Pliocene Atlantic molluscan assemblages from the Mondego Basin (Portugal): Age and palaeoceanographic implications

The Pliocene molluscan assemblage from the Mondego Basin (Portugal, Western Iberia) plays a particularly important role in the understanding of the palaeobiogeography of Neogene–Quaternary molluscs of the Atlantic Frontage of Europe and the western Mediterranean. The importance of these Portuguese molluscan deposits is stressed, as it is the only assemblage representative of the southern portion of the Pliocene French–Iberian biogeographical Province.The Pliocene marine fossiliferous deposits of the Mondego Basin (central-west Portugal) are dated using their nannofossil and molluscan assemblages, as well as Strontium dating. The results suggest a late Zanclean to early Piacenzian age. Chronologically they are equivalent to the Mediterranean Pliocene Molluscan Unit 1 (MPMU1). However, due to the more northern geographical location of the Mondego Basin assemblages, their molluscan content is closer to that of MPMU2 than to that of MPMU1 in the Mediterranean.The presence of a stock of thermophilic taxa in the Mondego assemblage, no longer existent in European waters, enabled us to suggest a palaeoenvironmental reconstruction for mid-Pliocene SSTs in the region. We put forward the hypothesis that the SSTs at the latitude of Mondego, during late Zanclean to early Piacenzian, would be characterized by a yearly SST pattern analogous to that of present-day Cape Blanc (West Africa). Consequently, whilst subtropical conditions existed in the Atlantic Zanclean to mid-Piacenzian at Mondego latitude in the Mediterranean fully tropical conditions prevailed at that time. The Mondego SST estimates correlate with those estimated for MPMU2 in the Mediterranean.The global palaeoenvironmental reconstruction of mid-Pliocene SSTs in the PRISM2 Project suggests, for western Iberia, at Mondego latitude, an August SST of about 23 °C, and a February temperature of about 17 to 18 °C. Our hypothesis suggests similar August SST differing in only half a degree Celsius (23.5 vs. 23 °C) and February SSTs slightly higher (19 vs. 17–18 °C).     

Sea-surface temperature for left-coiling Neogloboquadrina populations inhabiting the westernmost Mediterranean in the middle Pleistocene and the Pleistocene-Pliocene transition

Using the modern analog methodology applied to planktonic foraminifers, we analyze the relation between the frequency of the coiling type in Neogloboquadrina populations and the sea-surface temperatures (SST) during the middle Pleistocene and the Pleistocene-Pliocene transition in the Alboran Sea (westernmost Mediterranean), close to the Atlantic connection. The results reveal that the present-day positive correlation between the two variables (r = 0.649) is maintained even with a higher coefficient (r = 0.783) in the middle Pleistocene but falls slightly (r = 0.517) in the Pleistocene-Pliocene transition due mainly to a dispersal of the temperatures for the samples bearing predominantly left-coiling Neogloboquadrina. The temperature used as a reference for the coiling change resulted 5-6 °C above its North Atlantic present-day reciprocal, but these thermal differences could be caused by: i) a slight overestimate (1–2 °C) due to the lumping of all neogloboquadrinids into a single variable when SST are estimated; ii) only the warmer range of temperatures for the left-coiling populations would be represented in the samples; and iii) a remarkable warming inside the westernmost Mediterranean during the summer stage mixing cold and warm assemblages in bottom sediments. In addition, these results in combination with those derived from the isotopic analyses (δ¹⁸O) in G. bulloides tests, suggest that during the Pliocene-Pleistocene transition two different populations of left-coiling Neogloboquadrina could have existed with different environmental requirements: one, derived from late Miocene-Pliocene (i.e., left-coiling N. acostaensis group), and another being the ancestor of the modern N. pachyderma (left-coiling). Similarity analyses were achieved in order to locate the position of the core-tops with the assemblages most analogous to those of the fossil samples containing left-coiling Neogloboquadrina. The results reinforce the idea that the presence of these forms in the Mediterranean during the intervals studied would be related mainly to the input of cold waters from the North Atlantic during glacial stages, although it could be secondarily favored by the establishment of upwelling conditions, as in the present-day North Alboran waters.     

