scholarly journals The intrinsic rate of increase of reindeer and caribou populations in arctic environments

Rangifer ◽  
1990 ◽  
Vol 10 (3) ◽  
pp. 169 ◽  
Author(s):  
D. C. Heard
Keyword(s):  
Primary Productivity ◽  
Bering Sea ◽  
Rangifer Tarandus ◽  
Intrinsic Rate ◽  
Maximum Growth ◽  
Intrinsic Rate Of Increase ◽  
Animal Population ◽  
Rate Of Increase ◽  
The Mean ◽  
The Bering Sea

The intrinsic rate of increase of an animal population, rm, is specific to the environment in which it is measured. Previous estimates of maximum growth rates for reindeer and caribou Rangifer tarandus populations were based on introductions to islands with cool oceanic climates. The mean intrinsic rate of increase of 6 populations was 0.26 ranging from 0.21 on St Paul Island in the Bering Sea to 0.29 in the Barff herd on South Georgia. I calculated rm for two Rangifer populations introduced to arctic environments to determine the effect of environmental severity on the intrinsic rate of increase. Reindeer on the Belcher islands increased at rm= 0.28 and caribou on Southampton Island increased at rm = 0.23 (mean = 0.26). The lower primary productivity and longer duration of snow cover in arctic environments did not affect the intrinsic rate of increase.

scholarly journals Biology and life-table of Typhlodromus (Anthoseius) athenas (Acari: Phytoseiidae) fed with the Old World Date Mite, Oligonychus afrasiaticus (Acari: Tetranychidae)

Acarologia ◽  
2018 ◽  
Vol 58 (1) ◽  
pp. 52-61
Author(s):  
Samah Ben Chaaban ◽  
Brahim Chermiti ◽  
Serge Kreiter
Keyword(s):  
Life Table ◽  
Intrinsic Rate ◽  
Phoenix Dactylifera ◽  
Reproductive Rate ◽  
Intrinsic Rate Of Increase ◽  
Net Reproductive Rate ◽  
Old World ◽  
Rate Of Increase ◽  
Wide Range ◽  
The Mean

The old world date mite Oligonychus afrasiaticus is an important spider mite pest of the date palms Phoenix dactylifera L. mostly in North Africa and the Middle East. A population of the predaceous mite Typhlodromus (Anthoseius) athenas has been recently found in Tunisia in association with a decrease of O. afrasiaticus densities. The objective of this paper was to assess the development and reproduction abilities of T. ( A.) athenas on O. afrasiaticus under laboratory conditions at two temperatures: 27 and 32 °C. The results obtained show that females of T. (A.) athenas develop in 5 days at 27 °C and 4.1 days at 32 °C. The mean fecundity of T. (A.) athenas was 32.1 and 23.2 eggs per female at 27 and 32 °C, respectively. Life table parameters were stimated: the net reproductive rate (Ro) 27.9 and 17.9 eggs/female, the intrinsic rate of increase (rm) 0.322 and 0,344 female/female/day and the mean generation time (T) 10.3 and 8.4 days at 27 and 32 °C, respectively. At both temperatures tested, T. (A.) athenas intrinsic rate of increase was greater than that of O. afrasiaticus (rm = 0.213 at 32 °C,against rm = 0.166 day1 at 27 °C). Typhlodromus (A.) athenas would be able to develop at a wide range of temperatures feeding on O. afrasiaticus and seems to be able to potentially control it.

Development, survival and reproduction of a potential biological control agent, Lasioseius japonicus Ehara (Acari: Blattisociidae), on eggs of Drosophila melanogaster (Diptera: Drosophilidae) and Sitotroga cerealella (Lepidoptera: Gelechiidae)

2020 ◽  
Vol 25 (8) ◽  
pp. 1461-1471
Author(s):  
Lixia Xie ◽  
Na Zhang ◽  
Xinran Wu ◽  
Kai Liu ◽  
Chenlin Liu ◽  
...  
Keyword(s):  
Generation Time ◽  
Intrinsic Rate ◽  
Reproductive Rate ◽  
Intrinsic Rate Of Increase ◽  
Sitotroga Cerealella ◽  
Finite Rate ◽  
Net Reproductive Rate ◽  
Rate Of Increase ◽  
Survival And Reproduction ◽  
The Mean

