Low Temperature Days Research Articles

Thermoperiodic Control of Floral Induction Involves Modulation of the Diurnal FLOWERING LOCUS T Expression Pattern.

Thermoperiodism is defined as the ability to discriminate between day temperature (DT) and night temperature (NT). Our aim was to shed light on the mechanistic basis of thermoperiodic floral induction with acceleration under lower DT than NT compared with other DT-NT combinations at the same average daily temperature (ADT), a response exploited in temperate area greenhouses. Arabidopsis thaliana floral pathway mutants and a lhy circadian clock mutant as well as the expression of floral integrators and LHY (LATE ELONGATED HYPOCOTYL) were studied under different DT-NT combinations, all at the same ADT. We show that acceleration of floral induction under lower DT than NT is linked to increased FT expression early during the day and generally increased LFY expression preceding visible flower buds, compared with higher DT than NT or equal DT and NT. Consistent with FLOWERING LOCUS T (FT) action through LEAFY (LFY), time to floral transition in ft-1 and lfy-1 was similar under all treatments, in contrast to the situation for soc1-1, which behaved like the wild type (WT). The lhy-21 mutants did not discriminate between opposite DT-NT combinations, whereas LHY expression in the WT differed in these temperature regimes. This might suggest that LHY plays a role in thermoperiodic control of floral induction. We conclude that thermoperiodic control of floral transition is associated with modulation of the diurnal expression patterns of FT, with timing of temperature alteration being important rather than ADT.

Climate factors influence the occurrence of white spot disease in cultured penaeid shrimp in Chanthaburi province, Thailand

This study investigated the prevalence of white spot disease (WSD) in an intensive shrimp culture area located in Chanthaburi province, Thailand, during 2009�2014. Retrospective data of 1952 WSD cases obtained from government laboratories were analyzed to study the asso- ciation between WSD occurrence and climate factors using negative binomial regression (NBR) models. Climate factors included daily atmospheric temperature, relative humidity, wind speed, total amount of rainfall and rain days during the disease notifications. The annual prevalence of WSD was significantly higher from 2009 to 2011 than from 2012 to 2014. Interestingly, the monthly WSD occurrence was unchanged between those time periods. A high number of WSD cases was found between October and February, while fewer cases were reported during March to June, and the lowest numbers were reported in May. The multivariate NBR model indicated significant associations between an increased number of WSD cases with decreased atmospheric tempera- ture and increased variation in daily atmospheric temperature. A high incident rate ratio (IRR) of WSD was observed when average atmospheric temperature ranged between 24.5 and 27.2°C (IRR: 2.53, 95% CI: 1.72�3.75) and there was increased variation in daily atmospheric temperature (IRR: 1.08, 95% CI: 0.99�1.20). The time series analysis concluded that low ambient atmospheric temperature and high daily atmospheric temperature variation were promoting factors for WSD occurrence.

Average Temperature, Diurnal Temperature Variation, and Stroke Hospitalizations

Studies assessing the relationship between meteorological factors and stroke incidence are inconsistent. We assessed the associations of average temperature and diurnal temperature fluctuations with ischemic stroke hospitalizations in a nationally representative sample of patients in the United States. Hospitalizations were identified for adults aged 18 years or older in the 2009-2011 Nationwide Inpatient Sample and linked with county-level monthly average temperatures from the United States National Climatic Data Center. Logistic regression models assessed the relationships of 5°F increases in average temperature and diurnal temperature variation (difference between high- and low-daily temperatures) with the odds of ischemic stroke hospitalization (International Classification of Diseases, Ninth Revision, Clinical Modification codes 433, 434, and 436), adjusting for patient characteristics and dew point. Models were stratified by age (18-64, ≥65 years), season, and region, with analysis at the hospitalization level. Increased average temperature was associated with decreased odds of stroke hospitalization among both age groups and across seasons in the Northeast, and among the elderly in the West. Increased diurnal temperature variation was associated with increased odds of stroke hospitalization for nearly all regions in the spring to fall seasons; associations were most pronounced in the Northeast and strongest in the spring. Lower average temperature and larger diurnal temperature variations were associated with stroke hospitalizations. Associations were strongest in the Northeast and largely similar across seasons and age. Further research is needed to explore the mechanisms underlying these associations. Understanding these patterns may lead to targeted prevention strategies for vulnerable populations during periods of extreme weather conditions.