Variability of sea-surface temperature and sea-ice cover in the Fram Strait over the last two millennia

A sediment core located on the West Spitzbergen margin in the Fram Strait (78°54.931′N, 6°46.005′E, water depth: 1497 m) was analyzed for its dinocyst content in order to reconstruct hydroclimatic variations of the last 2500 years. The relative abundance of dinocyst taxa and principal component analysis show a major transition at about 300 cal. years BP. It is characterized by the disappearance of thermophilic taxa Spiniferites mirabilis-hyperacanthus and Impagidinium sphaericum and the increase of polar–subpolar taxa Impagidinium pallidum and Pentapharsodinium dalei. Sea-surface temperature (SST) estimates suggest warmer conditions than present (anomaly～+2 °C) averaging at 7 °C in summer until 300 cal. years BP, although cooling pulses are recorded around 1700, 1500, 1200 and 800 cal. years BP. The last 300 years were marked by a cooling from 7.6 to 3.5 °C and sea-ice cover increasing up to 7 months/yr. The results demonstrate that the Fram Strait area is sensitive to hydroclimatic variations, notably with respect to sea-ice and SSTs, which are linked to the relative strength of northward flow of North Atlantic waters to the East and southward outflow of cold and fresh waters from the Arctic Ocean. Based on our data, the warmest part of our record around 1320 cal. years BP is the only interval of the last 2500 years that provides a possible analogue for the modern post-AD 2000 interval, which is characterized by sea-ice free conditions.     

Carbon and oxygen isotope evidence for high-frequency (104–105 yr) and My-scale glacio-eustasy in Middle Pennsylvanian cyclic carbonates (Gray Mesa Formation), central New Mexico

We combine cyclo- and sequence stratigraphy along with whole rock δ¹³C and conodont apatite δ¹⁸O analysis to document high-frequency (10⁴–10⁵ yr) and My-scale sea-level changes for the Middle Pennsylvanian (Desmoinesian or Moscovian) Gray Mesa Formation of central New Mexico. Approximately 75 subtidal cycles (1–8 m) are grouped into 4 1/2 My-scale depositional sequences (40–80 m). About 50% of the cycles show evidence of prolonged subaerial exposure at cycle tops with the development of calcretes, diagenetic mottling, and regolith intraclasts. High-resolution δ¹³C analysis of whole rock limestones across nine of the cycles indicates that the cycle tops were diagenetically altered by isotopically light, meteoric fluids during sea-level fall and lowstand. These δ¹³C trends support the interpretation that high-frequency sea-level changes were responsible for cycle development.Conodont apatite δ¹⁸O values from sampled cycles indicate that the high-frequency sea-level changes were driven by glacio-eustasy combined with changes in surface seawater temperature (SST). δ¹⁸O values from conodont apatite, spanning parts of three depositional sequences indicate that My-scale glacio-eustasy and/or SST changes controlled sequence development. δ¹⁸O shifts indicate that the magnitudes of 10⁴–10⁵ yr glacio-eustasy were between ～ 55 and 170⁺ m combined with tropical SST changes of ～ 1.5°–6 °C. Calculated My-scale glacio-eustatic oscillations were between ～ 60 and 140 m with SST changes of < 3.5 °C. The most plausible driver for the My-scale paleoclimate changes is long-period obliquity (～ 1.2 My) variations. These calculated high-frequency, glacio-eustatic values are similar or greater than Pleistocene values, and lie within the range estimated for other Middle Pennsylvanian successions using a variety of independent eustatic proxies. The similarity in range of magnitudes between high-frequency and My-scale sea-level changes combined with the large differences in magnitudes between individual high-frequency sea-level oscillations helps explain the lack of systematic cycle-stacking patterns within these Pennsylvanian icehouse sequences.     

Gelation of high methoxy pectin by acidification with d-glucono-δ-lactone (GDL) at room temperature