Lasioseius japonicus is a species of soil-dwelling predatory mite with great potential for controlling insect pests and has a broad application prospect in biological control. This study was conducted under indoor conditions to explore the development, survival and reproduction of L. japonicus on two diets. Through the construction of two-sex life table of L. japonicus, it was revealed that, when it preyed on eggs of Drosophila melanogaster, the intrinsic rate of increase (r) was 0.2614 d-1, the net reproductive rate (R0) was 57.76 offspring, the finite rate of increase (λ) was 1.2988 d-1, and the mean generation time (T) was 15.49 d. When preying on eggs of Sitotroga cerealella, the intrinsic rate of increase (r) of L. japonicus was 0.1560 d-1, the net reproductive rate (R0) was 20.96 offspring, the finite rate of increase (λ) was 1.1690d-1, and the mean generation time (T) was 19.41 d. In addition, the life expectancy and population growth trend of L. japonicus were simulated based on the above two alternative prey species. The results showed that feeding on the eggs of D. melanogaster is more beneficial to the growth and reproduction of L. japonicus.

Resistant rose cultivar affects life table parameters of two-spotted spider mite and its predators Phytoseiulus persimilis and Amblyseius swirskii (Phytoseiidae) 

2019 ◽  
Vol 24 (9) ◽  
pp. 1620-1630 ◽  
Author(s):  
Zahra Alipour ◽  
Yaghoub Fathipour ◽  
Azadeh Farazmand ◽  
Mostafa Khanamani
Keyword(s):  
Life Table ◽  
Phytoseiulus Persimilis ◽  
Intrinsic Rate ◽  
Reproductive Rate ◽  
Intrinsic Rate Of Increase ◽  
Net Reproductive Rate ◽  
Resistant Cultivars ◽  
Rate Of Increase ◽  
The Mean ◽  
Two Spotted Spider Mite

Herbivores' host plant resistance may also affect performance of their predators. The effect of susceptible ('Yellow') and resistant ('Roulette') rose cultivars on demographic parameters of the two-spotted spider mite (TSSM), Tetranychus urticae Koch and its predators Phytoseiulus persimilis Athias-Henriot and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) was determined under laboratory conditions. The obtained data were analyzed using the two-sex life table theory. The development rate of different life stages of TSSM and its predators on the susceptible and resistant rose cultivars were significantly different. Total development time of juvenile stages of TSSM and A. swirskii on the resistant cultivar was longer than that on the susceptible one, although no significant differences were obtained in the case of P. persimilis. By using the two-sex life table, the intrinsic rate of increase (r) of TSSM on the susceptible and resistant cultivars was 0.205 and 0.143 day-1, respectively. In addition, the net reproductive rate (R0) of TSSM on the susceptible and resistant cultivars was 26.46 and 11.47 eggs per individual, respectively; however, the mean generation time (T) of TSSM on these cultivars was 15.92 and 16.92 days, respectively. Furthermore, the value of the intrinsic rate of increase (r) in P. persimilis on the susceptible and resistant cultivars was 0.217 versus 0.163 day-1as well as in A. swirskii on the mentioned cultivars was 0.147 versus 0.117 day-1, respectively. There was no significant difference between the values of the net reproductive rate (R0) in P. persimilis on the susceptible and resistant rose cultivars, but in A. swirskii the value of this parameter on the susceptible cultivar was significantly higher than that on the resistant one. The mean generation time (T) in both predators on the resistant cultivar was longer than the susceptible one. In conclusion, resistance of the rose cultivar negatively affected the population growth parameters of TSSM and its both predators.

scholarly journals Biotic potential and reproductive parameters of Spodoptera cosmioides (Walker) (Lepidoptera: Noctuidae) in the laboratory

2019 ◽  
Vol 79 (3) ◽  
pp. 488-494 ◽  
Author(s):  
A. Specht ◽  
V. F. Roque-Specht
Keyword(s):  
Intrinsic Rate ◽  
Reproductive Rate ◽  
Intrinsic Rate Of Increase ◽  
Reproductive Parameters ◽  
Finite Rate ◽  
Net Reproductive Rate ◽  
Biotic Potential ◽  
Rate Of Increase ◽  
The Mean ◽  
Lepidoptera Noctuidae

