Long-term population projections: Scenarios of low or rebounding fertility.

The size of the human population is projected to peak in the 21st century. But quantitative projections past 2100 are rare, and none quantify the possibility of a rebound from low fertility to replacement-level fertility. Moreover, the most recent long-term deterministic projections were published a decade ago; since then there has been further global fertility decline. Here we provide updated long-term cohort-component population projections and extend the set of scenarios in the literature to include scenarios in which future fertility (a) stays below replacement or (b) recovers and increases. We also characterize old-age dependency ratios. We show that any stable, long-run size of the world population would persistently depend on when an increase towards replacement fertility begins. Without such an increase, the 400-year span when more than 2 billion people were alive would be a brief spike in history. Indeed, four-fifths of all births-past, present, and future-would have already happened.

Probabilistic County-Level Population Projections.

Population projections provide predictions of future population sizes for an area. Historically, most population projections have been produced using deterministic or scenario-based approaches and have not assessed uncertainty about future population change. Starting in 2015, however, the United Nations (UN) has produced probabilistic population projections for all countries using a Bayesian approach. There is also considerable interest in subnational probabilistic population projections, but the UN's national approach cannot be used directly for this purpose, because within-country correlations in fertility and mortality are generally larger than between-country ones, migration is not constrained in the same way, and there is a need to account for college and other special populations, particularly at the county level. We propose a Bayesian method for producing subnational population projections, including migration and accounting for college populations, by building on but modifying the UN approach. We illustrate our approach by applying it to the counties of Washington State and comparing the results with extant deterministic projections produced by Washington State demographers. Out-of-sample experiments show that our method gives accurate and well-calibrated forecasts and forecast intervals. In most cases, our intervals were narrower than the growth-based intervals issued by the state, particularly for shorter time horizons.

Comparative demographics, population projections and egg maturation patterns of four eupelmid egg parasitoids on the factitious host Antherae pernyi.

BACKGROUND: The genera Anastatus and Mesocomys (both Hymenoptera: Eupelmidae) are important solitary egg endoparasitoids as biological control agents for lepidopterous and hemipterous pests worldwide. Here, we comparatively evaluated the demographic parameters of four important eupelmid egg parasitoids (Anastatus fulloi, A. japonicus, Mesocomys albitarsis and M. trabalae) reared on the factitious host eggs of the Chinese oak silkworm Antheraea pernyi, using age-stage two-sex life tables, their population projections as well as egg maturation patterns. RESULTS: Both the age-specific net reproductive rate (lx mx ) and reproductive value (vxj ) increased initially and then gradually decreased with increasing age in all four parasitoid species. Overall, the two Mesocomys species had higher survival rates at stable age-stage distribution, peak reproductive values, and intrinsic rates of increase than the two Anastatus species. Mesocomys albitarsis had the longest longevity, whereas A. japonicus had the longest oviposition days and mean generation time. The two Mesocomys species are thus projected to have faster population increase than the two Anastatus species. Adult females of all four parasitoid species emerged with only a few mature eggs (< 6 eggs) and most of their eggs were matured post-emergence (strict synovigeny). The estimated 90% of lifetime complement of reproduction (offspring) and realized days were 374 and 32 for A. japonicus, 337 and 22 for M. trabalae, 330 and 19 for M. albitarsis and 147 and 28 for A. fulloi. CONCLUSION: Our results indicated that the two Mesocomys species have higher control capacity than the two Anastatus species. Provision of adult food for these strictly synovigenic parasitoids would be essential to prolong their lifespan and continuously produce eggs for parasitizing their hosts for mass rearing or augmentative biological control programs. © 2023 Society of Chemical Industry.

A two-sex renewal model and its population projection.

Population projections rely on one-sex renewal models. Consequently, changing the projection of male mortality does not affect the projection of birth, contradicting commonsense. A two-sex renewal model is presented in this paper to provide a better description of reproduction and more reasonable population projections. This model is nonlinear and includes the one-sex renewal models as special cases. In this model, age-specific birth rates are defined for two sexes jointly; total fertility, net reproduction rate, and intrinsic growth rate are also derived for two sexes jointly; and age-specific populations approach or converge to stable status. Applying the two-sex renewal model to Australia, it indicates that one-sex models underestimated the intrinsic growth rate by 14 percent. Compared to the results of one-sex models, the two-sex model would provide higher growth rate for low-fertility countries, and lower growth rate for high-fertility countries. In other words, the one-sex models are commonly biased. If the two-sex model is applied to all the countries, it would project smaller populations for the world in the future.

