THE WITHIN FIELD SPATIAL PATTERN OF THE LARVAL EGYPTIAN ALFALFA WEEVIL, <i>HYPERA BRUNNEIPENNIS</i> (COLEOPTERA: CURCULIONIDAE): AN APPLICATION OF PARAMETER ESTIMATES IN SIMULATION

Christensen, J. B.; Gutiérrez, A. P.; Cothran, Warren R.; Summers, Charles G.

doi:10.4039/ent1091599-12

Cited by 15 publications

(13 citation statements)

References 7 publications

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“…These methods have been used successfully in California to describe the distribution of Egyptian alfalfa weevil in alfalfa (Christensen et al 1977) and various predators in cotton (Byerly et al 1978). …”

Section: May 1980mentioning

confidence: 99%

The Phenology and Distribution of Aphids in California Alfalfa as Modified by Ladybird Beetle Predation (Coleoptera: Coccinellidae)

1980

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Can. Ent. 112: 489-495 (1980) The phenologies and distributions of pea aphid (Acyrthosiphon $sum (Harris)), blue alfalfa aphid (A. kondoi (Shinji)), and spotted alfalfa aphid (Therioaphis maculata (Buckton)) were intensively studied in California alfalfa. The results showed, as expected, that aphid populations across all densities were aggregated; but that ladybird beetle (Hippodamia convergens (G.-M.)) predation increased the degree of aggregation. The distribution parameters of the aphids were estimated using methods developed by Iwao and Kuno (1971). The distribution and abundance of prey in the field greatly influence the success of predators and, via nutrition, their survival, growth, and reproduction. A knowledge of these relationships is essential if satisfactory field models of predator-prey interactions are to be developed. This paper is part of a series on the interactions of pea aphid (Acyrthosiphon pisum (Harris)), blue alfalfa aphid (A. kondoi (Shinji)), and spotted alfalfa aphid (Therioaphis maculata (Buckton)) and their ladybird beetle predator Hippodamia convergens (G.-M.) in alfalfa. In this paper we report an analysis of the phenology and distribution of these organisms, and use this information to estimate the influence of prey distribution on predation success of H. convergens in the field. Resume Methods Analysis of Prey Distribution in the FieldLloyd (1967) developed a method ("Patchiness" = x*/Z) which is affected little by changes in density, to measure the distributions of organisms & nature.Patchiness is defined as the ratio of mean crowding (X*) to the mean (X), where X* is defined asand S2 is the population variance. Values of x*/X less than, equal to, or greater than 1 indicate uniform, random, and aggregated distributions respectively. Iwag and Kuno (1971) showed that the slope (P) of the regression line of X* on X provided an equivalent measure of dispersion and, in addition, found that the intercept (a) was a measure of the units of that dispersion (i.e. a + 1).

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Section: May 1980mentioning

confidence: 99%

The Phenology and Distribution of Aphids in California Alfalfa as Modified by Ladybird Beetle Predation (Coleoptera: Coccinellidae)

1980

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“…We computed the correlation between the % older leaves infested with CBF ( (IWAO, 1969, CHRISTENSEN et al, 1977.…”

Section: Resultsmentioning

confidence: 99%

“…However, little is known of the dispersion pattern of CBF or how best to detect it on urban citrus trees. Data on the dispersion pattern are necessary in the formulation of sampling schemes (MORRIS, 1960) and for use in conjunction with economic threshold data to ascertain the need for control measures (CHRISTENSEN et al, 1977). Accordingly, this research was undertaken to determine 1978.…”

Section: Introductionmentioning

confidence: 99%

Detection of, and sampling procedures for, the citrus blackfly in urban southern Florida

Dowell

Cherry²

1981

Population Ecology

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Summary The dispersion pattern of the citrus blackfly (CBF)Aleurocanthus woglumi Ashby on urban citrus trees was studied in southern Florida. There was no usable correlation (r2=0.41) between the % of older leaves infested with CBF versus that on the newest mature flush, but there was a strong correlation (r2=0.87) between the % of leaves in the newest mature flush infested with CBF and loge(x¯+1), where truex¯ is the number of egg spirals of CBF/leaf on the same leaves. CBF egg spirals are distributed among the flushes in groups rather than singly and the flushes are not over‐dispersed. Visual surveys proved superior to sticky traps for the detection of CBF at low densities (<5% leaves infested) on citrus trees in an urban setting. A sampling procedure is described herein based upon visual surveys.

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“…Morris (1955) suggested that an acceptable level of precision in field studies of insect populations is D = 0.10, where D is the ratio of the standard error of the mean to the mean. This suggestion has been widely adhered to in insect population studies, although D ~ 0.20 is usually regarded as acceptable (e.g., Christensen et al 1977). In this study, sample size (n = 200) was fixed at a level where two teams of three workers could sample the six plots and transport the samples 190 km to the extraction laboratory at Ruakura on one day.…”

Section: Resultsmentioning

confidence: 99%

Sampling whitefringed weevil (Graphognathus leucoloma) populations

East

1980

New Zealand Journal of Agricultural Research

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Estimates of whitefringed weevil (Graphognathus leucoloma (Boheman)) population density which included all life-history stages present were made in late spring and early summer (October-December), when eggs and larvae weighing less than 3 mg were absent. Analysis of28 whitefringed weevil population samples from 0.2 ha study plots containing a wide range of population densities revealed that division of the plots into 10 equal-sized strata and proportional allocation of sampling units (lO-cm-diameter soil cores) among strata produced small but consistent gains in precision. The relationships of sample variance to mean (S2 = 1.905 m12o) and mean crowding to mean density (rll = 0.39 + 1.37 m) showed that whitefringed weevil populations have an aggregated distribution. These relationships were used to determine the number of sampling units necessary to attain specified levels of precision at different population densities.

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THE WITHIN FIELD SPATIAL PATTERN OF THE LARVAL EGYPTIAN ALFALFA WEEVIL, HYPERA BRUNNEIPENNIS (COLEOPTERA: CURCULIONIDAE): AN APPLICATION OF PARAMETER ESTIMATES IN SIMULATION

Cited by 15 publications

References 7 publications

The Phenology and Distribution of Aphids in California Alfalfa as Modified by Ladybird Beetle Predation (Coleoptera: Coccinellidae)

The Phenology and Distribution of Aphids in California Alfalfa as Modified by Ladybird Beetle Predation (Coleoptera: Coccinellidae)

Detection of, and sampling procedures for, the citrus blackfly in urban southern Florida

Sampling whitefringed weevil (Graphognathus leucoloma) populations

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