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Eastern North American monarch butterflies (Danaus plexippus) embark on a yearly migration between summer breeding grounds in the northern United States and southern Canada and overwintering sites in central Mexico, traveling up to 4300 km. This annual multi-generational migration cycle, like many seasonal natural phenomena, may be impacted by recent changes in climate and habitat. We investigated long-term trends in monarch abundance and fall migration timing over a 29-year period in Cape May, New Jersey, using data collected from daily population surveys designed to track patterns of occurrence during the fall migration period through Cape May (1 Sept-31 Oct). Between 1992 and 2020, the migration midpoint, average peak migration day and first peak migration day shifted between 16 and 19 days later in the season, an average of approximately six days per decade. This observed shift in migration timing is correlated with increasing temperatures in September and October in northeastern monarch breeding grounds over the study period. Our data do not demonstrate a significant directional trend in monarch abundance over the study period, yet population data collected at overwintering sites in Mexico indicate a substantial decline over the same period. Further postponement of fall migration may lead to lower migration success and exacerbate the overall decline of this iconic species.

Quantifying the responses of forest disturbances to climate warming is critical to our understanding of carbon cycles and energy balances of the Earth system. The impact of warming on bark beetle outbreaks is complex as multiple drivers of these events may respond differently to warming. Using a novel model of bark beetle biology and host tree interactions, we assessed how contemporary warming affected western pine beetle (Dendroctonus brevicomis) populations and mortality of its host, ponderosa pine (Pinus ponderosa), during an extreme drought in the Sierra Nevada, California, United States. When compared with the field data, our model captured the western pine beetle flight timing and rates of ponderosa pine mortality observed during the drought. In assessing the influence of temperature on western pine beetles, we found that contemporary warming increased the development rate of the western pine beetle and decreased the overwinter mortality rate of western pine beetle larvae leading to increased population growth during periods of lowered tree defense. We attribute a 29.9% (95% CI: 29.4%-30.2%) increase in ponderosa pine mortality during drought directly to increases in western pine beetle voltinism (i.e., associated with increased development rates of western pine beetle) and, to a much lesser extent, reductions in overwintering mortality. These findings, along with other studies, suggest each degree (°C) increase in temperature may have increased the number of ponderosa pine killed by upwards of 35%-40% °C-1 if the effects of compromised tree defenses (15%-20%) and increased western pine beetle populations (20%) are additive. Due to the warming ability to considerably increase mortality through the mechanism of bark beetle populations, models need to consider climate's influence on both host tree stress and the bark beetle population dynamics when determining future levels of tree mortality.

Knowing the distribution of migratory species at different stages of their life cycle is necessary for their effective conservation. For the Monarch butterfly (Danaus plexippus), although its overwintering distribution is well known, the available information on premigration distribution is limited to the studies estimating the natal origins of overwintering Monarchs in Mexico (i.e., postmigration data). However, the premigration distribution and the natal origins of overwintering Monarchs can be equivalent only if we assume that migrating Monarchs have the same mortality rate irrespective of their origins. To estimate Monarchs’ premigration distribution, we used data reported by community scientists before Monarchs start their fall migration, that is, before migration mortality, and controlled for sampling bias. Our premigration distribution map indicated that Minnesota, Texas, and Ontario are the states/provinces with the highest abundance of Monarch in North America. Although this higher estimated abundance can be related to the large sizes of these states/provinces, this information is still important because it identifies the management jurisdictions with the largest responsibility for the conservation of the premigration population of Monarchs. Our premigration distribution map will be useful in future studies estimating the rates, distribution, and causes of mortality in migrating Monarchs., Our paper provides the first quantitative estimate of the premigration distribution of Monarch butterflies across North America. Our results showed that Minnesota, Texas, and Ontario are the states/provinces with the highest abundance of Monarchs before they start their fall migration. This information is important because it identifies the management jurisdictions with the largest responsibility for the conservation of the premigration population of Monarchs. Our premigration distribution map will be useful in future studies estimating the rates, distribution, and causes of mortality in migrating Monarchs.

Declines in the abundance and diversity of insects pose a substantial threat to terrestrial ecosystems worldwide. Yet, identifying the causes of these declines has proved difficult, even for well-studied species like monarch butterflies, whose eastern North American population has decreased markedly over the last three decades. Three hypotheses have been proposed to explain the changes observed in the eastern monarch population: loss of milkweed host plants from increased herbicide use, mortality during autumn migration and/or early-winter resettlement and changes in breeding-season climate. Here, we use a hierarchical modelling approach, combining data from >18,000 systematic surveys to evaluate support for each of these hypotheses over a 25-yr period. Between 2004 and 2018, breeding-season weather was nearly seven times more important than other factors in explaining variation in summer population size, which was positively associated with the size of the subsequent overwintering population. Although data limitations prevent definitive evaluation of the factors governing population size between 1994 and 2003 (the period of the steepest monarch decline coinciding with a widespread increase in herbicide use), breeding-season weather was similarly identified as an important driver of monarch population size. If observed changes in spring and summer climate continue, portions of the current breeding range may become inhospitable for monarchs. Our results highlight the increasingly important contribution of a changing climate to insect declines.

Insect herbivores require a variety of habitats across their life cycle, with behavior often mediating transitions between life stages or habitats. Human management strongly alters urban habitats, yet herbivore behavior is rarely examined in cities. We review the existing literature on several key behaviors: host finding, feeding, egg placement and pupation location, and antipredator defense. We emphasize that unapparent portions of the life cycle, such as the habitat of the overwintering stage, may influence if urbanized areas act as population sources or sinks. Here, management of the soil surface and aboveground biomass are two areas with especially pressing research gaps. Lastly, high variability in urban environments may select for more plastic behaviors or greater generalism. We encourage future research that assesses both behavior and less apparent portions of insect life cycles to determine best practices for conservation and management.

Passive integrated transponder (PIT) tags allow a range of individual‐level data to be collected passively and have become a commonly used technology in many avian studies. Although the potential adverse effects of PIT tags have been evaluated in several species, explicit investigations of their impacts on small (, We investigated lethal (mortality) and nonlethal (body condition) effects of different two PIT tagging methods (implants or leg band embedded) compared with birds that were color banded but not fitted with PIT tags. In a sample of over 200 birds followed for more than two years, we found no evidence of differences in survival or body condition across any of these three treatments.

BACKGROUND: The tree-of-heaven root and trunk weevils, Eucryptorrhynchus scrobiculatus (TRW) and E. brandti (TTW) are important boring pests of Ailanthus altissima in China. Overwintering TRW and TTW adults can continue to damage A. altissima trees and reproduce after they emerge from the soil each year. There is a lack of studies regarding the development of control measures during the overwintering period. A polyethylene terephthalate bottle trap (PETBT) and corrugated paper box trap (CPBT) were evaluated for their ability to trap TRW and TTW adults descending from trees to overwinter in the soil in Wutongshu and Shabatou locations in Ningxia, China. This article is protected by copyright. All rights reserved. RESULTS: Significantly more overwintering TRW adults were caught by the PETBT than the CPBT. There were no significant differences in the TTW captures in PETBT when compared to the CPBT. Both PETBT and CPBT have little effect on trapping overwintering TTW adults. Further trapping studies showed that PETBT treatments significantly reduced overwintering TRW numbers caught in population monitoring trap nets placed on the A. altissima tree trunks (an average annual reduction of 42% than the untreated trees). CONCLUSION: These results demonstrate that PETBT is effective for trapping overwintering TRW adults. PETBT could be recommended as an alternative for managing TRW in the framework of integrated pest management. This article is protected by copyright. All rights reserved.