Undocumented Older Latino Immigrants in the United States: Population Projections and Share of Older Undocumented Latinos by Health Insurance Coverage and Chronic Health Conditions, 2018-2038.

OBJECTIVES: This article focuses on the older Latino undocumented population and anticipates how their current demographic characteristics and health insurance coverage might affect future population size and health insurance trends. METHODS: We use the 2013-2018 American Community Survey as a baseline to project growth in the Latino 55 and older undocumented population over the next 20 years. We use the cohort component method to estimate population size across different migration scenarios and distinguish between aging in place and new immigration. We also examine contemporary health insurance coverage and chronic health conditions among 55 and older undocumented Latinos from the 2003-2014 California Health Interview Survey. We then project health insurance rates in 2038 among Latino immigrants under different migration and policy scenarios. RESULTS: If current mortality, migration, and policy trends continue, projections estimate that 40% of undocumented Latino immigrants will be 55 years or older by 2038-nearly all of whom will have aged in place. Currently, 40% of older Latino undocumented immigrants do not have insurance. Without policies that increase access to insurance, projections estimate that the share who are uninsured among all older Latinos immigrants will rise from 15% to 21%, and the share who is both uninsured and living with a chronic health condition will rise from 5% to 9%. DISCUSSION: Without access to health care, older undocumented immigrants may experience delayed care and more severe morbidity. Our projections highlight the need to develop and enact policies that can address impending health access concerns for an increasingly older undocumented Latino population.

Footprints to singularity: A global population model explains late 20th century slow-down and predicts peak within ten years.

Projections of future global human population are traditionally made using birth/death trend extrapolations, but these methods ignore limits. Expressing humanity as a K-selected species whose numbers are limited by the global carrying capacity produces a different outlook. Population data for the second millennium up to the year 1970 was fit to a hyper-exponential growth equation, where the rate constant for growth itself grows exponentially due to growth of life-saving technology. The discrepancies between the projected growth and the actual population data since 1970 are accounted for by a decrease in the global carrying capacity due to ecosystem degradation. A system dynamics model that best fits recent population numbers suggests that the global biocapacity may already have been reduced to one-half of its historical value and global carrying capacity may be at its 1965 level and falling. Simulations suggest that population may soon peak or may have already peaked. Population projections depend strongly on the unknown fragility or robustness of the Earth's essential ecosystem services that affect agricultural production. Numbers for the 2020 global census were not available for this study.

Population-Based Projection of Vision-Related Disability in Australia 2020 - 2060: Prevalence, Causes, Associated Factors and Demand for Orientation and Mobility Services.

PURPOSE: To project the prevalence, causes, associated factors of vision-related disability and demand for orientation and mobility (O&M) services in Australia from 2020 to 2060. METHODS: The age-specific prevalence and main causes of vision-related disability were estimated based on primary data of 74,862 participants in 2015 Survey of Disability, Ageing and Carers. Logistic regression analyses were performed to identify associated factors for the outcome variables including vision-related disability, cataract, macular degeneration and glaucoma. Future prevalence of vision-related disability and demand for O&M services were forecasted using the population projections by the Australian Bureau of Statistics through 2060. RESULTS: The main causes of vision-related disability are non-specific sight loss, cataracts, macular degeneration and glaucoma. Health-related associations for vision-related disability are older age, having a history of stroke, having diabetes, depression, heart disease and hearing impairment. The number of Australians with vision-related disability (283,650, 1.10%) and demand for O&M services (123,317, 0.48%) in 2020 will increase to 559,161 (1.38%) and 237,694 (0.59%) respectively in 2060. CONCLUSIONS: The number of people with vision-related disability and in need of O&M services in Australia will grow exponentially over the coming decades. General health promotion and specific strategies of early detection and timely treatments of the major eye diseases may ameliorate the trend in vision-related disability.

Degree day-based model predicts pink bollworm phenology across geographical locations of subtropics and semi-arid tropics of India.

