Coma Temperature Research Articles

Intraspecific cold tolerance of the weed biological control agent alligatorweed thrips, Amynothrips andersoni, in the USA

ABSTRACT Biological control of the invasive plant, alligatorweed (Alternanthera philoxeroides (Mart.) Griseb.) is geographically variable, due in part to reduced overwintering survival of control agents in cold climates. Alligatorweed thrips, Amynothrips andersoni O’Neill, may have more utility in colder climates than the widely-established alligatorweed flea beetle, Agasicles hygrophila Selman & Vogt, due to greater cold tolerance. However, it remains unknown whether variation in cold tolerance exists among introduced A. andersoni populations or whether it is driven by local adaptation, leading to enhanced cold tolerance in high-latitude populations. We cultured six populations of A. andersoni from field sites spanning seven degrees of latitude in Louisiana, Arkansas, and North Carolina, USA then compared cold tolerance as supercooling point, chill coma temperature, and mortality at sub-freezing temperatures. We did not find significant variation in SCP between populations, which averaged −22.6 ± 0.67°C. Chill coma temperature was lowest for thrips in the most northern North Carolina population (0.07 ± 0.18°C), which suggests local adaptation to winter temperatures may have occurred there. Sub-freezing mortality did not differ between populations and was low at 96 h exposures down to −8°C. At −12°C, mortality was high (58 ± 7%) in exposure durations as short as 6 h and nearly 100% mortality at 24 h. Cold winter temperatures are not likely to prevent establishment of A. andersoni throughout much of the southeastern USA where alligatorweed occurs but questions remain about factors that may limit thrips persistence in some areas where alligatorweed is submerged or senesced during winter months.

Thermal tolerance does not explain the altitudinal segregation of lowland and alpine aquatic insects

Elevation gradients provide powerful study systems for examining the influence of environmental filters in shaping species assemblages. High-mountain habitats host specific high-elevation assemblages, often comprising specialist species adapted to endure pronounced abiotic stress, while such harsh conditions prevent lowland species from colonizing or establishing. While thermal tolerance may drive the altitudinal segregation of ectotherms, its role in structuring aquatic insect communities remains poorly explored. This study investigates the role of thermal physiology in shaping the current distribution of high-mountain diving beetles from the Sierra Nevada Iberian mountain range and closely related lowland species. Cold tolerance of five species from each altitudinal zone was measured estimating the supercooling point (SCP), lower lethal temperature (LLT) and tolerance to ice enclosure, while heat tolerance was assessed from the heat coma temperature (HCT). Alpine species exhibited wider fundamental thermal niches than lowland species, likely associated with the broader range of climatic conditions in high-mountain areas. Cold tolerance did not seem to prevent lowland species from colonizing higher elevations, as most studied species were moderately freeze-tolerant. Therefore, fundamental thermal niches seem not to fully explain species segregation along elevation gradients, suggesting that other thermal tolerance traits, environmental factors, and biotic interactions may also play important roles.

Thermal tolerances of littorinid snails from temperate and subtropical South Africa

Environmental temperature affects ectotherm performance and fitness because physiological performance increases up to a sublethal optimum temperature; this is not fixed, but depends on the species and individual history. We explored the influence of species identity, size and thermal history on thermal tolerance in four species of littorinid snails in South Africa. As expected, heat coma temperature (HCT) was lower than the lethal temperatures (LT50), and was greater for juveniles, while LT50 was greater for adults. The ranking by both metrics was Echinolittorina natalensis > Littoraria glabrata > Afrolittorina africana > A. knysnaensis, reflecting their biogeographical distributions. No species showed an effect of laboratory acclimation for 14 days at temperatures from 20 to 35 °C, though HCT was lower for field fresh individuals than for all other treatments. Nor was there acclimatisation of LT50 between seasons. Bioregion is a proxy for lifetime acclimatisation yet the Afrolittorina species showed nonsignificant differences between conspecifics from different regions. The effect of size differed between the two metrics, and field fresh individuals showed lower HCT values than laboratory-treated individuals—which taken together indicates the need for care when interpreting the results of lab work. The thermal tolerances of these species reflect their biogeography and appear fixed with little or no plasticity, rendering these littorinids vulnerable to future climate warming.

