理因子(包括CO_2-温度处理水平和时间)、供试品种及其生长条件之间复杂的交互作用。目前这一方向有限的认识多来自于封闭或半封闭气室的研究,未来研究的重点是利用稻田T-FACE(Temperature-Free Air CO_2Enrichment)技术结合气室试验展开更多更深入的学科交叉研究,研明CO_2浓度与温度的交互作用对水稻关键生长过程的影响,并找出这些互作效应的生物学机制,增强人们对气候假定情景下水稻响应的预测能力,进而更加有效地制订出应对气候变化的适应策略。     

The effect of temperature on progeny allocation and short interval timing in a parasitoid wasp

Abstract The parasitoid wasp Trichogramma dendrolimi Matsumura sets the number of progeny allocated to its insect egg hosts according to the duration of its initial transit walk across the host surface. Although cooling the wasp reduces its walking speed, reduced temperature does not affect progeny allocation. By locally heating and cooling the wasps, the initial transit can be thermally uncoupled from the subsequent oviposition. Using this technique we show that the timing of initial transit duration is temperature-dependent. These findings suggest that short interval timing by Trichogramma differs physiologically from the temperature compensated clocks that have been described for other insects.     

The effects of personal interaction on triglyceride and uric acid levels, and coronary risk in a managerial population: a longitudinal study

This two year longitudinal study of managers investigated whether the level of interaction with other individuals was a job stressor that influences coronary risk factors. The results presented here show that increased levels of interaction were associated with increased serum triglyceride and increased serum uric acid levels. It is suggested that past research positing stress effects from responsibility for people may be due to interaction levels rather than responsibility per se. It was also found that Type A behavior and physical activity levels moderated these effects. While it is difficult to say that personal interaction, as a job stressor, contributes very significantly to either coronary risk factors or coronary heart disease the evidence supports the hypothesis that the amount of interaction has some specific stress effects.     

The effect of ambient temperature on the relationship between ventilation and metabolism in a small parrot (Agapornis roseicollis)

Summary Values for basal metabolism, standard tidal volume (V _T), standard minute volume ( ), and mean extraction efficiency (EO₂) in the thermal neutral zone (TNZ) inAgapornis roseicollis (1.84 ml·min^–1; 0.95 ml·br^–1, STPD; and 33.3 ml·min^–1, STPD; and 22.5%; respectively) were all very similar to values for these parameters previously measured inBolborhynchus lineola, a similarly sized, closely related species from a distinctly different habitat.Having both a lower critical temperature (T_lc) below and an upper critical temperature (T_uc) above those ofB. lineola, the TNZ ofA. roseicollis extended from 25° to at least 35°C. The thermal conductance below the TNZ ofA. roseicollis was 14% less than that ofB. lineola. Therefore, at 5°C the standard metabolic rate (SMR) of the former is 17% less than that of the latter, and at 35°C it is 20% less. At 5°CA. roseicollis has a lower EO₂ and at 35°C a higher EO₂ than that ofB. lineola. The patterns of resting energy metabolism and of ventilation ofA. roseicollis and ofB. lineola are consistent with the former species being better suited to living in a more variable thermal environment than the latter.MeanV _T has a weak positive correlation with the rate of oxygen consumption ( ) at a constant ambient temperature (T _a) but a much stronger correlation when resting increases in response to a decrease inT _a.V _t is the only ventilatory parameter which is linearly correlated toT _a from 35° to –25°C. The data suggest thatT _a may have a regulatory effect onV _T somewhat independent of or .     

