The Spatial Pattern of Aphis gossypii οn Cotton

The spatial distribution of Aphis gossypii (Glover) on cotton was studied by using Taylor’s power law, the negative binomial parameter k and the iδ-index of aggregation. Both k and iδ were related to density with curvilinear relationships and indicated that aggregation decreases as density increases up to densities of, approximately, two individuals per leaf. At the very high densities (more than three individuals per leaf) the calculated values of the two indices recognized a tendency for an increased aggregation again. A strong linear relationship between the log mean and the log variance of the population density was obtained confirming the wide applicability of Taylor’s power law. However, the established relationship (b=1.433) assumes, for the range of the observed densities, a continuous decrease in the degree of aggregation as density increases. It is suggested that the changes in the degree of aggregation throughout the season and in relation to density are related to natural mortality.

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Spatial distribution and sequential sampling of Nysius spp. (Hemiptera: Lygaeidae) on sunflowers

Australian Journal of Experimental Agriculture ◽

10.1071/ea9880279 ◽

1988 ◽

Vol 28 (2) ◽

pp. 279 ◽

Cited By ~ 2

Author(s):

PG Allsopp ◽

S Iwao ◽

LR Taylor

Keyword(s):

Power Law ◽

Negative Binomial ◽

Sequential Sampling ◽

Binomial Model ◽

Sequential Decision ◽

Taylor’S Power Law ◽

Crop Development ◽

Precision Level ◽

Taylor's Power Law ◽

Mixed Populations

Counts of adults of mixed populations of Nysius vinitor Bergroth and N. clevelandensis Evans on preflowering and postflowering sunflowers did not conform to the Poisson distribution because of overdispersion. Preflowering samples did not conform to the negative binomial model, but postflowering samples did with a common k of 3.78. Both sets of samples fitted significantly (P<0.01) Iwao's patchiness regression and Taylor's power law, but with significantly (P<0.01) different intercepts and slopes, respectively. Relationships to determine sample sizes for fixed levels of precision and fixed-precision-level stop lines are developed for both stages of crop development using Taylor's power law. Sequential decision plans based on Iwao's regression are developed for use in the management of Nysius spp. on preflowering and postflowering sunflowers.

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NOTES ON THE SPATIAL PATTERN OF HYPERA POSTICA (COLEOPTERA: CURCULIONIDAE) ON ALFALFA

The Canadian Entomologist ◽

10.4039/ent1041995-12 ◽

1972 ◽

Vol 104 (12) ◽

pp. 1995-1999 ◽

Cited By ~ 13

Author(s):

C. D. F. Miller ◽

M. K. Mukerji ◽

J. C. Guppy

Keyword(s):

Spatial Pattern ◽

Power Law ◽

Negative Binomial ◽

Immature Stages ◽

Hypera Postica ◽

Taylor’S Power Law ◽

Binomial Series ◽

Taylor's Power Law

AbstractThe Poisson and the negative binomial series, Taylor’s power law, and Morisita’s Iδ-index were used to interpret the dispersion of field counts of the immature stages of Hypera postica (Gyll.) on alfalfa. The data conformed consistently to an overdispersed distribution. Transformations are offered for stabilizing the variance of field counts.

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Spatial patterns and sequential sampling plans for melolonthine larvae (Coleoptera: Scarabaeidae) in southern Queensland sugarcane

Bulletin of Entomological Research ◽

10.1017/s0007485300018228 ◽

1989 ◽

Vol 79 (2) ◽

pp. 251-258 ◽

Cited By ~ 15

Author(s):

P. G. Allsopp ◽

R. M. Bull

Keyword(s):

Power Law ◽

Negative Binomial ◽

Sequential Sampling ◽

The Other ◽

Taylor’S Power Law ◽

Functional Relationships ◽

Taylor's Power Law ◽

Mean And Variance ◽

Population Dispersion ◽

Population Counts

AbstractThe within-row dispersion characteristics of larvae of Antitrogus mussoni (Blackburn), A. parvulus Britton, Lepidiota crinita Brenske, L. negatoria Blackburn, L. noxia Britton and L. picticollis Lea in sugarcane were determined in studies in southern Queensland, Australia. The Poisson distribution, negative binomial distribution, Iwao's regression model and Taylor's power law analysis were used to determine the relationship between mean and variance of larval counts. All methods examined showed that the larvae were slightly aggregated. Taylor's power law generally gave equivalent or better fits to the population dispersion compared with the other models. The power law relationship for L. picticollis differed from those of the other five species, and a common relationship for those five species was determined. Relationships to determine sample sizes for fixed levels of precision and fixed-precision-level stop lines for sequential sampling were developed for both L. picticollis and the other five species. There were functional relationships between the variance and mean of untransformed population counts for all species, and the suitability of transformation functions is discussed.