Thermal biology of aquatic insects in alpine lakes: Insights from diving beetles

Abstract High mountain areas are especially vulnerable to global warming, as they experience faster temperature changes than lowlands in a climate change context. Notably, increased temperatures and frequency of extreme flooding and droughts, and the consequent decrease in ice cover and water availability fluctuations, will induce important physical changes in alpine freshwater systems. Thus, assessing thermal limits and exploring overwintering strategies of aquatic alpine insects is pivotal to understanding how aquatic communities of high‐mountain fresh waters will respond to climate change. However, knowledge on these topics is still scarce for aquatic alpine insects. Here, the thermal biology of adults of five diving beetle species from alpine lakes located in the Sierra Nevada mountain range (southern Iberia) was studied. Cold tolerance was measured estimating the supercooling point (SCP), lower lethal temperature (LLT), tolerance to ice enclosure and to submersion, whereas heat tolerance was assessed from the heat coma temperature and upper lethal temperature. All of the species survived ice enclosure for 3 h. Furthermore, three of the studied species had SCPs higher than their LLTs, suggesting that they could be freeze‐tolerant. All species except Agabus nevadensis also were tolerant to submersion, which could be a key adaptation for overwintering underwater below the ice cover as adults, reducing risk from freezing conditions in the air. The species did not differ significantly in their upper thermal limits, which were similar to those of other dytiscids from lower altitudes. Overall, our results suggest that increasing temperatures is not expected to be the most important threat for the water beetle populations in Sierra Nevada, but rather the colonisation of alpine lakes by lowland dytiscids in a warmer climate scenario.

Feeling the heat: Bumblebee workers show no acclimation capacity of upper thermal tolerance to simulated heatwaves

Climate change is our most significant challenge in the 21st century and among the main drivers of biodiversity loss. Recent distributional shifts and declines in crucial pollinators, such as bumblebees, seem to be associated to this phenomenon. However, despite future climate projections on climate warming, few studies have assessed the ability of temperate bumblebees to acclimate to extreme weather events, such as heatwaves. This study estimates the upper critical thermal limits (Critical Thermal Maximum (CTmax) and Heat Coma Temperature (HCT)), of the bumblebee subspecies Bombus terrestris audax, and assesses whether CTmax increases following exposure to a simulated heatwave. The critical thermal maximum occurred between 48.9 and 52.7 °C, while the heat coma temperature varied between 50.7 and 53.4 °C. After measurement of HCT, around 23% of bees survived 24 h or longer, but coordination was never recovered. There was no significant association between upper critical thermal limits and body mass, which highlights the need to investigate other factors to comprehend the mechanisms behind thermal tolerance limits. Furthermore, the heatwave treatments had no significant effect on the CTmax of bumblebee workers, indicating no acclimation capacity of upper thermal tolerance to simulated heatwaves. Our study provides insights into the upper thermal tolerance limits of Bombus terrestris audax and reveals that exposure to heatwave-like events does not change the upper thermal tolerance of bees, highlighting the need to develop effective strategies that might enable them to cope with extreme weather events.

Landscape effects on the thermotolerance of carabid beetles and the role of behavioral thermoregulation.

Physiological thermotolerance and behavioral thermoregulation are central to seasonal cold adaptation in ectothermic organisms. For species with enhanced mobility, behavioral responses may be of greater importance in the cold stress response. Employing the carabid beetles as a study organism, the current study compared physiological thermotolerance and behavioral thermoregulation in carabid species inhabiting cereal fields in different landscape contexts, from fine grain heterogeneous "complex" landscapes to homogenous "simple" landscapes. Physiological thermotolerance was determined via measurement of the CTmin and chill coma temperature. Behavioral responses to cold temperature exposure were determined employing a purpose built arena, and thoracic temperature measured to estimate the efficacy of the behavior as a form of behavioral thermoregulation. Results revealed an influence of landscape composition on the cold tolerance of carabid beetles, although species differed in their sensitivity to landscape intensification. A reduced effect of landscape on the thermotolerance of larger carabid beetles was observed, thought to be the consequence of greater mobility preventing local acclimation to microclimatic variation along the landscape intensification gradient. Investigation into behavioral thermoregulation of the 3 largest species revealed burrowing behavior to be the main behavioral response to cold stress, acting to significantly raise carabid body temperature. This finding highlights the importance of behavioral thermoregulation as a strategy to evade cold stress. The use of behavioral thermoregulation may negate the need to invest in physiological thermotolerance, further offering explanation for the lack of landscape effect on the physiological thermotolerance of larger carabids.