Monochamus alternatus alternatus Hope (Coleoptera: Cerambycidae) is the primary vector of pine wilt disease in China and Taiwan. It has a partially bivoltine life cycle with facultative diapause at the final larval instar that is mediated by the initial larval density. To evaluate the effect of density-related induction of diapause on population fluctuation, one, two or four newly hatched larvae were inoculated on individual Pinus thunbergii bolts and the life-history traits including diapause were investigated. This experiment indicated that as initial population size/bolt (crowding) increased, the diapause incidence, larval stage survival, adult body size, development time of nondiapause individuals and pupal period of diapause individuals decreased. The analysis indicated that larval interference as well as food shortage suppressed diapause induction. Increasing larval density decreased the probability of diapausing, survival, adult body mass and other traits. Using the data obtained from this study, a simple mathematical model indicated that inverse density-dependent induction of diapause in the first generation had a destabilizing effect on the population size of overwintering generation, which was composed of diapause larvae of the first and second generations; whereas, direct density-dependent induction of diapause exerted a stabilizing effect on it.

Pine wilt disease was first discovered in Dongtang town, Liaoning Province, China, in 2017. Monochamus saltuarius Gebler is a new vector of pinewood nematode and the only known vector in Liaoning Province. The biology of this pest has not been reported thus far; therefore, it is necessary to study its life history. During 2018 and 2019, we collected 138 and 491 adult M. saltuarius beetles, respectively, to analyze their eclosion from larva to adult stage. In mid-March, overwintering larvae began to feed (on xylem) and seek nutrition in preparation for pupation and eclosion. The adults began to appear in mid-April, and the population reached its peak in late May. The life span of the adults was 28–76 days. After approximately 1 week of supplemental nutrition (feeding on twigs), adults began to mate and lay eggs. The egg stage of M. saltuarius lasted 4–8 days. The larvae in Dongtang town have 4 instars and overwinter in tunnels as 3rd–4th instars. The 1st-instar stage lasted 3–9 days, the 2nd-instar stage lasted 11–23 days, the 3rd-instar stage lasted 30–130 days, and the 4th-instar stage lasted 44–180 days. The pupal stage lasted 7–12 days, and the life span of the adults was 28–76 days. In this study we systematically monitored the life history of M. saltuarius for the first time. Our objective was to lay a foundation for improving control of this pinewood nematode vector.

Background For many insects, including invasive species, overwintering survival is achieved behaviourally (e.g. through migration) or physiologically by entering diapause, a state of arrested physiological development that may be accompanied with depressed supercooling points (SCPs). Diapause allows in situ adaptation to adverse environmental conditions, providing sufficient parent propagules for insect pest proliferation when optimal conditions resurface. This phenomenon has however not been observed in the invasive South American tomato pinworm Tuta absoluta in its Mediterranean invaded areas. Moreover, no studies have looked at its overwintering survival in sub-Saharan Africa. Here, we thus investigated the cold hardiness of Tuta absoluta larvae and adults to better explain its local overwintering adaptation strategy. Results Larval lower lethal temperatures ranged from -1 to -17 °C for 0.5 to 4 h durations. Adults showed lower temperature activity limits than larvae albeit freeze strategy experiments showed neither survived internal freezing. Fasting and dehydration pre-treatment generally depressed SCPs, although asymmetrically, conferring more negative SCPs for larvae. Ramping rates, synonymic to diurnal temperature changes also significantly affected SCPs while, inoculative freezing significantly compromised freezing temperatures in both larvae and adults. Conclusion Our results suggest that (i) Tuta absoluta larvae and adults are chill-susceptible and may successfully overwinter, (ii) larvae appear more cold hardy than adults and (iii) ecological factors e.g. inoculative freezing, cooling rates, feeding- and hydration-status may affect cold hardiness. These results are important in determining species range limits, population phenology, modelling pest risk status and allows temporal life-stage specific targeting of management strategies.

Overwinter environmental conditions are a major driver of larval survival, recruitment, and reproductive pre-conditioning in Antarctic krill (Euphausia superba). Few winter studies exist from which to infer impacts of changing environmental conditions on the biology of krill. Here demographic and maturity patterns of krill during five winters are examined at an overwintering hotspot in the northern Antarctic Peninsula. Two different recruitment pulses were present over the 5 years of the study. A large recruitment event was evident in winter 2012, followed by cohort growth tracked through winter 2014. A recruitment event also occurred in 2015, despite lower abundance of larvae in 2013 and 2014. The recruitment pulse in 2015 was correlated with the intrusion of high salinity water, characteristic of the Weddell Sea, during a positive El Nino–Southern Oscillation phase, suggesting recruitment was driven by advection of recruits into the northern Antarctic Peninsula. Despite the inter-annual environmental variability, most female krill were in resting reproductive stages in all years. The lack of variability in female reproductive status during winter may impose a developmental constraint to earlier spawning than previously considered; the time necessary to advance from resting stages to reproductive maturity may limit the ability of krill to adapt to trends in the timing and magnitude of the spring bloom. The observed patterns of recruitment and variation in maturity stages highlight the complexity of krill population dynamics and should be considered when projecting population responses of Antarctic krill to climate-driven changes in the Southern Ocean.

The current climate warming is associated with the development of a second generation in populations of species such as Pyrrhocoris apterus (L.) (Heteroptera: Pyrrhocoridae), which, in Central Europe, were univoltine in the 1980s. Females of the first generation that develop in spring either enter diapause immediately following the adult moult or after a period of oviposition that gives rise to a second generation. In 2005-2010, in overwintering populations, 3 ± 0.6% of females were fertilized. We explored the possibility that the females that overwintered in a fertilized state were those that had oviposited in the previous season. To test this hypothesis, we reared females of the first generation that moulted to the adult stage in June-August under natural conditions. For these females, we recorded oviposition, mortality and overwintering in the fertilized state. In 2004-2007, the majority (78%) of the first-generation females that oviposited in summer also died before winter and the rest entered dormancy and overwintered. Most of the overwintering females that had laid eggs before overwintering were fertilized. However, the majority (63%) of females that overwintered in the fertilized state had not laid eggs in the previous season; they only copulated and stored the sperm until the next spring. The presence of fertilized females in a hibernating population thus indicates pre-winter sexual activity but not the percentage of first-generation females that oviposit before overwintering.

Early life stage tarpon (Megalops atlanticus) have been collected in the western Atlantic Ocean north of Florida where it has been assumed that individuals migrate from estuarine areas at the onset of winter because water temperature during winter is too low for survival. However, there is anecdotal evidence of juvenile tarpon present during winter in this region. We conducted a tag-recapture study to examine potential overwinter survival in a tidally-restricted, upland pond in coastal South Carolina where tarpon have been observed during winter months. We also estimated the age structure of tarpon in this location to determine if age-0 fish were temporarily using this pond or if there were older individuals present, indicating the pond may be occupied for extended periods of time. We recaptured 29 of the 95 individuals tagged and released during January 2016 through October 2018. Of those 29 recaptured individuals, 13 survived one winter and two survived over two winters. Water temperature during winter in a nearby tidal creek was lower than in the pond, which appeared to provide a thermal refuge for tarpon. Estimated ages for 36 individuals ranged from 0 to 3 years (n = 10, 20, 5, 1, respectively). To our knowledge this is the northernmost documented overwintering of juvenile tarpon. Determining the extent of this type of habitat in the region and examining the population dynamics of tarpon in these locations could ultimately help determine how this region contributes to the productivity of adult tarpon populations.

