A GENERAL METHOD FOR ESTIMATING CEREAL APHID POPULATIONS IN SMALL GRAIN FIELDS BASED ON FREQUENCY OF OCCURRENCE

1995 ◽  
Vol 127 (1) ◽  
pp. 59-63 ◽  
Author(s):  
G.L. Hein ◽  
N.C. Elliott ◽  
G.J. Michels ◽  
R.W. Kieckhefer
Keyword(s):  
Weighted Average ◽  
Aphid Species ◽  
Parameter Estimates ◽  
Single Model ◽  
Cereal Aphid ◽  
Grain Aphid ◽  
Aphid Density ◽  
Single Set ◽  
General Method ◽  
Aphid Populations

AbstractSimilarities in population parameters among aphid species led us to investigate the potential for a single set of parameters that can be used to develop a ‘generic’ sampling plan for multiple small grain aphid species. A weighted average for the slope and intercept used to relate the proportion of infested tillers to the number of aphids per tiller was determined from the data in 15 published reports. These average parameter estimates were used to predict the number of aphids per tiller in 48 wheat fields sampled for four aphid species. The predicted estimates were regressed on the observed estimates with neither slopes nor intercepts differing significantly from one or zero, respectively. Therefore, it appears the single model is adequate for predicting aphid density for the aphid species tested.

scholarly journals Comparison of Field Population Growths of Three Cereal Aphid Species on Winter Wheat

2011 ◽  
Vol 39 (No. 2) ◽  
pp. 61-64 ◽  
Author(s):  
V. Jarošík ◽  
A. Honěk ◽  
A. Tichopád
Keyword(s):  
Winter Wheat ◽  
Rhopalosiphum Padi ◽  
Intrinsic Rate ◽  
Aphid Species ◽  
Population Increase ◽  
Intrinsic Rate Of Increase ◽  
Cereal Aphid ◽  
Metopolophium Dirhodum ◽  
Aphid Density ◽  
Rate Of Increase

Population growths of three aphid species colonising winter wheat stands, Metopolophium dirhodum, Rhopalosiphum padi and Sitobion avenae, were analysed by regression method. The calculations were based on counts in 268 winter wheat plots at 3 or 7 day intervals over 10 (leaves) or 6 (ears) years. The population dynamics of a particular species differed widely between years. Density independent exponential growth of the population was most common, but its rate differed significantly between species, and for S. avenae also between populations on leaves and ears, on which the populations grew fastest. Field estimates of the intrinsic rate of increase derived from the exponential growths ranged between 0.010–0.026 in M. dirhodum, 0.0071–0.011 in R. padi, and between 0.00078–0.0061 and 0.0015–0.13 in S. avenae on leaves and ears, respectively. In the populations with the most vigorous population growth, S. avenae on ears and M. dirhodum on leaves, the rate of population increase significantly decreased with increasing aphid density.  

scholarly journals Influence of Plant Diversity on the Numerical Response ofEriopis connexa(Coleoptera: Coccinellidae) to Changes in Cereal Aphid Density in Wheat Crops

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
María C. Tulli ◽  
Dora M. Carmona ◽  
Ana M. Vincini
Keyword(s):  
Plant Diversity ◽  
Aphid Species ◽  
Linear Increase ◽  
Numerical Response ◽  
Cereal Aphids ◽  
Cereal Aphid ◽  
Higher Plant ◽  
Metopolophium Dirhodum ◽  
Aphid Density ◽  
Eriopis Connexa

Cereal aphids cause economic injury to wheat crops. In Argentina,Eriopis connexais an indigenous ladybird. In the present study, the numerical response ofE. connexato changes in aphid density on wheat crops with high and low plant diversity was investigated. The study was carried out in Balcarce, Buenos Aires, Argentina, from September to December 2007 and 2008, on two wheat crops with either a higher plant diversity (HPD) with refuge strips or a lower plant diversity (LPD) without refuge strips. Crops were sampled every week and the abundance of aphids andE. connexawas recorded. The dominant aphid species wereSchizaphis graminum, Metopolophium dirhodum,andSitobion avenae.Eriopis connexashowed a linear increase in the numerical response to an increase in aphid density, which varied in space and time. The abundance ofE. connexaincreased in relation to the crop development and aphid population and was higher in the HPD than in the LPD system. This predator increased its reproductive numerical response only in 2008, with a significant liner response in the HPD system. This suggests that the potential ofE. connexaas a predator of cereal aphids also increases directly in proportion to landscape vegetal diversity.