Acclimation Effects of Natural Daily Temperature Variation on Longevity, Fecundity, and Thermal Tolerance of the Diamondback Moth (Plutella xylostella).

Simple SummaryDiurnal, monthly, or seasonal temperatures can fluctuate substantially. Daily temperature amplitudes (DTAs) can significantly impact the traits of insects but there is limited evidence from the natural environment. Therefore, we studied the acclimation effects of DTA on the longevity, total fecundity, early fecundity, and thermal tolerance of adult diamondback moths (Plutella xylostella) under environmental conditions. The longevity, total fecundity, early fecundity, and heat thermal tolerance of adults significantly changed under different DTAs. These findings highlight the effects of DTA on the acclimation response in the P. xylostella phenotype, and DTA should be incorporated into prediction models for assessing insect populations and the effects of climate change.Daily temperature amplitudes (DTAs) significantly affect the ecological and physiological traits of insects. Most studies in this field are based on laboratory experiments, while there is limited research on the effects of changes in DTA on insect phenotypic plasticity under natural conditions. Therefore, we studied the acclimation effects of DTA on the longevity, total fecundity, early fecundity, and the thermal tolerance of adult diamondback moths (Plutella xylostella L.) under naturally occurring environmental conditions. As DTAs increased, male longevity and total fecundity decreased, and early fecundity increased. An increase in DTA was significantly associated with the increased heat coma temperature (CTmax) of both males and females, but had no significant effect on their cold coma temperature (CTmin). Our findings highlight the effects of DTA on the acclimation response of P. xylostella and emphasize the importance of considering DTA in predicting models for assessing insect populations and the effects of climate change.

Gas-phase Modeling of the Cometary Coma of Interstellar Comet 2I/Borisov

Abstract Comet 2I/Borisov is the first interstellar comet observed in the solar system, providing a unique opportunity to understand the physical conditions that prevailed in a distant unknown planetary system. Observations of the comet show that the CO/H2O ratio is higher than that observed in solar system comets at a heliocentric distance r h < 2.5 au. We aim to study the gas-phase coma of comet 2I/Borisov using a multifluid chemical-hydrodynamical model. The gas-phase model includes a host of chemical reactions, with the neutrals, ions, and electrons treated as three separate fluids. Energy exchange between the three fluids due to elastic and inelastic scattering and radiative losses are also considered. Our model results show that in the region of the coma beyond ∼100 km of the nucleus, e−−CO inelastic collisions leading to vibrational excitation of CO causes a loss of energy from the electron fluid. We find a high abundance of CO+ and HCO+ ions, and we show how these two ions affect the creation/destruction rates of other ions such as H2O+, H3O+, N-bearing ions, and large organic ions. We find that the presence of CO leads to a higher abundance of large organic ions and neutrals such as CH 3 OH 2 + , CH 3 OCH 4 + , and CH3OCH3, as compared to a typical H2O-rich solar system comet. We conclude that the presence of a large amount of CO in the coma of comet 2I/Borisov, combined with a low production rate, affects the coma temperature profile and flux of major ionic species significantly.

Genetic Variability, Population Differentiation, and Correlations for Thermal Tolerance Indices in the Minute Wasp, Trichogramma cacoeciae.

Simple SummaryAugmentative biological control relies on the more or less frequent/abundant releases of biological control agents (BCAs) that have to be adapted to their short-term local environment including (micro-)climatic conditions. Thermal biology of BCAs is thus a key component for their success. The extent to which thermal tolerance indices may be relevant predictors of the field efficiency is however still poorly documented. Within this frame, we investigated the intraspecific variability for the ability to move at low temperatures in the minute wasp, Trichogramma cacoeciae. We collected, molecularly characterized, and compared for their thermal tolerance indices numerous strains originating from three contrasting geographic areas. Our findings evidenced both a geographic differentiation between strains for one of the thermal tolerance indices and a positive correlation between two of them, demonstrating the existence of an intraspecific variability. Temperature is a main driver of the ecology and evolution of ectotherms. In particular, the ability to move at sub-lethal low temperatures can be described through three thermal tolerance indices—critical thermal minimum (CTmin), chill coma temperature (CCT), and activity recovery (AR). Although these indices have proven relevant for inter-specific comparisons, little is known about their intraspecific variability as well as possible genetic correlations between them. We thus investigated these two topics (intraspecific variability and genetic correlations between thermal tolerance indices) using the minute wasp, Trichogramma cacoeciae. Strains from T. cacoeciae were sampled across three geographic regions in France—two bioclimatic zones along a sharp altitudinal cline in a Mediterranean context (meso-Mediterranean at low elevations and supra-Mediterranean at higher elevations) and a more northwestern area characterized by continental or mountainous climates. Our results evidenced a significant effect of both the longitude and the severity of the cold during winter months on CCT. Results were however counter-intuitive since the strains from the two bioclimatic zones characterized by more severe winters (northwestern area and supra-Mediterranean) exhibited opposite patterns. In addition, a strong positive correlation was observed between CCT and CTmin. Neither strain differentiation nor the covariations between traits seem to be linked with the molecular diversity observed on the part of the mitochondrial marker COI.

