Fitness, parasitoids, and biological control: an opinion

2001 ◽  
Vol 133 (3) ◽  
pp. 429-438 ◽  
Author(s):  
B.D. Roitberg ◽  
G. Boivin ◽  
L.E.M. Vet
Keyword(s):  
Biological Control ◽  
Developmental Rate ◽  
Natural Conditions ◽  
Mating Ability ◽  
Evolutionary Theories ◽  
Rate Of Increase ◽  
Rearing Conditions ◽  
Ecological Applications ◽  
Per Capita ◽  
Direct Measures

AbstractFitness, defined as the per capita rate of increase of a genotype with reference to the population carrying the associated genes, is a concept used by biologists to describe how well an individual performs in a population. Fitness is rarely measured directly and biologists resort to proxies more easily measured but with varying connection to fitness. Size, progeny survival, and developmental rate are the most common proxies used in the literature to describe parasitoid fitness. The importance of the proxies varies between papers looking at evolutionary theories and those assessing ecological applications. The most direct measures of fitness for parasitoids are realised fecundity for females and mating ability for males, although these proxies are more difficult to measure under natural conditions. For practical purposes, measure of size, through body size or mass, is the proxy easiest to use while providing good comparative values; however, care must be taken when using a single proxy, as proxies can be affected differently by rearing conditions of the parasitoid.

scholarly journals Faculty Publishing Productivity: Comparisons over Time

2006 ◽  
Vol 67 (3) ◽  
pp. 230-239 ◽  
Author(s):  
John M. Budd
Keyword(s):  
Academic Librarians ◽  
Tenure Track ◽  
Data Set ◽  
Part Time Faculty ◽  
Time Period ◽  
Rate Of Increase ◽  
Part Time ◽  
Per Capita ◽  
Time Faculty ◽  
Over Time

Concerns about higher education abound, and these include concerns about productivity. The present study extends two previous examinations of faculty publishing productivity covering the years 1991 to 1993 and 1995 to 1997. Both members of ARL and a group of institutions included in ACRL’s data set are included. For both groups there are some increases in mean total numbers of publications, although the rate of increase has decreased since the second time period. Per capita rates of publication demonstrate an even flatter pattern. In recent years, there have been some changes in the dynamics of universities’ faculties; there are more part-time faculty and more faculty who are not on the tenure track. These factors, coupled with the publishing data, point to activities that all academic librarians should be aware of.

scholarly journals The Effect of Weak Electrolyte Solutions on the Hatching Rate of the Eggs of Tricho-Strongylus Retortaeformis (Zeder) and its Interpretation in Terms of a Proposed Hatching Mechanism of Strongyloid Eggs

1958 ◽  
Vol 35 (3) ◽  
pp. 584-601
Author(s):  
P. A. G. WILSON
Keyword(s):  
Water Permeability ◽  
Electrolyte Solutions ◽  
Hatching Rate ◽  
Natural Conditions ◽  
Ionic Solutions ◽  
Rate Of Increase ◽  
Egg Membrane ◽  
Hatching Eggs ◽  
Colligative Properties

1. The influence of solutions of NaCl on the hatching of eggs of Trichostrongylus retortaeformis is studied. It is shown that the effects are not the consequence of colligative properties, but are related to ionic phenomena. 0.05 N-NaCl slows down the rate of hatch without impairing the ultimate ‘hatchability’ of the eggs. Processes of development up to hatching are not slowed down. 2. The effect demonstrated in the case of NaCl is shown to be shared by eight other electrolytes, the depression in the rate of hatch being proportional to the mobility of the ions in solution. On the assumption that the effect of the ions is due to a penetration of the egg membrane(s) the rate of entry is shown to be controlled by the speed of the slower ion in any one salt. 3. The influence of NaCl on the permeability of hatching eggs to water is studied. It is shown that the rate of increase in permeability is slowed down sufficiently in NaCl to control the rate of hatch. The inference that water permeability is a necessary prerequisite for hatching is made, a further hypothetical process being invoked to account for the rate of hatch in the absence of NaCl, since it is not then controlled by changes in water permeability. 4. The probability that the net effect of ionic solutions on the eggs is one concerned with the rate of breakdown of the inner wax-like layer of the egg is strengthened by experiments demonstrating that the depressing influence of NaCl is antagonized by ‘Teepol’, though the comparable influence of other, non-emulsifying, compounds cannot be explained. 5. The role of water permeability in the hatching mechanism is investigated. 6. A hatching mechanism of strongyloid eggs is proposed which involves two processes, the first dependent upon the osmotic relationships of the unhatched larva to its environment, the second being some sort of chemical weakening of the outer shell. 7. It is suggested that the effect of ions on hatching rate assists the ‘embryonated egg’ to survive under natural conditions when the hatched first-stage larva might otherwise be destroyed by desiccation.