Rheological comparisons have been made between preparations of high methoxy pectin (DE ≈ 70%) gelled by acidification with d-glucono-δ-lactone (GDL) on holding for 16 h at 25 °C in the presence of 60 wt% sucrose, and otherwise identical preparations gelled by acidification with citric acid at high temperature and cooling from 90 to 25 °C at 1 °C/min. Two series of experiments were carried out for both methods of acidification. In the first series, the concentration of pectin (c) was held constant at 1.0 wt% and the final pH attained after holding (with GDL) or cooling (with citric acid) was varied from 3.75 to 2.25. In the second series, the final pH was held constant at 3.0 and c was varied from 0.25 to 2.00 wt%. All samples were then heated (1 °C/min) from 25 to 90 °C. Rheological changes on cooling/holding and heating were characterised by low-amplitude oscillatory measurements of storage modulus (G′) and loss modulus (G′′) at 1 rad s^?1 and 0.5% strain, and mechanical spectra were recorded at 25 °C. Selected samples, gelled with GDL, were also characterised by compression testing (at 25 °C), and a direct linear relationship was found between the logarithm of yield stress and log G′.The concentration-dependence of moduli for the samples acidified to pH 3.0 with GDL had the form typical of biopolymer gels, with log G′ versus log c approaching a limiting slope of 2 as c was raised above the minimum critical gelling concentration (c_o ≈ 0.3 wt%). Under all conditions of pH and pectin concentration studied, the values of G′′ (at 25 °C) for the samples acidified with citric acid were higher than those of the corresponding GDL-induced networks. The values of G′ were also higher, except at very low pH (below ～2.7 at c = 1.0 wt%) or very high concentrations of pectin. At pectin concentrations above ～1.5 wt%, the moduli of the samples gelled with citric acid (at pH 3.0) levelled out, or decreased slightly, with the values of G′ dropping below those of the GDL-induced networks towards the end of the concentration range studied (at c ≈ 2 wt%). All samples acidified with citric acid showed gel-like response (G′ > G′′) at 90 °C, attributed to hydrophobic association. The downturn in moduli at 25 °C for high concentrations of pectin is attributed to formation and disruption of strong networks during mixing with citric acid at high temperature (“pregelation”). It is suggested, however, that “weak gels” formed at lower concentrations or at pH values above ～2.7 may enhance gel properties by preserving a continuous network as hydrophobic junctions dissociate on cooling and are replaced by hydrogen-bonded junctions, in contrast to random percolation during gelation with GDL at 25 °C. On re-heating from 25 to 90 °C, the reverse processes (dissociation of hydrogen-bonded structures and formation of hydrophobic associations) were evident in an initial reduction and subsequent increase in moduli, as observed in previous studies. Similar heating traces were obtained for samples acidified with GDL to pH values above ～3.0 (at c = 1.0 wt%) or with pectin concentrations below ～1.0 wt% (at pH 3.0). However, at higher concentrations or lower values of pH (i.e. conditions favourable to extensive intermolecular association) an abrupt decrease in G′, with an accompanying maximum in G′′, was observed on heating through the temperature range ～60–80 °C. This is attributed to excessive hydrophobic association, causing collapse of network structure. It is further suggested that, for samples acidified with citric acid, there is preferential association of chain sequences of high ester content into hydrophobic junctions at 90 °C, leaving sequences with a high content of unesterified carboxyl groups available to form long hydrogen-bonded junctions during cooling, and thus giving gels that are stronger and more resistant to network collapse.     

Rising temperatures may increase growth rates and microcystin production in tropical Microcystis species

Rising temperatures (1.4–6 °C) due to climate change have been predicted to increase cyanobacterial bloom occurrences in temperate water bodies; however, the impacts of warming on tropical cyanobacterial blooms are unknown. We examined the effects of four different temperatures on the growth rates and microcystin (MC) production of five tropical Microcystis isolates (M. ichthyoblabe (two strains), M. viridis, M. flos-aquae, and M. aeruginosa). The temperature treatments are based on current temperature range in Singapore's reservoirs (27 °C and 30 °C), as well as projected mean (33 °C) and maximum temperatures (36 °C) based on tropical climate change estimates of +6 °C in air temperature. Increasing temperatures did not significantly affect the maximum growth rates of most Microcystis strains. Higher growth rates were only observed in one M. ichthyoblabe strain at 33 °C and M. flos-aquae at 30 °C where both were isolated from the same reservoir. MC-RR and MC-LR were produced in varying amounts by all four species of Microcystis. Raised temperatures of 33 °C were found to boost total MC cell quota for three Microcystis strains although further increase to 36 °C led to a sharp decrease in total MC cell quota for all five Microcystis strains. Increasing temperature also led to higher MC-LR:MC-RR cell quota ratios in M. ichthyoblabe. Our study suggests that higher mean water temperatures resulting from climate change will generally not influence growth rates of Microcystis spp. in Singapore except for increases in M. ichthyoblabe strains. However, toxin cell quota may increase under moderate warming scenarios depending on the species.     

