scholarly journals Population Projection under Changing Fertility Conditions

2015 ◽  
Vol 19 (2) ◽  
pp. 86-88
Author(s):  
Tika Ram Aryal
Keyword(s):  
Birth Rate ◽  
Science And Technology ◽  
Age Distribution ◽  
Natural Increase ◽  
Population Projection ◽  
Stability Conditions ◽  
Reproduction Rate ◽  
Fertility Schedule ◽  
Gradual Change ◽  
Net Reproduction

This paper attempts to derive model for population projection under gradual change in fertility schedule on stability conditions using birth trajectory at time t for 0 < t ? a . The projected population can be obtained when the data of the rate of natural increase, net reproduction rate, age variance of the net maternity function, birth rate of the initial stable population along with its age distribution are available of the population.Journal of Institute of Science and Technology, 2014, 19(2): 86-88

scholarly journals Fertility trends and net reproduction in Agincourt, rural South Africa, 1992—2004 1

2007 ◽  
Vol 35 (69_suppl) ◽  
pp. 68-76 ◽  
Author(s):  
Michel L. Garenne ◽  
Stephen M. Tollman ◽  
Mark A. Collinson ◽  
Kathleen Kahn
Keyword(s):  
South Africa ◽  
Fertility Transition ◽  
Age Groups ◽  
Natural Increase ◽  
Reproduction Rate ◽  
Modern Contraceptive ◽  
Fertility Level ◽  
Fertility Trends ◽  
Net Reproduction ◽  
Rural South Africa

Aims: To analyse trends in fertility rates and net reproduction rates in Agincourt, a rural area of South Africa located in the former homeland of Gazankulu near the Mozambican border. Trends are analysed in the context of widely available modern contraceptive methods and increasing HIV/AIDS. Methods: A health and demographic surveillance system has been in place since 1992, covering a population of approximately 70,000 persons, with an annual census update and comprehensive recording of births and deaths. It was complemented by a retrospective study of fertility at baseline. Retrospective and prospective data were used to calculate trends in fertility, survival, and net reproduction. When possible, they were compared with data from other censuses and surveys in the same ethnic group. Results: The fertility transition has almost ended over a course of 25 years in Agincourt. The total fertility rate (TFR) averaged 6.0 in 1979 and 2.3 in 2004. Fertility declined in proportionate fashion in all age groups including adolescents in the recent period. The net reproduction rate (NRR) declined from 1.8 to 1.0 during the prospective period (1992—2004). At current rates of change in fertility and mortality, the NRR can be expected to reach 0.63 by the year 2010. Conclusions: The situation of a below-replacement fertility level is new for rural Africa, and is likely to have many demographic, economic and social implications. The population could decline in the country as a whole, and is nearly static in Agincourt because of negative migration flows balancing the small excess from natural increase.

The replacement of generations in Serbia in the period 1950-2000

Stanovnistvo ◽  
2001 ◽  
Vol 39 (1-4) ◽  
pp. 45-71 ◽  
Author(s):  
Goran Penev
Keyword(s):  
Birth Cohort ◽  
20Th Century ◽  
Regional Differences ◽  
Cohort Analysis ◽  
Reproduction Rate ◽  
Demographic Analysis ◽  
Period Analysis ◽  
Net Reproduction

The article deals with the replacement of generations in Serbia, its dynamics in the second half of the 20th century, and the importance of direct determinants. It points to the major regional differences in the domain of the population reproduction among the large areas of Serbia (Central Serbia, Vojvodina, and Kosovo-Metohija). Two approaches of demographic analysis were applied: period and cohort analysis. Basic indicators, definitions, and shortcomings were presented. The results of the period analysis indicate that up until 1988 (with the exceptions of 1957 and 1981), the fertility in Serbia constantly reached a level of fertility necessary to ensure the replacement. Since 1989, the net reproduction rate has constantly been below unity. In Central Serbia and Vojvodina, the population has not been reproducing itself for more than 45 years (since 1956). The situation has been completely different in Kosovo-Metohija, where fertility has been above the level necessary to ensure reproduction during the entire second half of 20th century. The cohort analysis applied to six chosen generations (birth cohort of 1950, 1955, 1960, 1965, 1970, and 1975) indicates that in Serbia, only women born in 1960 ensured the replacement. In Central Serbia and Vojvodina, none of the studied generations succeeded in ensuring the replacement, while in Kosovo-Metohija all generations did.