Events during one stage of the annual cycle can reversibly affect an individual's condition and performance not only within that stage, but also in subsequent stages (i.e. reversible state effects). Despite strong conceptual links, however, few studies have been able to empirically link individual-level reversible state effects with larger-scale demographic processes. We studied both survival and potential reversible state effects in a long-distance migratory shorebird, the Hudsonian Godwit Limosa haemastica. Specifically, we estimated period-specific survival probabilities across the annual cycle and examined the extent to which an individual's body condition, foraging success and habitat quality during the nonbreeding season affected its subsequent survival and reproductive performance. Godwit survival rates were high throughout the annual cycle, but lowest during the breeding season, only slightly higher during southbound migration and highest during the stationary nonbreeding season. Our results indicate that overwintering godwits foraging in high-quality habitats had comparably better nutritional status and pre-migratory body condition, which in turn improved their return rates and the likelihood that their nests and chicks survived during the subsequent breeding season. Reversible state effects thus appeared to link events between nonbreeding and breeding seasons via an individual's condition, in turn affecting their survival and subsequent reproductive performance. Our study thus provides one of the few empirical demonstrations of theoretical predictions that reversible state effects have the potential to influence population dynamics.

Understanding factors that affect the population dynamics of insect pest species is key for developing integrated pest management strategies in agroecosystems. Most insect pest populations are strongly regulated by abiotic factors such as temperature and precipitation, and assessing relationships between abiotic conditions and pest dynamics can aid decision-making. However, many pests are also managed with insecticides, which can confound relationships between abiotic factors and pest dynamics. Here we used data from a regional monitoring network in the Pacific Northwest United States to explore effects of abiotic factors on populations of an intensively managed potato pest, the potato psyllid (Bactericera cockerelli Šulc), which can vector Candidatus Liberibacter psyllaurus, a bacterial pathogen of potatoes. We assessed effects of temperature on psyllid populations, and show psyllid population growth followed predictable patterns within each year, but there was considerable variation across years in psyllid abundance. Examination of seasonal weather patterns suggested that in 2017, when psyllid populations were less abundant by several orders of magnitude than other years, a particularly long and cold period of winter weather may have harmed overwintering populations and limited population growth. The rate of degree-day accumulation over time, as well as total degree-day accumulation also affected trap catch abundance, likely by mediating the number of psyllid generations per season. Our findings indicate that growers can reliably infer the potential magnitude of risk from potato psyllids using monitoring data, date of first detection, seasonal weather patterns, and population size early in the growing season.

Overwintering Drosophila often display adaptive phenotypic differences beneficial for survival at low temperatures. However, it is unclear which morphological traits are the best estimators of abiotic conditions, how those traits are correlated with functional outcomes in cold tolerance, and whether there are regional differences in trait expression.We used a combination of controlled laboratory assays, and collaborative field collections of invasive Drosophila suzukii in different areas of the United States, to study the factors affecting phenotype variability of this temperate fruit pest now found globally.Laboratory studies demonstrated that winter morph (WM) trait expression is continuous within the developmental temperature niche of this species (10–25°C) and that wing length and abdominal melanization are the best predictors of the larval abiotic environment.However, the duration and timing of cold exposure also produced significant variation in development time, morphology, and survival at cold temperatures. During a stress test assay conducted at −5°C, although cold tolerance was greater among WM flies, long‐term exposure to cold temperatures as adults significantly improved summer morph (SM) survival, indicating that these traits are not controlled by a single mechanism.Among wild D. suzukii populations, we found that regional variation in abiotic conditions differentially affects the expression of morphological traits, although further research is needed to determine whether these differences are genetic or environmental in origin and whether thermal susceptibility thresholds differ among populations within its invaded range., We explored how seasonal traits are correlated with functional outcomes in cold tolerance in D. suzukii, and whether there are regional differences in trait expression. While wing length and abdominal melanization were the best predictors of the larval abiotic environment, the duration and timing of cold exposure also produced significant physiological variation. Because we observed morphotype variation among wild D. suzukii populations, in different regions of the Eastern United States, a population‐centered research and modeling approach may be required to assign morphotype labels and predict overwintering survival outcomes.

Maize (Zea mays L.) is the only reproductive and feeding host plant of the corn leafhopper Dalbulus maidis (DeLong and Wolcott) (Hemiptera: Cicadellidae) in Brazil and this insect is the only vector of the causal agents of corn stunting diseases in South America. The ability of D. maidis to survive on other plant species in the absence of their host plant is an area of speculation. This study observed the ability of D. maidis to use other plant species as overwintering or shelter plants during the maize off-season in central Brazil. This study was carried out in the Embrapa Cerrados (Planaltina/DF, Brazil) experimental field in August 2017, August 2018, and September 2018, during which maize plants were not present in the field. In these months, several plant species present in the field were sampled using an entomological net. Samples of D. maidis collected were sorted out in the laboratory, identified by sex, and counted. Twenty-nine plant species belonging to nine botanical families were sampled. In all, a total of 146 D. maidis adults were collected from 17 plant species which include, 64 in August 2017, 67 in August 2018, and 15 in September 2018. Approximately 93% of these collections were made on plants of the Poaceae family. The number of D. maidis females collected were higher than the number of males in all the sampling periods. This study therefore, suggest that during the maize off-season, part of the D. maidis population can survive and shelter on other plants of the Poaceae family.

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), the spotted-wing drosophila, is an invasive pest of fruit crops, which appeared in eastern Canada in 2010. It represents a major threat to lowbush blueberry (Vaccinium angustifolium Aiton; Ericaceae) in the Saguenay-Lac-Saint-Jean region, Québec, Canada, at the northern limits of its distribution. The dynamics, overwintering capacity, population fluctuations, and damage to lowbush blueberry of D. suzukii are unknown in Saguenay-Lac-Saint-Jean. We aimed to 1) document D. suzukii abundance and phenology in lowbush blueberry in separate localities; 2) evaluate the potential of D. suzukii to overwinter and examine population dynamics over three seasons; and 3) study the spatial distribution of D. suzukii in lowbush blueberry fields with respect to forested borders. Drosophila suzukii is abundant in lowbush blueberry fields of Saguenay-Lac-Saint-Jean. In spring, D. suzukii were absent until late June, when few summer-morph females appeared. Drosophila suzukii densities started to increase regularly in August, with increasing male proportions, to culminate in fall at high levels with balanced sex ratios. Overwintering remains uncertain, D. suzukii being undetectable in spring despite intensive trapping. Appearance of diapausing winter morphs at high densities indicates that D. suzukii responds appropriately to local conditions preceding cold winter. Models of variation of D. suzukii densities and lowbush blueberry fruit infestation with distance from borders indicate that forest borders are favoured habitats over lowbush blueberry fields and the source of D. suzukii moving to some extent into lowbush blueberry fields.

The suppression of overwintering population is essential in integrated pest management, but little is known about the biological mortality factors that reduce the overwintering density of Chilo suppressalis. Here, we examine the parasitism of overwintering larvae, and assume that key parasitoids strengthen the over-wintering population suppression. The natural parasitism incidence and related dominant parasitoids in overwintering larvae were investigated in two successive winters, in 2015–2016 and 2016–2017. Parasitism rates were also assessed in larvae collected from 15 different counties in 2016. The results showed that the parasitism incidence and dominant parasitoids in overwintering C. suppressalis larvae were significantly different for different sampling dates and sites. Overwintering larvae of C. suppressalis were mainly parasitized by Cotesia chilonis, and less often by Eriborus sinicus and Microgaster russata. Regression analysis indicated that the natural incidence of parasites in overwintering C. suppressalis larvae was positively correlated with the over-wintering larval density. The current work provides support for overwintering pest management strategies by showing the effectiveness of parasitoid communities as a bio-mortality factor for suppressing overwintering density.

