POPULATION DENSITY AND DYNAMICS OF LARCH CASEBEARER (LEPIDOPTERA: COLEOPHORIDAE) IN THE BLUE MOUNTAINS OF OREGON AND WASHINGTON BEFORE THE BUILD-UP OF EXOTIC PARASITES

1983 ◽  
Vol 115 (9) ◽  
pp. 1095-1102 ◽  
Author(s):  
R. B. Ryan
Keyword(s):  
Biological Control ◽  
Population Density ◽  
Population Change ◽  
Control Program ◽  
Density Dependent ◽  
Blue Mountains ◽  
Coleophora Laricella ◽  
Before And After

AbstractPopulation density and parasitism of larch casebearer, Coleophora laricella (Hübner), were monitored for 10 years before parasites introduced for biological control became abundant. Overwintering densities remained fairly stable at about 100 larvae per 100 buds. The factor most closely correlated with population change was something, as yet unknown, other than the native parasites, which tended to be inversely density-dependent. The data will serve as the “before” period in a before and after evaluation of the biological control program.

scholarly journals Subtle changes of the crystalline lens after cycloplegia: a retrospective study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Cheng Dai ◽  
Meng Liu ◽  
Xiaodong Lv ◽  
Binzhong Li
Keyword(s):  
Retrospective Study ◽  
Children And Adolescents ◽  
Population Change ◽  
Anterior Segment ◽  
Anterior Chamber Depth ◽  
Crystalline Lens ◽  
Equivalent Diameter ◽  
Crystalline Morphology ◽  
Significant Difference ◽  
Before And After

Abstract Background The purpose of this study was to evaluate the shape of the crystalline lens in terms of biometry and diopters before and after cycloplegia using the CASIA2 swept-source (SS) optical coherence tomography (OCT) system on the anterior segment. Methods This was a retrospective study. Children and adolescents (26 males and 29 females, aged 4–21 years) with simple ametropia were selected for optometry and CASIA2 imaging at 2 separate visits before and after cycloplegia. Diopter values were derived from the spherical power (S) obtained by optometry. Biometric parameters of the crystalline lens, including the anterior chamber depth (ACD), anterior and posterior curvature of the lens (ACL and PCL), lens thickness (LTH), lens decentration (LD), lens tilt (LT), and equivalent diameter of the lens (LED), were measured by the CASIA2 system. The differences in these parameters after compared with before cycloplegia were determined, and their relationships were analyzed. Results Fifty-five participants (106 eyes) were initially enrolled. There was a significant difference (P < 0.05) in the S (t=-7.026, P < 0.001), ACD (t=-8.796, P < 0.001), ACL (t=-13.263, P < 0.001) and LTH (t = 7.363, P < 0.001) after compared with before cycloplegia. The change in the PCL (t = 1.557, P = 0.122), LD (t = 0.876, P = 0.383), LT (t = 0.440, P = 0.661) and LED (t=-0.351, P = 0.726) was not statistically significant (P > 0.05). There was a significant (P < 0.05) correlation of the change in the S with that in the ACL (r = 0.466, P < 0.001), LTH (r=-0.592, P < 0.001), and LED (r = 0.223, P = 0.021) but not the PCL (r = 0.19, P = 0.051), LD (r=-0.048, P = 0.0628) or LT (r=-0.022, P = 0.822). Furthermore, the change in the ACD was closely related to the change in crystalline morphology. However, in children and adolescents, we found that the change in crystalline morphology was unrelated to age. Conclusions Changes in lens morphology after compared with before cycloplegia are mainly related to the ACL and LTH, but there is no difference in the PCL, LD, LT, or LED. In the adolescent population, change in the S is related to change in the ACL, LED and LTH. However, age is unrelated to the shape and tendency of the crystalline lens. Further research is required to determine whether the same conclusion applies to different age groups and different refractive states (myopia, hyperopia, emmetropia) .

scholarly journals “Predator-In-First”: A Preemptive Biological Control Strategy for Sustainable Management of Pepper Pests in Florida

2020 ◽  
Vol 12 (18) ◽  
pp. 7816
Author(s):  
Vivek Kumar ◽  
Lucky Mehra ◽  
Cindy L. McKenzie ◽  
Lance S. Osborne
Keyword(s):  
Biological Control ◽  
Pest Management ◽  
Control Strategy ◽  
Frankliniella Occidentalis ◽  
Management Strategies ◽  
Control Program ◽  
Field Conditions ◽  
High Rate ◽  
Polyphagotarsonemus Latus ◽  
Consistent Performance

The early establishment of a biocontrol agent in the production system, whether in the greenhouse, nursery, or field, is essential for the success of the biological control program, ensuring growers’ profitability. In an effort to develop a sustainable pest management solution for vegetable growers in Florida, we explored the application of a preemptive biological control strategy, “Predator-In-First” (PIF), in regulating multiple pepper pests, Bemisia tabaci Gennadius, Frankliniella occidentalis Pergande, and Polyphagotarsonemus latus Banks under greenhouse and field conditions during different growing seasons. In these studies, two bell pepper cultivars (7039 and 7141) and the phytoseiid mite Amblyseius swirskii Athias–Henriot were used as a model system. Pepper seedlings (~8 week) of each cultivar were infested with varying rates of A. swirskii (20 or 40 mites/plant or one sachet/10 plant) and allowed to settle on plant hosts for a week before planting in pots or field beds. Results showed a comparative consistent performance of the treatment with the high rate of phytoseiids (40 mites/plant) in regulating B. tabaci and F. occidentalis populations in greenhouse studies, and B. tabaci and P. latus pests under field conditions. During two fall field seasons, higher marketable yields of 12.8% and 20.1% in cultivar 7039, and 24.3% and 39.5% in cultivar 7141 were observed in the treatment with the high rate of phytoseiids compared to the untreated control, indicating yield benefits of the approach. The outcome of the study is encouraging and demonstrates that PIF can be an important tool for organic vegetable growers and a potential alternative to chemical-based conventional pest management strategies. The advantages and limitations of the PIF approach in Florida pepper production are discussed.

