Cumulative Degree Days Research Articles

Predicting Emergence in a Midwestern Population of the Green June Beetle,Cotinis nitida(L.) (Coleoptera: Scarabaeidae)

Green June beetle, Cotinis nitida (L.), is an important pest of grapes, peaches, blackberries, blueberries, apples, and pears, yet cumulative degree days that this species requires for outbreak have not been delineated. We monitored green June beetle populations in Mountain Grove, Missouri, USA, for five consecutive years (2009–2013) using traps baited with isopropanol. Our results show that cumulative degree day (CDD) calculation with starting point of March 1st, single sine method of calculation, and 10°C as the base temperature may be used for forecasting green June beetle population dynamics. Five year average ± SE was 888.96 ± 36.78 CDD for the first catch of the green June beetle and 1237.68 ± 25.31 CDD for peak trap catch. Our data also suggest that in the relatively rainy environment in Mountain Grove, the departures from the five year average observed in a given year were not correlated with precipitation preceding the first flight and peak activity of green June beetle populations.

Ice-block fall and snow avalanche hazards in northern Gaspésie (eastern Canada): Triggering weather scenarios and process interactions

The database of the Québec Ministry of Transport allowed us to analyze the occurrence of ice-block falls and snow avalanches for the past decades along national road 132. The results show that ice structure collapse may be categorized into three distinct phases by using daily temperatures (minimum, maximum, and average) and the cumulative degree day (temperatures above 0°C) since the March 1st, corresponding to the beginning of the ice wall melting period: 1) a short and intense period of ice-block falls from the mid-April to the beginning of May; 2) a period of constant activity, mainly during the two first weeks of May; and 3) isolated residual activity, with a low frequency of ice-block falls until the month of June. The snow avalanche days were mainly characterized by significant snowfalls or rain-on-snow events with temperature>0°C. The multi-hazard probability was then evaluated based on the timing and relative frequency of ice-block fall and the modeling of sufficient snowpack for avalanching. This simple method to assess the synergistic effect of hillslope processes allows a better understanding of the spring avalanche regime related to the collapse of ice structures. These findings are expected to assist in the management of natural hazards and to improve our knowledge of spatiotemporal dynamics of mass-wasting events on highways.

Climate-Driven Phenological Change: Developing Robust Spatiotemporal Modeling and Projection Capability.

Our possibility to appropriately detect, interpret and respond to climate-driven phenological changes depends on our ability to model and predict the changes. This ability may be hampered by non-linearity in climate-phenological relations, and by spatiotemporal variability and scale mismatches of climate and phenological data. A modeling methodology capable of handling such complexities can be a powerful tool for phenological change projection. Here we develop such a methodology using citizen scientists’ observations of first flight dates for orange tip butterflies (Anthocharis cardamines) in three areas extending along a steep climate gradient. The developed methodology links point data of first flight observations to calculated cumulative degree-days until first flight based on gridded temperature data. Using this methodology we identify and quantify a first flight model that is consistent across different regions, data support scales and assumptions of subgrid variability and observation bias. Model application to observed warming over the past 60 years demonstrates the model usefulness for assessment of climate-driven first flight change. The cross-regional consistency of the model implies predictive capability for future changes, and calls for further application and testing of analogous modeling approaches to other species, phenological variables and parts of the world.

Sharp altitudinal gradients in Magellanic Sub-Antarctic streams: patterns along a fluvial system in the Cape Horn Biosphere Reserve (55°S)

Magellanic Sub-Antarctic streams run through steep, low-altitude mountainous gradients characterized by a topography that supports a mosaic of evergreen, mixed, and deciduous forests, peat lands, and scrublands. Here, the macroinvertebrate fauna and their ecological interactions are poorly known. This study linked the distribution, community composition, and functional feeding structure of benthic macroinvertebrates with physicochemical and thermal patterns along the altitudinal gradient of a Magellanic Sub-Antarctic watershed. Invertebrates were collected during the austral summers of 2008, 2009, and 2010 at five different altitudes. Our results indicate that benthic macroinvertebrate community distributions are predominantly affected by temperature and certain species show distribution restrictions through the altitudinal gradient studied. Temperature profiles indicate that this Sub-Antarctic watershed is characterized by a sharp thermal gradient, in which cumulative degree-days (°C) per year sharply increase through a relatively short altitudinal gradient (0–600 m above sea level). With the results from this study, we can now study thermal tolerances of altitude-restricted species or project changes in their distributions and voltinism patterns according to climate change scenarios. Ecosystems at higher latitudes and altitudes are experiencing some of the fastest rates of warming on the planet, and Magellanic Sub-Antarctic watersheds could be considered as “sentinel systems,” providing early warning of wider scale change.

