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See how nematodes are emerging from the infected cadaver of a cassava scale insect.
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What is the Cassava Scale?
The cassava scale is an insect. It is a serious pest in certain cassava production areas of the Congo Basin. The scientific name for the insect is Stictococcus vayssierei—it belongs to the scale family Stictococcidae (Hemiptera).
How Does the Cassava Scale Damage Plants?
The cassava scale is a sap-sucking insect. The larvae and adult females of the scale insect attack feeder roots of germinating cuttings. The withdrawal of water and nutrients weakens the plants and causes extensive leaf-fall, wilting tip dieback, and plant death.
The cassava scale produces honeydew (carbohydrates), which attracts the ant species Anoplolepis tenella (Hymenoptera: Formicidae) primarly. The ants obtain honeydew by tending scale insects and, in return, they protect them from predators. Both ants and scale insects are winners in this partnership called mutualism. This obligate association results in a proliferation of the hemipteran, quickly increasing the damage caused to plants.
Are There Any Control Measures Against the Cassava Scale?
Efforts to control the cassava scale rely mostly on cultural practices such as the management of planting time, plant resistance and ant control. All with limited results.
Are Any Biological Controls Effective Against the Cassava Scale?
A study — carried out under laboratory and greenhouse conditions — indicated the moderate or high susceptibility of adult females to entomopathogenic/beneficial nematodes The results from this study were sufficiently encouraging to embark on in situ testing.