Plausible bounds for maximum rate of increase in magpie geese (Anseranas semipalmata): implications for harvest

2005 ◽  
Vol 32 (5) ◽  
pp. 465 ◽  
Author(s):  
Barry W. Brook ◽  
Peter J. Whitehead
Keyword(s):  
Intrinsic Rate ◽  
Maximum Sustainable Yield ◽  
Management Policy ◽  
Population Increase ◽  
Sustainable Harvest ◽  
Precautionary Approach ◽  
Conservation Implications ◽  
Rate Of Increase ◽  
Prior Estimate ◽  
Over Exploitation

We used improved information on fecundity and credible estimates of survival to define the plausible bounds of maximum intrinsic rate of population increase (r m) in magpie geese and explored the management and conservation implications, given current estimates of off-take. We considered previous estimates of r m (0.78, based on time-series analysis of aerial count data) and the corresponding predicted maximum sustainable harvest rates (30–39% per annum) to be excessive, thereby risking poor management decisions. In contrast, our estimate of the maximum plausible range of r m (0.11–0.28) is substantially lower than the previous estimate, and suggests maximum harvest rates of no more than 5–14% of total population size per annum. We consider that it would be unwise to adopt the prior estimate of r m for management policy because it would risk over-exploitation. Our results embody a more precautionary approach to assessing maximum sustainable yield for magpie geese in northern Australia, and are not confounded by migration. The move from a simple empirical model to a partially mechanistic one reflects a significant improvement in understanding, but must nevertheless be viewed as part of an ongoing process of model refinement and testing.

Potential Rates of Increase of a Harbour Porpoise (Phocoena phocoena) Population Subjected to Incidental Mortality in Commercial Fisheries

1991 ◽  
Vol 48 (12) ◽  
pp. 2429-2435 ◽  
Author(s):  
Thomas H. Woodley ◽  
Andrew J. Read
Keyword(s):  
Gulf Of Maine ◽  
Intrinsic Rate ◽  
Frequency Equation ◽  
Harbour Porpoise ◽  
Population Increase ◽  
Intrinsic Rate Of Increase ◽  
Natural Mortality ◽  
Phocoena Phocoena ◽  
Rate Of Increase ◽  
Incidental Mortality

We estimated the potential intrinsic rate of increase (r) of the harbour porpoise (Phocoena phocoena) population in the Bay of Fundy and Gulf of Maine using empirical data on reproductive rates (mx) and several hypothetical survival (Ix) schedules. Schedules of Ix, to maximum ages of 12 and 15 yr, were calculated from two potential natural mortality (nx) schedules combined with several schedules of incidental mortality (hx) estimates. The most realistic results were obtained when nx of non-calves were calculated from Caugley's (1966. Ecology 47: 906–918) smoothed age-frequency equation for Himalayan thar (Hemitragus jemlahicus) and applied in conjunction with a range of calf natural mortality estimates, this model indicates that harbour porpoises have a limited capacity for population increase, and populations are unlikely to sustain even moderate levels of incidental mortality (4% of the population per year). Extending the maximum age used in the models from 12 to 15 yr does little to increase estimates of r for the harbour porpoise population, and hence their susceptibility to incidental mortality.

scholarly journals Comparison of Field Population Growths of Three Cereal Aphid Species on Winter Wheat

2011 ◽  
Vol 39 (No. 2) ◽  
pp. 61-64 ◽  
Author(s):  
V. Jarošík ◽  
A. Honěk ◽  
A. Tichopád
Keyword(s):  
Winter Wheat ◽  
Rhopalosiphum Padi ◽  
Intrinsic Rate ◽  
Aphid Species ◽  
Population Increase ◽  
Intrinsic Rate Of Increase ◽  
Cereal Aphid ◽  
Metopolophium Dirhodum ◽  
Aphid Density ◽  
Rate Of Increase

Population growths of three aphid species colonising winter wheat stands, Metopolophium dirhodum, Rhopalosiphum padi and Sitobion avenae, were analysed by regression method. The calculations were based on counts in 268 winter wheat plots at 3 or 7 day intervals over 10 (leaves) or 6 (ears) years. The population dynamics of a particular species differed widely between years. Density independent exponential growth of the population was most common, but its rate differed significantly between species, and for S. avenae also between populations on leaves and ears, on which the populations grew fastest. Field estimates of the intrinsic rate of increase derived from the exponential growths ranged between 0.010–0.026 in M. dirhodum, 0.0071–0.011 in R. padi, and between 0.00078–0.0061 and 0.0015–0.13 in S. avenae on leaves and ears, respectively. In the populations with the most vigorous population growth, S. avenae on ears and M. dirhodum on leaves, the rate of population increase significantly decreased with increasing aphid density.  

