CBN-V Video Archives - S3-12
Quality Deterioration in Cassava due to Scale Insect (Aonidomytilus albus) Infestation

Premkumar T. and S.N. Moorthy

Central Tuber Crops Research Institute, Trivandrum, 695 017, Kerala, India prem@ctcri.ren.nic.in

        The scale insect (Aonidomytilus albus) is the most serious pest infesting cassava stems when these are stored for subsequent planting. The nymphs and adults suck sap from the bark portion of infested stem causing desiccation of the stored material. Occasionally, mildly infested stems are planted without the knowledge of the farmers and the scale insects multiply and encrust the stem. Biochemical changes in the bark portion of the infested and uninfested stem and also tubers were estimated. Comparison of changes in constituents like phenol, starch and sugar contents in the bark portion showed that the phenol content was twofold higher in infested stem. The sugar, starch and dry matter contents were lowered due to the infestation. Analysis of phenol, sugars and starch contents in tubers from uninfested and infested plants showed that there was no significant difference in sugar and phenol contents, but that there was significant reduction in starch content. The dry matter content in the uninfested sample was 1.5 times greater than infested samples. Comparison of cooking quality revealed that the tubers from infested plants exhibited very poor quality. Studies revealed that biochemical changes occur due to the infestation and the most significant change takes place with regard to the starch contents in the infested tubers.

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