The possible macroeconomic and sectoral impacts of carbon taxation on Turkey’s economy: A computable general equilibrium analyses

2018 ◽  
Vol 29 (5) ◽  
pp. 784-801
Author(s):  
Levent Aydın
Keyword(s):  
General Equilibrium ◽  
Carbon Emissions ◽  
Computable General Equilibrium ◽  
Carbon Tax ◽  
Model Simulation ◽  
Effective Means ◽  
Carbon Taxes ◽  
Rate Of Increase ◽  
Carbon Taxation ◽  
Per Capita

Although the idea of carbon tax was debated widely in the early 1970s, the first carbon taxes were imposed in some Northern European countries at the beginning of the 1990s. Since the Paris summit in 2015, there has been a growing interest in carbon tax that has begun to increase again. Although Turkey’s share of carbon emissions in terms of total global emissions is low, the rate of increase in emissions has increased in recent years and should be a cause for concern. Therefore, the aim of this paper is to analyze the possible effects of carbon taxes on Turkey’s economy by disaggregating the electricity sector a by using the computable general equilibrium model. Simulation results show that carbon taxation is a highly effective means to reduce carbon emissions. Despite all sectors being adversely affected, some low emission energy, textile, and other service sectors benefit from carbon pricing. The results also indicate macroeconomic costs of imposing a carbon tax at $7 per ton of carbon in terms of the decrease in GDP by 0.061% and associated with per capita utility of the representative household by 0.09% in scenario a. Imposition of successively higher carbon taxes in scenario b and scenario c results in 5.75, 12.02, and 16.95% reduction in carbon emissions at decreasing rate, respectively. However, these reductions are also accompanied by a decrease in real GDP and per capita utility from household expenditure, as macroeconomic costs, in scenarios a, b, and c at increasing rates.

Gross national income and antibiotic resistance in invasive isolates: analysis of the top-ranked antibiotic-resistant bacteria on the 2017 WHO priority list

2019 ◽  
Vol 74 (12) ◽  
pp. 3619-3625 ◽  
Author(s):  
Alessia Savoldi ◽  
Elena Carrara ◽  
Beryl Primrose Gladstone ◽  
Anna Maria Azzini ◽  
Siri Göpel ◽  
...  
Keyword(s):  
Low Income ◽  
National Income ◽  
Resistant Bacteria ◽  
Middle Income ◽  
Priority List ◽  
Income Status ◽  
Rate Of Increase ◽  
Invasive Infections ◽  
Per Capita ◽  
Klebsiella Spp

Abstract Objectives To assess the association between country income status and national prevalence of invasive infections caused by the top-ranked bacteria on the WHO priority list: carbapenem-resistant (CR) Acinetobacter spp., Klebsiella spp. and Pseudomonas aeruginosa; third-generation cephalosporin-resistant (3GCR) Escherichia coli and Klebsiella spp.; and MRSA and vancomycin-resistant Enterococcus faecium (VR E. faecium). Methods Active surveillance systems providing yearly prevalence data from 2012 onwards for the selected bacteria were included. The gross national income (GNI) per capita was used as the indicator for income status of each country and was log transformed to account for non-linearity. The association between antibiotic prevalence data and GNI per capita was investigated individually for each bacterium through linear regression. Results Surveillance data were available from 67 countries: 38 (57%) were high income, 16 (24%) upper-middle income, 11 (16%) lower-middle income and two (3%) low income countries. The regression showed significant inverse association (P<0.0001) between resistance prevalence of invasive infections and GNI per capita. The highest rate of increase per unit decrease in log GNI per capita was observed in 3GCR Klebsiella spp. (22.5%, 95% CI 18.2%–26.7%), CR Acinetobacter spp. (19.2% 95% CI 11.3%–27.1%) and 3GCR E. coli (15.3%, 95% CI 11.6%–19.1%). The rate of increase per unit decrease in log GNI per capita was lower in MRSA (9.5%, 95% CI 5.2%–13.7%). Conclusions The prevalence of invasive infections caused by the WHO top-ranked antibiotic-resistant bacteria is inversely associated with GNI per capita at the global level. Public health interventions designed to limit the burden of antimicrobial resistance should also consider determinants of poverty and inequality, especially in lower-middle income and low income countries.

