Loss Assessment of Stored Rice Infested by Sitotroga cerealella(OLIVIER)(Lepidoptera : Gelechiidae)

Stored brown and rough rice of 2 high-yield cultivars, Shinpo-38 (Japonica type, S-38) and Nankin 11 (Indica type, N-11), were artificially infested with Sitotroga cerealella (OLIVIER). Losses were assessed for 13 weeks at 28°C and 70% R.H. by measuring 6 or 7 loss criteria.The criteria were adult insect number, moisture content of rice, germinability, % kernels stained by the TZ method, fat acidity value (FAV), weight of 1, 000 kernels (TGM) and weight of 200-ml volume of kernels (SVW). N-11 cultivar had a thicker and more intact husk than S-38 cultivar. The moth population grew most in the rough rice of S-38 and least in that of N-11. Moisture content and FAV were not sensitive indicators of deterioration losses in the infested rice. Germinability and the TZ test effectively indicated a decline in seed quality due to infestation treatment and aging. In comparison to non-infested controls, TGM decreased by 14.3, 12.4, 6.7 and 7.5% in S-38 rough and brown rice and N-11 rough and brown rice, respectively, over 13 weeks. SVW showed slightly lower loss estimates than TGM. The loss assessment by these criteria indicated resistance of N-11 rough rice to S.cerealella. The properties of the loss criteria are discussed.