Susceptibility of Aromatic and Non- aromatic Rice to Sitophilus oryzae L. and their Influence on the Insect and Infestation Rate under Sub-Himalayan Plains of West Bengal

Relative susceptibility of local aromatic and non-aromatic rice grains to rice weevil, Sitophilus oryzae L. (Curculionidae, Coleoptera) was studied under laboratory conditions in the sub-Himalayan plains of West Bengal in two seasons (viz. winter and spring-summer) during 2020-2021. Results revealed that after 9 weeks of storage, the highest mean grain weight loss due to S. oryzae varied from 14.30% to 20.89% in the two types of rice grains in two seasons. The corresponding highest mean grain damage % ranged from 36.89 % to 41.56%. The grain weight loss and grain infestation % were always higher in the aromatic rice (Uttar Sugandhi) compared to non-aromatic rice (Jaldhepa) and also in the spring-summer season than the winter months. Carbohydrate and protein content of grains were reduced to the extent of 9.08% to 15.28% and 18.62% to 32.58% in aromatic and non-aromatic rice during winter and spring-summer seasons respectively as a result of infestation of S. oryzae. During winter and spring-summer seasons, from 5 pairs of adult weevils, a total of 188.60 and 142.20 and 264 and 237 number of adults were produced in aromatic and non-aromatic rice cultivars respectively at 9 weeks after their release. The adult population was always female biased.