Using demographic methods to construct Bayesian priors for the intrinsic rate of increase in the Schaefer model and implications for stock rebuilding

2001 ◽  
Vol 58 (9) ◽  
pp. 1871-1890 ◽  
Author(s):  
M K McAllister ◽  
E K Pikitch ◽  
E A Babcock
Keyword(s):  
Intrinsic Rate ◽  
Maximum Sustainable Yield ◽  
Production Model ◽  
Intrinsic Rate Of Increase ◽  
Point Estimate ◽  
Parameter Estimates ◽  
Model Parameters ◽  
Sustainable Yield ◽  
Rate Of Increase ◽  
Demographic Methods

Even though Bayesian methods can provide statistically rigorous assessments of the biological status of fisheries resources, uninformative data (e.g., declining catch rate series with little variation in fishing effort) can produce highly imprecise parameter estimates. This can be counteracted with the use of informative Bayesian prior distributions (priors) for model parameters. We develop priors for the intrinsic rate of increase (r) in the Schaefer surplus production model using demographic methods and illustrate the utility of this with an application to large coastal sharks in the Atlantic. In 1996, a U.S. stock assessment obtained a point estimate for r of 0.26. For such long-lived and low-fecund organisms, this could potentially be too high. Yet it was used to predict that within about 10 years, a 50% reduction in the 1995 catch level should result in >50% chance of increasing the population to the abundance required to produce maximum sustainable yield. In contrast, a Bayesian assessment that used demographic analysis to construct a prior for r with a median of 0.07 and coefficient of variation (CV) of 0.7 indicated that within 30 years, this policy would have only a very small chance of increasing the population to maximum sustainable yield.

Reproductive potential in the parasitoid Eupelmus orientalis (Hymenoptera: Eupelmidae)

1994 ◽  
Vol 84 (2) ◽  
pp. 199-206 ◽  
Author(s):  
G. Doury ◽  
D. Rojas-Rousse
Keyword(s):  
Life Cycle ◽  
Callosobruchus Maculatus ◽  
Reproductive Potential ◽  
Intrinsic Rate ◽  
Population Increase ◽  
Intrinsic Rate Of Increase ◽  
Net Reproductive Rate ◽  
Offspring Production ◽  
Rate Of Increase ◽  
Age Dependent

AbstractEupelmus orientalis (Crawford) (Hymenoptera: Eupelmidae) is a solitary ectoparasitoid of the larvae and pupae of West African bruchids. Since the biology of this species was unknown, studies were carried out on its reproductive biology. The age-dependent fecundity and offspring production of virgin and mated females of E. orientalis were determined under laboratory conditions at 33°C:23°C, 50%:80% r.h., L:D 12:12 on its host Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae) during the first 15 days of the life cycle. No differences were found between virgin and mated females for any parameter. A study of the age-dependent fecundity and offspring production was also carried out under the same conditions over the entire life cycle of mated females. The resulting data were used to determine the longevity and reproductive potential of the species, particularly through the calculated life tables and estimation of the intrinsic rate of increase. With ten hosts per female per day, E. orientalis females had a mean longevity of 45.75±5.09 days. They laid an average of 219.91±39.08 eggs, parasitized 154.27±26.17 hosts, and produced 166.77±9.41 offspring, consisting of 80.46±14.10 males and 86.31±10.04 females. The total mean developmental time was 18.58±0.22 days for males and 20.03±0.21 days for females. The net reproductive rate (Ro) was 62.33 female progeny per adult female, and the intrinsic rate of population increase (rm) was 0.1389 per day. The generation time (G) was 29.76 days and the doubling time (DT) 4.99 days. These results constitute the first step to determine the potential of E. orientalis as an agent for the biological control of bruchidae, especially C. maculatus.

