Overwintering Behavior Research Articles

European Culex pipiens Populations Carry Different Strains of Wolbachia pipientis.

The mosquito Culex pipiens occurs in two ecotypes differing in their mating and overwintering behavior: pipiens mate in open environments and diapause, and molestus also mate in small spaces and is active throughout the year. Cx. pipiens carry Wolbachia endosymbionts of the wPip strain, but the frequency of infection differs between studied populations. Wolbachia infection affects the host reproductive success through cytoplasmic incompatibility. wPip Wolbachia is divided into five types, wPip I-V. The type of wPip carried varies among Cx. pipiens populations. In northern European locations different wPip types are found in the two ecotypes, whereas in southern locations, they often carry the same type, indicating differences in hybridization between ecotypes. In this study, Cx. pipiens specimens of both ecotypes were collected from Sweden and compared to specimens from Norway, England, Italy, and the Netherlands, as well as Cx. quinquefasciatus from Mali and Thailand. The abundance varied, but all specimens were infected by Wolbachia, while the tested specimens of other mosquito species were often uninfected. The wPip strains were determined through the sequence analysis of Wolbachia genes ank2 and pk1, showing that Cx. pipiens ecotypes in Scandinavia carry different wPip strains. The observed differences in wPip strains indicate that hybridization is not frequent and may contribute to barriers against hybridization of the ecotypes in Sweden and Norway.

Differences in adult nutritional requirements impact the population growth and survival of two related species of rice leaffolders to produce interspecific differentiation

Nutrition is a limiting feature of species evolution. The differences in nutritional requirements are the evolutionary result of differential adaptations to environmental changes, explaining differences in their ecological traits. Cnaphalocrocis medinalis and Cnaphalocrocis exigua, two related species of rice leaffolders, have similar morphology and feeding properties but different migration and overwintering behaviors. However, it is unclear whether they have evolved adult nutritional differentiation traits to coexist. To explore this issue, this study examined the effects of carbohydrates and amino acids on their reproductive and demographic parameters. The findings indicate that carbohydrate intake prolonged the longevity and population growth of two rice leaffolders, but amino acid intake promoted egg hatching only. However, nutrient deficiency made it impossible for C. medinalis to reproduce successfully and survive, but it did not affect C. exigua. The population expansion and survival of migratory C. medinalis relied on adult nutritional intake. Conversely, the nutrients necessary for C. exigua overwintering activity mostly came from the storage of larvae. The difference in nutritional requirements for population growth and survival between the two rice leaffolders partially explained their differences in migration and overwintering.

Understanding the temporal dynamics of a lowland river fish community at a hazardous intake and floodgate to inform safe operation

Entrainment and mortality of freshwater fish at hazardous pumping station intakes used for Flood Risk Management (FRM) are of global concern. Although upstream and downstream passage of diadromous fish has received considerable attention, the ecological behaviours of river-resident fish at these structures and how to protect these species from entrainment is poorly-understood. At a lowland flood-relief pumping station and floodgate situated off-channel (River Foss) to the main-river Yorkshire Ouse (York, England), multi-beam sonar (Dual-Frequency Identification Sonar: DIDSON) was used over a pluriannual (three years) period to investigate diel movements of river-resident fish in response to the variations in temperature, hydrology and pump and floodgate operation, and to determine fish-friendly management options. Diel lateral movements of thousands of river-resident fish between the main-river, floodgate operated channel (River Foss) and off-channel pump forebay were predominantly during the crepuscular period and daytime, proposing important considerations for when managers should operate pumps and associated flood infrastructure. Seasonal diel movements increased throughout winter during a baseline year (no pump operation) and overwintering behaviour was influenced by cooling river temperatures. A Generalized Linear Mixed Model (GLMM) revealed fish entered the off-channel forebay when river levels were stable and not when they were rising or falling, suggesting hydrological stability was important for the ecological function of this fish community. Two years of impact data (pumps operated) then revealed pump operations severely disrupted the ecological functions of local fish populations, which was also uniquely quantified over two independent 24h periods during which temporal fish counts were reduced by 85%. A trial period where the floodgate was lowered ahead of dawn significantly reduced fish immigration into the hazardous forebay when compared to two different hydrological periods. Modifying when the floodgate and pumps operate, including lowering the floodgate ahead of fish immigration at dawn, and starting pumps during the night (but not day), are therefore promising non-engineered management options to prevent immigration of fish into the hazardous off-channel pump forebay and to reduce entrainment and mortality risk during pump operation.