The mechanisms by which invasive species negatively affect native species include competition, predation, and the introduction of novel pathogens. Moreover, if an invasive species is a competent disease reservoir, it may facilitate the long-term maintenance and spread of pathogens in ecological assemblages and drive the extinction of less tolerant or less resistant species. Disease-driven loss of biodiversity is exemplified by the amphibian–chytrid fungus system. The disease chytridiomycosis is caused by the aquatic chytrid fungus Batrachochytrium dendrobatidis (Bd) in anurans and is associated with worldwide amphibian population declines and extinctions. For amphibian species that metamorphose and leave infected aquatic habitats, the mechanisms by which Bd persists over winter in these habitats remains a critical open question. A leading hypothesis is that American bullfrogs (Rana catesbeiana), a worldwide invasive species, are tolerant to Bd and serve as a reservoir host for Bd during winter months and subsequently infect native species that return to breed in spring. Using outdoor mesocosms, we experimentally examined if two strains of Bd could overwinter in aquatic systems, in the presence or absence of bullfrog tadpoles, and if overwintered Bd could be transmitted to tadpoles of two spring-breeding species: Pacific treefrogs (Pseudacris regilla) and Cascades frogs (Rana cascadae). We found that only 4 of 448 total animals (one bullfrog and three spring breeders) tested positive for Bd after overwintering. Moreover, two of the three infected spring breeders emerged from tanks that contained overwintered Bd but in the absence of infected bullfrogs. This suggests that Bd can persist over winter without bullfrogs as a reservoir host. We found no effect of Bd strain on bullfrog survival after overwintering. For Pacific treefrogs, Bd exposure did not significantly affect mass at or time to metamorphosis while exposure to bullfrogs reduced survival. For Cascades frogs, we found an interactive effect of Bd strain and bullfrog presence on time to metamorphosis, but no main or interactive effects on their survival or mass at metamorphosis. In short, bullfrog tadpoles rarely retained and transmitted Bd infection in our experiment and we found limited evidence that Bd successfully overwinters in the absence of bullfrog tadpoles and infects spring-breeding amphibians.

International audience; The wedge-tailed shearwater (WTS) population of New Caledonia is one of the largest in the world, yet its biology and foraging ecology are poorly known. We studied WTS from 4 colonies in New Caledonia. We examined foraging behaviour and habitats using GPS receivers and light sensors during and outside the breeding season, respectively, and compared our findings with those from other WTS populations worldwide. During breeding, New Caledonian WTS alternated short foraging trips close to the colony over the lagoon, or off the reef edge, with longer trips over distant, deep waters. Whereas neighboring colonies overlapped at sea, especially during short trips, there was a clear separation of foraging zones between the pairs of colonies located in the southern versus northwestern parts of New Caledonia. Although WTS actively foraged and commuted to foraging zones during the day, they mainly returned to the colony or rested at night, indicating that they feed mainly during the day. Active foraging did not take place in more productive areas, suggesting that it may instead be related to the presence of sub-surface predators. Outside the breeding season, birds from 3 colonies had similar trans-equatorial migratory behaviour. All left New Caledonia at the same time of the year with a fast, northeasterly movement and wintered over deep waters in the same sector of the northwestern tropical Pacific Ocean. At overwintering sites, they spent most of their non-foraging time presumably sitting on the water, especially at night, making a slow westward movement before returning to New Caledonia. WTS from New Caledonia forage over warm, oligotrophic deep waters throughout their life cycle, and the species appears to have a flexible foraging strategy adapted to the various environmental conditions encountered across its wide tropical range.

Global warming has pronounced impacts on the physiology, development and behavior of multiple organisms and affects the geographical distribution of arthropods. Yet, little is known about how a heightened ambient temperature influences migratory insects that are globally relevant to agriculture. Here, we quantified the extent to which increases in surface temperature, over the span of 3 decades, impact long-distance migration processes of the globally important cutworm Agrotis ipsilon (Lepidoptera: Noctuidae). Multi-year monitoring in China indicated how high-altitude migrants of A. ipsilon annually attain two distinct seasonal peaks, i.e., during spring and summer. Stable isotope analyses of field-caught individuals further showed a gradually shifting origin of migrant populations, with ground-level A. ipsilon abundance partially reflecting population levels of high-altitude migrants. Over a 27-year time period, respective population peaks for overwintering and the first-generation A. ipsilon adults were reached 17 and 8 days earlier in the year. Also, the northern border of the A. ipsilon potential overwintering area progressed northward by 58–232 km, and its migration range expanded by 708 km. Our work reveals how a progressively increasing surface temperature affects long-distance migration of a cosmopolitan agricultural pest and alters the population phenology and geographical distribution of A. ipsilon in eastern Asia. Global warming thus influences ecological dynamics in temperate agro-ecosystems and can magnify the economic impacts of long-distance migratory pests.

The population of monarch butterflies east of the Rocky Mountains has noticeably declined over the past two decades. The decline is due, in part, to loss of breeding and forage habitat in the Southern and Midwestern USA. To support a resilient overwintering population of six hectares of occupied forest canopy, approximately 1.6–1.8 billion additional ramets of milkweed are needed in the summer breeding range. Milkweed establishment that facilitates natural behavior of monarchs is necessary for effective conservation restoration. This study explored the effect of milkweed ramet density on larval search behavior, milkweed utilization, and survival without predation, parasitism, or competition. Under our experimental greenhouse conditions, monarch larvae abandoned their natal ramet, and subsequent ramets, prior to the pre-pupal wandering stage and before all available leaf biomass on a ramet was consumed. This is consistent with previous field observations. Larvae consumed biomass from three or four milkweed ramets that totaled the approximate biomass of single 10–35 cm ramet. Movement behavior suggests that isolated ramets may not support development through pupation, even though an isolated ramet could provide enough biomass. Our results suggest milkweed patches containing at least two to four ramets of closely-spaced common milkweed would provide sufficient biomass for development and increase the likelihood that larvae moving in random directions would encounter non-natal ramets to support development. Larval movement behavior and biomass requirements are critical aspects of monarch larval biology that should be considered in habitat restoration and maintenance plans, monitoring survey designs and protocols, and population modeling.

The first observations of the aphid Prociphilus fraxini (Fabricius, 1777) being involved in a mutualistic relationship with the ant Prenolepis nitens (Mayr, 1853) in Europe is documented. Mutualism of an aphid generation living with the ants Prenolepis nitens and Lasius brunneus (Latreille, 1798) is discussed in reference to the possible development of an overwintering parthenogenetic population of the aphid, persisting on the roots of its secondary host, Picea abies, due to coevolution of the aphid with ants.

