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Derivation of an Index for Assessing the Resistance of Zebu Cattle to Rhipicephalus Appendiculatus Neumann (Acarina:Ixodidae)

  • S. Nokoe
  • P. B. Capstick
  • A. A. Latif
  • D. K. Punyua
Research Article

Abstract

A quantitative measure for assessing the level of resistance of zebu cattle to Rhipicephalus appendiculatus is discussed. Basic data for the derivation of the mathematical index were from artificial infestation of cattle to adults, nymphs and larvae of the Rusinga Island stock of the tick species. Observed variables were the weights and numbers of the engorged/detached instars.

The index derivation process was by the use of the stepwise discriminant function procedure and the Mahalanobis distance. These procedures led to die derivation of an index which was a function of the engorged weights of the female and nymphal instars, the numbers of detached females and the Mahalanobis distance. Variables associated with the larval instar were found to be insignificant and were therefore not included in the index function.

The derived index is capable of discriminating between susceptible and resistant cattle, and can be used to monitor changes in the resistance levels of cattle over time.

Key Words

Rhipicephalus appendiculatus artificial challenge Mahalanobis distance discriminant function tick resistance index 

Résumé

Un index mathématique base sur les résultats obtenus aprésune infestation des vaches avec le Rhipicephalus appendiculatus a été étudie. L’index est dérivé d’une fonction analytique discriminante qui a comme principle variables le nombre des femelles ayant pris du sang et les poids des femelles et chrysalides engorgées. Cet index est capable de discriminér entre les vaches sucepttbles et résistantes et peut être utilises pour observer les changements du niveau de resistance chez les vaches.

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References

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Copyright information

© ICIPE 1993

Authors and Affiliations

  • S. Nokoe
    • 1
  • P. B. Capstick
    • 1
  • A. A. Latif
    • 1
  • D. K. Punyua
    • 1
  1. 1.The International Centre of Insect Physiology and EcologyNairobiKenya

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