scholarly journals Generation time ratio, rather than voracity, determines population dynamics of insect – natural enemy systems, contrary to classical Lotka-Volterra models

2021 ◽  
Vol 10 (2) ◽  
pp. 133-140
Author(s):  
Pavel Kindlmann ◽  
Zuzana Štípková ◽  
Anthony F. G. Dixon
Keyword(s):  
Population Dynamics ◽  
Natural Enemy ◽  
Generation Time ◽  
Volterra Models ◽  
Time Ratio

Production and population dynamics of Ampelisca tenuicornis (Amphipoda) with notes on the biology of its parasite Sphaeronella longipes (Copepoda)

1977 ◽  
Vol 57 (4) ◽  
pp. 955-968 ◽  
Author(s):  
Martin Sheader
Keyword(s):  
Population Dynamics ◽  
Generation Time ◽  
Population Studies ◽  
Generation Length ◽  
Two Generations ◽  
The Mediterranean

Ampelisca tenuicornis Lilljeborg, 1855, is a member of a widely distributed genus of benthic tube-dwelling amphipods. Population studies of A. macrocephala Lilljeborg in the Øresund show it to have a generation length of 2 years (Kanneworff, 1965), and A. vadorum Mills off Massachusetts, U.S.A., produces two generations per year (Mills, 1967). A. brevicornis (Costa) in the Mediterranean breeds throughout the year with a generation time of 5–7 months (Kaim-Malka, 1969), but has only one generation per year in Helgoland Bight (Klein, Rachor & Gerlach, 1975).

scholarly journals Linking lineage and population observables in biological branching processes

2019 ◽  
Author(s):  
Reinaldo García-García ◽  
Arthur Genthon ◽  
David Lacoste
Keyword(s):  
Population Dynamics ◽  
Generation Time ◽  
Doubling Time ◽  
Branching Processes ◽  
Underlying Mechanism ◽  
Population Doubling ◽  
Population Doubling Time ◽  
Division Rate ◽  
Fluctuation Theorems ◽  
The Mean

Using a population dynamics inspired by an ensemble of growing cells, a set of fluctuation theorems linking observables measured at the lineage and population levels are derived. One of these relations implies inequalities comparing the population doubling time with the mean generation time at the lineage or population levels. We argue that testing these inequalities provides useful insights into the underlying mechanism controlling the division rate in such branching processes.

scholarly journals Population dynamics of rice leaffolders (Lepidoptera: Pyralidae) and their natural enemies in irrigated rice in the Philippines

1999 ◽  
Vol 89 (5) ◽  
pp. 411-421 ◽  
Author(s):  
J. de Kraker ◽  
A. van Huis ◽  
K.L. Heong ◽  
J.C. van Lenteren ◽  
R. Rabbinge
Keyword(s):  
Population Dynamics ◽  
Natural Enemies ◽  
Natural Enemy ◽  
Survival Rates ◽  
The Philippines ◽  
Cnaphalocrocis Medinalis ◽  
Irrigated Rice ◽  
Larval Stages ◽  
Ovipositional Preference ◽  
Rice Leaffolders

AbstractPopulations of rice leaffolders and their natural enemies were studied in eight crops of irrigated rice in Laguna Province, the Philippines. The rice leaffolder complex consisted of three species: Cnaphalocrocis medinalis (Guenée), Marasmia patnalis Bradley and M. exigua Butler. Leaffolder population dynamics were characterized by an egg peak at maximum tillering and a broad larval peak around booting stage. Peak densities ranged from 0.2 to 2.0 larvae per hill. Most larvae originated from immigrant moths and there was no substantial second generation. The seasonal percentage egg parasitism by Trichogramma sp. ranged from 0 to 27%, and percentage larval parasitism from 14 to 56%. The braconid Macrocentrus philippinensis Ashmead was the most commonly reared larval parasitoid. Forty natural enemy taxa that may attack rice leaffolders were identified from suction and sweepnet samples: 24 predator taxa and 16 parasitoid taxa. The estimated survival rates from leaffolder egg to larval stages and between larval stages showed large variation between rice crops, but were not clearly correlated with observed levels of parasitism, natural enemy abundance, or natural enemy to leaffolder ratios. It is suggested that the generally low densities of rice leaffolders in Philippine transplanted rice are caused by their ovipositional preference for crops at the maximum tillering stage, allowing for only one generation, and by high immature mortality caused by the abundant and diverse complex of natural enemies.

scholarly journals Plant genotypic diversity increases population size of a herbivorous insect

2011 ◽  
Vol 278 (1721) ◽  
pp. 3108-3115 ◽  
Author(s):  
Shunsuke Utsumi ◽  
Yoshino Ando ◽  
Timothy P. Craig ◽  
Takayuki Ohgushi
Keyword(s):  
Population Dynamics ◽  
Population Size ◽  
Natural Enemy ◽  
Genotypic Variation ◽  
Genotypic Diversity ◽  
Community Genetics ◽  
Aphid Population ◽  
Herbivorous Insect ◽  
Mixed Genotype ◽  
The Impact

It is critical to incorporate the process of population dynamics into community genetics studies to identify the mechanisms of the linkage between host plant genetics and associated communities. We studied the effects of plant genotypic diversity of tall goldenrod Solidago altissima on the population dynamics of the aphid Uroleucon nigrotuberculatum . We found genotypic variation in plant resistance to the aphid in our experiments. To determine the impact of plant genotypic diversity on aphid population dynamics, we compared aphid densities under conditions of three treatments: single-genotype plots, mixed-genotype plots and mixed-genotype-with-cages plots. In the latter treatment plants were individually caged to prevent natural enemy attack and aphid movement among plants. The synergistic effects of genotypes on population size were demonstrated by the greater aphid population size in the mixed-genotype treatment than expected from additive effects alone. Two non-exclusive hypotheses are proposed to explain this pattern. First, there is a source–sink relationship among plant genotypes: aphids move from plant genotypes where their reproduction is high to genotypes where their reproduction is low. Second, natural enemy mortality is reduced in mixed plots in a matrix of diverse plant genotypes.

scholarly journals Temperature-induced Multi-species Cohort Effects in Sympatric Snakes

2021 ◽  
Author(s):  
Richard King
Keyword(s):  
Population Dynamics ◽  
Generation Time ◽  
Cohort Effects ◽  
Reproductive Phenology ◽  
Thamnophis Sirtalis ◽  
Temperature Dependent ◽  
Present Evidence ◽  
June July ◽  
Size Data ◽  
Operative Temperatures

In reptiles, reproductive maturity is often determined by size rather than age. Consequently, growth early in life may influence population dynamics through effects on generation time and survival to reproduction. Because reproductive phenology and pre- and post-natal growth are temperature-dependent, environmental conditions may induce multi-species cohort effects on body size in sympatric reptiles. I present evidence of this using ten years of neonatal size data for three sympatric viviparous snakes, Dekay’s Brownsnakes (Storeria dekayi), Red-bellied Snakes (S. occipitomaculata) and Common Gartersnakes (Thamnophis sirtalis). End-of-season neonatal size varied in parallel across species such that snout-vent length was 36-61% greater and mass was 65-223% greater in years when gestating females could achieve higher April-May (vs. June-July or August-September) operative temperatures. Thus, temperature had a larger impact during follicular enlargement and ovulation than during gestation or post-natal growth. Multi-species cohort effects like these may affect population dynamics and increase with climate change.

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