Population Dynamics of Culex restuans and Culex pipiens (Diptera: Culicidae) Related to Climatic Factors in Northwest Ohio.

Two species of Culex mosquitoes are common throughout much of North America. Culex restuans Theobold is a native species, whereas Culex pipiens L. is a European immigrant that has been in North America since the 1600s. Larvae of Cx. restuans are numerically dominant in spring and early summer but Cx. pipiens dominates by mid-summer. This transition is termed the "Culex crossover" and has been previously explored in larval populations, largely because Cx. pipiens is more likely to transfer West Nile virus to humans. Adult mosquitoes of both species were captured in 14 light traps in Lucas County, OH, between May and October 1980-2011. We examined this 31-yr, continuous record of adult populations for signs of a species crossover, relationships between abundances of both species and climate factors, and evidence of interspecific competition. The total cumulative degree-days (above 0°C), total cumulative precipitation, and total number of each species were calculated for each day of January-September (annual) and May-September (mosquito season) of each year. On average, adult Cx. pipiens became numerically dominant over Cx. restuans on day 175 ± 21 (June 24), consistent with the Culex crossover reported for their larvae. Pearson correlations showed that abundances of both species were related to temperature and precipitation, but Cx. pipiens tended to be positively related to climatic factors, whereas Cx. restuans showed negative correlations. Moreover, abundances of the two species were more positively than negatively related to one another, providing no evidence of interspecific competition.

Biology and temperature requirements of the invasive seed bug Leptoglossus occidentalis (Heteroptera: Coreidae) in Europe

Leptoglossus occidentalis, a species native to North America, has been expanding through European conifer forests. The fast spread across the European con- tinent demonstrates its great invasive potential and poses a threat to conifer seed orchards. To better understand its potential distribution and population growth in infested regions, the temperature-dependent development in laboratory as well as life history, phenology, and winter survival were investigated in southern Slovakia during 2009-2011. The lower temperature thresholds to complete embryonic and postembryonic development estimated with the linear model were 13.38 and 14.37 � C, respectively. The number of degree-days required for completion of development from egg to adult estimated by the linear model was 533 � C. Overwintered adults or late nymphal instars became active in mid-March, oviposition was not observed before mid-April, and nymphs passing through five stages reached adulthood after mid-July. Individual females laid on average 31 eggs (max 78). The second generation started in August but did not complete its de- velopment till winter, although part of the 5th instar nymphs did survive until spring. Using temperature data of 41 localities across Europe and cumulative degree-days for complete life cycle, a prediction of the potential number of generations per year was made. In conditions of southern Slovakia L. occidentalis was univoltine, but up to four generations per year were estimated depending on the lo- cality in Europe.

Hydration as a possible colonization cue: Rain may promote seed release from black cottonwood trees

Within the Salicaceae, the poplar trees and willow shrubs display an r-selection reproductive strategy, with the production of vast numbers of seeds but these are tiny, viability lasts only a few weeks, and very few seedlings establish and mature to contribute to the woodland populations. The timing of seed release is consequently critical and for cottonwoods, riparian poplars, seed release has been reported to follow the spring peak in river flow. To investigate the prospective coordination between environmental conditions and seed release we undertook daily observations of black cottonwoods (Populus trichocarpa) over four summers along the lower Duncan River in southeastern British Columbia, Canada. Seed release involved a sequence of pulses with the first after about 400 cumulative degree days (base 5°C) in the growth season. There were four or five pulses annually with each extending one to six days and occurring through June and July and unexpectedly, into early August. The pulses of seed release were not coordinated with changes in river flow but all 18 pulses over the four years followed rain events. We thus conclude that in a humid climate mountain ecoregion, rain and possibly post-rain warming may provide environmental cues that trigger cottonwood seed release. This hygrisence could retain the near-mature seeds on the maternal tree, prolonging their viability, and their release after rain would provide moist substrates, benefitting seedling establishment. We further conclude that in a humid ecoregion, the river flow pattern would be less important for riparian seedling colonization than in semi-arid regions, where summer rain is sparse. In all ecoregions, occasional high river flows are essential for the fluvial geomorphic disturbance that creates the barren seedling colonization sites, and also to exclude flood-intolerant upland vegetation from encroaching into the riparian recruitment zones.