Mortality attributable to extreme temperatures in Spain: A comparative analysis by city

BackgroundThe Low Temperature Days (LTD) have attracted far less attention than that of High Temperature Days (HTD), though its impact on mortality is at least comparable. This lower degree of attention may perhaps be due to the fact that its influence on mortality is less pronounced and longer-term, and that there are other concomitant infectious winters factors. In a climate-change scenario, the studies undertaken to date report differing results. The aim of this study was to analyse mortality attributable to both thermal extremes in Spain's 52 provinces across the period 2000–2009, and estimate the related economic cost to show the benefit or “profitability” of implementing prevention plans against LTD. MethodsPrevious studies enabled us: to obtain the maximum daily temperature above which HTD occurred and the minimum daily temperature below which LTD occurred in the 52 provincial capitals analysed across the same study period; and to calculate the relative and attributable risks (%) associated with daily mortality in each capital. These measures of association were then used to make different calculations to obtain the daily mean mortality attributable to both thermal extremes. To this end, we obtained a summary of the number of degrees whereby the temperature exceeded (excess °C) or fell short (deficit °C) of the threshold temperature for each capital, and calculated the respective number of extreme temperatures days. The economic estimates rated the prevention plans as being 68% effective. ResultsOver the period considered, the number of HTD (4373) was higher than the number of LTD (3006) for Spain as a whole. Notwithstanding this, in every provincial capital the mean daily mortality attributable to heat was lower (3deaths/day) than that attributable to cold (3.48deaths/day). In terms of the economic impact of the activation of prevention plans against LTD, these could be assumed to avoid 2.37 deaths on each LTD, which translated as a saving of €0.29M. Similarly, in the case of heat, 2.04 deaths could be assumed to be avoided each day on which the prevention plan against HTD was activated, amounting to a saving of €0.25M. While the economic cost of cold-related mortality across the ten-year period 2000–2009 was €871.7M, that attributable to heat could be put at €1093.2M. ConclusionThe effect of extreme temperatures on daily mortality was similar across the study period for Spain overall. The lower number of days with LTD meant, however, that daily cold-related mortality was higher than daily heat-related mortality, thereby making prevention plans against LTD more “profitable” prevention plans against HTD in terms of avoidable mortality.

Numbers of Stroke Patients and Stroke Subtypes According to Highest and Lowest Daily Temperatures in Seoul.

Background and PurposeThere is conflicting evidence for whether or not the incidence of stroke is influenced by the daily temperature. The association between daily temperature and incidence of stroke is largely unknown in Korea. This study attempted to evaluate whether the maximum or minimum daily temperature is associated with increased numbers of strokes and stroke subtypes among Seoul residents.MethodsWe obtained the maximum and minimum daily temperatures in Seoul from the Korean Meteorological Administration between January 2005 and December 2014. Consecutive patients with acute stroke were registered who visited the emergency room or outpatient clinic in Soonchunhyang University Hospital, Seoul. The residential addresses of cases were restricted to within a 2-kilometer radius of this hospital. The stroke events were prospectively recorded with onset time, and were classified by subtypes. The categories of daily temperature were divided by 10℃ from the mean temperature. The mean daily number of strokes was calculated during the study period. One-way analysis of variance and Duncan's post-hoc test were applied to compare the number of strokes among the temperature groups.ResultsIn total, 2,313 acute strokes were identified during the period: 1,643 ischemic strokes and 670 hemorrhagic strokes. The number of cases was significantly higher when the maximum daily temperature was >32℃ or ≤3℃ (p=0.048) or the minimum daily temperature was ≤-11.0℃ (p=0.020). The lowest maximum daily temperature was associated with increased instances of intracerebral hemorrhage (p=0.029) and small-vessel occlusion (p=0.013), while the highest maximum daily temperature was associated with an increased instance of large-artery atherosclerosis (p=0.045).ConclusionsThe daily temperature had measurable and different associations with the number of strokes and strokes subtypes in Seoul, Korea.