Overwintering aggregation patterns of European catfish Silurus glanis

Animal aggregation, particularly in large-bodied species, is both a fascinating and intriguing phenomenon. Here we analyzed the overwintering behavior of the European catfish, Silurus glanis Linnaeus, 1758, the largest freshwater fish in Europe. By tracking 47 subadults and adults in a shallow lake in southeastern France, we reported a consistent aggregative behavior across four successive winters. By implementing time series analysis and Cox proportional hazard models, we investigated the dynamics of these aggregations (formation, stability, dislocation), and the factors that govern it, whether external (temperature, time of the day) or specific to the fish (size, key individuals). These aggregations lasted 1.5–2 months and mainly took place in a single small 4 m-deep area whose environmental conditions (temperature, oxygen, substrate) did not differ from other parts of the lake. In some periods during winter, all tagged fish were aggregated, which suggests that a large proportion of the lake population gathered there. Low temperatures (below 9 °C) triggered the formation of aggregations. They became more stable with decreasing temperatures, while individuals more frequently left the aggregation, preferentially at dusk and at night, when temperatures increased. The largest individuals swam more frequently back and forth to the aggregation. Irrespective of their size, some individuals consistently arrived earlier in the aggregation in winter and left later. This predictable seasonal grouping of individuals and, more generally, the knowledge provided by such studies on how species use space have important operational value and are useful for species conservation as well as for species control.

Hibernation in Reeves' Turtles (Mauremys reevesii) in Qichun County, Hubei Province, China: Hibernation Beginning and End and Habitat Selection.

Hibernation protects turtles from extreme winter conditions. Reeves' turtle (Mauremys reevesii) is a medium-sized aquatic turtle that lives in freshwater habitats in lowland areas with still or slowly moving water. Currently, little is known regarding its overwintering behavior. In the current study, 20 Reeves' turtles from the wild were investigated using radiotelemetry in the field to determine the beginning and end dates of, and habitat selected for, hibernation. Hibernation began in late October 2021 and arousal began in March 2022. Reeves' turtles do not appear to be limited in their selection of suitable hibernation habitats, which included fish ponds, abandoned ponds (ponds not being used for farming), marshes, and abandoned fields (fields not being used for farming). In the aquatic hibernation habitats, only herbage cover was significantly different between the selected and random habitats (t = 2.525, df = 9, p = 0.033). In the terrestrial hibernation habitats, there were significant differences in the canopy (Z = -2.201, p = 0.028), slope gradient (Z = -2.032, p = 0.042), herbage cover (Z = -2.379, p = 0.017), and distance from the habitat edge (Z = -2.524, p = 0.012) between the selected and random habitats. This indicates that Reeves' turtles prefer to hibernate at the soft edges of flat habitats with low canopy and high herbage cover when hibernating in terrestrial habitats and prefer to hibernate at sites with high herbage cover when hibernating in aquatic habitats. To the best of our knowledge, this is the first study to investigate hibernation in wild Reeves' turtles in the field, and the results identify key ecological variables correlated with habitat selection during hibernation. This knowledge could inform local conservation measures related to farming activities.

Winter torpor expression varies in four bat species with differential susceptibility to white-nose syndrome