Antioxidant defense mechanisms of cereal aphids based on ascorbate and ascorbate peroxidase

Biologia ◽  
2009 ◽  
Vol 64 (5) ◽  
Author(s):  
Iwona Łukasik ◽  
Sylwia Goławska ◽  
Agnieszka Wójcicka
Keyword(s):  
Caffeic Acid ◽  
Ascorbate Peroxidase ◽  
Defense Mechanisms ◽  
Antioxidant Defense ◽  
Rhopalosiphum Padi ◽  
Aphid Species ◽  
Cereal Aphids ◽  
Cereal Aphid ◽  
Antioxidant Responses ◽  
Grain Aphid

AbstractEffects of plant o-dihydroxyphenols on ascorbate (ASA) content and ascorbate peroxidase (APOX) activity in the tissues of the grain aphid Sitobion avenae and the bird cherry-oat aphid Rhopalosiphum padi were studied. Among the aphid morphs, the highest ASA content and APOX activity were noted for larvae and the lowest for wingless apterae. When exposed to o-dihydroxyphenols, aphids of both species contained significantly lower concentrations of ASA and higher APOX activity than the controls. Among the studied compounds, caffeic acid had the strongest effect on ASA-based antioxidant responses in that caffeic acid caused a 5-fold decrease of ASA in aphid tissues. The influences of the plant o-dihydroxyphenols on antioxidant defense mechanisms within the cereal aphid species are discussed.

STUDY REGARDING THE APHIDOFAGOUS FAUNA STRUCTURE IN THE PEACH ORCHARDS FROM CONSTANTA COUNTY IN 2020

2020 ◽  
Vol 13 ◽  
pp. 110-114
Author(s):  
Andrei Chiriloaie-Palade ◽  
Mădălina Radulea ◽  
Gheorghe Lămureanu ◽  
Ștefan Ion Mocanu ◽  
Maria Iamandei
Keyword(s):  
Myzus Persicae ◽  
Management System ◽  
Green Peach Aphid ◽  
Aphid Species ◽  
Insect Species ◽  
Essential Component ◽  
Intensive Use ◽  
Predatory Insect ◽  
Predatory Insects ◽  
Aphid Populations

"The cosmopolitan aphid species Myzus persicae is a key pest of peach orchards in south and southeastern Romania. The phenomenon of resistance induced by the intensive use of insecticides is a matter of concern for farmers and protectionists, making necessary integrated measure for the control of this pest. Conservation of natural enemy’s populations is an essential component of any management system proposed for pest aphids. The aim of the study was to determine the structure of predatory insects associated with Myzus persicae populations in peach orchards. The research was carried out in three orchards from two localities from Constanta County, in peach plantations with Springcrest variety aged 7, 11 and 12 years. As a result of this study, there were determined a total of 15 predatory insect species belonging to eight systematic families: Coccinellidae, Chrysopidae, Hemerobiidae, Syrphydae, Cecidomyiidae, Panorpidae, Nabidae and Forficulidae, which naturally contribute to the reduction of the green peach aphid populations. "

Trophic interactions between three species of cereal aphid (Hemiptera: Aphididae) and spring wheat (Poaceae): implications for pest management

2007 ◽  
Vol 139 (6) ◽  
pp. 850-863 ◽  
Author(s):  
Samuel M. Migui ◽  
Robert J. Lamb
Keyword(s):  
Spring Wheat ◽  
Trophic Interactions ◽  
Plant Biomass ◽  
Rhopalosiphum Padi ◽  
Aphid Species ◽  
Economic Damage ◽  
Cereal Aphids ◽  
Cereal Aphid ◽  
Economic Thresholds ◽  
Specific Impact

