Determination of Damage Threshold of Green Spider Mite, Mononychellus Tanajoa (Bondar) on Cassava

  • T. O. Ezulike
  • R. I. Egwuatu
Research Article


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.

Key Words

Economic threshold damage threshold economic damage level economic injury level infestation level pest density population Mononychellus tanajoa 


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.

Mots Clefs

Seuil economique seuil du dommage niveau du dommage economique niveau de la perte economique niveau d’infestation mite ravageur densite population Mononychellus tanajoa 


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Copyright information

© ICIPE-ICIPE Science Press 1990

Authors and Affiliations

  • T. O. Ezulike
    • 1
  • R. I. Egwuatu
    • 2
  1. 1.National Root Crops Research Institute, UmudikeUmuahiaNigeria
  2. 2.Department of Crop ScienceUniversity of NigeriaNsukkaNigeria

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