Studies examining the overwintering behaviors of North American hibernating bats are limited to a handful of species. We deployed temperature-sensitive transmitters on four species of bat that exhibit differences in their susceptibility to white nose syndrome (WNS; Myotis grisescens, M. leibii, M. sodalis, and Perimyotis subflavus) to determine if these differences are correlated with behavior exhibited during hibernation (i.e., torpor expression and arousal frequency). Mean torpor skin temperature (Tsk) and torpor bout duration varied significantly among species (P ≤ 0.024), but arousal Tsk and duration did not (P ≥ 0.057). One of the species with low susceptibility to WNS, M. leibii, had significantly shorter torpor bout durations (37.67 ± 26.89 h) than M. sodalis (260.67 ± 41.33 h), the species with medium susceptibility to WNS. Myotis leibii also had significantly higher torpor Tsk (18.57 °C ± 0.20) than M. grisescens (13.33 °C ± 0.60), a second species with low WNS susceptibility. The high susceptibility species, Perimyotis subflavus, exhibited low torpor Tsk (14.42 °C ± 0.36) but short torpor bouts (72.36 ± 32.16 h). We demonstrate that the four cavernicolous species examined exhibit a wide range in torpid skin temperature and torpor bout duration. Information from this study may improve WNS management in multispecies hibernacula or individual species management by providing insight into how some species may differ in their techniques for overwinter survival.

The Milieu Souterrain Superficiel as hibernation habitat for bats: implications for white-nose syndrome.

Recent studies have revealed that western populations of little brown bats (Myotis lucifugus) in North America exhibit different hibernation behavior than their eastern counterparts. Understanding these differences is essential for assessing the risk white-nose syndrome (WNS) poses to western bat populations. We used acoustic monitoring and radiotelemetry to study the overwintering behavior of little brown bats near Juneau, Alaska during 2011–2014. Our objectives were to identify the structures they use for hibernation, measure the microclimates within those structures, and determine the timing of immergence and emergence and the length of the hibernation season. We radiotracked 10 little brown bats to underground hibernacula dispersed along two ridge systems. All hibernacula were ≤ 24.2 km from where the bats were captured. Eight bats hibernated in the “Milieu Souterrain Superficiel” (MSS), a network of air-filled underground voids between the rock fragments found in scree (talus) deposits. Two bats hibernated in holes in the soil beneath the root system of a tree or stump (rootball). At least two hibernacula in the MSS were reused in subsequent years. Average MSS and rootball temperatures were warmer and more stable than ambient temperature and were well below the optimal growth range of the fungus that causes WNS. Temperatures in the MSS dropped below freezing, but MSS temperatures increased with depth, indicating bats could avoid subfreezing temperatures by moving deeper into the MSS. Relative humidity (RH) approached 100% in the MSS and under rootballs and was more stable than ambient RH, which also was high, but dropped substantially during periods of extreme cold. Acoustic monitoring revealed that bats hibernated by late October and began emerging by the second week of April; estimates of minimum length of the hibernation season ranged from 156 to 190 days. The cold temperatures, dispersed nature of the hibernacula, and close proximity of hibernacula to summering areas may slow the spread and reduce the impacts of WNS on local populations of little brown bats.

Overwintering behavior reduces mortality for a terrestrial turtle in forests managed with prescribed fire

Prescribed fire is an essential management practice in pyrogenic ecosystems, but fire can also be a significant disturbance and source of mortality for both target and non-target species. Seasonal periods of animal inactivity may provide opportunities to design burn plans that minimize negative impacts to species of conservation concern, but few studies have rigorously examined this possibility. Using radiotelemetry, we studied overwintering behavior and interactions with fire in a forest-dwelling terrestrial turtle, the Eastern Box Turtle (Terrapene carolina carolina), over an eight-year period at two sites that use prescribed fire in forest management. Turtles at both sites selected predominantly hardwood forests and mesic habitats and avoided upland pine forests. Turtles buried deepest (2.9 – 3.2 cm) below the soil-litter interface in late February and then moved gradually shallower until emergence in early April. Emergence timing varied over a 58-day period, but was consistent within individuals from year to year. Turtles also maintained fidelity to refuge locations, but those overwintering in burned areas selected sites over twice as far from refuges used in previous years compared to those in unburned areas. The areas and habitats selected by turtles during winter served as refugia from fire, and those whose refuges did burn remained buffered from lethal temperatures even at shallow burial depths. The only fire-related injury or mortality occurred during seasons of surface activity. Timing burning and other forest management practices during periods of winter dormancy may thus minimize threats to turtle populations, but modifications to prescribed fire regimes must also be balanced with other management objectives.