Ambient Humidity Affects Development, Survival, and Reproduction of the Invasive Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), in China

2021 ◽  
Author(s):  
Limei He ◽  
Shengyuan Zhao ◽  
Abid Ali ◽  
Shishuai Ge ◽  
Kongming Wu
Keyword(s):  
Spodoptera Frugiperda ◽  
Fall Armyworm ◽  
Intrinsic Rate ◽  
Intrinsic Rate Of Increase ◽  
Reproduction Rate ◽  
Ambient Humidity ◽  
Rate Of Increase ◽  
Population Forecasting ◽  
Survival And Reproduction ◽  
Net Reproduction

Abstract Ambient humidity can directly affect the water balance in insects. The migratory fall armyworm, Spodoptera frugiperda Smith, has spread to more than 60 countries and regions in Africa, Asia, and Oceania that have a great difference in average ambient humidity. Understanding the effects of ambient humidity changes on its development, survival, and reproduction can help to predict its population dynamics in different habitats. Therefore, we evaluated the effects of atmospheric relative humidity (RH) on the development, survival, and reproduction and soil moisture on the pupation and emergence of fall armyworm. As a result, survival and pupal mass increased significantly with increasing RH. Among the five RHs tested, 80% RH was the most suitable for fall armyworm with the highest intrinsic rate of increase (r), finite rate of increase (λ), and net reproduction rate (R0). The population growth at the different RHs in decreasing order was 80 &gt; 100 &gt; 60 &gt; 40 &gt; 20%. A relative moisture (RM) of soil from 6.80 to 47.59% was suitable for fall armyworm pupation, survival, and eclosion, but fall armyworm could not pupate normally in soil with 88.39 and 95.19% RM. The survival and emergence rate of fall armyworm pupae were reduced by irrigation that increased the RM after the mature larvae entered the soil. These findings may be helpful for refining laboratory rearing protocols, population forecasting, and management of fall armyworm.

Birth Control: Reversal or Postponement?

1960 ◽  
Vol 3 ◽  
pp. 59-73 ◽  
Author(s):  
Leo A. Orleans
Keyword(s):  
Natural Resources ◽  
Birth Control ◽  
Death Rate ◽  
Birth Rate ◽  
Natural Increase ◽  
Vital Rates ◽  
The People ◽  
The World ◽  
Communist China ◽  
Annual Population

Whereas throughout most of the world the results of the 1953 censusregistration of Communist China, reporting a population of 582·6 million, evoked anxiety and even alarm, the Communists expressed only pride and overwhelming confidence. As a people “liberated from the oppressive chains of capitalism,” Communist leaders felt that their horizons were unlimited and that feeding and caring for a population of this size presented no problems under a system in which people are “the most precious of all categories of capital.” The simultaneous release of vital rates which indicated a birth rate of 37 per thousand population and a death rate of 17 per thousand, further stressed the “great vitality of the people of new China.” The 2 per cent, natural increase (excess of births over deaths), resulting in an annual population growth of some 12 million, was declared, in line with Marxist doctrine, to be an asset in a country with vast new lands and unexploited natural resources, where additional people create additional wealth.

scholarly journals STUDI LALAT PENGOROK DAUN LIRIOMYZA SPP. PADA PERTANAMAN BAWANG DAUN, DAN PARASITOID OPIUS CHROMATOMYIAE BELOKOBYLSKIJ & WHARTON (HYMENOPTERA: BRACONIDAE)

2009 ◽  
Vol 9 (1) ◽  
pp. 22-31
Author(s):  
Rusli Rustam ◽  
Aunu Rauf ◽  
Nina Maryana ◽  
Pudjianto Pudjianto ◽  
Dadang Dadang
Keyword(s):  
Age Distribution ◽  
Host Density ◽  
Field Studies ◽  
Reproductive Value ◽  
Laboratory Studies ◽  
Demographic Parameter ◽  
Liriomyza Huidobrensis ◽  
Stable Age Distribution ◽  
Net Reproduction ◽  
Density Results