Highly resolved proton matrix ENDOR of oriented photosystem II membranes in the S2 state

Proton matrix ENDOR was performed to investigate the protons close to the manganese cluster in oriented samples of photosystem II (PS II). Eight pairs of ENDOR signals were detected in oriented PS II membranes. At an angle of θ = 0° between the membrane normal vector n and the external field H₀, five pairs of ENDOR signals were exchangeable in D₂O medium and three pairs were not exchangeable in D₂O medium. The hyperfine splitting of 3.60 MHz at θ = 0° increased to 3.80 MHz at θ = 90°. The non-exchangeable signals with 1.73 MHz hyperfine splitting at θ = 0°, which were assigned to a proton in an amino acid residue, were not detected at θ = 90° in oriented PS II or in non-oriented PS II. Highly resolved spectra show that only limited numbers of protons were detected by CW-ENDOR spectra, although many protons were located near the CaMn₄O₅ cluster. The detected exchangeable protons were proposed to arise from the protons belonging to the water molecules, labeled W1-W4 in the 1.9 Å crystal structure, directly ligated to the CaMn₄O₅ cluster, and nearby amino-acid residue.     

Wind and temperature controls on Alexandrium blooms (2000–2007) in Thau lagoon (Western Mediterranean)

Since 1998, blooms of Alexandrium catenella/tamarense in the lagoon of Thau developed regularly each autumn, reaching a maximum of several millions cells per liter in 2004. By contrast, spring blooms occurred only twice (in 2000 and 2007). During these periods, sea surface temperatures (SST) and the wind patterns appear to impact the bloom occurrences much more than the apparent limiting resources such as inorganic nutrients. The analysis of SST and wind from April to June and September to November (from 2000 to 2007) indicates first that there has to be an initial wind stress in order to resuspend the cysts buried in the sediment. Blooms then occur after a period of weak winds (<4 m s⁻¹) and of stable SST close to 20 °C (±2 °C). Those conditions appear to be most favorable for germination of Alexandrium cysts and its ensuing vegetative growth. This period of stability (a few days to a few weeks) allows the development of the inoculum from the cyst's germination, its cohesion because of reduced hydrodynamics, and development of vegetative cells that are sensitive to agitation. Strong winds during 1–2 day periods can interrupt the bloom dynamics by dispersing (advection due to southeasterly winds) and/or eliminating (turbulence due to northwesterly winds) the vegetative cells. In the spring, under the same conditions of optimal SST, strong wind episodes dominate and those, as well as biological factors very likely lead to a lower occurrence of blooms relative to the fall situation.     

A reduced core to skin temperature gradient,not a critical core temperature,affects aerobic capacity in the heat

The purpose of this study was to determine the impact of the core to skin temperature gradient during incremental running to volitional fatigue across varying environmental conditions. A secondary aim was to determine if a “critical” core temperature would dictate volitional fatigue during running in the heat. 60 participants (n=49 male, n=11 female; 24±5 yrs, 177±11 cm, 75±13 kg) completed the study. Participants were uniformly stratified into a specific exercise temperature group (18 °C, 26 °C, 34 °C, or 42 °C) based on a 3-mile run performance. Participants were equipped with core and chest skin temperature sensors and a heart rate monitor, entered an environmental chamber (18 °C, 26 °C, 34 °C, or 42 °C), and rested in the seated position for 10 min before performing a walk/run to volitional exhaustion. Initial treadmill speed was 3.2 km h⁻¹ with a 0% grade. Every 3 min, starting with speed, speed and grade increased in an alternating pattern (speed increased by 0.805 km h⁻¹, grade increased by 0.5%). Time to volitional fatigue was longer for the 18 °C and 26 °C group compared to the 42 °C group, (58.1±9.3 and 62.6±6.5 min vs. 51.3±8.3 min, respectively, p<0.05). At the half-way point and finish, the core to skin gradient for the 18 °C and 26 °C groups was larger compared to 42 °C group (halfway: 2.6±0.7 and 2.0±0.6 vs. 1.3±0.5 for the 18 °C, 26 °C and 42 °C groups, respectively; finish: 3.3±0.7 and 3.5±1.1 vs. 2.1±0.9 for the 26 °C, 34 °C, and 42 °C groups, respectively, p<0.05). Sweat rate was lower in the 18 °C group compared to the 26 °C, 34 °C, and 42 °C groups, 3.6±1.3 vs. 7.2±3.0, 7.1±2.0, and 7.6±1.7 g m⁻² min⁻¹, respectively, p<0.05. There were no group differences in core temperature and heart rate response during the exercise trials. The current data demonstrate a 13% and 22% longer run time to exhaustion for the 18 °C and 26 °C group, respectively, compared to the 42 °C group despite no differences in beginning and ending core temperatures or baseline 3-mile run time. This capacity difference appears to result from a magnified core to skin gradient via an environmental temperature advantageous to convective heat loss, and in part from an increased sweat rate.     