Nile Tilapia and Blue Tilapia Fry Production in a Subtropical Climate Based on Degree Days

The relationship between production in subtropical earthen ponds of fry suitable for hormonal sex inversion and degree days was quantified for Nile tilapia (Oreochromis niloticus; Egypt strain) and blue tilapia (O. aureus). Degree days were calculated for each trial as the sum of mean daily water column temperature minus the reference temperature, 15°C. No fry from either species were harvested at fewer than 124–126 degree days. Total fry production for each increased linearly as cumulative degree days increased from 129 to 281 degree days. Production of fry suitable for hormonal sex inversion was positively related to cumulative degree days only from 115 to 215 degree days. Tilapia fry too large for hormonal sex inversion were not observed until greater than 200 cumulative degree days and increased with increasing degree days thereafter. Optimal production in earthen ponds in a subtropical climate of Nile tilapia and blue tilapia fry suitable for hormonal sex inversion was obtained at 190–215 degree days.

Thermal Biology of the South American Apple SnailAsolene platae(Caenogastropoda: Ampullariidae)

Asolene platae is a freshwater snail of the Ampullariidae native from La Plata River basin in South America. Water temperature has an overwhelming influence on the biology of apple snails, though there are no systematic studies related to the thermal biology of this species. The effect of temperature on the activity, growth and mortality of A. platae was studied through laboratory experiments using constant temperatures of 15, 20, 25, 30 and 35°C. The lower threshold and cumulative degree-days for the embryonic development were estimated under fluctuating temperature. Water temperature had a significant effect on the activity of A. platae, being almost null at 15°C, reaching its maximum in the range 25–30°C and decreasing above 30°C. Regardless of temperature, snails remained resting nearly half of the time, exhibiting less activity than other apple snails across similar temperatures. Mortality was higher for hatchlings than for adults at all temperatures with the exception of 35°C, which resulted in high levels of mortality for both groups. Growth of hatchlings was significantly affected by temperature, being highest between 25 and 35°C. The lower temperature threshold for the embryonic development was around 16°C and the cumulative degree-days to complete development were estimated between 107.5 and 120.5°C.d. The optimum temperature for A. platae would be 25–30°C. Temperatures of 35°C and above would be harmful, while temperatures below 20°C resulted in rapid decreasing in activity and slower growth rates. The information about the thermal requirements of A. platae will be useful optimizing rearing conditions and developing predictive models of the potential distribution of A. platae in scenarios where it is introduced outside of its native range.

Evidence for recent evolution in an invasive species, Microstegium vimineum, Japanese stiltgrass

SummaryThe establishment and spread of invasive plants are often associated with a ‘general‐purpose genotype’, with a corresponding high degree of phenotypic plasticity when introduced to a new environment. Evolutionary potential of invasive species following introduction should also be considered, however, as such changes can facilitate rapid range expansion. In this study, we utilised seed from three geographically distinct mid‐Atlantic populations of an invasive species, Microstegium vimineum (Japanese stiltgrass), to assess whether populations varied in their biomass and reproductive responses to light and nitrogen under neutral glasshouse conditions. To assess evolutionary adaptation, we quantified and correlated the abiotic environment from each collection location with the final biomass and seed production of that population under common glasshouse conditions. For M. vimineum, growth and reproductive responses to a common set of abiotic parameters (e.g. light) under these conditions indicated considerable phenotypic variation between and within populations. Interestingly, the degree of variation of seed production and final biomass among populations in the glasshouse was strongly correlated with growing season length and cumulative degree days recorded near each population location. These latter data indicated that M. vimineum, introduced into this region <100 years ago, may be undergoing adaptive evolution. Although additional populations of M. vimineum need to be examined, this study suggests that local evolutionary adaptation may be occurring rapidly and could, potentially, be an important aspect in the establishment and spread of this invasive species.