Studies on Leafminer Liriomyza spp. in Green Onion Fields, and Parasitoid Opius chromatomyiae Belokobylskij & Wharton (Hymenoptera: Braconidae).  Field studies were conducted to determine population abundance of leafminers and their parasitoids in green onion fields in Puncak, West Java. In addition to that, laboratory studies were carried out to determine demographic parameter of Opius chromatomyiae as well as response of parasitoid to increasing host density. Results revealed that green onions were infested by two species of leafminers, Liriomyza huidobrensis and Liriomyza chinensis.  Leafminer flies emerged from Erwor leaves (54.5) were significantly higher than those of RP leaves (18.65) (P = 0.0005). However, number of  leafminer flies caught on sticky traps was not statistically different (P = 0.297).  Two species of parasitoid, Hemiptarsenus varicornis and O. chromatomyiae, were associated with leafminers in green onion fields. Higher number of parasitoids emerged from Erwor leaves (13.68) as compared to RP (6.90) (P =0.0007 ). However, level of parasitization were 24.36% on Erwor and 28.45% on RP, and was not significantly different (P = 0.387). Laboratory studies indicated that net reproduction (Ro) of O. chromatomyiae was 28.55, generation time (T) 15.96 days, intrinsic growth rate 0.21, and total of reproductive value 223.64.  The stable age distribution of parasitoid were 37.93% eggs, 24.92% larvae, 20.36% pupae and 16.78% adults.  The parasitoid showed functional response type II to increasing host density, with a = 0.08 and Th = 2.58.

ANNUAL SUMMARY OF VITAL STATISTICS—1968

PEDIATRICS ◽  
1969 ◽  
Vol 44 (6) ◽  
pp. 1031-1034
Author(s):  
Myron E. Wegman
Keyword(s):  
Birth Rate ◽  
Marriage Rate ◽  
The United States ◽  
Vital Statistics ◽  
Natural Increase ◽  
Annual Number ◽  
Sharp Rise ◽  
Death Rates ◽  
The Third ◽  
Number Of Births

Infant mortality declined again in 1968, for the third successive year, and there is some evidence of a more rapidly downward trend in the unacceptably higher infant death rates which have existed among some population groups. The birth rate also declined again, but the marriage rate showed rather a sharp rise ( Table I ). With an excess of births over deaths of 1.55 million persons, the rate of natural increase was 7.8 per 1,000 population. Births Once more there was a decline in annual number of births, although a smaller one than last year. Nevertheless, with a rising population the birth rate fell to 17.4, the lowest ever recorded in the United States.

The age distribution in the Taimyr population wild northern deer (Rangifer Tarandus) in the first decades of 21 centuries

2021 ◽  
pp. 15-21
Author(s):  
A. Shapkin ◽  
R. Ivanova ◽  
N. Arsentseva ◽  
N. Sukhanova
Keyword(s):  
Age Structure ◽  
Rangifer Tarandus ◽  
Age Distribution ◽  
Age Groups ◽  
Base Material ◽  
Middle Level ◽  
Reproduction Rate ◽  
Male And Female ◽  
Field Samples ◽  
Wild Deer

Objective: mathematical demography means to identify and evaluate the age distribution of male and female of Taimyr tundra reindeer in the first decade of the XXI century and future trends in demographic situation Taimyr population.Materials and methods. The base material for evaluating the current state of the population age structure Taimyr steel fishing representative sample of male and female wild deer (n = 10845 individuals) collected in the West, Central and Taimyr Putorana in 2001-2008., And the deer samples (n = 1569 individuals), the floor of which is unknown. Determination of individual animals from age and older (n = 9773 individuals) performed on histological sections of cutters according to the corresponding procedure. To repay the random deviations of sample data because of a lack of presence of immature animals (calves, yearlings, young 1-2 years) (selectivity of fishing is directed primarily at the production of individuals older than 3 years, why animals in different age groups in the samples is greater than there are in the population) applies a smoothing procedure. Then, positive deviation of the number of individuals in the same age group were leveled due to negative deviations in adjacent groups.Results. By smoothed age ranges of the field samples from 2001-2008 the current age distribution of Taimyr wild reindeer calculated and analyzed. The study showed that the theoretical current age distribution of males with realized breeding is 77.03, females - 80.56, in the combined groups of animals - 82.35%. The real population has 18-19 age generations of males and females. The reproductive core of males from 3 to 10 years old is 48.43%, individuals of age limit 11 years and older occupy 1.96% of this sex and age structure, calves and young animals for 1-2 years - 24.64%. For the reproductive part of females aged 3–15 years, the overall age distribution is 55.34%, and the proportion of juveniles and young animals, according to calculations, is determined in this part of the population at 25.16%. In the combined current age distribution, males, females: calves and young animals accounted for 27.72%, the sexually mature part with animals of older and age-specific ages - 54.63%.Conclusion. Demographic Taimir population modeling operation in the first decade of the XXI century long materials commercial samples collected at commercial points shown at current age distribution of the realized and reproduction conditions for existing commercial load males - 77.03 for females - 80.56 and for unified groups (males, females) - 82.4%. Meanwhile, the steady state and stable age distribution Taimyr tundra wild deer can reach a middle-level only when the fecundity of female reproductive generations with clean reproduction rate (R0) equal in population groupings 1.0