Migratory bird populations frequently consist of individuals that overwinter variable distances from the breeding site. Seasonal changes in photoperiod, which varies with latitude, underlie seasonal changes in singing frequency in birds. Therefore, migratory populations that consist of individuals that overwinter at different latitudes with large overwintering ranges could experience within‐population variation in seasonal production of song. To test the influence of overwintering latitude on intrapopulation variance in song production in the spring, we subjected two groups of Eastern Song Sparrows (Melospiza melodia melodia) from the same partially migratory breeding population to different photoperiodic schedules associated with a 1,300‐km difference in overwintering location. One group remained on the natural photoperiodic schedule of the breeding site (resident group) while the other group experienced a nonbreeding photoperiod that mimicked a southern migration in the fall followed by a northern migration back to the breeding site in the spring (migratory group). We compared song output between the two groups in three different stages (nonbreeding, prebreeding, and breeding). Little singing occurred during nonbreeding stage sample dates (20 November, 6 December) for the resident group, and no singing occurred for the migrant group. During the prebreeding stage (27 January, 7 February), significantly more singing occurred in the resident group than in the migrant group. During the breeding stage (21 March, 4 April), after a simulated migration for the migrants, song output was similar in both groups. These results suggest that within‐population variation in wintering latitude may contribute to variation in seasonal changes in singing behavior, which may covary with readiness to breed. Studies utilizing confirmed migrants and residents, rather than merely simulated migrants and residents, are also needed to better understand these processes., Migratory bird populations often consist of individuals that overwinter at different distances from a common breeding site. In the laboratory, we compared singing behavior between two groups of birds (one “migratory” and one “resident”) that we subjected to natural photoperiods of Tampa, Florida, and Bloomington, Indiana, respectively. We found that the residents sang more during the prebreeding stage, but after a simulated spring migration, song output in the two groups was the same.

Many animals are shifting migrations in response to human activities. In particular, human-induced changes to climate and habitat (e.g., urbanization) likely facilitate animals becoming year-round residents. Because migration can be energetically expensive, shifts to sedentary behavior could minimize energetic demands incurred and any immunosuppressive effects. Residency in urban habitats could also provide abundant resources and allow sedentary animals to invest more in immunity. However, urban habitats could also expose sedentary animals to novel stressors that counter such benefits. To examine how recent shifts to residency affects physiology in ways that may shape infectious disease dynamics, we analyzed leukocyte profiles of two dark-eyed junco (Junco hyemalis) populations from southern California: the Laguna Mountain population, in which birds breed in high-elevation forests and migrate altitudinally, and the urban University of California San Diego population, which was likely established by overwintering migrants in the 1980s and has since become non-migratory. Over a two-year study of each population’s breeding season, we found no difference in the ratios of heterophils to lymphocytes between populations. However, urban residents had more leukocytes than birds from the altitudinal migrant population. A multivariate analysis suggested urban residents had fewer monocytes, but effect sizes were small. These results suggest no differences in energy demands or stressors between urban resident and altitudinal migrant populations during their breeding season. However, urban residency may confer immunological benefits through anthropogenic resources, which could have important consequences for disease dynamics..

Construction economics of plant roots exhibit predictable relationships with root growth, death, and nutrient uptake strategies. Plant taxa with inexpensively constructed roots tend to more precisely explore nutrient hotspots than do those with costly constructed roots but at the price of more frequent tissue turnover. This trade-off underlies an acquisitive to conservative continuum in resource investment, described as the “root economics spectrum (RES).” Yet the adaptive role and genetic basis of RES remain largely unclear. Different ecotypes of switchgrass (Panicum virgatum) display root features exemplifying the RES, with costly constructed roots in southern lowland and inexpensively constructed roots in northern upland ecotypes. We used an outbred genetic mapping population derived from lowland and upland switchgrass ecotypes to examine the genetic architecture of the RES. We found that absorptive roots (distal first and second orders) were often “deciduous” in winter. The percentage of overwintering absorptive roots was decreased by northern upland alleles compared with southern lowland alleles, suggesting a locally-adapted conservative strategy in warmer and acquisitive strategy in colder regions. Relative turnover of absorptive roots was genetically negatively correlated with their biomass investment per unit root length, suggesting that the key trade-off in framing RES is genetically facilitated. We also detected strong genetic correlations among root morphology, root productivity, and shoot size. Overall, our results reveal the genetic architecture of multiple traits that likely impacts the evolution of RES and plant aboveground–belowground organization. In practice, we provide genetic evidence that increasing switchgrass yield for bioenergy does not directly conflict with enhancing its root-derived carbon sequestration.

Allee effects are processes that become disrupted at low population sizes, causing further declines to eventual extinction. Identifying Allee effects in natural populations is important for both ecological theory and conservation efforts but challenging because populations typically only experience them briefly before collapsing. In 2018, the Western monarch butterfly population fell below the threshold that scientists predicted would trigger Allee effects. Here we show that since 2018, the Western monarch population has expanded more slowly during spring and summer breeding and filled a smaller breeding range. Other aspects of the monarch life cycle (winter survival, fecundity, morphology) have not declined after the crash. However, winter survival is much lower and wing sizes of overwintering monarchs are larger now than in the 20th century, suggesting higher mortality and selection for increased dispersal in recent decades. Delayed arrival to parts of the Western monarch breeding range is a novel Allee effect, which could lead to temporal mismatches between monarchs and their and host plants.

Simple Summary Populations of western monarch butterflies, which formerly populated coastal overwintering sites in California in numbers exceeding one million, dwindled to less than 2000 in 2020/21. In the same winter, breeding populations of monarchs occurred commonly in the San Francisco Bay urban area for the first time. The urgent conservation need to understand this possible shift in overwintering strategy prompted this first study of the viability and ecology of monarch breeding populations in the South Bay urban area of San Francisco during January–June 2021. Adult monarchs along with eggs and larvae were common during winter and most of spring, utilizing non-native ornamental milkweed and multiple nectar sources from native and ornamental plants. Evidence from weekly counts and tagged butterflies indicated increased dispersal to the north and east during late April-mid-May, possibly representing spring migration to the Pacific Northwest and eastern California. Infection of reared adult monarchs with a protozoan parasite was high. Winter breeding of monarchs in the San Francisco urban area as an alternative and sustainable overwintering strategy for the western US population will likely depend on the continued presence of ornamental milkweeds, sustainable co-existence of monarchs and protozoan parasites, and successful migration to the greater western US during spring. Abstract The western North American monarch butterfly population assessed by counts of non-reproductive overwintering butterflies at coastal sites in California declined to less than 2000 in 2020/21. Simultaneously, reports of reproductive monarchs increased in San Francisco urban areas, perhaps representing a shift in overwintering strategy. To better understand monarch winter breeding in the Bay area, we studied adult and immature populations in Santa Clara County during January–June 2021. Adult monarchs were common with numbers ranging from 0.23–1.54/min during ~30 min weekly surveys at one site, with lowest numbers late April to mid-May. Eggs and larvae, primarily on ornamental milkweeds, were found on nearly all survey dates with lowest numbers mid-late April to mid-May. Levels of infection of adults by the parasite Ophryocystis elektroscirrha were consistently high during the study (69.3–77.5%). From 499 monarchs tagged post-eclosion, recovery rates of 19.2–23.6% occurred from releases in January-February and May-June but only 11.9–13.0% from March-April releases. Although distances were small, butterflies tagged in April were recovered from greater distances than other months. Tagged monarchs flew primarily north or east. There were reduced numbers of adult monarchs during late April-mid-May with some evidence of northerly and easterly emigration at the same time from tagged butterflies, suggesting some movement out of the South Bay area, perhaps representing spring migration. We conclude that monarchs can successfully breed and maintain populations on ornamental milkweeds during winter at urban sites in the South Bay of San Francisco and may still migrate during spring to remain part of the wider western population.

Understanding the interaction between insects and microclimate can be essential in order to plan informed and efficient treatments against agricultural pests. Microclimatic factors such as humidity and temperature can influence the population dynamics of the invasive agricultural pest Halyomorpha halys, the brown marmorated stink bug. The aim of this work was to evaluate the level of transpiration of H. halys in dry, normal and humid microclimates according to the sex, physiological conditions and developmental stage of individuals. Water loss during diapause and the effect of population density on insects’ transpiration were also assessed, as were the nutritional preferences of adults upon exiting diapause. Our data demonstrate that microclimatic conditions significantly influence the transpiration of this pest species. The effect of sex and feeding status on insects’ water loss is marked, while population density does not influence water loss in diapausing individuals. The first nutritional need of the overwintering generations is represented by hydration, likely due to the water loss during diapause.