There is a global concern about the effects of climate change driven shifts in species phenology on crop pests. Using geographically and temporally extensive data set of moth trap catches and temperatures across the cotton growing states of India, we predicted the phenology of cotton pink bollworm Pectinophora gossypiella (Saunders). Our approach was centered on growing degree days (GDD), a measure of thermal accumulation that provides a mechanistic link between climate change and species' phenology. The phenology change was predicted by calculating absolute error associated with DD and ordinal date, an alternative predictor of phenology, for peak moth abundance. Our results show that GDD outperformed the ordinal dates in predicting peak moth abundance in 6 out of 10 selected locations. Using established thresholds of 13.0/34.0 °C, mean DD accumulated between the consecutive moth peaks across different years were estimated at 504.05 ± 4.84. Seven generations were determined for pink bollworm in a cropping season, the length of which varied between 35 and 73 days in response to temperature. Pink bollworm population reached its peak during third generation which can be the target for management actions. The study provides essential information for developing pink bollworm management strategies under climate change.

Sublethal effects of three insecticides on fitness parameters and population projection of Brevicoryne brassicae (Hemiptera: Aphididae).

The cabbage aphid, Brevicoryne brassicae (L.), is one of the major insect pests of cole crops in Iran. In most instances outbreaks are normally kept under control by application of insecticides. In this study, the sublethal effects (LC30) of three insecticides, acetamiprid, buprofezin, and thiamethoxam-lambda cyhalothrin, (TLC) were evaluated on the population growth rate of the progeny of insecticide-treated cabbage aphid adults. The age-stage, two-sex life table method was used to analyze the collected data. The results indicated that the insecticide applications affected the duration of the preadult period, their survival, reproduction, life span/longevity, and consequently, the population growth rate of the F1 generation. The indicators of the greatest sublethal effects were noted in the progeny of the TLC-treated adults. These included the lowest net reproductive rate (R0), intrinsic rate of increase (r), finite rate of increase (λ), and the longest mean generation time (T). The highest values of r, λ, R, and the lowest value of T occurred in the control group followed by, in order, the acetamiprid and buprofezin groups. These research findings will be useful in the development and implementation of future aphid management programs.

Prospective measures of aging for Central and South America.

By conventional measures, it is often remarked that Central and South America is one of the fastest aging geographic regions in the world. In recent years, however, scholars have sought to problematize the orthodox measures and concepts employed in the aging literature. By not taking dynamic changes in life expectancy into account, measures which hold chronological age constant (e.g. defining a boundary to old age at 60 or 65) represent a very narrow view of population aging. Furthermore, such constant measures may misrepresent differences between territories when performing a comparative analysis. Prospective measures based on the number of years until death present an alternative approach which can adapt to dynamic changes in life expectancy and differences over time and space. The objective of this paper, then, is to apply the new 'prospective' measures of aging to the territories of Central and South America. We calculate prospective median age; an alternative old-age threshold based on the age at which remaining life expectancy is 15 years, and calculate prospective old-age dependency ratio for 1950-2100 using estimated and projected life tables from the latest iteration of the UN's World Population Prospects. These new measures present a very different view of aging in Central and South America. While there are significant differences across countries, the pace and scale of aging are considerably slower and diminished when compared to standard, orthodox measures based on fixed chronological ages. Applying these new measures can not only serve to present a more realistic view of aging which maps onto demographic reality but can also serve to reconceptualize and reframe the issue as something which is far more manageable (e.g. through institutional reform) than is often perceived to be.

Cerebral palsy in Canada, 2011-2031: results of a microsimulation modelling study of epidemiological and cost impacts. / La paralysie cérébrale au Canada, 2011-2031 : résultats d'une étude de modélisation par microsimulation des répercussions épidémiologiques et économiques.

INTRODUCTION: The objective of our study was to present model-based estimates and projections on current and future health and economic impacts of cerebral palsy in Canada over a 20-year time horizon (2011-2031). METHODS: We used Statistics Canada's Population Health Model (POHEM)-Neurological to simulate individuals' disease states, risk factors and health determinants and to describe and project health outcomes, including disease incidence, prevalence, life expectancy, health-adjusted life expectancy, health-related quality of life and health care costs over the life cycle of Canadians. Cerebral palsy cases were identified from British Columbia's health administrative data sources. A population-based cohort was then used to generate the incidence and mortality rates, enabling the projection of future incidence and mortality rates. A utility-based measure (Health Utilities Index Mark 3) was also included in the model to reflect various states of functional health to allow projections of health-related quality of life. Finally, we estimated caregiving parameters and health care costs from Canadian national surveys and health administrative data and included them as model parameters to assess the health and economic impact of cerebral palsy. RESULTS: Although the overall crude incidence rate of cerebral palsy is projected to remain stable, newly diagnosed cases of cerebral palsy will rise from approximately 1800 in 2011 to nearly 2200 in 2031. In addition, the number of people with the condition is expected to increase from more than 75 000 in 2011 to more than 94 000 in 2031. Direct health care costs in constant 2010 Canadian dollars were about $11 700 for children with cerebral palsy aged 1-4 years versus about $600 for those without the condition. In addition, people with cerebral palsy tend to have longer periods in poorer health-related quality of life. CONCLUSION: Individuals with cerebral palsy will continue to face challenges related to an ongoing need for specialized medical care and a rising need for supportive services. Our study offers important insights into future costs and impacts associated with cerebral palsy and provides valuable information that could be used to develop targeted health programs and strategies for Canadians living with this condition.

