Ngeve, J.M. 2003 The cassava root mealybug (Stictococcus vayssierei Richard) (Homoptera: Stictococcidae): a threat to cassava production and utilization in Cameroon.. International Journal of Pest Management 49(4): 327-333.

Notes: The spread and severity of Stictococcus vayssierei, a root mealybug of cassava (Manihot esculenta Crantz), was monitored from 1990 to 1998 with 5 cassava genotypes in five sites in the sub-humid forest region of Cameroon. Pest frequency was low (12.5%) in 1990 but rapidly increased to 87.5% in 1994. Pest impact was more severe in the dry season than in the wet season. The improved clones were more tolerant of the pest than the local variety, and infestation was more severe in Nkolnkoumou and Mbalmayo than in the other sites. S. vayssierei adversely affected root yields and root counts; for instance, clone 8034 suffered a 27% depression in root yields and a 33% reduction in root counts. The pest was more severe when cassava was planted on the flat (30 mealybugs/hill) than when planted on ridges (16 adults/hill); plants also sprouted better (91%) when cassava was planted on ridges than when planted on the flat (71%). S. vayssierei infestation was also more severe when cassava was intercropped with maize and groundnuts than when planted alone. Techniques have to be developed for large-scale rearing of S. vayssierei inoculum in the laboratory for use in uniform screening of genotypes by artificial infestation. Monocropping is recommended in areas where pest impact is very severe. Also, disinfestation of cuttings with insecticidal bioproducts should be exploited to reduce pest impact. Finally, rhizosphere biocontrol agents such as endomycorrhizae should be studied to determine their usefulness in controlling the pest under farming conditions in Cameroon.