The fish parasite, Neoergasilus japonicus (Harada, 1930), native to Eastern Siberia and the Amur River catchment area, invaded European water bodies in the middle of the last century, possibly due to the human-mediated distribution of fish in the Amur complex (i.e., the genera Hypophthalmichthys and Ctenopharyngodon). In the deep karst lake, Grand Laoucien (Marseille area, France), this species had an unusually high population density (from 1000 ind./ m3 in zooplankton to 4000 ind./ m3 in the nearshore area) during the free-living period of its life cycle. The annual cycle of N. japonicus includes a 5-month overwintering of fertilized females attached to fish fins and, following this, a five- to six-generation chain from March to November, when the free-living stages in the population alternate with parasite females which attach to their hosts for breeding. The population density of the parasites in zooplankton increased exponentially from spring to autumn, which positively correlated with temperature. We found a strong correlation between N. japonicus density and the community development of microphytobenthos, but not between N. japonicus and phyto- or zooplankton dynamics. The local contributing factors included a seasonal three-fold decrease in water levels and the development of anoxia in profundal waters, which led to a high ambient fish density and thus susceptibility to the parasite. Although the free-living parasite represented only 1% of zooplankton production, it consumed up to 25% of small invertebrate productivity. The maximum intensity of infection reached 140 parasites per fish, or 4.14 per g of weight. The high infection of fish with this parasite, in our opinion, indicated the danger it poses to the local ichthyofauna, which first encountered this new parasite.

Climate change alters the extent and structure of sea-ice environments, which affects how they function as a habitat for polar species. Identifying sea-ice characteristics that serve as indicators of habitat quality will be crucial to the monitoring and management of climate change impacts. In the Southern Ocean, Antarctic krill is a key prey species and fishery target. Krill larvae depend upon sea-ice habitats to survive the winter and recruit to the population in spring. Existing observations of sea-ice characteristics lack sufficient spatiotemporal coverage to quantify which ones contribute to favourable overwintering habitat, leading to uncertainties in how current and future changes in sea ice affect krill populations. Here, we derive regional-scale indices of annual krill recruitment spanning 35 years across the southwest Atlantic. To develop meaningful indicators of sea-ice habitat, we selected variables from a high-resolution sea-ice model that are hypothesized as relevant for larval habitat use. The resulting correlations between recruitment and sea-ice indicators vary by region and show remote connections to sea ice that correspond with established theories of larval transport. Through an improved representation of sea-ice habitat quality, as compared with using more traditional satellite-derived variables such as sea-ice extent and duration, we highlight plausible regions of overwintering habitat. Our findings improve current understanding of how krill are likely responding to changing sea ice and support emerging views that larval habitat use is complex. Furthermore, regional variation in larval dependence on sea ice may provide pockets of resilience to change for the broader krill population.

Changes in biometric characteristics of a migrating bird population at a given capture site could reflect that the migration strategies of the species may be changing. A robust data set (15,520 records) was used to analyse the changes in biometric characteristics of the Eurasian Blackcap Sylvia atricapilla in western Hungary between August and October during the study period (2001–2019). All age and sex classes displayed similar phenology of monthly captures and biometric change: the average wing length, fat score and body mass increased in the migrating population from August to October. This could be explained by changes in the morphometric distribution of different migrating populations, in later months more birds might arrive from a larger distance, primarily from the Baltic regions and the Czech Republic. The biometrics of juvenile birds captured in August did not change significantly from 2001 to 2019, while the wing lengths decreased and fat scores increased significantly between 2001 and 2019 in September and October in both sex classes. This could be explained by a change in the migration distance or different morphology of individuals from the north which stopped over at the study area. Due to the global warming and habitat changes in the last decade, the shorter migration route and favourable conditions at overwintering areas north of the Sahara or around the Mediterranean could favour Blackcaps which migrate a shorter distance.

Aedes albopictus is an invasive mosquito species responsible for local transmission of chikungunya and dengue viruses in Europe. In the absence of available treatments, insecticides-based control remains one of the most important viable strategies to prevent emerging problems. Diflubenzuron (DFB) and Bacillus thuringiensis var. israelensis (Bti) are among the most commonly used larvicides for Ae. albopictus control with consequent concerns for the potential development of resistance. Studies on the resistance emergence in Ae. albopictus and its persistence in the wild to both DFB and Bti are essential for the efficient and sustainable planning of the control programmes. In this context, larvae from a recently laboratory established population were subjected to increasing selective pressure for nine successive generations using both DFB and Bti. The resistance levels and the overwintering success of the selected populations relative to control (colonies that received no selection) were determined. Results revealed an 8.5- and 1.6-fold increase on the resistance levels following selection with DFB and Bti, respectively. The selection process to both larvicides had no apparent impacts on the overwintering capability relative to control, suggesting the successful persistence of the selected individuals in the wild on an annual base.

Many insects are in clear decline, with monarch butterflies (Danaus plexippus) drawing particular attention as a flagship species. Falling numbers of overwintering monarchs are well documented, but there has been debate regarding population trends of summer breeding populations. Here, we compile a series of long-term monarch monitoring datasets, some which are analyzed here for the first time, that reveal highly variable responses across the migratory geographic range, but no broad net decline in numbers of breeding monarchs. We also did not find evidence that sampling biased towards natural sites was masking declines at disturbed sites. Overall, our results suggest a robust resiliency in summer populations that thus far has allowed recovery from losses during the winter. Thus, monarchs may not require as much breeding habitat restoration as once thought, and focus should be on conserving the fall and spring migration.

Long-term species surveys are effective tools for identifying changes in population demography which is of particular importance for those in threatened habitats such as grasslands. Due to their cryptic nature, snakes can benefit greatly from these types of surveys but multiyear surveys for snakes are rare in Pennsylvania and the surrounding region. We conducted coverboard surveys of the grassland specialist Northern Black Racer (Coluber constrictor constrictor) over eight years separated into two sampling periods (2008-2012 and 2015-2017) across a habitat-mosaic in south-central Pennsylvania. We recorded information on their body size, demography, and monthly activity. We compared these traits between the sampling periods to determine how they vary over time. A total of 70 Northern Black Racers were captured during this project. As expected, grasslands were heavily exploited by Northern Black Racers highlighting their importance to this species. There was a shift from relatively larger-bodied, older individuals towards relatively smaller-bodied, younger individuals between the sampling periods, but the sex ratio remained unchanged. Monthly activity of adults was unimodal in both sampling periods, but the month of peak activity varied and there was a possible effect of precipitation on this difference. The change in age structure between the sampling periods suggested that a widespread mortality event, possibly from exceedingly cold overwintering conditions, may have culled older individuals resulting in a younger cohort to fill the void. As Northern Black Racers are an important grassland predator, our data show the benefits of long-term surveys through detecting changes in demographics that could potentially influence long-term survival of a population.