AbstractThe susceptibilities of genetically diverse Canadian spring wheats, Triticum aestivum L. and Triticum durum Desf., to three aphid species, Rhopalosiphum padi (L.), Sitobion avenae (Fabricius), and Schizaphis graminum (Rondani), were investigated. Trophic interactions measured as changes in biomass of aphids and wheat plants were used to quantify levels of resistance, components of resistance, and impact of aphids on yield. Plants in field cages were infested with small numbers of aphids for 21 days at heading. These plants were usually more suitable for the development of S. avenae and S. graminum than of R. padi. Partial resistance, measured as seed production by infested plants as a proportion of that by a control, varied from 11% to 59% for different aphid species and wheat classes when all wheat plants were infested at the same stage. Cultivars within wheat classes responded similarly to each of the aphid species. None of the wheat cultivars showed agriculturally effective levels of antibiosis. The specific impact of each aphid species and wheat class varied from 5 to 15 mg of plant biomass lost for each milligram of biomass gained by the aphids. Canadian Western Red Spring wheat had a lower specific impact and therefore was more tolerant to aphids than the other two classes, but not tolerant enough to avoid economic damage at the aphid densities observed. Plants did not compensate for feeding damage after aphid feeding ceased, based on the higher specific impacts observed for mature plants than for plants that were heading. The interactions between aphids and plants show that current economic thresholds probably underestimate the damage caused by cereal aphids to Canadian spring wheat.

Length-at-Age Analysis: Can You Get What You See?

1992 ◽  
Vol 49 (4) ◽  
pp. 632-643 ◽  
Author(s):  
T. J. Mulligan ◽  
B. M. Leaman
Keyword(s):  
Growth Model ◽  
Time Trend ◽  
Single Point ◽  
Mortality Rates ◽  
Individual Growth ◽  
Parameter Estimates ◽  
Von Bertalanffy ◽  
Model Ambiguity ◽  
Von Bertalanffy Growth Model ◽  
Single Set

Observations at a single point in time of length-at-age (LAA) for a long-lived rockfish (Sebastes alutus) show that old fish are shorter than intermediate-aged fish. Fitting of a von Bertalanffy growth model to these data produces a systematic trend in the residual of observed versus calculated LAA. We examined how such LAA data can lead to erroneous conclusions about individual growth, and whether asymptotic growth can give rise to such data. We considered two hypotheses: (i) that a time trend in growth rate resulted in larger fish in more recent years and (ii) that there are multiple growth types, where growth and mortality rates are directly related. Using a general growth model that incorporated both (i) and (ii), we show that both hypotheses can generate data identical to those for the rockfish. A single set of LAA data is inadequate for describing individual growth; however, if sufficient data are available, model ambiguity can be resolved and reasonable parameter estimates obtained. Analysis of the rockfish data indicates that (ii) is more likely to explain the observations than (i). We show how fisheries on such species may preclude our understanding these biological relationships.

scholarly journals A large-scale field study of bacterial communities in cereal aphid populations across Morocco

2018 ◽  
Vol 94 (3) ◽  
Author(s):  
Samir Fakhour ◽  
Jérôme Ambroise ◽  
François Renoz ◽  
Vincent Foray ◽  
Jean-Luc Gala ◽  
...  
Keyword(s):  
Field Study ◽  
Bacterial Communities ◽  
Large Scale ◽  
Cereal Aphid ◽  
Scale Field ◽  
Large Scale Field ◽  
Aphid Populations

The Difference Between Causal Analysis and Predictive Models: Response to “Comment on Young and Holsteen (2017)”

2018 ◽  
Vol 48 (2) ◽  
pp. 431-447 ◽  
Author(s):  
Cristobal Young
Keyword(s):  
Treatment Effects ◽  
Robustness Analysis ◽  
Model Space ◽  
Parameter Estimates ◽  
Single Model ◽  
Omitted Variable Bias ◽  
The Difference ◽  
Variable Bias ◽  
Definition Of ◽  
Model Robustness

The commenter’s proposal may be a reasonable method for addressing uncertainty in predictive modeling, where the goal is to predict y. In a treatment effects framework, where the goal is causal inference by conditioning-on-observables, the commenter’s proposal is deeply flawed. The proposal (1) ignores the definition of omitted-variable bias, thus systematically omitting critical kinds of controls; (2) assumes for convenience there are no bad controls in the model space, thus waving off the premise of model uncertainty; and (3) deletes virtually all alternative models to select a single model with the highest R 2. Rather than showing what model assumptions are necessary to support one’s preferred results, this proposal favors biased parameter estimates and deletes alternative results before anyone has a chance to see them. In a treatment effects framework, this is not model robustness analysis but simply biased model selection.

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