The `Natural Enemy Ravine' in Cereal Aphid Population Dynamics: A Consequence of Predator Activity or Aphid Biology?

10.2307/4077 ◽  
1981 ◽  
Vol 50 (2) ◽  
pp. 605 ◽  
Author(s):  
Nick Carter ◽  
A. F. G. Dixon
Keyword(s):  
Population Dynamics ◽  
Natural Enemy ◽  
Aphid Population ◽  
Cereal Aphid

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.

The Migratory Ambit of the Hop Aphid and its Significance in Aphid Population Dynamics

10.2307/4207 ◽  
1979 ◽  
Vol 48 (3) ◽  
pp. 955 ◽  
Author(s):  
L. R. Taylor ◽  
I. P. Woiwod ◽  
R. A. J. Taylor
Keyword(s):  
Population Dynamics ◽  
Aphid Population

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.

The role of large-scale spatially explicit and small-scale localized processes on the population dynamics of cereal aphids

2005 ◽  
Vol 95 (6) ◽  
pp. 579-587 ◽  
Author(s):  
L. Winder ◽  
G.J.K. Griffiths ◽  
J.N. Perry ◽  
C.J. Alexander ◽  
J.M. Holland ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Spatial Pattern ◽  
Large Scale ◽  
Aphid Population ◽  
Small Scale ◽  
Spatially Explicit ◽  
Cereal Aphids ◽  
Field Scale ◽  
Crop Density ◽  
Activity Density

AbstractA field-scale study of the spatially explicit interaction between the carabid Poecilus cupreus Linnaeus, and two common aphid species (Sitobion avenae (Fabricius) and Metopolophium dirhodum (Walker)) in winter wheat was conducted. All three species showed considerable spatial pattern at the field scale. Activity-density of P. cupreus was an order of magnitude higher in the central part of the field compared to its periphery. Where P. cupreus activity-density was highest, S. avenae and M. dirhodum population peaks were delayed. Additionally, in the case of M. dirhodum, lower maximum counts were evident where P. cupreus activity-density was highest. An analysis of the movement of individual P. cupreus using release–recapture indicated that those beetles within the centre of the field exhibited reduced displacement, which may have caused the generation or maintenance of spatial pattern. Crop density was also measured throughout the field. Although crop density had no large-scale spatial pattern, its variability at the small-scale was consistent with an influence on aphid population dynamics. This study demonstrates empirically that both large-scale spatially explicit and small-scale localized processes influenced aphid population dynamics simultaneously.

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