The Effects of Day and Night Temperature on the Dry Matter Accumulation of Oriental Hybrid Lily ‘Siberia’ as they Relate to the Photosynthetic and Respiratory Characteristics

The net photosynthetic rate on a per-plant basis of the Oriental hybrid lily ‘Siberia’ was low at the leafing stage but increased rapidly at the visible flower bud and flowering stages. The range of 20 to 25°C was the optimum temperature for photosynthesis at the three plant developmental stages under PPFD of 700 to 850 μmol photons m-2 s-1. The respiration rate increased with the increasing temperature quadratically (in aerial plant parts) or exponentially (in underground parts). The ‘Siberia’ plants were grown under three day temperature (DT) conditions of 28°C, 24°C or 20°C, with a night temperature (NT) of 15°C or three NTs of 25°C, 20°C or 15°C, with DT of 25°C in the growth chambers. At the flowering stage, the plants grown under low DT of 20°C had a high dry weight (DW) of the total plant, flowers, bulb, and roots, and a high DW/fresh weight (FW) ratio of the leaves, stem, and bulb. The plants grown under low NT of 15°C had a high DW of the total plant and stem, and a high DW/FW ratio of the leaves and bulb. The plants that were grown under a low NT had a long stem length by the positive DIF effect, which was supported by sufficient dry mater accumulation. The plants grown under low DT of 20°C showed a high relative growth rate (RGR) and net assimilation rate (NAR) from planting to flowering, whereas the NT condition did not affect the RGR or NAR. Discipline: Horticulture Additional key words: cut flower quality, growth analysis, positive DIF effect

Application of climatological monitoring for the candidate CTA site at Izaña (Tenerife)

The location of Izaña (Tenerife, Canary Islands) has been proposed for hosting the Cherenkov Telescope Array (CTA). To support the site-testing campaign, we obtained climate normals from the 10 year long series recorded at Izana by the atmospheric Observatory (CIAI), we have also compared the wind regime with a simultaneous 10 year database at the neighbouring astronomical site (OT) and with the available simultaneous preliminary wind data for the proposed CTA location. The results show a smooth temperature profile with sporadic but moderate extremes and a low daily (24 h) temperature range. Rainfall is extremely sporadic (287 mm/y) with low intensity. Wind speed and gusts show high stability and moderate values and dispersions. The lowest winds are in the summer. Speed episodes greater than 100 km/h are very rare and 11 data points have been recorded with gusts above 150 km/h over the 10 years. The dominant wind direction is WNW. There is an excellent correlation for wind speed between the CIAI and OT, with a slight difference in the dominant wind direction (N versus WNW). The wind data recorded directly at the CTA location also show very good correlation in trends, the wind speed at the CTA site being ≈ 24% lower. The dominant wind direction at the CTA site is NW.

Analysis of structural and qualitative features of phytin deposition in ripe flax seeds

Characteristics of phytin storage in mature flax seeds, namely, concentration range, effect of weather and climatic conditions of the vegetation period, and morphology and size of phytate globoids in aleurone grains, have been determined. The content of phytic acid in flax seeds harvested in 2005–2009 ranged from 29.3 to 35.4 g/kg. High amounts of precipitation and low average daily temperature during seed ripening promoted accumulation of large amounts of phytin in seeds. Scanning electron microscopy showed that phytin globoids in the storage parenchyma of flax cotyledons are electron-dense spherical concretions ranging from 2.3 to 5.6 μm in diameter. Element composition analysis showed that phytic acid salts from flax contained K, Mg, Mn, Ca, and Fe.