Thermal acclimation alters Na+/K+-ATPase activity in a tissue-specific manner in Drosophila melanogaster

Insects, like the model species Drosophila melanogaster, lose neuromuscular function and enter a state of paralysis (chill coma) at a population- and species-specific low temperature threshold that is decreased by cold acclimation. Entry into this coma is related to a spreading depolarization in the central nervous system, while recovery involves restoration of electrochemical gradients across muscle cell membranes. The Na+/K+-ATPase helps maintain ion balance and membrane potential in both the brain and hemolymph (surrounding muscles), and changes in thermal tolerance traits have therefore been hypothesized to be closely linked to variation in the expression and/or activity of this pump in multiple tissues. Here, we tested this hypothesis by measuring activity and thermal sensitivity of the Na+/K+-ATPase at the tagma-specific level (head, thorax and abdomen) in warm- (25 °C) and cold-acclimated (15 °C) flies by measuring Na+/K+-ATPase activity at 15, 20, and 25 °C. We relate differences in pump activity to differences in chill coma temperature, spreading depolarization temperature, and thermal dependence of muscle cell polarization. Differences in pump activity and thermal sensitivity induced by cold acclimation varied in a tissue-specific manner: While thermal sensitivity remained unchanged, cold-acclimated flies had decreased Na+/K+-ATPase activity in the thorax (mainly muscle) and head (mainly composed of brain). We argue that these changes may assist in maintenance of K+ homeostasis and membrane potential across muscle membranes, and discuss how reduced Na+/K+-ATPase activity in the brain may counterintuitively help insects delay coma onset in the cold.

Measuring the evolutionary potential of a winter-active parasitic wasp to climate change.

In temperate climates, as a consequence of warming winters, an increasing number of ectothermic species are remaining active throughout winter months instead of diapausing, rendering them increasingly vulnerable to unpredictable cold events. One species displaying a shift in overwintering strategy is the parasitoid wasp and biological control agent Aphidius avenae. The current study aimed to better understand the consequence of a changing overwintering strategy on the evolutionary potential of an insect population to adapt to the cold stress events, set to increase in frequency, even during milder winters. Using a parental half-sibling breeding design, narrow-sense heritability of the cold tolerance, morphology and longevity of A. avenae was estimated. The heritability of cold tolerance was estimated at 0.07 (CI95% = [0.00; 0.25]) for the Critical Thermal Minima (CTmin) and 0.11 (CI95% = [0.00; 0.34]) for chill coma temperature; estimates much lower than those obtained for morphological traits (tibia length 0.20 (CI95% = [0.03; 0.37]); head width 0.23 (CI95% = [0.09; 0.39]); wing surface area 0.28 (CI95% = [0.11; 0.47])), although comparable with the heritability estimate of 0.12 obtained for longevity (CI95% = [0.00; 0.25]). The heritability estimates obtained thus suggest that A. avenae possesses low adaptive potential against cold stress. If such estimates are indicative of the evolutionary potential of A. avenae cold tolerance, more emphasis may be placed on adaptive phenotypic plasticity at the individual level to persist in a changing climate, with potential implications for the biological control function they provide.