Development response of Spodoptera exigua to eight constant temperatures: Linear and nonlinear modeling

Temperature-dependent development of Spodoptera exigua (Hübner) were evaluated at eight constant temperatures of 12, 15, 20, 25, 30, 33, 34 and 36 °C with a variation of 0.5 °C on sugar beet leaves. No development occurred at 12 °C and 36 °C. Total developmental time varied from 120.50 days at 15 °C to 14.50 days at 33 °C. As temperature increased from 15 °C to 33 °C, developmental rate (1/developmental time) of S. exigua increased but declined at 34 °C. The lower temperature threshold (T_min) was estimated to be 12.98 °C and 12.45 °C, and the thermal constant (K) was 294.99 DD and 311.76 DD, using the traditional and Ikemoto–Takai linear models, respectively. The slopes of the Ikemoto–Takai linear model for different immature stages were different, violating the assumption of rate isomorphy. Data were fitted to three nonlinear models to predict the developmental rate and estimate the critical temperatures. The T_min values estimated by Lactin-2 (12.90 °C) and SSI (13.35 °C) were higher than the value estimated by Briere-2 (8.67 °C). The estimated fastest development temperatures (T_fast) by the Briere-2, Lactin-2 and SSI models for overall immature stages development of S. exigua were 33.4 °C, 33.9 °C and 32.4 °C, respectively. The intrinsic optimum temperature (T_Φ) estimated from the SSI model was 28.5 °C, in which the probability of enzyme being in its native state is maximal. The upper temperature threshold (T_max) values estimated by these three nonlinear models varied from 34.00 °C to 34.69 °C. These findings on thermal requirements can be used to predict the occurrence, number of generations and population dynamics of S. exigua.     

Ecophysiological requirements on seed germination of a Mediterranean perennial grass (Stipa tenacissima L.) under controlled temperatures and water stress

Stipa tenacissima L. (alpha grass) steppes are one of the most representative ecosystems in arid Mediterranean ecosystems. On the one hand these steppes, which are perpetually exposed to climate and strong anthropogenic pressure, have undergone severe degradation. On the other hand, the ability of S. tenacissima to regenerate naturally is significantly reduced. In this study the germination response and seedling emergence of S. tenacissima are examined in relation to the main environmental factors (water stress and temperature) under laboratory-controlled conditions. The main aim of this paper was to investigate the influence of temperature over a temperature range (10 °C–30 °C) and water stress induced by the solutions of polyethylene glycol (PEG)-6000 (0 to − 1.6 MPa) for a period of 30 days, on the germination behavior of S. tenacissima seeds. The results showed that temperatures between 10° and 20 °C seem to be favorable for the germination of this species, with optimum temperatures among accessions found in 20 °C. When seeds were water-stressed, germination severely decreased at − 0.8 MPa, indicating that the accession resistance limits to the water stress, and was completely inhibited at − 1.6 MPa. Consequently, the final germination percentage (FGP) decreased and the mean time germination (MTG) increased. Based on the empirical data of the germination rate, we estimated that the parameters of the thermal time and hydrotime models showed different values in all accessions which proves the difference between accession adaptive capacities.     

Optimizing isothermal titration calorimetry protocols for the study of 1:1 binding: Keeping it simple

BackgroundSuccessful ITC experiments require conversion of cell reagent (titrand M) to product and production or consumption of heat. These conditions are quantified for 1:1 binding, M + X ⇔ MX.MethodsNonlinear least squares is used in error-propagation mode to predict the precisions with which the key quantities — binding constant K, reaction enthalpy ΔH°, and stoichiometry number n — can be estimated over a wide range of the dimensionless quantity that governs isotherm shape, c = K[M]₀. The measurement precision σ_q is estimated from analysis of water–water blanks.ResultsWhen the product conversion exceeds 90%, the parameter relative standard errors are proportional to σ_q/q_tot, where the total heat q_tot ≈ ΔH° [M]₀ V₀. Specifically, σ_K/K × q_tot/σ_q ≈ 25 for c = 10 ^− 3 − 10, ≈ 11 c^1/3 for c = 10 − 10⁴. For c > 1, n and ΔH° are more precise than K; this holds also at smaller c for the product n × ΔH° and for ΔH° when n can be held fixed. Use of as few as 10 titrant injections can outperform the customary 20–40 while also improving productivity.ConclusionThese principles are illustrated in experiment design using the program ITC-PLANNER15.General significanceSimple quantitative guidelines replace the “c rules” that have dominated the literature for decades. This article is part of a Special Issue entitled Microcalorimetry in the BioSciences — Principles and Applications, edited by Fadi Bou-Abdallah.     

