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

Published online by Cambridge University Press:  10 July 2009

A. B. Salifu  and
C. J. Hodgson
A. B. Salifu
Affiliation:
Department of Biological Sciences, Wye College, University of London, Ashford, Kent, TN25 5AH, UK
C. J. Hodgson*
Affiliation:
Department of Biological Sciences, Wye College, University of London, Ashford, Kent, TN25 5AH, UK
*
* All correspondence should be sent to the second author in the first instance.
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Abstract

The 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.

Type
Original Articles
Information
Bulletin of Entomological Research , Volume 77 , Issue 3 , September 1987 , pp. 441 - 449
Copyright
Copyright © Cambridge University Press 1987

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