Seasonal estuarine movements of green crabs revealed by acoustic telemetry

Green crabsCarcinus maenasare considered among the most influential invasive species in temperate estuaries worldwide. Yet management can be hindered by the lack of high-resolution data on green crab movement ecology. We addressed this knowledge gap by coupling passive acoustic telemetry and water quality monitoring to examine daily and seasonal movements of individual green crabs in the Webhannet River Estuary (Maine, USA). We tracked 22 adult green crabs (mean [±SD] carapace width = 63.8 ± 6.5 mm) between 2 successive tagging deployments from July 2018-January 2019, with one receiver maintained until mid-April 2019. Overall, our study demonstrated the viability of using acoustic telemetry to assess seasonal movements of green crabs, with an average (±SE) individual detection rate of 27.9 ± 2.8 detections h-1from July-January. Most crabs remained localized to very specific regions of the estuary, with each region representing a 300-600 m linear distance. Logistic regression models indicated that movements by green crabs to the downstream area were associated with a shift in temperature below 10°C, regardless of sex. From January-April 2019, 9 crabs were found to overwinter in the downstream area, potentially taking refuge in deeper waters. Movement patterns identified in this study further contribute to our understanding of the distances traveled and the areas used by green crabs, as well as further resolve overwintering behavior with consequences for mortality risk due to low temperatures. This additional knowledge of adult green crab movement and dispersal dynamics is valuable to resource managers considering intervention strategies.

Formation of overwintering aggregation of Halyomorpha halys (Hemiptera: Pentatomidae) in laboratory conditions

AbstractOverwintering aggregations of Halyomorpha halys (Hemiptera: Pentatomidae) in human‐made structures cause nuisance problems and enable this pest to invade new countries. Therefore, understanding the overwintering aggregation behaviors of H. halys would serve as a basis to mitigate these pest problems. In this study, we induced adult H. halys to exhibit overwintering behaviors in laboratory conditions and assessed how this pest responded to a potential overwintering structure and settled in the structure over 24 hours. A potential overwintering micro‐habitat was provided to H. halys in reproductive diapause by establishing a 5‐mm gap between two acrylic panels facing each other. This experimental arena was kept in a cage at 11°C, 12:12 (L:D), and 30% relative humidity (RH). A total of 50 adults (sex ratio = 1:1) was released into the cage for each replication. First, more females than males crawled into the 5‐mm gap and settled in the experimental arena: the proportion of females having settled in the arena was 68.64 ± 3.03%. Second, when H. halys were settling in the arena, they did not significantly synchronize their dorsal or ventral side directions with other individuals. Third, H. halys tended to settle in the lower section of the experimental arena. Finally, 69.1 ± 3.9% of overwintering H. halys were found to settle solitarily, not touching other individuals in the experimental arena. Further studies are warranted to validate our results in semi‐field conditions in which more H. halys are released and monitored for longer times.

Seasonal morphotypes of Drosophila suzukii differ in key life-history traits during and after a prolonged period of cold exposure.

Seasonal polyphenism in Drosophila suzukii manifests itself in two discrete adult morphotypes, the “winter morph” (WM) and the “summer morph” (SM). These morphotypes are known to differ in thermal stress tolerance, and they co‐occur during parts of the year. In this study, we aimed to estimate morph‐specific survival and fecundity in laboratory settings simulating field conditions. We specifically analyzed how WM and SM D. suzukii differed in mortality and reproduction during and after a period of cold exposure resembling winter and spring conditions in temperate climates. The median lifespan of D. suzukii varied around 5 months for the WM flies and around 7 months for the SM flies. WM flies showed higher survival during the cold‐exposure period compared with SM flies, and especially SM males suffered high mortality under these conditions. In contrast, SM flies had lower mortality rates than WM flies under spring‐like conditions. Intriguingly, reproductive status (virgin or mated) did not impact the fly survival, either during the cold exposure or during spring‐like conditions. Even though the reproductive potential of WM flies was greatly reduced compared with SM flies, both WM and SM females that had mated before the cold exposure were able to continuously produce viable offspring for 5 months under spring‐like conditions. Finally, the fertility of the overwintered WM males was almost zero, while the surviving SM males did not suffer reduced fertility. Combined with other studies on D. suzukii monitoring and overwintering behavior, these results suggest that overwintered flies of both morphotypes could live long enough to infest the first commercial crops of the season. The high mortality of SM males and the low fertility of WM males after prolonged cold exposure also highlight the necessity for females to store sperm over winter to be able to start reproducing early in the following spring.