A comparison of sexual competitiveness and demographic traits of Anastrepha obliqua (Macquart) (Diptera: Tephritidae) among fruit-associated populations

2018 ◽  
Vol 109 (3) ◽  
pp. 333-341
Author(s):  
E. Hernández ◽  
L. Ruiz-Montoya ◽  
J. Toledo ◽  
P. Montoya ◽  
P. Liedo ◽  
...  
Keyword(s):  
Mangifera Indica ◽  
Field Performance ◽  
Intrinsic Rate ◽  
Population Increase ◽  
Intrinsic Rate Of Increase ◽  
Reproduction Rate ◽  
Demographic Traits ◽  
Rate Of Increase ◽  
Anastrepha Obliqua ◽  
Spondias Purpurea

AbstractThe control of Anastrepha obliqua includes the sterilization of mass-reared insects grown in isolation in a constantly controlled environment. Through time, laboratory mass-reared colonies may produce flies with lower field performance. To recover the genetic variation and aptitude of mass-reared populations, wild insects are introduced into mass-reared colonies. Our aim in this study was to determine whether the host species from two localities influence the life history traits of A. obliqua. We collected flies as larvae from infested fruits of Spondias purpurea, S. mombin, Mangifera indica cv. ‘piña’, and M. indica cv. ‘coche’ from two localities in Chiapas, Mexico. There were significant differences in the mating competitiveness of males collected from mango cv. ‘coche’ compared with mass-reared males. There were no differences in the mating propensity between flies from the two localities, even in the number of matings, when weight was considered as a covariable. The mass-reared strain showed the earliest age at first oviposition. The locality affected the longevity and oviposition period, and these influenced the birth rate, intrinsic rate of increase, finite rate of population increase, mean generation time, and doubling time. According to the demographic parameters, the population of S. mombin would allow artificial colonization in less time, considering that it has a high reproduction rate starting at an early age. Even in the propensity test, it had the highest number of matings. However, males with greater sexual competitiveness and longevity for colonization corresponded to those collected from S. purpurea.

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.

scholarly journals STATUS OF INFESTATION AND BIOLOGY OF PEPPER FRUIT FLY, Atherigona orientalis (Schiner) (Diptera: Muscidae)

2019 ◽  
Vol 19 (1) ◽  
pp. 64
Author(s):  
Febrina Herawani ◽  
Aunu Rauf ◽  
Sugeng Santoso
Keyword(s):  
Intrinsic Rate ◽  
Fruit Fly ◽  
Reproductive Rate ◽  
Bactrocera Dorsalis ◽  
Population Increase ◽  
Intrinsic Rate Of Increase ◽  
Net Reproductive Rate ◽  
Rate Of Increase ◽  
Pepper Fruit ◽  
The Status

Status of Infestation and Biology of Pepper Fruit Fly, Atherigona orientalis (Schiner) (Diptera: Muscidae). Numerous muscid flies Atherigona orientalis (Schiner) (Diptera: Muscidae) emerged from fruitfly-infested pepper fruits. It is not known whether A. orientalis is primary or secondary pest, and its biology is poorly studied.  Research was conducted with the objectives to determine the status of infestation of A. orientalis on pepper fruits, and to study its biology. Field survey was conducted in pepper fields in Bogor, whereas study on its biology was done in laboratory. Field surveys showed that flies emerged from fruitfly-infested fruits consisted of 86.1% A. orientalis, 4.8% Bactrocera dorsalis, and 9.1% other fly species.  Fruits having only A. orientalis representing 79.7% of the infested fruits. Number of A. orientalis flies emerged per fruit ranged 1-24, with an average of 3.5 individuals. Laboratory study showed incubation period of eggs was 1.62 d, larva development lasted 11.93 d, and pupa 5.08 d.  Longevity of female adult was 32.85 d and male 31.40 d. Number of eggs laid by a single female ranged 12-191, with an average of 83.80. Net reproductive rate R0 =36.052, intrinsic rate of increase rm = 0.136, mean generation time T = 26.482, doubling time Dt = 5.098, and finite rate of increase λ = 1.145. Overall, our research indicated that A. orientalis was a primary pest of pepper fruits, with a high potential of population increase.