The role of chromium and nickel on the thermal and mechanical properties of FeNiCr austenitic stainless steels under high pressure and temperature: a molecular dynamics study

The effect of Cr and Ni content on thermo-mechanical properties of FeNiCr austenitic stainless steel under ambient and high pressure and temperature were investigated by MD simulations. The FCC structure was selected as optimum structure for FeNiCr system based on obtained MD results from Bonny EAM potential and valid experimental results. The structural and mechanical properties of pure Fe, Ni, and Cr were also estimated based on this potential, indicating good agreement with experimental results. These properties were computed for four experimental case studies which showed less than 10% error. Moreover, the elastic constants of the Fe–(8–18)Ni–(18–25)Cr systems were estimated. Results showed that bulk modulus increases by increasing the Ni and Cr contents, which can be connected to the changes in bonding electrons. The thermal properties of FeNiCr were calculated in ambient and high pressure. Although thermo-mechanical properties confirm good agreement with experimental results at the ambient condition, however, they indicate that FeNiCr Bonny potential is not applicable at high pressure. In order to tackle this issue, a hybrid potential was used at high Pressure/Temperature. The results illustrate enhanced mechanical properties, increase of melting point and reduction of LTE in high pressure and deteriorated mechanical properties at high temperature.     

The effects of climate change on species composition,succession and phenology: a case study

Climate change and its role in altering biological interactions and the likelihood of invasion by introduced species in marine systems have received increased attention in recent years. It is difficult to forecast how climate change will influence community function or the probability of invasion as it alters multiple marine environmental parameters including rising water temperature, lower salinity and pH. In the present study, we correlate changes in environmental parameters to shifts in species composition in a subtidal community in Newcastle, NH through comparison of two, 3‐year periods separated by 23 years (1979–1981 and 2003–2005). We observed concurrent shifts in climate related factors and in groups of organisms that dominate the marine community when comparing 1979–1981 to 2003–2005. The 1979–1981 community was dominated by perennial species (mussels and barnacles). In contrast, the 2003–2005 community was dominated by annual native and invasive tunicates (sea‐squirts). We also observed a shift in the environmental factors that characterized both communities. Dissolved inorganic nitrogen and phosphate characterized the 1979–1981 community while sea surface temperature, pH, and chlorophyll a characterized the 2003–2005 community. Elongated warmer water temperatures, through the fall and early winter months of the 2000s, extended the growing season of native organisms and facilitated local dominance of invasive species. Additionally, beta‐diversity was greater between 2003–2005 than 1979–1981 and driven by larger numbers of annual species whose life‐history characteristics (e.g., timing and magnitude of recruitment, growth and mortality) are driven by environmental parameters, particularly temperature.     

The effect of temperature on reproduction in the summer and winter annual Arabidopsis thaliana ecotypes Bur and Cvi

Background and Aims

Seed yield and dormancy status are key components of species fitness that are influenced by the maternal environment, in particular temperature. Responses to environmental conditions can differ between ecotypes of the same species. Therefore, to investigate the effect of maternal environment on seed production, this study compared two contrasting Arabidopsis thaliana ecotypes, Cape Verdi Isle (Cvi) and Burren (Bur). Cvi is adapted to a hot dry climate and Bur to a cool damp climate, and they exhibit winter and summer annual phenotypes, respectively.

Methods

Bur and Cvi plants were grown in reciprocal controlled environments that simulated their native environments. Reproductive development, seed production and subsequent germination behaviour were investigated. Measurements included: pollen viability, the development of floral structure, and germination at 10 and 25 °C in the light to determine dormancy status. Floral development was further investigated by applying gibberellins (GAs) to alter the pistil:stamen ratio.

Key Results

Temperature during seed development determined seed dormancy status. In addition, seed yield was greatly reduced by higher temperature, especially in Bur (>90 %) compared with Cvi (approx. 50 %). The reproductive organs (i.e. stamens) of Bur plants were very sensitive to high temperature during early flowering. Viability of pollen was unaffected, but limited filament extension relative to that of the pistils resulted in failure to pollinate. Thus GA applied to flowers to enhance filament extension largely overcame the effect of high temperature on yield.

Conclusions

High temperature in the maternal environment reduced dormancy and negatively affected the final seed yield of both ecotypes; however, the extent of these responses differed, demonstrating natural variation. Reduced seed yield in Bur resulted from altered floral development not reduced pollen viability. Future higher temperatures will impact on seed performance, but the consequences may differ significantly between ecotypes of the same species.