Impact of Canada's Pacific Salmon Fleet Control Program

1979 ◽  
Vol 36 (7) ◽  
pp. 764-769 ◽  
Author(s):  
Peter H. Pearse ◽  
James E. Wilen
Keyword(s):  
Key Words ◽  
Statistical Data ◽  
Pacific Salmon ◽  
Control Program ◽  
Resource Rent ◽  
The Real ◽  
Before And After ◽  
Salmon Fishery

The available statistical data are analyzed to appraise the success of Canada's Pacific salmon fleet rationalization program, in terms of the extent to which it has prevented fishing costs from rising in pace with the value of the catch. It is found that while the fleet's revenues increased at about the same rate before and after the scheme was introduced in 1969, the real capital employed increased more slowly under the controls than earlier. The program has, nevertheless, failed in its purpose of preventing further expansion of redundant capital in the fleet. The reasons for this failure, and for certain apparent shifts in the structure of the fleet, are discussed. Key words: Pacific salmon fishery, capitalization, economic rationalization, resource rent

Density-Dependent Population Growth

2020 ◽  
pp. 29-46
Author(s):  
Michael J. Fogarty ◽  
Jeremy S. Collie
Keyword(s):  
Population Density ◽  
Population Growth ◽  
Density Dependence ◽  
Multiple Equilibria ◽  
Dynamical Behavior ◽  
Logistic Growth ◽  
Density Dependent ◽  
Per Capita ◽  
Discrete Time Models ◽  
Complex Dynamical Behavior

The observation that no population can grow indefinitely and that most populations persist on ecological timescales implies that mechanisms of population regulation exist. Feedback mechanisms include competition for limited resources, cannibalism, and predation rates that vary with density. Density dependence occurs when per capita birth or death rates depend on population density. Density dependence is compensatory when the population growth rate decreases with population density and depensatory when it increases. The logistic model incorporates density dependence as a simple linear function. A population exhibiting logistic growth will reach a stable population size. Non-linear density-dependent terms can give rise to multiple equilibria. With discrete time models or time delays in density-dependent regulation, the approach to equilibrium may not be smooth—complex dynamical behavior is possible. Density-dependent feedback processes can compensate, up to a point, for natural and anthropogenic disturbances; beyond this point a population will collapse.

A new species of Aculops (Acari: Prostigmata: Eriophyidae) from Serbia on Dipsacus laciniatus L. (Dipsacaceae), a weed target of classical biological control in the United States of America

Zootaxa ◽  
2012 ◽  
Vol 3192 (1) ◽  
pp. 59 ◽  
Author(s):  
BRIAN RECTOR ◽  
RADMILA U. PETANOVIĆ
Keyword(s):  
Biological Control ◽  
United States Of America ◽  
Control Program ◽  
Classical Biological Control ◽  
The United States ◽  
Morphological Characters ◽  
Mite Species ◽  
The Family ◽  
Eriophyoid Mite ◽  
A New Species

A new eriophyoid mite species, Aculops orlovacae n. sp. (Acari: Prostigmata: Eriophyidae) collected from Dipsacus laciniatus L. (Dipsacaceae) in northern Serbia, is described and illustrated, including digital micrographs depicting key morphological characters. Differential diagnosis is provided in comparison with Aculops salixis Xue, Song et Hong, Aculops rhodensis (Keifer), Aculops hussongi Keifer and Aculops oblongus (Nalepa). This is the first eriophyoid mite species in the genus Aculops described from a host plant in the family Dipsacaceae and it is only the second eriophyoid known from a host species in the genus Dipsacus L. This mite was found during surveys for natural enemies of Dipsacus spp., as part of a classical biological control program.

scholarly journals Effect of Population Density of Pseudomonas fluorescens on Production of 2,4-Diacetylphloroglucinol in the Rhizosphere of Wheat

1999 ◽  
Vol 89 (6) ◽  
pp. 470-475 ◽  
Author(s):  
Jos M. Raaijmakers ◽  
Robert F. Bonsall ◽  
David M. Weller
Keyword(s):  
Biological Control ◽  
Population Density ◽  
Supporting Evidence ◽  
Pseudomonas Spp ◽  
Fluorescent Pseudomonas ◽  
Naturally Occurring ◽  
Rhizosphere Population ◽  
First Time ◽  
Take All

The role of antibiotics in biological control of soilborne pathogens, and more generally in microbial antagonism in natural disease-suppressive soils, often has been questioned because of the indirect nature of the supporting evidence. In this study, a protocol for high pressure liquid chromatography/mass spectrometry is described that allowed specific identification and quantitation of the antibiotic 2,4-diacetylphloroglucinol (Phl) produced by naturally occurring fluorescent Pseudomonas spp. on roots of wheat grown in a soil suppressive to take-all of wheat. These results provide, for the first time, biochemical support for the conclusion of previous work that Phl-producing fluorescent Pseudomonas spp. are key components of the natural biological control that operates in take-all—suppressive soils in Washington State. This study also demonstrates that the total amount of Phl produced on roots of wheat by P. fluorescens strain Q2-87, at densities ranging from approximately 105 to 107 CFU/g of root, is proportional to its rhizosphere population density and that Phl production per population unit is a constant (0.62 ng/105 CFU). Thus, Phl production in the rhizosphere of wheat is strongly related to the ability of the introduced strain to colonize the roots.

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