The spatial ecology of brown trout (Salmo trutta) and dace (Leuciscus leuciscus) in an artificially impounded riverine habitat: results from an acoustic telemetry study

Determining where fish are distributed across days and seasons is valuable for understanding their ecology, evolution and conservation. The results presented here provide insight into the spatial and temporal distribution of brown trout (native salmonid species) and dace (invasive cyprinid species) in an artificially impounded section of lowland river, demonstrating that both species remain relatively local to their release point and do not exhibit wide-ranging movements from late summer into winter. Commonalities in the movement patterns were observed between the species despite their contrasting life histories, but there were also important differences observed both in their home range and activity patterns over the duration of the study. In general dace were much more active than trout. Both trout and dace exhibited clear crepuscular peaks in movement with higher displacement rates being observed during dawn and dusk periods which remained consistent over the duration of the study. Both species exhibited a high residency which may be a direct result of the artificial barrier present, promoting residency. Trout showed a significant increase in displacement rates and a drop in residency in November which may represent putative spawning behaviour. In general home range sizes remained stable over the tracking period for both species. Home range size was affected by fish length for both species, with larger individuals being more localised then smaller individuals. We propose that the diel patterns observed are primarily driven by foraging activity and opportunity which changes with seasonal influences and onset of potential spawning period and/or overwintering behaviour. This study demonstrates how data derived from telemetry studies can reveal movement behaviours of fish species associated with undertaking basic ecological requirements (feeding, shelter etc.) which are regulated by variation in the environment. Understanding the interplay between the environment and an animal’s behaviour is important from a conservation management perspective with increasing environmental pressures and predicted regime changes. From a fishery management viewpoint these data can feed into stock status monitoring in difficult to monitor impounded lowland riverine habitat and also increase our understanding of how potential human induced changes affect fish populations.

Overwintering behaviour of Diphyus quadripunctorius (Müller) (Hymenoptera: Ichneumonidae, Ichneumoninae) in south-east Scotland

Overwintering behaviour of adult females of the ichneumonid Diphyus quadripunctorius (Müller) in caves and mines in south east Scotland was monitored over two successive winters. This is a univoltine larva-pupal parasitoid of certain Noctua species, parasitizing their larvae in spring. The species was found in rather few of the sites investigated, but in one site in particular it was numerous. There the species was present over the period mid-July until the end of March. It remained semi-active through the winter in all these subterranean sites, some of which were prone to flooding. The ambient temperatures were always well above freezing, which probably allowed the insects to move to safety, although some drowned individuals were found. Wider data drawn from the National Museums of Scotland collection suggest that, in S. Europe as well as in Britain, D. quadripunctorius enters the sites in which it will eventually overwinter rather soon after emergence from its host pupae in early to mid-summer.

Lethal Effects of High Temperatures on Brown Marmorated Stink Bug Adults before and after Overwintering.

The invasive brown marmorated stink bug, Halyomorpha halys, is causing economic and ecological damage in invaded areas. Its overwintering behavior warrants mitigation practices in warehouses and shipping operations. The aim of this study was to characterize the mortality response curves of H. halys adults to short high-temperature exposure. Here we compared field-collected individuals entering (ENA) and exiting diapause (EXA). EXA adults displayed increased susceptibility to high temperatures compared to ENA individuals. Complete mortality of all tested individuals was obtained after 10 min exposure at 50.0 °C, and after 15 (EXA) or 20 min (ENA) at 47.5 °C. The nutritional status of these insects had no effect on high-temperature tolerance. The mortality curves obtained here may be used for the definition of cost-effective heat treatments aimed at the H. halys control.