Growth of Individual Tomato Fruits under Assimilate Limitation Associated with Successively-later Set Fruits

The time course of growth of individual tomato fruits (Solanum lycopersicum) was analyzed in relation to the fruit initiation date and cumulative degree days of growth. Experimental data of dry weight (DW), fresh weight (FW), radial diameter (FDIAM), and dry matter concentration (DMC) of three different cohorts of fruits of determinate fresh-market tomato cultivar Florida 47 were determined under field conditions in Florida during spring of 2006 and 2007. Successively later cohorts (1 week intervals) had longer lags prior to rapid growth, slower maximum growth during the rapid phase, and smaller DW, FW, and FDIAM at maturity. These growth patterns were analyzed by fitting the data to a three-parameter Gompertz function for DW, FW, and FDIAM, and to a fourparameter modified Gompertz function for DMC. The good agreement of predicted and measured Original Research Article Rybak et al.; AJEA, 6(2): 60-73, 2015; Article no.AJEA.2015.065 61 values indicates that the growth of individual tomato fruits followed the classical S-shaped Gompertz function. The Gompertz function was suitable to describe the slow growth that occurs in tomato fruits immediately after fertilization. The equation was able to predict the increasing duration of this lag and slower maximum growth and smaller final DW, FW, and size for successively later initiated cohorts of fruits. These results confirm the role of sink-source relationships (time of fruit set) on the growth of tomato fruits over time. This study will provide information potentially useful to improve existing tomato crop growth models that are presently limited because they do not predict practical outputs such as fresh weight and size of individual fruits.

Large‐scale simulation of temperature‐dependent phenology in wintering populations of Bactrocera oleae (Rossi)

AbstractTo implement Area‐Wide Pest Management protocols at a regional scale (Liguria, northern Italy), egg deposition and adult flight of olive fruit fly, Bactrocera oleae, were monitored during 2009, 2010 and 2011. The consequence of complete generation in late winter – early spring was also examined. The reliability of a degree‐day model was tested to simulate the insect cycle, starting from October oviposition and considering a 379.01°C cumulative degree‐day (CDD) needed to complete development. The model was validated and then used to simulate olive fruit fly phenology in the region of Liguria, using a GIS approach and the agrometeorological network in the region. The output of the CDD model was mapped with two different spatialization modelling techniques, geostatistical autocorrelation and regression correlation, and altitude, aspect and distance from the sea were assessed as elements of variability. The regression correlation model provided a more accurate indication of B. oleae diversity at the local scale than the geostatistical autocorrelation model and identified the high spatial climatic variability of Liguria. The potential application of the distribution of days after oviposition and prediction error maps in support of pest management planning is discussed.

Influence of thermal regime and land use on benthic invertebrate communities inhabiting headwater streams exposed to contrasted shading

Headwaters account for a high proportion of total freshwater stream-channel length in a drainage basin and are critical habitats for rare, endangered, and specialized species. In the context of climate warming, increasing water temperatures may be an ultimate threat to cold-adapted species even in temperate ecosystems. Climate change effects on streams may interact with other pressures such as pollution or habitat fragmentation, confounding their real impact on biological communities.Three headwater streams exposed to contrasted shading and land use conditions were sampled over a three-year period in spring and autumn (2010–2012). Five stations distributed along the longitudinal continuum were chosen in the upstream part of each stream. In addition to benthic invertebrate sampling, water temperature was recorded continuously using data loggers.Results showed that the riparian woodland associated with forested land use throughout the catchment clearly moderated winter temperature minima, summer temperature maxima and thermal variability compared to open river channels with narrow or absent riparian tree cover. Although, the variability in macroinvertebrate species distribution was mainly attributed to anthropogenic land use in the catchment, a significant part of the variability was explained by temperature descriptors such as the number of cumulative degree-days in summer and extremes in winter temperature. Trichoptera species preferring headwaters and cold water temperatures were found exclusively in the forested unimpacted stream. Conservation issues are discussed in relation to the predicted loss of the potential future distributions of these Trichoptera cold-adapted species.