Abstract In this study we evaluate the biotic potential and reproductive parameters of Spodoptera cosmioides (Walker, 1858) under controlled conditions (25 ± 1 °C, 70 ± 10% RH and 14 hour photophase). Females, on average, (14.433 days) did not live significantly longer than their male counterparts (13.100 days). The mean durations of the pre-oviposition, oviposition and post-oviposition periods were 2.767, 10.600 and 1.067 days, respectively. The mean fecundity of females was 5,073.533 eggs and the mean fertility was 5,021.027 larvae. On average, females copulated 1.167 times. Fecundity was positively correlated with the number of copulations (r = 0.583, P <0.001). The number of copulations, however, was negatively correlated whit the duration of the pre-oviposition (r = -0.560, P = 0.007) and oviposition (r = -0.479, P = 0.048) periods, and overall longevity (r = -0.512, P = 0.031). The biotic potential was estimated at 6.547 x 1021 individuals/female/year. The net reproductive rate (Ro) was 2,193.722 times per generation and the mean generation time (T) was 46.407 days. The intrinsic rate of increase (rm) was 0.166, with a finite rate of increase (λ) of 1.180, per week.

Effects of different almond cultivars on biological and population responses of Schizotetranychus smirnovi (Acari: Tetranychidae)

2021 ◽  
Vol 26 (5) ◽  
pp. 962-972
Author(s):  
Zarir Saeidi ◽  
Alireza Nemati ◽  
Elham Riahi
Keyword(s):  
Growth Parameters ◽  
Reproductive Potential ◽  
Total Mortality ◽  
Intrinsic Rate ◽  
Developmental Time ◽  
Intrinsic Rate Of Increase ◽  
Population Responses ◽  
Rate Of Increase ◽  
The Mean ◽  
Population Growth Parameters

The development, longevity, and reproductive potential of Schizotetranychus smirnovi concerning different almond cultivars including Sefid, Azar, Shokofeh, Shahrood6, Shahrood7, Ferragnes, Shahrood13, Shahrood21, Rabie, Nonpareil, and Mamaei were investigated in the current study. Our results indicated the longest developmental time of females on Shahrood21 (7.35 ± 0.10), while the shortest duration of this parameter was found on Rabie (6.21 ± 0.10) and Nonpareil (5.88 ± 0.17) cultivars. The total mortality ranged from 13.30 to 50.00% on Azar and Shokofeh, respectively. On the majority of cultivars, the highest proportion of mortality among all stages was allocated to larvae which indicated that it was the most sensitive stage. The fecundity of S. smirnovi on Mamaei (34.19 ± 3.60), Sefid (30.50 ± 2.67), and Ferragnes (30.31 ± 3.02) was significantly higher than other cultivars. However, the lowest fecundity (11.21 ± 1.70) was observed on Shokofeh cultivar. Moreover, different cultivars resulted in significant differences in all population growth parameters. Azar had the highest value of both intrinsic rate of increase (r) (0.2675 ± 0.0164) and finite rate of increase (λ) (1.3067 ± 0.0213), whereas the value of these parameters on Shokofeh and Shahrood21 were significantly lower than other cultivars. The mean generation time (T) ranged from 9.51 ± 0.16 on Shahrood7 to 11.69 ± 0.39 d on Shahrood21 cultivar. According to our results, Mamaei, Nonpareil, Rabie, Ferragnes and Azar cultivars were more susceptible, while Shokofeh, Shahrood21, and Shahrood13 seemed to be more tolerant to S. smirnovi.

scholarly journals Interaction Between Bt-Transgenic Cotton and the Whitefly’s Parasitoid, Encarsia Formosa (Hymenoptera: Aphelinidae)

2014 ◽  
Vol 54 (3) ◽  
pp. 272-278 ◽  
Author(s):  
Solmaz Azimi ◽  
Shima Rahmani ◽  
Masoud Tohidfar ◽  
Ahmad Ashouri ◽  
Alireza Bandani ◽  
...  
Keyword(s):  
Intrinsic Rate ◽  
Developmental Time ◽  
Reproductive Rate ◽  
Intrinsic Rate Of Increase ◽  
Bt Cotton ◽  
Encarsia Formosa ◽  
Net Reproductive Rate ◽  
Preoviposition Period ◽  
Rate Of Increase ◽  
The Mean