Changing Migratory Behaviors and Climatic Responsiveness in Birds

Change of avian migratory behavior is one of the best-studied phenomena presumably associated with contemporary climate change, yet to what degree these behavioral changes represent responses to climate warming is still controversial. We investigated the inter-specific variation in change of migratory behavior over three decades at a Central-European site, testing whether the type and extent of such changes are predicted by the species’ responsiveness to short-term variation in large-scale climatic indices. We found that species with earlier arrivals after winters with higher North-Atlantic Oscillation indices were more likely to overwinter at the study site; this behavior was more frequent in the second than in the first half of the study, although the extent of this change was not predicted quantitatively by short-term climatic responsiveness. Overwintering was more prevalent in short-distance migrants with more complex diets and larger population sizes. Furthermore, species arriving earlier after summers with higher Sahel rainfall indices increasingly advanced their first arrival date, whereas species that do not molt in the pre-breeding season increased their frequency of overwintering in more recent years. Our results demonstrate that interspecific variation in short-term climatic responsiveness predicts long-term changes in migratory behaviors, supporting that the latter are responses to climate change. Furthermore, the type of response (advancing arrivals or overwintering near the breeding grounds) depends on life history. Finally, we found that overwintering behavior during the study period predicted subsequent trends in population size, suggesting that information on temporal changes in migratory strategy may help conservation planning and risk assessment.

Effect of overwintering on survival and vector competence of the West Nile virus vector Culex pipiens

BackgroundWest Nile virus (WNV) is a mosquito-borne virus that is mainly transmitted among birds by Culex pipiens mosquitoes. The species Cx. pipiens consists of two biotypes named pipiens and molestus, which together can form hybrids. One of the major distinctions between the biotypes is their overwintering behaviour. Adults of biotype pipiens diapause during winter, whereas biotype molestus remains actively blood-feeding. Diapausing may affect survival and vector competence of biotype pipiens. The aims of this study were therefore to identify the biotype composition of diapausing Cx. pipiens mosquitoes, to quantify survival throughout the autumn and winter months, and to determine effects of overwintering on vector competence of emerging Cx. pipiens mosquitoes for WNV.MethodsDiapausing mosquitoes were collected at two typical overwintering locations in the Netherlands. A selection of Cx. pipiens mosquitoes was identified to biotype using real-time PCR. Survival of diapausing Cx. pipiens mosquitoes during autumn and winter was monitored by placing cages with either field-collected or laboratory-reared females in houses and sheds. Vector competence of field-collected (diapausing) and laboratory-reared (non-diapausing) Cx. pipiens mosquitoes was determined to gain insight in the effect of overwintering on WNV transmission.ResultsThe majority (92%) of diapausing Cx. pipiens females were identified as biotype pipiens. More than 70% of diapausing Cx. pipiens mosquitoes was able to survive for more than four months in sheds, whereas diapausing in houses resulted in 100% mortality in that same period. In contrast, non-diapausing Cx. pipiens biotype pipiens mosquitoes reared in the laboratory died within a week in both houses and sheds. Vector competence of Cx. pipiens mosquitoes that had diapaused during the autumn and winter months was comparable to non-diapausing laboratory-reared mosquitoes.ConclusionsThis study confirms that the majority of Cx. pipiens mosquitoes in their typical overwintering site belongs to the pipiens biotype. It shows that more than two-third of diapausing Cx. pipiens mosquitoes is able to survive winter under sheltered winter conditions. Finally, vector competence for WNV of mosquitoes that emerge from overwintering sites is not affected by their relatively old age.

Responses of Overwintering Halyomorpha halys (Hemiptera: Pentatomidae) to Dead Conspecifics.

Overwintering brown marmorated stink bugs (Halyomorpha halys) (Stål) are a notable domestic nuisance. In addition to disruptive activity, dead individuals remain in homes, sometimes in large numbers. To better understand the effects of these remains on overwintering behavior, adult H. halys were subjected to several experiments to test their responses to dead conspecifics. In non-tactile tests of individuals exposed to groups of dead conspecifics, H. halys did not respond to 1-yr-old desiccated dead conspecifics, but avoided corpses that were freshly killed. In tactile tests of individuals exposed to groups of dead conspecifics, H. halys joined those corpse aggregations significantly more often than not, and preferred corpses to cotton when given a choice. In tests of exposure of overwintering individuals to fresh dead conspecifics over the course of a winter, no necrophagy or evidence of survival advantage was observed, but overall females had higher survival rates than males.