Comparison of upper sublethal and lethal temperatures in three species of rice planthoppers

Temperature is an important environmental factor for ectotherms’ fitness and survival. The upper sublethal and lethal temperatures were compared between adults of three closely related destructive planthopper species, the small brown planthopper (Laodelphax striatellus, SBPH), the brown planthopper (Nilaparvata lugens, BPH), and the white-backed planthopper (Sogatella furcifera, WBPH) in the absence and presence of the host plant (Oryza sativa, var. Taichong1). Values of the critical thermal maxima (CTmax) were higher in SBPH than in both BPH and WBPH and higher in BPH than in WBPH, and values of the heat coma temperatures (HCT) were higher in both BPH and SBPH than in WBPH. CTmax and HCT values were higher in the presence than in the absence of plant material. Between sexes, females generally showed higher CTmax and HCT than males. The upper lethal temperatures (ULT50) measured in the absence of plant material were not significantly different among the planthopper species. The planthoppers also exhibited different behaviors in an increasing temperature regime, with fewer insects dropping-off from the plant in SBPH than in BPH and WBPH. These results indicate that SBPH and BPH are more heat tolerant than WBPH. The findings highlight the biological divergence in closely related planthopper species and the importance of performing the heat tolerance measurement in an ecologically relevant setting, which serves to predict seasonal and spatial occurrence patterns of the destructive planthopper species.

Seasonal Change in Distribution and Heat Coma Temperature of Oceanic Skaters, Halobates (Insecta, Heteroptera: Gerridae).

A series of studies were conducted during two cruises between Tokyo and Honolulu in September 2010 and from February to March 2012. The aims of the studies were to (1) compare the distribution of three species of Halobates oceanic skaters, H. germanus, H. micans, and H. sericeus, with respect to their temperature limits; (2) identify the lower temperature limit of H. sericeus, the species that displays the widest distribution range (40°N–35°S) latitude; and (3) test the hypothesis that H. sericeus can change their temperature tolerance to adapt to seasonal changes in sea surface temperatures. The heat coma temperature (HCT) was measured during the two cruises and the values were compared between the two populations of H. sericeus. The species collected in September 2010 were H. germanus, H. micans, and H. sericeus. H. sericeus was dominant, occupying more than 90% of the collecting sites. H. germanus and H. micans were collected in the northern and western part of the cruise track (29–34°N, 141–151°E), and not in the southern and eastern part. The population density of these two species was 9000–150,000/km2 in the first cruise, which took place in summer. On the other hand, H. sericeus was collected throughout the cruise track during that cruise. The population density of H. sericeus was relatively high, at 4000–310,000/km2, in the southern and eastern part of the cruise track (19–29°N, 152°E–165°W). In February and March 2012, only H. sericeus was collected at a density of 17,000–80,000/km2 and only in the eastern and southern part, at 25°–28°N, 169°E–178°W. No Halobates oceanic skaters were found in the western or northern part (30°N and further north, 159°E and further west) during that cruise. The lower limit for the inhabitation of sea surface temperatures appeared to be 27.8 °C or slightly lower for H. germanus and H. micans, but was 22.1 °C or slightly lower for H. sericeus. H. sericeus specimens, mostly adults, that had been collected during the two cruises were used in heat coma experiments. Summer specimens showed significantly higher heat coma temperatures (HCTs) than the winter specimens. This difference in HCTs may be the result of relatively long term temperature acclimation in the summer or winter for the adults that inhabit the temperate and subtropical areas along the cruise tracks between Tokyo and Honolulu in the Pacific Ocean. This temperature plasticity of H. sericeus may be related to the wider latitude area inhabited by this species (main range: 40°N–25°S).

Limited thermal acclimation capacity in cave beetles

Thermal tolerance is a key vulnerability factor for species that cannot cope with changing conditions by behavioural adjustments or dispersal, such as subterranean species. Previous studies of thermal tolerance in cave beetles suggest that these species may have lost some of the thermoregulatory mechanisms common in temperate insects, and appear to have a very limited thermal acclimation ability. However, it might be expected that both thermal tolerance and acclimation ability should be related with the degree of specialization to deep subterranean environments, being more limited in highly specialized species. To test this hypothesis, we use an experimental approach to determine the acclimation capacity of cave beetles within the tribe Leptodirini (family Leiodidae) with different degrees of specialization to the deep subterranean environment. For this, we acclimate groups of individuals at a temperature close to their upper thermal limit (20ºC) or a control temperature (approximately that of the cave in which they were found) for 2 or 10 days (short- vs. long-term acclimation). a temperature close to their upper thermal limit (20ºC) or a control temperature (approximately that of the cave in which they were found) for 2 or 10 days (short- vs. long-term acclimation). Upper thermal limits (heat coma temperature, HC) are then measured for each individual using a ramping protocol (rate of increase of 1ºC/min) combined with infrared thermography and video recording. Preliminary results in a deep subterranean species (Speonomidius crotchi, with an intermediate degree of specialization) showed no significant effect of acclimation temperature in HC at any of the exposure times. Such reduced thermal plasticity could be also expected for other highly specialized subterranean species. The potential implications of these findings for subterranean biodiversity in a climate change context are discussed.