Гендерно-климатические особенности обращаемости населения за медицинской помощью по поводу артериальной гипертензии

Definition risk factors, the proof of their role in human health, as well as a quantitative characteristic of dependences of harmful effects on the levels of exposure to specific factors are one of the fundamental problems of modern clinical medicine, epidemiology, toxicology, occupational health, environmental and other sections of biology and medicine. The object of this study is the population of the city of Tula (22282 patients) and Astrakhan (27776 patients) who applied for emergency medical care apropos of diseases characterized by high blood pressure (ICD I10-I15) in 2013. Women at the age older than working age are the most weather-sensitive group. In the winter time there is a tendency to increase the number of calls to the AG at low amplitude changes daily temperature at high air humidity, wind speed. In spring there is increasing dependence on the number of calls AG at low mean temperature, maximum temperature, speed of wind. In summer there is a significant dependence of increasing the number of calls on AG low average daily temperature, maximum temperature, at low amplitude changes daily temperature; there is a tendency of increasing the number of calls to hypertension in increasing atmospheric pressure difference, while increasing humidity. There are more pronounced changes during sudden changes of weather conditions and a short period of adaptation to temperature changes and humidity.

English

Cassava’s ( Manihot esculenta Crantz) importance as a food security crop in Sub Saharan Africa is enhanced by its special traits such as tolerance to drought and high yields under drought stress. However, full understanding of tolerance mechanisms under hydrothermal stress in cassava is a key in developing highly tolerant varieties with increased yield. In our study, the effects of low soil moisture and increased temperature on cassava physiology were investigated. Twenty (20) cassava varieties were evaluated in a Randomized Complete Block Design in western Uganda. Hydrothermal stress was described as a period of no rainfall for a period of eight weeks leading to low soil moisture (contents between 28 to 35%) and average daily temperatures of ≥35°C. The average daily relative humidity during this period was considerably low (≤40%) further complementing already enhanced stress conditions. As such, the contents of important biochemicals and secondary metabolites in the plants were altered in a bid to counteract the effects of stress. Significant differences occurred in accumulation of main biochemicals such as soluble proteins (P<0.05), free reducing sugars (P<0.05) and bound reducing sugars (P<0.05) while reductions in the total starch yield by 70 to 100% of the original composition before stress were observed in all the test varieties. Changes in pigment properties were also observed with a decrease in the total carotenoid content (~65%) and chlorophyll a ( Chla ) (~40%) but no significant changes were observed for chlorophyll b ( Chlb ). Secondary metabolites such as phenolics and tannins too depicted varied but non-significant changes and they existed in low quantities. There were also significant changes in the phenotype (foliar portion of the plant) with at least two mechanisms of tolerance identified. The study showed the importance of carbohydrate and nitrogen cycle related metabolites in mediating tolerance in cassava by affecting their phenotypic expression in the plant. Keywords: Hydrothermal stress, bio-chemicals, pigments, secondary metabolites, cassava. African Journal of Biotechnology , Vol 13(31) 3173-3186

PENGEMBANGAN DATA LOGGER SUHU AIR BERBIAYA RENDAH

Water temperature data logger merupakan sebuah alat perekam suhu perairan dari waktu ke waktu secara otomatis sehingga memungkinkan untuk mendapatkan gambaran dari kondisi suhu perairan yang dipantau. Penelitian ini bertujuan untuk menghasilkan desain dan kontruksi water temperature data logger berbiaya rendah. Casing dirancang berbentuk silinder menggunakan bahan aluminium dengan diameter 3.20 cm dan panjang 16.50 cm. Sistem elektronik terdiri atas mikrokontroler ATmega 328P sebagai pusat pengendali, DS18B20 sebagai sensor suhu, mini motor DC sebagai indikator getar, DS3231 sebagai penanda waktu, dan micro SD card sebagai media penyimpanan. Uji kinerja water temperature data logger menunjukan casing kedap dan tenggelam jika dimasukan ke air sehingga tidak perlu penambahan pemberat. Baterai dapat bertahan selama 10 hari 8 jam pada interval pencuplikan 30 menit. Nilai galat kalibrasi sensor antara (-0.37)-0.41 o C dengan nilai RMSE 0.23 °C. Pengukuran suhu air Danau Institut Pertanian Bogor pada tanggal 10-20 Oktober 2013 berkisar antara 27.69-31.63 °C dengan suhu harian terendah pada pukul 5:30-8:30 WIB dan tertinggi pada pukul 12:00-16:00 WIB. Uji-t perbandingan data suhu antara water temperature data logger dengan termometer selama dua hari di kolam menunjukan bahwa data tidak berbeda nyata.