English

Studies were conducted to estimate the impact of increase in temperature on number of generations of tobacco caterpillar, Spodoptera litura on peanut for seven different locations of various agro ecological zones of the country for baseline (1961 to 1990), present (1991 to 2005), near future (2021 to 2050) and distant future (2071 to 2098) climate change (A1B) scenarios. The daily minimum and maximum temperature (MinT and MaxT) records were used to obtain cumulative degree days (DD) for each generation of insect using a temperature threshold of 10°C. Faster accumulation of degree days will making it possible for one or two additional generations with shortened life cycle (completion of generation would be 5 to 6 days earlier) of S. litura was inferred for both near and distant-future climate change scenarios (CCS) compared to baseline and present periods, at all locations. The additional number of generations and variation in the generation time of S. litura across seven growing locations of India imply the definitive and differential impacts, respectively of the projected increasing temperature in the future CCS.   Key words: Arachis hypogaea, climate change scenario, degree days, generation time, number of generation, Spodoptera litura.

Water temperature affects life-cycle duration of tadpoles of Natal cascade frog

Direct and indirect effects of climate change on amphibians include range shifts and changes in community structure. The Natal cascade frog Hadromophryne natalensis has an altitudinal range of some 2 400 m in KwaZulu-Natal, and presents an opportunity to assess how increased water temperatures may impact on widely distributed amphibians. We sampled populations of tadpoles at three sites near the upper and lower altitudinal extremes of their range, measuring total length, mass and habitat water temperatures. Except for the spring survey, frequency–size class data showed bimodal curves at the two high-altitude sites and unimodal curves at the low-altitude site, suggesting a two-year aquatic life cycle in the cooler, higher rivers and a one-year life cycle at the warmer site. These data were consistent with cumulative degree days, which doubled from the higher- to the lower-altitude sites. Tadpoles at the warmer, lower-altitude site were in worse condition than those at the cooler, higher-altitude sites. We hypothesise that, while thermal changes may not result in rapid, large range shifts for this species, there are a number of unknown variables that may result from potential reductions in life-cycle length, including changes in competitive behaviour and community structure linked to asynchronies between species.

Effect of open-field experimental warming on the leaf phenology of oriental oak (Quercus variabilis) seedlings

Aims An open-field warming experiment enables us to test the effects of projected temperature increase on change in plant phenology with fewer confounding factors and to study phenological response to temperature ranges beyond natural variability. This study aims to (i) examine the effect of temperature increase on leaf unfolding and senescence of oriental oak (Quercus variabilis Blume) under experimental warming and (ii) measure temperature-related parameters used in estimating phenological response to temperature elevation. Methods Using an open-field warming system with infrared heaters, we increased the air temperature by ~3°C in the warmed plots compared with that of the control plots consistently for 2 years. Leaf unfolding and senescence dates of Q. variabilis seedlings were recorded and temperature-related phenological parameters were analysed. Important Findings The timing of leaf unfolding was advanced by 3–8 days (1.1– 3.0 days/°C) and the date of leaf senescence was delayed by 14–19 days (5.0–7.3 days/°C) under elevated air temperatures. However, the cumulative degree days (CDD) of leaf unfolding were not significantly changed by experimental warming, which suggest the applicability of a constant CDD value to estimate the change in spring leaf phenology under 3°C warming. Consistent ranges of advancement and temperature sensitivity in spring phenology and delayed autumn phenology and proposed temperature parameters from this study might be applied to predict future phenological change.

Spectral differentiation of wheat, mustard and chickpea crops grown under variable water supply situations

Spectral differentiation of wheat, mustard and chickpea grown under variable water supply was done by using hand held spectro-radiometer and infra-red thermometer. Red and infra-red reflectance from the crop canopy and canopy thermal environment through canopy-air temperature difference were recorded at various stages of the crop growth. Spectral indices, such as IR/R, Normalized Difference Vegetation Index (NDVI) and Infrared-Red (IR-R, from the spectro-radiometric observation) and cumulative stress degree days were developed, which were subsequently used to differentiate these crops through Leaf Area Index (LAI), biomass and final grain yield. The three crops were spectrally variant among themselves as well as within each crop grown under differential sequence of limited/moderate inputs of water. This study, through development of transfer function for linking with satellite derived indices, can effectively assist in operational satellite remote sensing for crops’ discrimination, crops’ growth condition assessment and yield forecasting.