The Biological Sediment Tolerance Index: Assessing fine sediments conditions in Oregon streams using macroinvertebrates

Fine sediments in excess of natural background conditions are one of most globally common causes of stream degradation, with well documented impacts on aquatic communities. The lack of agreement on methods for monitoring fine sediments makes it difficult to share data, limiting assessments of stream conditions across jurisdictions. We present a model that circumvents these limitations by inferring fine sediments in Oregon streams through sampling of macroinvertebrates. Tolerances to fine sediments (<0.06 mm diameter) were calculated for 240 macroinvertebrate taxa, from a calibration dataset of 446 sites across Oregon, as well as an independent validation dataset of 50 samples. Weighted averaging methods were used to infer fine sediment levels in streams by weighting the tolerances of modeled taxa observed in a sample by their abundances. The final model, the Biological Sediment Tolerance Index (BSTI), showed a strong relationship to measured fine sediments (calibration r² = 0.49, validation r² = 0.58). Root-mean-squared-error was small in the calibration dataset (2% fines), but larger in the validation dataset (14% fines). Repeatability was assessed by examining variability in BSTI at 14 sites across Oregon. Because field methods for sampling macroinvertebrates are standardized across resource agencies in Oregon and the responses of macroinvertebrates represent the actual effects of fine sediments on stream ecosystems, the BSTI may offer water resource managers’ a cost-effective method for assessing fine sediment conditions in their ongoing efforts to improve water quality across the state.     

Fire service instructor's undergarment choice to reduce Interleukin-6 and minimise physiological and perceptual strain

Fire Service Instructors frequently experience high levels of physiological and perceptual strain during live fire exposures. Instructors are also at risk of cardiovascular illnesses, with cardiac death being the greatest cause of fire fighter death. Current practice for UK instructors is to select undergarment type based on personal preference, between a boiler suit (BOILER) and a wicking base layer (WBL). Research suggests that shorts and t-shirt (SHORTS) may also be a beneficial alternative undergarment choice. The UK South East Fire Service requested an investigation to identify if undergarment selection can lessen the strain experienced by instructors, and reduce the acute inflammatory response to fire exposures. Eight males completed three 45 min sessions in a heat chamber (49.5±1.4 °C and 16.9±4.3% RH) whilst performing intermittent walking. At the end of heat exposure change in heart rate was not effected by garment type (p=0.061, ηp²=0.373). Change in rectal temperature was different between garments (p=0.009, η_p²=0.271), with trends suggesting that BOILER resulted in a greater change (1.03±0.60 °C) than SHORTS (0.76±0.37 °C, p=0.589, d=0.21) and WBL (0.72±0.33 °C, p=0.545, d=0.25). Interleukin-6 post exposure was greater for BOILER (6.96±0.28 pg mL⁻¹) than both SHORTS (6.59±0.30 pg mL⁻¹, p=0.043, d=0.42) and WBL (6.45±0.43 pg mL⁻¹, p=0.031, d=0.51). Overall, undergarment type had little impact on physiological or perceptual strain. However, wearing WBL or SHORTS may reduce the inflammatory response, and consequently decrease the risk of cardiovascular events.     

