author(s)
A Nayak, MJ Baig, PK Mohapatra and KS Behera

abstract
Rice crop is attacked by several insect pests from nursery to harvest. Investigation was carried out to determine the effect of feeding damages caused by the insect pests yellow stem borer (YSB), white backed plant hopper (WBPH), brown plant hopper (BPH) and leaf folder (LF) on the biochemical parameters of rice plant. Rice plants damaged by these insects were analyzed for the quantitative and qualitative changes in biochemical profile e.g. starch, nitrogen, soluble sugar, protein, total chlorophylls and carotenoids. The experiments have been conducted in a rice cultivar TN1 susceptible to all the insects. Standard biochemical procedures were followed to analyse different biochemical parameters. The concentration of starch in leaf was highest in the control, followed by YSB, WBPH, BPH and LF damaged plants in a sequence. Feeding by WBPH and BPH reduced the total nitrogen concentration of the leaf more compared to the other two insects. Total soluble sugar concentration in leaves of damaged plant was the maximum in the control plants exceeding the level of 20 (mg/g fresh weight) and insect feeding reduced it by more than half. YSB and BPH effects were more severe in comparison to the other two insects. Similar to the carbohydrates, leaf protein concentration (mg/g fresh weight) was also declined by insect feeding. In sharp contrast to the biochemicals, insect feeding did not have significant effect of chlorophyll a concentration of the leaf. Similar to chlorophyll a, the concentration of chlorophyll b was not influenced by insect feeding severely and the effects were marginal. The concentration of leaf carotenoids did not change much with insect feeding, but reduced marginally compared to the control plants. The level of reduction was maximum for BPH infestation.