The western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is a major pest of semi-protected strawberry crops in the UK. These crops are grown outdoors but sheltered by clear polythene tunnels during the growing season from about April to October. The aims of the study were (1) to test whether F. occidentalis overwinters in strawberry crops in central England, where overwintering in outdoor crops has not previously been demonstrated and (2) to test whether overwintering affects the thrips population during the following season. F. occidentalis was found breeding on several crop weeds that often flower throughout the year, including common chickweed (Stellaria media), groundsel (Senecio vulgaris) and dandelion (Taraxacum officinale). F. occidentalis female adults were found throughout the winter in flowers of these weeds and caught every month on blue sticky traps. Transparent emergence traps placed over various locations in a second-year crop in March caught adult thrips over the following month, showing that thrips survived within the crop. Second-year strawberry crops had earlier infestations and significantly more F. occidentalis adults per flower than nearby first-year crops at the start of the season, indicating that thrips that overwinter in and around retained crops contribute to pest build-up in the following season. Control of overwintering F. occidentalis after the end of first-year cropping before second-year cropping, or growing crops for only 1 year, is a potential strategy to improve thrips management in strawberry. The survival of F. occidentalis over winter on outdoor crops raises concerns that the species could in time become established on other outdoor crops.

Ips subelongatus is a species of bark beetle experiencing population outbreaks in Korea. In this study, a predictive model and empirical prediction were used to forecast the spring flight of these beetles in Japanese larch forests. The number of beetles caught in pheromone traps was investigated in larch forests thinned in 2009, 2010, 2012, or 2013. Data from the sites thinned in 2009, 2010, or 2012 were used in the predictive model based on a degree-day model that was validated using data from the site thinned in 2013. The lower threshold temperature for flight (LTF) and a thermal sum for the spring flight of I. subelongatus were estimated. The empirical prediction that beetles initiate their flight when daily maximum temperatures reach 16 or 20°C was tested using daily maximum temperature and the beetles caught. The LTF was estimated as 5.97°C, with 42.95 degree-days required for initiation of spring flight. The median flight dates were estimated with a discrepancy from 1 to 3 d by the predictive model. Using the empirical prediction, differences between the day when daily maximum temperature reached 16 or 20°C and flight peak days ranged from 4 to 45 d. These results demonstrate that the predictive model is more suitable than the empirical prediction for predicting the spring flight of I. subelongatus. Overwintering I. subelongatus adults seem to need to gain a determined thermal sum before initiating spring flight rather than merely waiting for the daily maximum temperature to exceed a critical temperature.

Asian earthworms in the pheretimoid group are currently invading hardwood forests in the northeastern USA. Population studies of these earthworms typically focus on life stages after hatching. However, the more cryptic part of these populations, cocoons, has largely been ignored. This paper is concentrating on cocoon abundance of two pheretimoid species through the year, and on identifying their readiness to hatch as determined by the presence of embryos that were well-advanced in their development. We wanted to know when viable cocoons were present and what their embryonic development was. We found that unhatched cocoons and ready-to-hatch embryos were present all year round. At the Horticultural Research Center of the University of Vermont, A. tokioensis cocoon abundance (mean ± standard error) varied between 1203 ± 167 m−2 in the winter and 498 ± 79 m−2 in the summer. Here A. agrestis varied between 439 ± 62 m−2 in the spring and 722 ± 70 m−2 in the fall. At another site dominated by A. agrestis, cocoon abundance varied between 753 ± 150 m−2 in the spring and 1386 ± 167 m−2 in the winter. Cocoon production was estimated at about 0.6 cocoons per worm per day. We raise the question whether cocoons have a longer-term survival function beyond overwintering of the population, akin to the function of the seed bank of annual plants.

The salinity tolerance and the effect of temperature were studied on the behavior and motor activity of the nonindigenous Indo-Pacific calanoid copepod Pseudodiaptomus marinus, first found in Sevastopol Bay (Black Sea) in autumn 2016. According to the index of median lethal salinity (LS50 ), the salinity tolerance range of adult P. marinus collected at 18.0 psu in November 2016 and subsequently reared in the laboratory amounted to 5.0-44.0 psu, independently of the acclimation regime. Females of P. marinus collected in December 2016 at 12.0°C became torpid at 8.0°C, a value typical of winter-spring Black Sea coastal areas. An increase in temperature from 8.0°C to 27.0°C led to an increase in the beat frequency of mouth appendages, swimming speed, and time spent cruising. However, at the same high temperature, the mean cruising speed in the feeding-current feeder P. marinus was 2-fold lower than that of the native, similarly sized cruise feeder Pseudocalanus elongatus. On the contrary, mouthpart beat frequency while cruising was 2-fold higher reaching 80 Hz, due to the creation of feeding currents in P. marinus. The results of our experiments confirm the euryhaline character of P. marinus, and point to an apparent ability to survive cold temperatures in a torpid state. This suggests the possibility of entering an overwintering stage to survive the adverse cold winter-spring environmental conditions of the Black Sea, similarly to the recent thermophilic Indo-Pacific invader Oithona davisae which established a successful population in the same area.

Winterhardiness is regarded as a parameter controlled by the activities performed by a large number of genes. In diallel crossbreeding, a researcher has complete combinations of genes that parental varieties possess. The paper analyses additivity and dominance of the crossbreeding population. It allows to assess the contribution made by the main types of gene interactions to parameter expression by decomposing the genotypic variant into a general and specific combination ability. The research aims at exploring the variability of winterhardiness of soft winter wheat and determining the system of genetic determination of this indicator. The experiment was conducted in the experimental field of Siberian Research Institute of Agriculture in Omsk in 2013-2014. The varieties and hybrids of F1 had triple sowing. The area of plant nutrition was 10 x 20 (cm2). The coulisse fallow was forecrop. The authors explored six samples of soft winter wheat and 30 F1 diallel hybrids. They observed reliable differences among genotypes according to “winterhardiness” parameter (P ≤ 0.05). Variability of this parameter is specified by meteorological conditions (95.07%) and determined by means of two-factor dispersion analysis. The authors used Heiman’s figures in order to evaluate and explore the genetic features of winter wheat winterhardiness (relationship between Wr and Vr - covariance and variant) and genetic parameters. The OCS effect was high (P

Human-induced changes in the climate and environment that occur at an unprecedented speed are challenging the existence of migratory species. Faced with these new challenges, species with diverse and flexible migratory behaviors may suffer less from population decline, as they may be better at responding to these changes by altering their migratory behavior. At the individual level, variations in migratory behavior may lead to differences in fitness and subsequently influence the population's demographic dynamics. Using lifetime GPS bio-logging data from 169 white storks (Ciconia ciconia), we explore whether the recently shortened migration distance of storks affects their survival during different stages of their juvenile life. We also explore how other variations in migratory decisions (i.e., time, destination), movement activity (measured using overall body dynamic acceleration), and early life conditions influence juvenile survival. We observed that their first autumn migration was the riskiest period for juvenile white storks. Individuals that migrated shorter distances and fledged earlier experienced lower mortality risks. In addition, higher movement activity and overwintering "closer-to-home" (with 84.21% of the tracked individuals stayed Europe or North Africa) were associated with higher survival. Our study shows how avian migrants can change life history decisions over only a few decades, and thus it helps us to understand and predict how migrants respond to the rapidly changing world. published

Understanding the ontogenetic and temporal shifts in krill diet during winter is crucial to elucidate the overwintering of krill in the Southern Ocean. Stable isotope analyses (15N/14N and 13C/12C) were utilized to explore the variation in diet of adult krill with size and month during the winter season (June to September 2016) at the South Georgia. Stable isotope signatures indicated that there were no significant differences in δ13C and δ15N values between sexes of krill. Nitrogen isotope signatures suggested increasing carnivory with size of adults throughout winter. Carbon isotope signatures revealed reduced food sources for the larger adults during early winter, but all adults could feed on similar food items during middle to late winter. The trophic niche of adults was similar during the winter season at the South Georgia. Our results provide insight for the diet of adult krill in the food-limited season and should be useful in understanding the energy transfer in the marine food web in the South Georgia ecosystem. Moreover, the information derived from this study can also be used to support krill fishery management and understand the interaction between krill population, top predators and fishery.