Cold storage of the egg parasitoids Trissolcus basalis (Wollaston) and Telenomus podisi Ashmead (Hymenoptera: Scelionidae)

Adults of Trissolcus basalis and Telenomus podisi were stored either at 15 or 18 °C after their immature development had been completed at 18 or 25 °C. Longevity of the parasitoids in the storage temperatures was evaluated, as well as fecundity and longevity following their return to 25 °C after different periods in reproductive diapause. Temperature during immature development influenced female longevity and highest mean longevity was obtained for females that developed to the adult stage at 25 °C and then were stored at 15 °C (ca. 13 months for T. basalis and 10 months for Te. podisi). For adults of T. basalis that developed at 25 °C, storage periods of 120 or 180 days at 15 or 18 °C did not affect fecundity. The fecundity of T. basalis females that developed at 18 °C and were stored for 120 days at 15 or 18 °C was not affected; however, after remaining for 180 days, fecundity was reduced in ca. 30 and 50%, respectively. Storage of Te. podisi adults at 15 or 18 °C significantly reduced fecundity. It is concluded that adults of T. basalis can be stored in the adult stage at 15 or 18 °C between two soybean crop seasons for mass production purposes, aiming the biological control of stink bugs.     

Impact of fluctuating temperatures on development of the koinobiont endoparasitoid Venturia canescens

The effect of temperature on the biology of Venturia canescens (Gravenhorst) (Hymenoptera: Ichneumonidae) is well understood under constant temperature conditions, but less so under more natural, fluctuating conditions. Herein we studied the influence of fluctuating temperatures on biological parameters of V. canescens. Parasitized fifth-instar larvae of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) were reared individually in incubators at six fluctuating temperature regimes (15–19.5 °C with a mean of 17.6 °C, 17.5–22.5 °C with a mean of 19.8 °C, 20–30 °C with a mean of 22.7 °C, 22.5–27.5 °C with a mean of 25 °C, 25.5-32.5 °C with a mean of 28.3 °C and 28.5–33 °C with a mean of 30 °C) until emergence and death of V. canescens adults. Developmental time from parasitism to adult eclosion, adult longevity and survival were recorded at each fluctuating temperature regime. In principle, developmental time decreased with an increase of the mean temperature of the fluctuating temperature regime. Upper and lower threshold temperatures for total development were estimated at 34.9 and 6.7 °C, respectively. Optimum temperature for development and thermal constant were 28.6 °C and 526.3 degree days, respectively. Adult longevity was also affected by fluctuating temperature, as it was significantly reduced at the highest mean temperature (7.0 days at 30 °C) compared to the lowest one (29.4 days at 17.6 °C). Survival was low at all tested fluctuating temperatures, apart from mean fluctuating temperature of 25 °C (37%). Understanding the thermal biology of V. canescens under more natural conditions is of critical importance in applied contexts. Thus, predictions of biological responses to fluctuating temperatures may be used in population forecasting models which potentially influence decision-making in IPM programs.     

Knee flexor strength and bicep femoris electromyographical activity is lower in previously strained hamstrings

The aim of this study was to determine if athletes with a history of hamstring strain injury display lower levels of surface EMG (sEMG) activity and median power frequency in the previously injured hamstring muscle during maximal voluntary contractions. Recreational athletes were recruited, 13 with a history of unilateral hamstring strain injury and 15 without prior injury. All athletes undertook isokinetic dynamometry testing of the knee flexors and sEMG assessment of the biceps femoris long head (BF) and medial hamstrings (MHs) during concentric and eccentric contractions at ±180 and ±60° s^?1. The knee flexors on the previously injured limb were weaker at all contraction speeds compared to the uninjured limb (+180° s^?1 p = 0.0036; +60° s^?1 p = 0.0013; ?60° s^?1 p = 0.0007; ?180° s^?1 p = 0.0007) whilst sEMG activity was only lower in the BF during eccentric contractions (?60° s^?1 p = 0.0025; ?180° s^?1 p = 0.0003). There were no between limb differences in MH sEMG activity or median power frequency from either BF or MH in the injured group. The uninjured group showed no between limb differences in any of the tested variables. Secondary analysis comparing the between limb difference in the injured and the uninjured groups, confirmed that previously injured hamstrings were mostly weaker (+180° s^?1 p = 0.2208; +60° s^?1 p = 0.0379; ?60° ^?1 p = 0.0312; ?180° s^?1 p = 0.0110) and that deficits in sEMG were confined to the BF during eccentric contractions (?60° s^?1 p = 0.0542; ?180° s^?1 p = 0.0473). Previously injured hamstrings were weaker and BF sEMG activity was lower than the contralateral uninjured hamstring. This has implications for hamstring strain injury prevention and rehabilitation which should consider altered neural function following hamstring strain injury.     