Plant Resistance in Some Modern Soybean Varieties May Favor Population Growth and Modify the Stylet Penetration of Bemisia tabaci (Hemiptera: Aleyrodidae)

2021 ◽  
Author(s):  
Mauricélia F Almeida ◽  
Clébson S Tavares ◽  
Euires O Araújo ◽  
Marcelo C Picanço ◽  
Eugênio E Oliveira ◽  
...  
Keyword(s):  
Population Growth ◽  
Bemisia Tabaci ◽  
Intrinsic Rate ◽  
Reproductive Rate ◽  
Genetically Engineered ◽  
Population Increase ◽  
Net Reproductive Rate ◽  
Bt Toxin ◽  
Demographic Performance

Abstract Complaints of severe damage by whiteflies in soybean fields containing genetically engineered (GE) varieties led us to investigate the role of transgenic soybean varieties expressing resistance to some insects (Cry1Ac Bt toxin) and to herbicide (glyphosate) on the population growth and feeding behavior of Bemisia tabaci (Gennadius) MEAM1 (Hemiptera: Aleyrodidae). In the laboratory, the whiteflies reared on the GE Bt soybeans had a net reproductive rate (R0) 100% higher and intrinsic rate of population increase (rm) 15% higher than those reared on non-GE soybeans. The increased demographic performance was associated with a higher lifetime fecundity. In electrical penetration graphs, the whiteflies reared on the GE soybeans had fewer probes and spent 50% less time before reaching the phloem phase from the beginning of the first successful probe, indicating a higher risk of transmission of whitefly-borne viruses. Data from Neotropical fields showed a higher population density of B. tabaci on two soybean varieties expressing glyphosate resistance and Cry1Ac Bt toxin. These results indicate that some GE soybean varieties expressing insect and herbicide resistances can be more susceptible to whiteflies than non-GE ones or those only expressing herbicide resistance. Most likely, these differences are related to varietal features that increase host-plant susceptibility to whiteflies. Appropriate pest management may be needed to deal with whiteflies in soybean fields, especially in warm regions, and breeders may want to consider the issue when developing new soybean varieties.

Influence of temperature on the development and reproduction of Cinara cedri (Hemiptera: Aphidoidea: Lachninae)

2021 ◽  
pp. 1-6
Author(s):  
Yingchao Ji ◽  
Guohua Li ◽  
Chenggang Zhou ◽  
Shuyan Yin
Keyword(s):  
Intrinsic Rate ◽  
Intrinsic Rate Of Increase ◽  
Threshold Temperature ◽  
Reproduction Rate ◽  
Cedrus Deodara ◽  
Developmental Threshold ◽  
Factors Affecting ◽  
Rate Of Increase ◽  
Influence Of Temperature On ◽  
Development Duration

Abstract Temperature is one of the main factors affecting insect growth, development and reproduction. The effects of temperatures (10, 15, 20, 25 and 30°C) on the development and reproduction of Cinara cedri Mimeur (Hemiptera: Aphidoidea: Lachnidae) fed on Cedrus deodara (Roxb.) G. Don were evaluated in this study. With the increase of temperature from 10 to 30°C, the development duration at different development stages gradually shortened. There was a significant positive correlation between the developmental rates and temperature, following a quadratic regression model. The lower developmental threshold temperature (C) and effective accumulated temperatures (K) for completing a generation were 4.13°C and 263.4 degree-days, respectively. The highest fecundity was observed at 20°C with 25.74 first-instar nymphs/female. Both the highest intrinsic rate of increase (r, 0.11 ± 0.03) and net reproduction rate (R0, 19.06 ± 2.05) were observed at 20°C, whereas the lowest values of r (0.05 ± 0.01) at 10°C and R0 (5.78 ± 0.88) at 30°C were observed. The results suggest that temperature significantly affects the biology of C. cedri and the optimal temperature for its development is 20°C.

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