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A sampling strategy to assess banana crops for damage by Radopholus similis and Pratylenchus goodeyi

Australian Journal of Experimental Agriculture ◽

10.1071/ea99122 ◽

2001 ◽

Vol 41 (5) ◽

pp. 675 ◽

Cited By ~ 5

Author(s):

J. M. Stanton ◽

A. B. Pattison ◽

R. A. Kopittke

Keyword(s):

Power Law ◽

Negative Binomial ◽

Sampling Strategy ◽

Disease Index ◽

Root Damage ◽

Radopholus Similis ◽

Taylor’S Power Law ◽

Taylor's Power Law ◽

Banana Crops ◽

Pratylenchus Goodeyi

The economic threshold of burrowing (Radopholus similis) and lesion nematode (Pratylenchus goodeyi) on banana may be used to determine whether it is economic to apply nematicide. However, to use such a threshold, a sampling strategy is essential to determine the severity of root damage caused by the nematode. Ten banana crops in south-eastern Queensland and northern New South Wales and 10 in northern Queensland were sampled several times over several years to determine the disease index (percentage cortical root damage caused by R. similis and P. goodeyi) and nematode populations in roots. The negative binomial distribution and Taylor’s power law analysis were used to determine the relationship between the mean and variance of the disease index and nematode populations. Taylor’s power law gave the better fit, and was therefore used to determine fixed-precision stop lines for sequential sampling for precision at 20–30% for disease index and 20–40% for nematode populations. Twenty samples per crop were sufficient to achieve 25% precision when assessing nematode infestations using disease index but only 40% precision when using nematode populations.

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Dispersion patterns and sequential sampling plans for Megalurothrips sjostedti (Trybom) (Thysanoptera: Thripidae) in cowpeas

Bulletin of Entomological Research ◽

10.1017/s0007485300011925 ◽

1987 ◽

Vol 77 (3) ◽

pp. 441-449 ◽

Cited By ~ 9

Author(s):

A. B. Salifu ◽

C. J. Hodgson

Keyword(s):

Power Law ◽

Negative Binomial ◽

Sequential Sampling ◽

Megalurothrips Sjostedti ◽

Taylor’S Power Law ◽

Regression Procedure ◽

Taylor's Power Law ◽

Mean And Variance ◽

Population Dispersion ◽

Population Counts

AbstractThe within-plant dispersion characteristics of Megalurothrips sjostedti (Trybom) on cowpeas were determined in studies in Nigeria. Iwao's regression procedure and Taylor's power law analysis were used to determine the relationship between the mean and variance of thrips counts. Both methods showed that adult thrips were randomly distributed within cowpea plants at initial low populations. At later high densities, Iwao's method provided a better fit of the population dispersion of larvae and adults and showed that both were aggregated. The negative binomial best described this aggregation at high population densities. Sequential count plans suitable for pest management surveys were developed using critical stop lines derived from Iwao's regression procedure and Taylor's power law, but the latter was found to require less effort to achieve the same level of precision. There was a functional relationship between the variance and mean of untransformed population counts, and the suitability of transformation functions is discussed.

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Sequential sampling plans for nematodes affecting sugarcane in Queensland

Australian Journal of Agricultural Research ◽

10.1071/ar9900351 ◽

1990 ◽

Vol 41 (2) ◽

pp. 351 ◽

Cited By ~ 3

Author(s):

PG Allsopp

Keyword(s):

Power Law ◽

Negative Binomial ◽

Sequential Sampling ◽

Taylor’S Power Law ◽

Functional Relationships ◽

Precision Level ◽

Taylor's Power Law ◽

Mean And Variance ◽

Population Counts ◽

The Relationship

The dispersion characteristics of root-lesion, root-knot, spiral, stubby-root, stunt and ring nematodes in soil, and root-lesion, root-knot and spiral nematodes in roots in sugarcane fields, were determined in studies in southern Queensland. The Poisson distribution, negative binomial distribution, Iwao's regression model and Taylor's power law analysis were used to determine the relationship between mean and variance of nematode counts. All methods showed that nematodes were aggregated (Iwao's G 1.12-1.65, Taylor's b 1.10-1.76). In general, Taylor's power law gave better fit compared with the other models (R2>0.61). Relationships to determine sample sizes for fixed levels of precision and fixed-precision-level stop lines for sequential sampling were developed for all species. There were functional relationships between variance and mean of untransformed population counts for all species, but suitable transformations eliminated significant correlations in most cases.

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