Aromatic rice varieties and grain types differ in their susceptibility to a Sitophilus oryzae attack during storage. Nine aromatic rice varieties (RD 6, RD 105, Chai Nat 2, RD 15, Dok Pa-yom, Nhang Mon S-4, Hom Ubon 80, RD 12, and R 258) were evaluated for their relative susceptibility to S. oryzae. ANOVA analysis of the results revealed that varieties R 258, Nhang Mon S-4, and RD 12 have a higher tolerance to S. oryzae infestation, while RD 6, RD 15, and Dok Pa-yom possess intermediate tolerance. Varieties RD 105, Hom Ubon 80, and Chai Nat 2 demonstrated less tolerance to S. oryzae. Egg oviposition, emerged adults, seed weight loss, damage incidence, and susceptibility index were significantly (p≤0.05) lower (9.71, 27.77, 4.23 g, 0.61, and 4.97, respectively) in R 258. The longest developmental period, 28.38 days was also found in R 258. Standardized multiple regression coefficients analysis showed that varietal susceptibility strongly dependent on the number of eggs laid and the developmental period. Interspecific crossing of R 258 to RD 12 and Nhang Mon S-4 is recommended to improve their resistance. High storage protection will be required for RD 105, Hom Ubon 80, and Chai Nat 2 to preserve grain quality.