Do farmers rapidly adapt to past growing conditions by sowing different proportions of early and late maturing cereals and cultivars?

In the short growing season of the northernmost European growing conditions, farmers are increasingly interested in expanding cultivation of later maturing crops at the expense of early maturing ones with lower yields. In this study we aimed to assess how the switching between spring cereals that differ in earliness was associated with different external factors. This was tested using unique datasets for regional cropping areas and cultivar use for the last 15 years. Early maturing barley was favored at the expense of later maturing wheat when a high number of days to crop maturity was required in the preceding year. In contrast, farmers reduced the barley area when a high number of cumulated degree days was required for a crop to mature in the previous year. A shift was recorded from early to late maturing cultivars. This study indicated that despite limited opportunities for farmers to alter land use, they readily responded to past conditions and used the knowledge gained for decision-making to reduce risk. This is a valuable operative model for studying adaptation to opportunities and constraints induced by climate change.

A High-Resolution Cumulative Degree Day-Based Model to Simulate Phenological Development of Grapevine

Common cumulative degree day models used to forecast grape growth stages often are only of local validity, restricted to a limited number of phenological stages, or do not take into consideration that the forcing effect of temperature is limited at higher temperatures. A new model was developed to simulate all 26 phenological stages (according to the BBCH scheme; Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie) of Vitis vinifera L. Muller-Thurgau between budburst and harvest. Sixty time series of grape phenology from four European countries were used to set up and validate the model. Three cumulative degree day models (starting with budburst: BBCH 09) with one, two, or three optimized temperature threshold values were compared. The incorporation of an upper threshold temperature, above which a further increase of the temperature will not accelerate plant development, and of a heat threshold, above which a further increase of the temperature leads to a development deceleration, significantly improved the accuracy of the model compared to previous cumulative degree day approaches. The threshold triplet 5oC, 20oC, and 22oC for lower (base), upper, and heat threshold temperature, respectively, allowed the most precise forecast. In 70.5 or 95.8% of the cases, phenological stages were correctly predicted in 3 or 7 days (assuming daily mean temperatures of 20oC), respectively, around the predicted cumulative degree day. The model can be used for a range of applications in viticultural research and practical viticulture and could further be parameterized for other varieties.

Changes in glacier equilibrium-line altitude in the western Alps from 1984 to 2010: evaluation by remote sensing and modeling of the morpho-topographic and climate controls

Abstract. We present time series of equilibrium-line altitude (ELA) measured from the end-of-summer snow line altitude computed using satellite images, for 43 glaciers in the western Alps over the 1984–2010 period. More than 120 satellite images acquired by Landsat, SPOT and ASTER were used. In parallel, changes in climate variables, summer cumulative positive degree days (CPDD) and winter precipitation, were analyzed over the same time period using 22 weather stations located inside and around the study area. Assuming a continuous linear trend over the study period: (1) the average ELA of the 43 glaciers increased by about 170 m; (2) summer CPDD increased by about 150 PDD at 3000 m a.s.l.; and (3) winter precipitation remained rather stationary. Summer CPDD showed homogeneous spatial and temporal variability; winter precipitation showed homogeneous temporal variability, but some stations showed a slightly different spatial pattern. Regarding ELAs, temporal variability between the 43 glaciers was also homogeneous, but spatially, glaciers in the southern part of the study area differed from glaciers in the northern part, mainly due to a different precipitation pattern. A sensitivity analysis of the ELAs to climate and morpho-topographic variables (elevation, aspect, latitude) highlighted the following: (1) the average ELA over the study period of each glacier is strongly controlled by morpho-topographic variables; and (2) the interannual variability of the ELA is strongly controlled by climate variables, with the observed increasing trend mainly driven by increasing temperatures, even if significant nonlinear, low-frequency fluctuations appear to be driven by winter precipitation anomalies. Finally, we used an expansion of Lliboutry's approach to reconstruct fluctuations in the ELA of any glacier of the study area with respect to morpho-topographic and climate variables, by quantifying their respective weight and the related uncertainties in a consistent manner within a hierarchical Bayesian framework. This method was tested and validated using the ELA measured on the satellite images.