Active layer thermal regime at different vegetation covers at Lions Rump, King George Island, Maritime Antarctica

Climate change impacts the biotic and abiotic components of polar ecosystems, affecting the stability of permafrost, active layer thickness, vegetation, and soil. This paper describes the active layer thermal regimes of two adjacent shallow boreholes, under the same soil but with two different vegetations. The study is location in Lions Rump, at King George Island, Maritime Antarctic, one of the most sensitive regions to climate change, located near the climatic limit of Antarctic permafrost. Both sites are a Turbic Cambic Cryosol formed on andesitic basalt, one under moss vegetation (Andreaea gainii, at 85ma.s.l.) and another under lichen (Usnea sp., at 86ma.s.l.), located 10m apart. Ground temperature at same depths (10, 30 and 80cm), water content at 80cm depth and air temperature were recorded hourly between March 2009 and February 2011. The two sites showed significant differences in mean annual ground temperature for all depths. The lichen site showed a higher soil temperature amplitude compared to the moss site, with ground surface (10cm) showing the highest daily temperature in January 2011 (7.3°C) and the lowest daily temperature in August (−16.5°C). The soil temperature at the lichen site closely followed the air temperature trend. The moss site showed a higher water content at the bottommost layer, consistent with the water-saturated, low landscape position. The observed thermal buffering effect under mosses is primarily associated with higher moisture onsite, but a longer duration of the snowpack (not monitored) may also have influenced the results. Active layer thickness was approximately 150cm at low-lying moss site, and 120cm at well-drained lichen site. This allows to classify these soils as Cryosols (WRB) or Gelisols (Soil Taxonomy), with evident turbic features.

Modelling influence of temperature on daily peak electricity demand in South Africa

The paper discusses the modelling of the influence of temperature on average daily electricity demand in South Africa using a piecewise linear regression model and the generalized extreme value theory approach for the period - 2000 to 2010. Empirical results show that electricity demand in South Africa is highly sensitive to cold temperatures. Extreme low average daily temperatures of the order of 8.20C are very rare in South Africa. They only occur about 8 times in a year and result in huge increases in electricity demand.

Influence of temperature to the short-term effects of various ozone metrics on daily mortality in Suzhou, China

Epidemiological studies have reported that both ozone (O3) and temperature are associated with daily mortality. However, few studies have explored the interactive effect between O3 and temperature on mortality. Moreover, whether different O3 metrics influence this interaction is still unknown. This study used a Poisson generalized additive model to examine the interactive effects of daily average temperature and O3 on mortality in Suzhou between 2008 and 2009. The results showed that the O3 effects were stronger in cold season and low temperature days. On days with low temperatures (0th–25th percentile), an interquartile range increment in 1-h maximum O3 corresponded to a 15.96% (95% CI: 1.52, 32.45) increase in total mortality and an 18.77% (95% CI: 0.09, 40.95) increase in cardiovascular mortality. On days with normal temperatures (26th–75th percentile) or high temperatures (76th–100th percentile), the estimates were only 2.04% (95% CI: −5.94, 10.69) or 1.65% (95% CI: −3.21, 6.76) for total mortality, and 7.82% (95% CI: −15.21, 37.10) or 6.14% (95% CI: −17.35, 36.31) for cardiovascular mortality. Using an 8-h maximum metric yielded similar interactive effects between ozone and temperature. For total and cardiovascular mortality, evidence indicates that low temperature has a stronger modifying effect on the 1-h maximum and the maximum 8-h average O3 concentrations than the 24-h average O3 concentrations. The interaction pattern of O3 with temperature was less sensitive at different cut-offs for temperature levels and including co-pollutants in the models. Our findings provide evidence that low daily average temperature significantly modifies the acute effects of ozone on daily mortality for both the 1-h maximum metric and the maximum 8-h average metric in Suzhou, China.