Temperature-dependent development of Lista haraldusalis (Walker) (Lepidoptera: Pyralidae) on Platycarya strobilacea

The effect of constant temperatures on development and survival of Lista haraldusalis (Walker) (Lepidoptera: Pyralidae), a newly reported insect species used to produce insect tea in Guizhou province (China), was studied in laboratory conditions at seven temperatures (19 °C, 22 °C, 25 °C, 28 °C, 31 °C, 34 °C, and 37 °C) on Platycarya strobilacea. Increasing the temperature from 19 °C to 31 °C led to a significant decrease in the developmental time from egg to adult emergence, and then the total developmental time increased at 34 °C. Egg incubation was the stage where L. haraldusalis experienced the highest mortality at all temperatures. The survival of L. haraldusalis was significantly higher at 25 °C and 28 °C, whereas none of the eggs hatched at 37 °C. Common and Ikemoto linear models were used to describe the relationship between the temperature and the developmental rate for each immature stage of L. haraldusalis. The estimated values of the lower temperature threshold and thermal constant of the total immature stages using Common and Ikemoto linear models were 11.34 °C and 11.20 °C, and 939.85 and 950.41 degree-days, respectively. Seven nonlinear models were used to fit the experimental data to estimate the developmental rate of L. haraldusalis. Based on the biological significance for model evaluation, Ikemoto linear, Logan-6, and SSI were the best models that fitted each immature stage of L. haraldusalis and they were used to estimate the temperature thresholds. These thermal requirements and temperature thresholds are crucial for facilitating the development of factory-based mass rearing of L. haraldusalis.     

Ways to measure body temperature in the field

Body temperature (T_b) represents one of the key parameters in ecophysiological studies with focus on energy saving strategies. In this study we therefore comparatively evaluated the usefulness of two types of temperature-sensitive passive transponders (LifeChips and IPTT-300) and one data logger (iButton, DS1922L) mounted onto a collar to measure T_b in the field. First we tested the accuracy of all three devices in a water bath with water temperature ranging from 0 to 40 °C. Second, we evaluated the usefulness of the LifeChips and the modified iButtons for measuring T_b of small heterothermic mammals under field conditions. For this work we subcutaneously implanted 14 male edible dormice (Glis glis) with transponders, and equipped another 14 males with data loggers to simultaneously record T_b and oxygen consumption with a portable oxygen analyzer (Oxbox). In one individual we recorded T_b with both devices and analyzed recorded T_b patterns.LifeChips are able to measure temperature within the smallest range from 25 to 40 °C with an accuracy of 0.07±0.12 °C. IPTT-300 transponders measured temperature between 10 and 40 °C, but accuracy decreased considerably at values below 30 °C, with maximal deviations of nearly 7 °C. An individual calibration of each transponder is therefore needed, before using it at low T_bs. The accuracy of the data logger was comparatively good (0.12±0.25 °C) and stable over the whole temperature range tested (0–40 °C). In all three devices, the repeatability of measurements was high.LifeChip transponders as well as modified iButtons measured T_b reliably under field conditions. Simultaneous T_b-recordings in one edible dormouse with an implanted LifeChip and a collar-mounted iButton revealed that values of both measurements were closely correlated. Taken together, we conclude that implanted temperature-sensitive transponders represent an appropriate and largely non-invasive method to measure T_b also under field conditions.     

Reliability and validity of skin temperature measurement by telemetry thermistors and a thermal camera during exercise in the heat

New technologies afford convenient modalities for skin temperature (T_SKIN) measurement, notably involving wireless telemetry and non-contact infrared thermometry. The purpose of this study was to investigate the validity and reliability of skin temperature measurements using a telemetry thermistor system (TT) and thermal camera (TC) during exercise in a hot environment. Each system was compared against a certified thermocouple, measuring the surface temperature of a metal block in a thermostatically controlled waterbath. Fourteen recreational athletes completed two incremental running tests, separated by one week. Skin temperatures were measured simultaneously with TT and TC compared against a hard-wired thermistor system (HW) throughout rest and exercise. Post hoc calibration based on waterbath results displayed good validity for TT (mean bias [MB]=−0.18 °C, typical error [TE]=0.18 °C) and reliability (MB=−0.05 °C, TE=0.31 °C) throughout rest and exercise. Poor validity (MB=−1.4 °C, TE=0.35 °C) and reliability (MB=−0.65 °C, TE=0.52 °C) was observed for TC, suggesting it may be best suited to controlled, static situations. These findings indicate TT systems provide a convenient, valid and reliable alternative to HW, useful for measurements in the field where traditional methods may be impractical.