S2-12
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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