Abstract Transgenic Bt cotton developed against lepidopteran pests may not be compatible with parasitoid of secondary pests such as Bemisia tabaci which attack many plants such as cotton. In this study, the effects of Bt cotton on the demographic parameters of Encarsia formosa, parasitoid of B. tabaci were assessed. The data were analysed using the age specific, two-sex life table parameters. The results indicated that pre-adult developmental time, the total preoviposition period (TPOP) and the adult preoviposition period (APOP) in the Bt cotton were significantly longer than in the non-Bt cotton. Also, fecundity and body size in both lines were significantly different. The fecundity was 23.64±0.73 and 43.75±0.89 eggs/females in the Bt and non-Bt cotton, respectively. All the population parameters were affected by the Bt cotton. The intrinsic rate of increase (r) was 0.15 day-1 in the non-Bt cotton but it was 0.10 day-1 in the Bt cotton. The finite rate of increase (λ) was 1.11 day-1 in the non-Bt cotton whilst it was 1.08 in the Bt cotton. The net reproductive rate (R0) in the non-Bt cotton was 36.75 but in the Bt cotton these parameters showed 19.62 offspring/individual. Also, the mean generation time (T ) in the non-Bt and Bt cotton was 22.69 and 27.79 days, respectively. The results illustrated, that although transgenic crops are effective tools for management of the target pests, they can adversely affect, either directly or indirectly, the natural enemies dependent on these plants.

Development, survivorship and reproduction of Eretmocerus sp. nr furuhashii (Hymenoptera: Aphelinidae) parasitizing Bemisia tabaci (Hemiptera: Aleyrodidae) on glabrous and non-glabrous host plants

2005 ◽  
Vol 95 (4) ◽  
pp. 313-319 ◽  
Author(s):  
B.-L. Qiu ◽  
P.J. De Barro ◽  
S.X. Ren
Keyword(s):  
Bemisia Tabaci ◽  
Host Plants ◽  
Survival Rates ◽  
Intrinsic Rate ◽  
Developmental Time ◽  
Intrinsic Rate Of Increase ◽  
Leaf Hairs ◽  
Rate Of Increase ◽  
Mean Lifetime ◽  
The Mean

AbstractThe developmental, survivorship and reproductive biology of Eretmocerus sp. nr furuhashii Rose & Zolnerowich parasitizing Bemisia tabaci (Gennadius) biotype B on tomato, cucumber, eggplant and collard at 26±0.5°C was studied. The mean longevity ranged from 6.5 days on tomato to 8.1 days on collard. The mean lifetime fecundities on tomato, cucumber, eggplant and collard were 35.4, 37.3, 41.4 and 46.4 eggs, whereas the mean lifetime fertility was 20.2, 22.7, 28.3 and 33.6 offspring, respectively. Developmental time was longest on cucumber (17.1 days) and shortest on collard (15.9 days). Survival rates varied significantly across host plants. Sex ratio (♀:♂) varied from 1.71 to 1.93 across the four hosts. The intrinsic rate of increase (rm) was highest (0.157) on collard and lowest on tomato (0.133). Mean generation time (R0) ranged from 14.7 to 20.9 days. All the data demonstrated that the reproductive success and overall performance of E. sp. nr furuhashii increased as the density of leaf hairs declined. As leaf hairs play a key role in determining efficacy, it is unlikely that effective biological control of B. tabaci using E. sp. nr furuhashii will be achieved on non-glabrous crop varieties.

Population growth of a copepod Gladioferens imparipes Thomson

1974 ◽  
Vol 25 (3) ◽  
pp. 351 ◽  
Author(s):  
RJ Rippingale ◽  
EP Hodgkin
Keyword(s):  
Population Growth ◽  
Field Data ◽  
Intrinsic Rate ◽  
Growth Potential ◽  
Intrinsic Rate Of Increase ◽  
Growth Equation ◽  
Animal Population ◽  
Rate Of Increase ◽  
High Population Growth ◽  
Maturation Rate

The intrinsic rate of increase of an animal population can be calculated from data on longevity, sex ratio, maturation rate and fecundity and can be expressed as r in the population growth equation Nt = N0ert. Laboratory and field data are used to calculate the value of r per day for the copepod Gladioferens imparipes Thomson. The r values obtained, 0.146 per day at 15� C and 0.293 per day at 25� C, are both high. This high population growth potential is interpreted as an adaptation to the estuarine habitat.