Summer mean daily air temperature extremes in Central Spitsbergen

Summer mean daily temperature extremes in Svalbard Lufthavn (Central Spitsbergen) in the period 1975–2010 and daily pressure patterns and directions of air circulation conducive to their occurrence were analyzed. Positive (negative) extremes of daily mean temperatures in the summer were determined as higher (lower) than or equal to the value of the 90th (10th) percentile. The annual number of selected days shows a great year-to-year variability, although the annual number of extremely low mean daily temperature (≤1.3 °C) was decreasing in the 1976–2010 period, with a rate of about 4 days per decade. At the same time, the number of days with extremely high mean daily temperatures (≤8.2 °C) was increasing with a rate of about 2 days per decade. The summer pressure patterns and the air circulation conditions have an impact on the occurrence of the air mean daily temperature extremes. Namely, anticyclones spreading east to the Svalbard Archipelago, accompanied by the Icelandic Low, cause the air inflow from the southerly direction and positive mean daily temperature extremes. A cyclonal system spreading east or southeast towards the archipelago, together with a high-pressure ridge over the North Atlantic, indicates the northern air flow and negative mean daily temperature extremes in summer. The results obtained in this study prove that the summer air temperature in the Atlantic region of the Arctic is partly controlled by air circulation, and despite the intensity and stability of the summer cyclones and anticyclones being weaker than in the winter, their position strongly determines the occurrence of mean daily temperature extremes in the summer.

Plum (Prunus domestica) Trees Transformed with Poplar FT1 Result in Altered Architecture, Dormancy Requirement, and Continuous Flowering

The Flowering Locus T1 (FT1) gene from Populus trichocarpa under the control of the 35S promoter was transformed into European plum (Prunus domestica L). Transgenic plants expressing higher levels of FT flowered and produced fruits in the greenhouse within 1 to 10 months. FT plums did not enter dormancy after cold or short day treatments yet field planted FT plums remained winter hardy down to at least −10°C. The plants also displayed pleiotropic phenotypes atypical for plum including shrub-type growth habit and panicle flower architecture. The flowering and fruiting phenotype was found to be continuous in the greenhouse but limited to spring and fall in the field. The pattern of flowering in the field correlated with lower daily temperatures. This apparent temperature effect was subsequently confirmed in growth chamber studies. The pleitropic phenotypes associated with FT1 expression in plum suggests a fundamental role of this gene in plant growth and development. This study demonstrates the potential for a single transgene event to markedly affect the vegetative and reproductive growth and development of an economically important temperate woody perennial crop. We suggest that FT1 may be a useful tool to modify temperate plants to changing climates and/or to adapt these crops to new growing areas.

강화지역의 기후특성 분석을 통한 '강화약쑥'의 생육 환경 연구

Eupatilin, one of representative medical components of mugwort, can be efficiently extracted from the `Gangwha Sajabalssuk`. The Eupatilin content may depend on environmental factors such as soil and regional climate in addition to a genetic factor and Gangwha region has a profitable environmental condition for the mugwort growth. In this study, the climatological characteristics of Gangwha was analyzed in order to find the environmental condition of mugwort containing high Eupatilin in term of atmospheric, oceanographic and land variables. The climate of Gangwha is characterized by the relatively low daily temperature and large diurnal variation with plenty of solar radiation, long sunshine duration and less cloudiness. According to our correlation analysis, the long sunshine duration and the large diurnal temperature variation are highly correlated with the Eupatilin contents. The result implies that Gangwha has the favorable conditions for the cultivation and the habitat of the high-Eupatilin concentrated mugwort. Because of the sea surrounding Gangwha Island with low salinity and moderate wind, the salt contained in sea breeze is relatively low compared to other regions. Furthermore, Gangwha has clean atmospheric environment compared to other regions because the concentrations of toxic gases harmful to crop growth such as nitrogen dioxide (), sulfite gas () and fine dust (PM-10) are lower in the air. The ozone () concentration is moderate and within the level of natural production. It is also found that moderately coarse texture or fine loamy soils known as good for water drainage and for the growth and cultivation of the `Gangwha-mugwort` are distributed throughout the areas around mountainous districts in Gangwha, coinciding with those of mugwort habitat.