Population projections of an endangered cactus suggest little impact of climate change.

Population projections coupled with downscaled climate projections are a powerful tool that allows predicting future population dynamics of vulnerable plants in the face of a changing climate. Traditional approaches used to predict the vulnerability of plants to climate change (e.g. species distribution models) fail to mechanistically describe the basis of a population's dynamics and thus cannot be expected to correctly predict its temporal trends. In this study, we used a 23-year demographic dataset of the acuña cactus, an endangered species, to predict its population dynamics to the end of the century. We used integral projection models to describe its vital rates and population dynamics in relation to plant volume and key climatic variables. We used the resulting climate-driven IPM along with climatic projections to predict the population growth rates from 1991 to 2099. We found the average population growth rate of this population between 1991 and 2013 to be 0.70 (95% CI 0.61-0.79). This result confirms that the population of acuña cactus has been declining and that this decline is due to demographic structure and climate conditions. However, the projection model also predicts that, up to 2080, the population will remain relatively stable mainly due to the survival of its existing adult individuals. Notwithstanding, the long-term viability of the populations can only be achieved through the recruitment of new individuals.

Temperature-Dependent Demography and Population Projection of Tamarixia radiata (Hymenoptera: Eulophidea) reared on Diaphorina citri (Hemiptera: Liviidae).

Tamarixia radiata Waterson (Hymenoptera: Eulophidea) is the principal natural enemy used for the control of the major citrus pest Diaphorina citri Kuwayama (Hemiptera: Liviidae). In this study, we collected the life-history data of T. radiata at four different temperatures (20, 27.5, 30, and 35°C) and analyzed them by using the age-stage, two-sex life table. The longest preadult developmental time (16.53 d) was observed at 20°C, whereas the shortest one was 7.29 d at 35°C. The preadult development rate was well-fitted to a linear equation. The lower threshold temperature (T0) was 7.85°C and the thermal summation (K) was 193.36 degree-day. The highest fecundity (F) was 322.7 eggs per female was at 27.5°C, whereas the lowest one was 10.8 eggs per female at 35°C. The net reproductive rate (R0) were 70.97, 169.42, 55.70, and 3.25 offspring at 20, 27.5, 30, and 35°C, respectively; the intrinsic rate of increase (r) were 0.1401, 0.3167, 0.3517, and 0.1143 d-1, respectively. The highest values of fecundity, net reproductive rate, intrinsic rate of increase, and finite rate of increase were observed at 27.5°C. The relationships among F, R0, Nf, and N in all treatments were consistent with R0=F×(Nf/N). The age of peak reproductive value was close to the total preoviposition period in all treatments. Population projections based on the age-stage, two-sex life table showed the dynamics of stage structure and its variability. Faster population growth was observed at 27.5 and 30°C.

Trends in the utilisation rates and acute hospital capacity needs for total hip replacements: results of an analysis of administrative data.

Total hip replacement surgery is the mainstay of treatment for end-stage hip arthritis. In 2014, there were 28227 procedures (incidence rate 252/100000 population). Using administrative data, we projected the future volume of total hip replacement procedures and incidence rates using two models. The constant rate model fixes utilisation rates at 2014 levels and adjusts for demographic changes. Projections indicate 32248 admissions by 2025 or an annual growth of 1.22% (incidence rate 273). The time trend model additionally projects the evolution in age-specific utilisation rates. 34895 admissions are projected by 2025 or an annual growth of 1.95% (incidence rate 296). The projections show a shift in performing procedures at younger age. Forecasts of length of stay indicate a substantial shortening. By 2025, the required number of hospital beds will be halved. Despite more procedures, capacity can be reduced, leading to organisational change (e.g. elective orthopaedic clinics) and more labour intensive stays.

The traits that predict the magnitude and spatial scale of forest bird responses to urbanization intensity.