Fertility life table and biology of Tetrastichus giffardianus (Hymenoptera: Eulophidae) in the larvae of Ceratitis capitata (Diptera: Tephritidae)

2020 ◽  
pp. 1-8
Author(s):  
Elania Clementino Fernandes ◽  
Mariana Macedo Souza ◽  
Dori Edson Nava ◽  
Janisete Gomes Silva ◽  
Elton Lucio Araujo
Keyword(s):  
Life Table ◽  
Ceratitis Capitata ◽  
Intrinsic Rate ◽  
Mass Rearing ◽  
Population Increase ◽  
Intrinsic Rate Of Increase ◽  
Rate Of Increase ◽  
Males And Females ◽  
The Mean ◽  
Time Required

Abstract Tetrastichus giffardianus is a gregarious koinobiont endoparasitoid of tephritids, including Ceratitis capitata, which is one of the most important fruit pests worldwide. The objective of this study was to evaluate the effect of constant temperatures on the biology and development of the egg-adult period of T. giffardianus in larvae/pupae of C. capitata to construct a fertility life table. The study was carried out in climatic chambers at constant temperatures of 15, 20, 25, 30, and 35 ± 1°C, 70 ± 10% relative humidity and a photophase of 12 h. Complete egg and larval development occurred only at temperatures of 20, 25, and 30°C. The mean longevity of males and females was inversely proportional to temperature. The time of development of the pre-imaginal period was influenced by temperature and ranged from 41 days at 20°C to 11 days at 25°C. The best T. giffardianus performance occurred at 25°C when the intrinsic rate of increase was 0.21, the mean generation time was 20.43 days, the time required to double the population was 3.33 days, and the finite rate of population increase (λ) was 1.23. The results of this study provided information for the establishment of mass rearing and an evaluation of the adaptability of T. giffardianus to different environments, which is necessary for the use of this parasitoid in the biological control of tephritid pests, particularly C. capitata.

Effect of temperature on life table parameters of Rhyncaphytoptus ficifoliae Keifer (Trombidiformes; Diptilomiopidae)

2019 ◽  
Vol 24 (8) ◽  
pp. 1394-1405
Author(s):  
Fereshteh Bahirae ◽  
Shahriar Jafari ◽  
Parisa Lotfollahi ◽  
Jahanshir Shakarami
Keyword(s):  
Life Table ◽  
Intrinsic Rate ◽  
Effect Of Temperature ◽  
Intrinsic Rate Of Increase ◽  
Life Table Parameters ◽  
Ambient Temperatures ◽  
Rate Of Increase ◽  
The Mean ◽  
Fig Trees ◽  
Increasing Temperature

Rhyncaphytoptus ficifoliae Keifer (Trombidiformes; Diptilomiopidae) is one of the important pests of fig trees that is widely distributed in fig orchards located in south-western Iran. The effect of six ambient temperatures (17, 20, 25, 30, 33 and 36°C) on life table parameters of R. ficifoliae was studied under laboratory conditions at 60±5% relative humidity and a photoperiod of 16: 8 h (L: D) on fig leaves. The life table parameters were estimated according to the age-stage, two-sex life table theory. In addition, the bootstrap technique was used for estimating the variances and standard errors of the population parameters. R. ficifoliae successfully developed and reproduced from 17 to 33°C, but the females reared at 36ºC laid a few eggs and died after several days. The longest and shortest total longevity of females were recorded at 25°C (48.50 days) and 33°C (14.33 days), respectively. The fecundity increased as temperature increased from 11.04 eggs at 17°C to 25.04 eggs at 25°C, then decreased and reached 12.44 eggs at 33°C. The lowest and highest values of the intrinsic rate of increase (r) were 0.043 and 0.234 day-1 that obtained at 17 and 30°C, respectively. The mean generation time (T) significantly decreased from 33.39 days to 9.63 days with increasing temperature from 17°C to 33°C. Our findings show that females reared at higher temperatures (>25°C) exhibit greater overall reproduction rates in comparison to lower temperatures.

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