Temperature Acclimation Ability by an Oceanic Sea Skater, Halobatesgermanus, Inhabiting the Tropical Pacific Ocean.

Temperature acclimation and heat shock experiments were performed on adult oceanic skaters, Halobates germanus, inhabiting the tropical Pacific Ocean. Acclimation for 10 or 24 h to 25 °C or 28 °C promoted significantly lower cool coma temperatures by specimens than acclimation to 31 °C. After heat shock by exposure to the relatively moderate temperature of 32.5 °C for 12 h, 52.9% or 61.1%% of specimens died in the 24 h period following acclimation at 28 °C or 31 °C, respectively, whereas all survived when there was no experience of heat shock. The average cool coma temperature was 14 to 17 °C in the specimens which had suffered no heat shock, whereas it was much higher (22 to 23 °C) in specimens that had suffered heat shock. The lower survival rate and the higher cool coma temperature can be attributed to damage suffered by exposure to 32.5 °C. The upper limit of the surface water temperature in the tropical ocean (15° N to 15° S) is currently around 30 to 31 °C, and Halobates appear to have no experience in 32 to 33 °C environments. Nevertheless, 32 °C, i.e., a temperaturethat is only slightly higher than 30 to 31 °C, may occur in the future due to global warming. This species may develop resistance to 32 to 33 °C in the near future.

Gas flow in near surface comet like porous structures: Application to 67P/Churyumov-Gerasimenko

We performed an investigation of a comet like porous surface to study how sub-surface sublimation with subsequent flow through the porous medium can lead to higher gas temperatures at the surface. A higher gas temperature of the emitted gas at the surface layer, compared to the sublimation temperature, will lead to higher gas speeds as the gas expands into the vacuum thus altering the flow properties on larger scales (kilometres away from the surface). Unlike previous models that have used modelled artificial structures, we used Earth rock samples with a porosity in the range 24–92% obtained from X-ray micro computed tomography (micro-CT) scans with resolution of some μm. Micro-CT scanning technology provides 3D images of the pore samples. The direct simulation Monte Carlo (DSMC) method for the rarefied gas dynamics is directly applied on the digital rock samples in an unstructured mesh to determine the gas densities, temperatures and speeds within the porous medium and a few centimetres above the surface. The thicknesses of the rock samples were comparable to the diurnal thermal skin depth (5 cm). H2O was assumed to be the outgassing species. We correlated the coma temperatures and other properties of the flow with the rock porosities. The results are discussed as an input to analysis of data from the Microwave Instrument on Rosetta Orbiter (MIRO) on the 67P/Churyumov- Gerasimenko.

Thermal acclimation capacity of Jack Beardsley mealybug (Pseudococcus jackbeardsleyi) to survive in a warming world

Abstract The study of thermal tolerance and acclimation capacity in Jack Beardsley mealybug, Pseudococcus jackbeardsleyi Gimpel and Miller is the crucial step in determining their abilities to cope with climate change. Thus, the aim of this research was to determine the effects of acclimation temperatures on the changes in thermal tolerance of P. jackbeardsleyi. The influences of acclimation temperature at moderate (25 °C) and high (35 °C) temperatures on their lower and upper thermal limits were measured composed of critical thermal minimum (CTmin), maximum (CTmax), chill coma temperature (CCT) and heat coma temperature (HCT) for first instar nymphs and adults. The important information derived from this study revealed that the upper thermal limits of adults are constrained to a relative narrow range that will make them sensitive to relative small changes in temperatures, whilst all mean upper thermal indices at 35 °C were significantly higher than at 25 °C for nymphs. For this highlight notice, nymphs have more potential to change their upper thermal limits which will allow them to withstand high temperatures in the field. These results are a sign to warn us that P. jackbeardsleyi could become highly noxious which cause severe outbreaks damage to the crops in the tropics under global warming.

Heat Coma Temperature and Supercooling Point in Oceanic Sea Skaters (Heteroptera, Gerridae).