Modeling temperature-mediated fluctuation in colony size in the fire ant, Solenopsis invicta

In the social insects, colony size is central to the survival of the queen. Two endogenous factors, worker longevity and queen's daily egg production, are known to determine maximum colony size. A third endogenous factor, duration of worker development from egg to adult, regulates the rate of colony growth. In this paper, we report findings from a simulation quantifying the effects of temperature on colony size in the fire ant, Solenopsis invicta. The monthly average temperature over a six year period for the panhandle of north Florida was interpolated to determine the effects of daily temperature on a queen's egg production, worker developmental time and worker longevity. Additional daily temperatures were simulated: 7°C higher and 7°C lower than daily temperatures for north Florida. As expected, colony size was the largest when annual temperatures were the highest across seasons, ranging from 57,000 to 187,000. Colony size at intermediate daily temperatures ranged from 14,000 to 103,000; small colonies recovered rapidly as temperatures warmed. Colony size at lower daily temperatures ranged from 14,000 to 21,000. Extended worker longevity at lower temperatures compensated for low egg production and longer developmental time. And vice versa, the queen's high rate of egg production and the shorter developmental time compensated for shorter worker longevity at high temperatures. Because the fire ant nest consists of a heat-collecting dome in which to incubate brood during cold weather, and deep chambers in which to cool workers during hot weather, colony size is likely to be higher and more stable than our simulation showed. The extended longevity of workers and queens at low temperatures, and perhaps their ability to hibernate below the permafrost, might explain the ability of ants to colonize habitats worldwide.

Weather variability affects abundance of larval Culex (Diptera: Culicidae) in storm water catch basins in suburban Chicago.

Culex pipiens L. (Diptera: Culicidae) and Culex restuans Theobald are the primary enzootic and bridge vectors of West Nile virus in the eastern United States north of 36 degrees latitude. Recent studies of the natural history of these species have implicated catch basins and underground storm drain systems as important larval development sites in urban and suburban locales. Although the presence of larvae in these habitats is well-documented, the influence of abiotic factors on the ecology of Culex larvae developing in them remains poorly understood. Therefore, we examined the effects of multiple abiotic factors and their interactions on abundance of Culex larvae in catch basins in the Chicago, IL, metropolitan area. Low precipitation and high mean daily temperature were associated with high larval abundance, whereas there was no correlation between catch basin depth or water depth and larval abundance. Rainfall was an especially strong predictor of presence or absence of larvae in the summer of 2010, a season with an unusually high precipitation. Regression tree methods were used to build a schematic decision tree model of the interactions among these factors. This practical, visual representation of key predictors of high larval production may be used by local mosquito abatement districts to target limited resources to treat catch basins when they are particularly likely to produce West Nile virus vectors.

Causes of mortality in a nestling population of free-living hihi (stitchbird—Notiomystis cincta)

The hihi is an endangered New Zealand species and its survival depends on the health of translocated populations. Low nestling survival was detected at Zealandia–Karori Sanctuary (KS) during the 2008–09 breeding season with 34% of eggs surviving to fledge. Samples obtained from live and dead hihi nestlings showed that several disease syndromes contributed to nestling deaths. Cause of death was diagnosed by necropsy and histopathology for 25 nestlings. Mortality was highest (60%) in nestlings ≤7 days old and was associated with seasonally low minimum daily temperatures (<11°C). Deaths in this age group were most commonly attributed to poor pulmonary aeration and starvation. Ventriculitis was associated with mortality in eight 6–19-day-old nestlings with no indication that weather was implicated. The remaining deaths were from a variety of unrelated events or causes. Candida albicans, Aspergillus sp. and an unidentified haemoparasite were found among the nestling population. There was no evidence of coccidia or other intestinal parasite infections. In contrast to translocated populations at other sites, nesting material recovered from nest boxes contained low densities of tropical fowl mites (Ornithonyssus bursa). To improve survival for nestlings up to 7 days old, extra food provisioning and nest box weather protection during inclement weather is suggested.