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Determination of damage threshold of green spider mite, Mononychellus tanajoa (Bondar) on Cassava

Published online by Cambridge University Press:  19 September 2011

T. O. Ezulike  and
R. I. Egwuatu
T. O. Ezulike
Affiliation:
National Root Crops Research Institute, Umudike, P.M.B. 7006 Umuahia, Imo State, Nigeria
R. I. Egwuatu
Affiliation:
Department of Crop Science, University of Nigeria, Nsukka, Nigeria
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Abstract

The damage threshold of the green spider mite, Mononychellus tanajoa (Bondar) on cassava was determined in the greenhouse using four levels of mite infestation namely: 5, 10, 15 and 20 adult mites per cassava plant. Cassava cuttings were planted in plastic buckets in the greenhouse. The plants were artificially infested at 10 weeks old after planting.

Visible symptoms of mite damage appeared on cassava leaves at 4 weeks after infestation and at this period, the average number of mites was found to be eight mites per leaf. The mean number of active stages of M. tanajoa (larvae, nymphs and adults) was highest at the infestation level of 20 mites per plant, followed by that of 15, 10 and 5, in that order. The mean number of eggs was also highest at the infestation level of 20 mites per plant.

Résumé

Le seuil du dommage economique causé par la mite, Mononychellus tanajoa (Bondar) sur le manioc fut determinée grâce une infestation d'un plant par 5, 10, 15 et 20 mites adultes dans une serre. Les plants de manioc furent plantés dans des seaux en plastique. Les plants de manioc furent infectées 10 semaines après la plantation. Les symptomes visibles du dommage causé par les mites apparaissaient sur les feuilles du manioc 4 semaines après l'infestation avec un nombre des mites par feuilles qui etait de 8. Le nombre moyen du stage actif de M. tanajoa (larves, chrysalydes et adultes) etait tres eleve a l'infestation de 20 mites par plant de manioc, suivit de 15, 10 et 5 mites. Le nombre moyen des ouefs fut aussi le plus eleve pour l'infestation de 20 mites par plant de manioc.

Keywords

Economic thresholddamage thresholdeconomic damage leveleconomic injury levelinfestation levelpestdensitypopulationMononychellus tanajoaSeuil economiqueseuil du dommageniveau du dommage economiqueniveau de la perte economiqueniveau d'infestationmiteravageurdensitepopulationMononychellus tanajoa
Type
Research Articles
Information
International Journal of Tropical Insect Science , Volume 11 , Issue 1 , February 1990 , pp. 43 - 45
Copyright
Copyright © ICIPE 1990

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References

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