Temperature-dependent reproduction and survival of Gyrodactylus bullatarudis (Monogenea) on guppies (Poecilia reticulata)

Parasitology ◽  
1984 ◽  
Vol 89 (2) ◽  
pp. 221-228 ◽  
Author(s):  
Marilyn E. Scott ◽  
D. J. Nokes
Keyword(s):  
Birth Rate ◽  
Poecilia Reticulata ◽  
Intrinsic Rate ◽  
Host Responses ◽  
Intrinsic Rate Of Increase ◽  
Temperature Dependent ◽  
Rate Of Increase ◽  
Survival And Reproduction ◽  
Average Fecundity ◽  
Per Capita

SummaryTemperature-dependent survival and reproduction of Gyrodactylus bullatarudis Turnbull, 1956 were examined at 17, 21, 25·5, 27·5 and 30 °C on isolated guppies under conditions where parasite density dependence and host responses were minimized. Parasites had the longest life-span (5·5 days) at 21 °C, the highest average fecundity (1·73 offspring) at 25·5 °C and the highest instantaneous per capita birth rate (0·543/parasite/day) at 27·5 °C. The intrinsic rate of increase of the parasite population was maximum (0·230/parasite/day) at 27·5 °C. Data obtained from this study indicate that G. bullatarudis are not able to survive at 30 °C.

scholarly journals A life table analysis to evaluate biological control of banks grass mite using the predatory mite, Galendromus flumenis (Acari: Phytoseiidae)

2017 ◽  
Vol 22 (1) ◽  
pp. 7 ◽  
Author(s):  
Fatemeh Ganjisaffar ◽  
Thomas M. Perring
Keyword(s):  
Biological Control ◽  
Growth Parameters ◽  
Intrinsic Rate ◽  
Developmental Time ◽  
Predatory Mite ◽  
Reproductive Rate ◽  
Intrinsic Rate Of Increase ◽  
Net Reproductive Rate ◽  
Rate Of Increase ◽  
Banks Grass Mite

The predatory mite, Galendromus flumenis (Chant) (Acari: Phytoseiidae), has shown promising traits for biological control of Banks grass mite, the major pest of date palms in California. In the present study, reproduction and population growth parameters of G. flumenis on Banks grass mite eggs were studied at 34ºC, 50±10% RH and a photoperiod of 16: 8 (L: D) hours. 100 percent of eggs hatched and 63.5 percent of the emerged larvae survived to adulthood. The total immature developmental time was 5.7 and 5.5 days for females and males, respectively. The sex ratio of G. flumenis was 0.70 (females/ females+ males). Mated females laid on average 1.6 eggs per day and 19.9 eggs during their mean ovipositional period of 12.5 days. The net reproductive rate (R0) was 11.5 females/ female/ generation, the intrinsic rate of increase (rm) was 0.200 females/ female/ day, the finite rate of increase (λ) was 1.222 population multiplication/ day, the mean generation time (T) was 12.2 days, and the doubling time (DT) was 3.5 days. The lower rm value of G. flumenis than that of its prey (0.24–0.48) explains why Banks grass mite escapes control by G. flumenis in field. These results suggest that augmentative release of this predator would offset the lower rm of the predator, thereby contributing to the control of Banks grass mite. Combined with the benefit of early releases determined in companion studies, future field studies with G. flumenis are being planned.

Per Capita Rate of Increase

2016 ◽  
Author(s):  
Monica Nordberg ◽  
Douglas M. Templeton ◽  
Ole Andersen ◽  
John H. Duffus
Keyword(s):  
Rate Of Increase ◽  
Capita Rate ◽  
Per Capita

Biological control of ticks

Parasitology ◽  
2004 ◽  
Vol 129 (S1) ◽  
pp. S389-S403 ◽  
Author(s):  
M. SAMISH ◽  
H. GINSBERG ◽  
I. GLAZER
Keyword(s):  
Biological Control ◽  
Entomopathogenic Nematodes ◽  
Biocontrol Agents ◽  
Parasitoid Wasps ◽  
Natural Conditions ◽  
Potential Value ◽  
Considerable Research ◽  
Production Strategies ◽  
Laboratory Results ◽  
Selection Of

Ticks have numerous natural enemies, but only a few species have been evaluated as tick biocontrol agents (BCAs). Some laboratory results suggest that several bacteria are pathogenic to ticks, but their mode of action and their potential value as biocontrol agents remain to be determined. The most promising entomopathogenic fungi appear to be Metarhizium anisopliae and Beauveria bassiana, strains of which are already commercially available for the control of some pests. Development of effective formulations is critical for tick management. Entomopathogenic nematodes that are pathogenic to ticks can potentially control ticks, but improved formulations and selection of novel nematode strains are needed. Parasitoid wasps of the genus Ixodiphagus do not typically control ticks under natural conditions, but inundative releases show potential value. Most predators of ticks are generalists, with a limited potential for tick management (one possible exception is oxpeckers in Africa). Biological control is likely to play a substantial role in future IPM programmes for ticks because of the diversity of taxa that show high potential as tick BCAs. Considerable research is required to select appropriate strains, develop them as BCAs, establish their effectiveness, and devise production strategies to bring them to practical use.

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