Heat coma temperatures (HCTs) and super cooling points (SCPs) were examined for nearly 1000 oceanic sea skaters collected from in the Pacific and Indian Oceans representing four Halobates species; H. germanus, H. micans, H. sericeus, and H. sp. Analysis was conducted using the entire dataset because a negative correlation was seen between the HCTs and SCPs in all four species. A weak negative correlation was seen between HCTs and SCPs with a cross tolerance between warmer HCTs and colder SCPs. The weakness of the correlation may be due to the large size of the dataset and to the variability in ocean surface temperature. The negative correlation does however suggest that oceanic sea skaters may have some form of cross tolerance with a common physiological mechanism for their high and low temperature tolerances.

Relationship between Cool Coma and Heat Coma Temperatures in the Oceanic Sea Skaters Halobates Collected near the Sumatra Island in the Indian Ocean

In the cruise, MR15-04 by R/V MIRAI, the samplings by the neuston net were performed in 23rd November to 14th December 2016 and three species of Halobates (H. germanus, H. micans, H. sp) were used for the temperature tolerance experiments after the collection. The neuston net was towed three times (3 × 15 min) on the starboard side of R/V MIRAI on the water surface with ship speed of 2 knot to water every 3 nights (19:00 - 20:00) at the fixed point in the south-western direction which was located at 50 km from the Sumatra island (4o03'S - 4o05'S, 101o53'E) in the Indonesia. Experiments on cool coma and heat coma were performed on the three species. Seconds for recovery from cool coma and heat coma were also examined on the Halobates in this study. Cool coma temperatures, gap temperature needed (temperature from the adapted temperature) for the cool coma and seconds for the recover from cool coma ranged 13.0oC to 25.0oC, 3.1oC to 16.1oC, 1 second to 4370 seconds, respectively. Heat coma temperature, gap temperature needed for the heat coma, seconds for the recover from heat coma ranged 29.4oC to 43.1oC, 1.9oC to 15.5oC, 2 seconds to 6420 seconds, respectively. The higher temperature of cool coma temperature during the last five days was shown when Madden-Julian Oscillation has passed over the ship, R/V MIRAI than the previous 10 days in the adults of H. germanus collected at the fixed place neat to Sumatra island (One way ANOVA: F-value = 2.314, df = 7, p = 0.028). Adults of un-described species, H. sp collected near to the Sumatra island, showed lower cool coma temperature [Mean ± SD: 15.51 ± 3.76 (9)] than those of H. germanus collected in the same place [16.96 ± 2.57 (191)]. This lower cool coma temperatures shown by this un-described species might be related to that this species should be a “shore” species inhabiting shore water in which many precipitation could cause the decreased surface temperature from 30oC - 31oC into about 25oC. Most of adults which suffered from the cool coma recovered within 20 seconds, whereas adults which suffered heat coma at 38oC and 39oC needed more than 200 seconds for the recovery and many of those which did it at more than 40oC needed more than 1000 second and some ones did not recover at all. All adults who suffered at more than 43oC did not recover at all. There were significant and negative correlation between cool and heat coma temperatures shown by the adults of H. germanus. This correlation might imply a common physiological mechanism for lower and higher temperature tolerances for this species.

Exposure to solar radiation drives organismal vulnerability to climate: Evidence from an intertidal limpet

Understanding the physiological abilities of organisms to cope with heat stress is critical for predictions of species’ distributions in response to climate change. We investigated physiological responses (respiration and heart beat rate) of the ectotherm limpet Patella vulgata to heat stress events during emersion and the role of seasonal and microclimatic acclimatization for individual thermal tolerance limits. Individuals were collected from 5 microhabitats characterized by different exposure to solar radiation in the high intertidal zone of a semi-exposed rocky shore in winter and summer of 2014. Upper thermal tolerance limits (heat coma temperatures – HCTs, and heart rate Arrhenius break temperatures - ABTs) were determined for individuals from each microhabitat in both seasons under laboratory conditions. While we found a clear seasonal acclimatization, i.e., higher HCTs and ABTs in summer than in winter, we did not find evidence for microhabitat-specific responses that would suggest microclimatic acclimatization. However, operative limpet temperatures derived from in-situ temperature measurements suggest that individuals from sun exposed microhabitats have a much narrower thermal safety margins than those from less exposed surfaces or within crevices. Microhabitat specific thermal safety margins caused by high thermal heterogeneity at small spatial scales and the lack of short term acclimatization will likely shape small scale distribution patterns of intertidal species in response to the predicted increase in the frequency and intensity of heat waves.