Population dynamics, vertical distribution and natural parasitism of eggs ofChrysodeixis includensbyTrichogrammaspp.in soybean

2016 ◽  
Author(s):  
Diego F Fraga
Keyword(s):  
Population Dynamics ◽  
Vertical Distribution ◽  
Natural Parasitism

scholarly journals Disturbance Frequency and Vertical Distribution of Seeds Affect Long-Term Population Dynamics: A Mechanistic Seed Bank Model

2013 ◽  
Vol 182 (2) ◽  
pp. 180-190 ◽  
Author(s):  
Eric Alan Eager ◽  
Chirakkal V. Haridas ◽  
Diana Pilson ◽  
Richard Rebarber ◽  
Brigitte Tenhumberg
Keyword(s):  
Population Dynamics ◽  
Vertical Distribution ◽  
Seed Bank ◽  
Disturbance Frequency

Horizontal and vertical distribution patterns, retention rates, and population dynamics of zooplankton on Western Bank, Scotian Shelf

2003 ◽  
Vol 60 (10) ◽  
pp. 1229-1244 ◽  
Author(s):  
Christian S Reiss ◽  
Ian A McLaren ◽  
Patricia Avendaño
Keyword(s):  
Population Dynamics ◽  
Vertical Distribution ◽  
Spatial Scales ◽  
Distribution Patterns ◽  
Zooplankton Biomass ◽  
Retention Rates ◽  
Local Production ◽  
Scotian Shelf ◽  
Particle Retention ◽  
Horizontal And Vertical Distribution

We assess the importance of retention rates and local production to the concentration of zooplankton on Western Bank, Scotian Shelf, during September and October 1998. We do so using (i) particle retention rates derived from an array of 25 current meters and inferences from hydrographic structure; (ii) observations on the horizontal and vertical distribution of zooplankton and ichthyoplankton; and (iii) a simple projection-matrix model of the population dynamics of two copepod species, Centropages typicus and Pseudocalanus spp. Zooplankton biomass and adult stages of copepods were more abundant in surface waters on the bank (p < 0.05) at broad (25 km) spatial scales. Zooplankton was correlated with ichthyoplankton abundance at this scale (r > 0.5, p < 0.001), a result of local production of both zooplankton and fish on the bank. The time-dependent anticyclonic circulation around Western Bank was variable, and particle retention rates were 18 and 33% for 20 days at 12.5 and 28.5 m, respectively. The population model showed that both C. typicus and Pseudocalanus spp. are capable of increasing their population size despite advective loss and mortality rates approaching 10%·day-1. We conclude that local production exceeding advective loss rates can explain the high concentrations of zooplankton on Western Bank.

Zooplankton Population Dynamics and Diaptomus Production in Waldsea Lake, a Saline Meromictic Lake in Saskatchewan

1979 ◽  
Vol 36 (12) ◽  
pp. 1431-1438 ◽  
Author(s):  
Michael C. Swift ◽  
U. Theodore Hammer
Keyword(s):  
Population Dynamics ◽  
Life Cycle ◽  
Vertical Distribution ◽  
Standing Crop ◽  
Brachionus Plicatilis ◽  
Dry Weight ◽  
Meromictic Lake ◽  
Zooplankton Species ◽  
Daphnia Similis ◽  
Zooplankton Population

Zooplankton population dynamics were monitored in meromictic saline Waldsea Lake, Saskatchewan, during 1974–75. The dominant zooplankton species were Diaptomus connexus, Brachionus plicatilis, Hexarthra fennica, and Daphnia similis. Diaptomus had a 1-yr life cycle. Overwintered late-stage copepodites molted into adults in May and June and were followed by sequential peaks in numbers of eggs, nauplii, and copepodites. The estimated annual production of this species was 0.6 g dry weight∙m−2 or 0.3 g C∙m−2. About 4% of the annual planktonic primary production would be required to support Diaptomus if it is 10% efficient. The standing crop of Brachionus and Hexarthra was highest in the spring and declined thereafter; Hexarthra was more abundant than Brachionus. The standing crop of Daphnia was much lower than that of either rotifer and showed a spring and fall peak in abundance. Differences in vertical distribution were present among the zooplankton species but no real vertical migrations were observed. Key words: Diaptomus connexus, zooplankton, population dynamics, production, saline meromictic lake

scholarly journals POPULATION DYNAMICS OF APHIDS ON BROCCOLI IN THE MEXICAN BAJIO VALLEY.

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1132a-1132
Author(s):  
Alfonso Hernández-Barajas ◽  
José Luis Vera-Medina ◽  
Dr. Benito Alvarado-Rodriguez
Keyword(s):  
Population Dynamics ◽  
Myzus Persicae ◽  
Green Peach Aphid ◽  
Parasitic Wasp ◽  
Brevicoryne Brassicae ◽  
Aphid Population ◽  
Cabbage Aphid ◽  
Prevalent Species ◽  
Natural Parasitism ◽  
Made In

During a two-year-period, a study was made in the field in order to know the ocurrence of aphids in the broccoli crop. It was possible to know that the total aphid population is higher in winter plantings where more than 240 aphids/plant were found Spring and fall plantings, in comparison, less than 20 aphids/plant were encountered. The species more common were the cabbage aphid (Brevicoryne brassicae L.), the most prevalent species in the crop, getting more than 80% of the population, and the green peach aphid (Myzus persicae Sulzer) with a little bit more than 17% of the total. The natural parasitism in all plantings was around 17%. By species, parasitism in B. brassicae was higher in springs (70% of the total) and fall plantings where the parasitic wasp Diaretiella rapa e (MacIntosh) was probably more active. The sane pattern was obtained for M. persicae, in which the parasitism was again higher in spring and fall plantings (20% of the total) and very low during the winter. Regarding leaf preference, a very defined pattern was found in the M. persicae than for B. brassicae.

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