Temperature-dependent life history of Eutetranychus africanus (Acari: Tetranychidae) on papaya

2020 ◽  
Vol 25 (3) ◽  
pp. 479-490
Author(s):  
Ming-ying Lin ◽  
Chin-hsing Lin ◽  
Yen-po Lin ◽  
Ching-tzu Tseng
Keyword(s):  
Life History ◽  
Immature Stage ◽  
Invasive Pest ◽  
Intrinsic Rate Of Increase ◽  
Reproduction Rate ◽  
Developmental Duration ◽  
Developmental Threshold ◽  
Rate Of Increase ◽  
History Of ◽  
Net Reproduction

This study was conducted to further understand the biology of Eutetranychus africanus Tucker, a newly invasive pest mite in Taiwan that can cause serious damage to papaya. We report the life history of E. africanus on papaya in laboratory conditions at 12, 17, 22, 27 and 32 ± 0.5 °C, with 70 ± 5 % relative humidity and a photoperiod of L12: D12. Eggs did not hatch at 12 °C. Both developmental duration and longevity were significantly shortened with the increase of temperature. The longest and shortest developmental durations of the immature stage were 37.28 days at 17 °C and 8.70 days at 32 °C, respectively. The longevity of both sexes varied similarly with the change in temperature, with shorter lifespan in males: Females survived for 3.64 days (shortest) at 32 °C to 17.50 days (longest) at 17 °C, whereas males survived for 11.00 days (longest) at 17 °C to 2.57 days (shortest) at 32 °C. The differences in fecundity were significant among all tested temperatures, with 17.61 eggs/female at 27 °C being the highest. The low developmental threshold and thermal summation of the full immature stage were 11.48 °C and 163.93 degree-days, respectively. In two-sex life table analysis, population parameters were significantly affected by temperature except the net reproduction rate. The highest intrinsic rate of increase was 0.1221 day−1 at 27 °C; the average generation time was the shortest (12.61 days) at 32 °C and the longest (48.70 days) at 17 °C. The highest net reproduction rate was 5.06 eggs/female at 27 °C. This report contributes background knowledge to the management of the damage caused by E. africanuson papaya.This study was conducted to further understand the biology of Eutetranychus africanus Tucker, a newly invasive pest mite in Taiwan that can cause serious damage to papaya. We report the life history of E. africanus on papaya in laboratory conditions at 12, 17, 22, 27 and 32 ± 0.5 °C, with 70 ± 5 % relative humidity and a photoperiod of L12: D12. Eggs did not hatch at 12 °C. Both developmental duration and longevity were significantly shortened with the increase of temperature. The longest and shortest developmental durations of the immature stage were 37.28 days at 17 °C and 8.70 days at 32 °C, respectively. The longevity of both sexes varied similarly with the change in temperature, with shorter lifespan in males: Females survived for 3.64 days (shortest) at 32 °C to 17.50 days (longest) at 17 °C, whereas males survived for 11.00 days (longest) at 17 °C to 2.57 days (shortest) at 32 °C. The differences in fecundity were significant among all tested temperatures, with 17.61 eggs/female at 27 °C being the highest. The low developmental threshold and thermal summation of the full immature stage were 11.48 °C and 163.93 degree-days, respectively. In two-sex life table analysis, population parameters were significantly affected by temperature except the net reproduction rate. The highest intrinsic rate of increase was 0.1221 day−1 at 27 °C; the average generation time was the shortest (12.61 days) at 32 °C and the longest (48.70 days) at 17 °C. The highest net reproduction rate was 5.06 eggs/female at 27 °C. This report contributes background knowledge to the management of the damage caused by E. africanus on papaya.

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