Characterization of Overwintering Behaviors and Sites of Bean Bug, Riptortus pedestris (Hemiptera: Alydidae), Under Laboratory and Field Conditions.

Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) is a major agricultural pest on leguminous plants and tree fruit in South Korea and Japan. Only anecdotal information is currently available about its overwintering behavior and ecology. Therefore, we conducted laboratory experiments and field sampling to characterize overwintering structures and landscapes that R. pedestris use and prefer in South Korea. Under laboratory conditions, we identified the overwintering structure preference of R. pedestris adults and analyzed their spatial distributions. Among tested structures including pile of rocks, rotten wood, and leaf litter, R. pedestris was almost exclusively found in leaf litter. Spatial analysis using Spatial Analysis by Distance IndicEs (SADIE) indicated that most overwintering R. pedestris showed no spatial-aggregation behavior in the test arena. Field surveys were also conducted to characterize overwintering landscapes during the two winter seasons between 2014 and 2016. We selected two distinct landscapes: mountain areas and agricultural areas. Mountain areas were high-elevation mountains remote from agricultural practice, whereas agricultural areas were low-elevation forested landscapes adjacent to agricultural fields, including soybeans. From the 2-yr field survey, 92% (11 out of 12 individuals) of overwintering R. pedestris were found in the agricultural area without a significant aggregation pattern.

High resting metabolic rates with low thermal dependence induce active dives in overwintering Pacific juvenile loggerhead turtles.

The metabolic rate and activity of sea turtles generally decreases with decreasing seasonal ambient temperature. Juvenile loggerhead turtles in the Mediterranean Sea made prolonged inactive dives (>400 min), indicating a state of dormancy during the cold winter period. However, seasonal differences in dive duration were not detected in juvenile loggerheads in the western North Pacific, even though the ambient water temperature changed by more than 10°C. Thus, metabolic states might differ among populations, explaining differences in the diving behaviour of juveniles during winter. Here, we tested the hypothesis that the active overwintering behaviour of juvenile loggerheads in the western North Pacific is driven by a high resting metabolic rate (RMR) with low thermal dependence. The RMR of juveniles in the western North Pacific (N=13) was 1.4-5.7 times higher (Q10=1.8) than that of juveniles in the Mediterranean Sea (Q10=5.4). To validate the high RMR values in the western North Pacific, the difference between core body temperature and ambient water temperature (ΔTb) was estimated from measured RMR and was compared with measured ΔTb The measured and estimated ΔTb matched each other. In addition, most of the dives conducted by the turtles in the western North Pacific were within the calculated aerobic dive limit (cADL) expected from the measured metabolic rate. Our results indicate that high RMR with low thermal dependence induces active diving during the overwintering periods of juvenile loggerheads in the western North Pacific, supporting the suggestion that metabolic states differ among populations.

Mapping the Potential Global Range of the Brown Marmorated Stink Bug, Halyomorpha halys, with Particular Reference to New Zealand

Originating from Asia, the brown marmorated stink bug (BMSB) is a significant pest of horticultural/agricultural crops, grapes, woody ornamental and herbaceous plants, and is also a nuisance to people, due to its overwintering behavior in human habitation. The global range of this pest is steadily increasing and previous predictions of environmental suitability have shown New Zealand to be highly suitable. Due to the economic value of horticultural and agricultural industries to the New Zealand economy, it is vital to understand the range of potential risk within the country. Global and New Zealand potential suitability for BMSB was modeled using three algorithms and the resulting predictions ensembled to predict the potential range under current climatic conditions and under trajectories of future low (Representative Concentration Pathways, RCP, 2.6) and high (RCP 8.5) greenhouse gas emissions for both 2050 and 2070. Under current conditions, models showed a high global suitability within latitudes 25°–50° N, southern South America, southeast and southwest regions of Australia and large areas of New Zealand. Modeling the effect of climate change on BMSB range in New Zealand resulted in a southerly range shift over time, particularly with high emissions trajectory. Currently, BMSB is not established in New Zealand and it is vital that this remains the case.