As humans continue moving to urban areas, there is a growing need to understand the effects of urban intensification on native wildlife populations. Forest species in remnant habitat are particularly vulnerable to urban intensification, but the mechanisms behind these effects are poorly understood. An understanding of how species traits, as proxies for mechanisms, mediate the effects of urban intensification on forest species can help fill this knowledge gap. Using a large point count dataset from the Second Pennsylvania Breeding Bird Atlas, we tested for the effects of species traits on the magnitude and spatial scale of the responses of 58 forest bird species to urbanization intensity in landscapes surrounding count locations. Average urbanization intensity effect size across species was -0.36 ± 0.49 (SE) and average scale of effect of urbanization intensity was 4.87 ± 5.95 km. Resident forest bird species that are granivorous or frugivorous, cavity-nesting, and have larger clutch sizes and more fledglings per clutch had more positive associations with increasing urbanization intensity in landscapes. In addition, the effect of urbanization intensity on forest birds manifested most strongly at larger spatial scales for granivorous, frugivorous, or omnivorous species that are cavity-nesting, have larger clutch sizes and longer wingspans, and flock in larger numbers. To our knowledge, the present study represents the first direct tests of the effects of species traits on both the magnitude and spatial scale of the effect of urbanization on forest birds, as well as the first evidence that migratory status, clutch size, wingspan, and fledglings per clutch are important determinants of the responses of forest birds to urbanization. We discuss the possible mechanisms underlying our results and their implications for forest bird conservation in urbanizing landscapes.

Improving estimation of puma (Puma concolor) population density: clustered camera-trapping, telemetry data, and generalized spatial mark-resight models.

Obtaining reliable population density estimates for pumas (Puma concolor) and other cryptic, wide-ranging large carnivores is challenging. Recent advancements in spatially explicit capture-recapture models have facilitated development of novel survey approaches, such as clustered sampling designs, which can provide reliable density estimation for expansive areas with reduced effort. We applied clustered sampling to camera-traps to detect marked (collared) and unmarked pumas, and used generalized spatial mark-resight (SMR) models to estimate puma population density across 15,314 km2 in the southwestern USA. Generalized SMR models outperformed conventional SMR models. Integrating telemetry data from collars on marked pumas with detection data from camera-traps substantially improved density estimates by informing cryptic activity (home range) center transiency and improving estimation of the SMR home range parameter. Modeling sex of unmarked pumas as a partially identifying categorical covariate further improved estimates. Our density estimates (0.84-1.65 puma/100 km2) were generally more precise (CV = 0.24-0.31) than spatially explicit estimates produced from other puma sampling methods, including biopsy darting, scat detection dogs, and regular camera-trapping. This study provides an illustrative example of the effectiveness and flexibility of our combined sampling and analytical approach for reliably estimating density of pumas and other wildlife across geographically expansive areas.

Population projections for U.S. counties by age, sex, and race controlled to shared socioeconomic pathway.

Small area and subnational population projections are important for understanding long-term demographic changes. I provide county-level population projections by age, sex, and race in five-year intervals for the period 2020-2100 for all U.S. counties. Using historic U.S. census data in temporally rectified county boundaries and race groups for the period 1990-2015, I calculate cohort-change ratios (CCRs) and cohort-change differences (CCDs) for eighteen five-year age groups (0-85+ ), two sex groups (Male and Female), and four race groups (White NH, Black NH, Other NH, Hispanic) for all U.S counties. I then project these CCRs/CCDs using ARIMA models as inputs into Leslie matrix population projection models and control the projections to the Shared Socioeconomic Pathways. I validate the methods using ex-post facto evaluations using data from 1969-2000 to project 2000-2015. My results are reasonably accurate for this period. These data have numerous potential uses and can serve as inputs for addressing questions involving sub-national demographic change in the United States.

Locust and Grasshopper Management.

Locusts and grasshoppers (Orthoptera: Acridoidea) are among the most dangerous agricultural pests. Their control is critical to food security worldwide and often requires governmental or international involvement. Although locust and grasshopper outbreaks are now better controlled and often shorter in duration and reduced in extent, large outbreaks, often promoted by climate change, continue to occur in many parts of the world. While some locust and grasshopper control systems are still curative, the recognition of the damage these pests can cause and the socioeconomic consequences of locust and grasshopper outbreaks have led to an increasing paradigm shift from crop protection to preventive management. Effective preventive management strategy relies on an improved knowledge of the pest biology and ecology and more efficient monitoring and control techniques.