Around the world, several pest tephritids are extending their ranges from warm tropical or Mediterranean climates into cooler temperate regions. The ability to tolerate climatic diversity is uncommon among insects, and understanding the population phenology drivers of such species across different parts of their range will be critical for their management. Here, we determined the role of temperature versus fruit availability on the population phenology of Queensland fruit fly, Bactrocera tryoni. Using a field site located at the subtropical/temperate interface, with host fruits continuously available, we monitored the development times and abundance of B. tryoni, a species which has invaded temperate Australia from the tropics. From fruit samples held at ambient and controlled conditions, the abundance of emerging flies was highly variable among collection dates, but the variance did not reflect the observed changes in temperature. For most samples, the survival rate of flies in a field site was lower than predicted by a day-degree population model fitted with mean daily field temperatures. The development time of the immature stage in the field was prolonged, presumably due to cooler ambient conditions, but the fitted day-degree population model consistently over-predicted estimated development times. Our results indicate that at the subtropical/temperate interface, the decline in B. tryoni populations during winter is only partly driven by temperature and host availability. We classify B. tryoni as a climate generalist, which likely employs physiological as well as behavioural mechanisms to achieve broad climatic tolerance ranges.

1. The invasive many-lined sun skink, Eutropis multifasciata, is established in much of southern Taiwan and is spreading northward. We investigated whether winter temperatures constrain further dispersion of this skink by comparing its cold tolerance to the spatial distribution of winter temperatures in Taiwan. 2. We measured the 28-day survival rate of this species at 4 constant temperatures (10−16 °C in 2 °C increments) and its critical thermal minimum (CTmin), i.e., the body temperature at which the righting reflex is lost during the cooling process. For comparison with the spatial distribution of temperatures over Taiwan, we used the biophysical model Niche Mapper™ in order to simulate the soil temperatures, where lizards are inactive in the winter, during the coldest month of the year, January, under three climatic scenarios (average temperature, average−3 °C, average+3 °C). 3. Our results indicate that this species has low tolerance to cold. Combining cold tolerance data with soil temperature data suggests that its upper elevation limit could range from 1000 m to 1500 m, above which the weather is lethal and precludes overwintering. The locations of sightings of E. multifasciata are consistent with this prediction, with no known locations above 500 m elevation. 4. This study highlights that the winter climate is a major factor in determining population establishment and hence in limiting this species’ range. Future studies would benefit from accounting for low winter temperatures and their potential influence on range limits of invasive species.

Birds overwintering at northern latitudes face challenging environments in which refined cognitive and behavioural responses to environmental stimuli could be a benefit. Populations of the same species from different latitudes have been shown to differ in their cognitive and behavioural responses, and these differences have been attributed to local adaptation. However, individuals overwintering at intermediate latitudes experience great breadth and variation in environmental conditions, and thus it is reasonable that these individuals would alter their responses based on current conditions. To determine within-species responses to environmental conditions we sampled birds from a single population at an intermediate latitude and assessed their problem solving abilities and their responses to novelty. We held birds overwinter in one of three experimental temperature regimes and assessed problem solving abilities and responses to novel stimuli in the spring. We found that overwinter temperature had no effect on problem solving ability. We also show that overwinter temperature had no effect on an individual's response to novelty. These findings strengthen the argument that differences in these behaviours seen at the population level are in fact driven by local adaptation, and that current environmental condition may have limited effects on these behaviours.

This study aimed to reveal some biological effects of black fly Aleurolobus marlatti (Hemiptera: Aleurodidae) on Christthorn. The research work was conducted in Baghdad during the period extending from June 2015 to March 2016. The purpose was to count the number of black fly A. marlatti’s generations, the appearance period, the overwintering insect and the appearance date. The results showed that the adult appearance began in the last week of March in the field. The generations were marked by insect population that fluctuated between highs and lows. Generations were analyzed both on an annual and monthly basis depending on fluctuations in temperature and relative humidity. The number of insects were noticed in the form of eight peaks representing eight generations per year in central Iraq.

Critical habitats such as nesting areas and overwintering sites are specific areas used by organisms to carry out important life functions. In many urbanized centers, critical habitats of at-risk species have often become degraded and/or fragmented because of human activities. Such is the case for the population of common snapping turtles (Chelydra serpentina) in Cootes Paradise Marsh, a highly urbanized ecosystem located at the western tip of Lake Ontario. In addition to these threats, mortality from collisions with cars on a four-lane highway at the western end of the marsh has greatly reduced wildlife populations. Here, we examine long-term changes in critical habitat distribution that has accompanied urbanization of Cootes Paradise Marsh from 1934 to 2010. We delineated potential nesting habitat for snapping turtles in 7 digitized aerial photos, using literature information and 2017 nesting surveys as guides. Between 1934 and 2010, total area of potential nesting habitat decreased by almost 50%. Nesting surveys confirmed that snapping turtles were disproportionately using created nesting mounds and this suggests that availability of natural nesting habitat is limited. We also radio tracked 11 snapping turtles to identify use of overwintering habitat. Temperature loggers monitored in-situ water temperatures at each turtle’s location and other unconfirmed habitats. The snapping turtle population overwintered in a wide range of upland terrestrial habitats and we found consistent characteristics regarding water temperature across both confirmed and unconfirmed sites, therefore suggesting overwintering habitat may not be limiting within the marsh.

Road mortality may contribute to the population decline of eastern monarch butterflies (Danaus plexippus L.). We estimated autumn monarch roadkill rates within the primary Oklahoma to Mexico southern migration corridor (i.e., Central Funnel). Dead monarchs were surveyed along Texas roadsides during four weeks of autumn migration in 2016 and 2017. Roadkill averaged 3.4 monarchs per 100 m transect, reaching 66 per 100 m in a roadkill hotspot in southwestern Texas. Extrapolations of Central Funnel roadkill based on survey data and road types were 3.6 and 1.1 million in 2016 and 2017, respectively. Spatial distribution of roadkill across the Central Funnel was projected from Texas survey data using 30 m resolution MaxEnt niche models. Highest roadkill probability was linked to arid climate and low human population density. The latter variables may not be directly related to roadkill, but instead represent indirect correlates of increased densities of monarchs where the migration corridor narrows southwards. The higher roadkill projected in southwest Texas and Mexico by MaxEnt models agrees with previously reported monarch roadkill hotspots. MaxEnt-based 2016–2017 projections for annual roadkill rates throughout the Central Funnel averaged 2.1 million. This figure is similar to the result by simple extrapolation, and represents about 3% of the overwintering monarch population for these years. Mitigation at roadkill hotspots in the Central Funnel could reduce monarch roadkill mortality during migration and contribute towards conservation efforts for the monarch butterfly.

Striped Bass in Canadian waters occur at the most northern extent of the species range. At these latitudes, overwintering represents a significant portion of annual activities (Nov- May). During the winter period, Striped Bass generally occupy inland waterways, aggregate densely, feed little, and conduct minimal movements rendering them vulnerable to fisheries exploitation, pollution and habitat alterations. Despite the importance of winter survival to population viability, the winter period remains an understudied aspect of Striped Bass ecology throughout the species range. Here we review what is known as well as the knowledge gaps regarding the overwintering ecology for Striped Bass in Canadian waters. We discuss: all reported Canadian Striped Bass overwintering locations and their characteristics; environmental conditions that may be required for Striped Bass winter survival; environmental cues that may cause Striped Bass to enter overwintering habitats in late fall and depart in early spring; possible threats to overwintering habitat; and we propose numerous research questions necessary for improving Striped Bass conservation and management both within Canada and across the species range.