Includes bibliographical references.

In agriculture, grain storage is crucial for future generations and food security. Because they generate significant losses and have an impact on the fate of grains during storage, insect pests are significant commercially. By reducing or eliminating insect pest populations while storing food, the rising demands of the world's population can be satisfied. One of the most popular cereals with a high dietary value and global reputation is rice. The most well-known rice pest in storage is the rice weevil (Sitophilus oryzae), which affects India's annual harvest to the tune of 10%. Furthermore, a significant infestation of pests may have a harm potential of up to 40%. Therefore, the present experiments were conducted to study on biology of Rice weevil, Sitophilus oryzae (L.) at different temperature regimes i.e., 20±1°C, 25±1°C and 30±1°C. and Varietal screening of different indigenous cultivars of stored rice grains against Rice weevil (S.oryzae). The experiments were conducted in Entomology laboratory of School of Crop Protection, CPGSAS, CAU(I), Umiam, Meghalaya and rice varieties were collected from collected from farmer’s granaries in Ri bhoi district, Meghalaya. The result of present study showed that the morphometrics of the eggs ,larva and pupa were found to be smallest at 20±1°C and largest at 30±1°C with a range such as Egg: length (0.32 to 0.37) mm and breadth (0.09 to 0.22) mm, Larva: length (0.25 to 7.4) mm and breadth(0.09 to 2.7) mm, Pupa: length (2.87 to 4.16) mm and breadth (1.62 to 2.02) mm at 20±1°C. The incubation period of eggs of S.oryzae was shortest (4.5±0.5) days at 30±1°C and longest (6.93±0.4) days at 20±1°C. The hatching percentage of eggs of S.oryzae was maximum (75.83±2.9) per cent at 30±1°C and minimum (29.17±3.4) at 20±1°C. The longest duration of total larval period was recorded at 20±1°C (43.77±2.10 days) and shortest at 30±1°C (22.63±1.5 days). Pupal period occupied as 10.33±0.83 days highest at 20±1°C and lowest at 30±1°C as 5.6±0.36 days. Male longevity found to be longest (5.52±1.17 days) without food at 30±1°C and longest (53.57±5.58) days with food at 30±1°C. Female longevity found to be longest (8.39±0.82) days and (70.58±4.52) days without and with food respectively at 30±1°C. At 20±1°C preoviposition, oviposition and post-oviposition periods were longest (6.43±0.9), (64.4±3.9) and (29 ± 2.1) days respectively and at 30±1°C pre-oviposition, oviposition and post-oviposition periods were shortest (4.9±1.1), (39.4±2.0) and (22.73±1.5) days respectively. It is concluded that the variety Jowain white showed higher percent weight loss at 30 days (9.5±0.2), 60 days (15.2±0.1) and 90 days (20.4±0.2). The variety Lakang baleigh showed lowest weight loss percent at 30 days (2.5±0.3), 60 days (4.2±0.1) and 90 days (8.3±0.3). The variety Jowain white had highest susceptible index (13.9±4.5) followed by Pnah sticky (13.6±1.5), Jowain red (13.1±1.9) and the variety Lakang baleigh showed least susceptible index (6.6±1.9). The variety Jowain white was found to be susceptible to the pest S.oryzae and Lakangbaleigh was relatively resistant. Growth index was found to be highest in the cultivar Mynriumiam (1.90±0.08) followed by Lakangbaso (1.88±0.04). Percent infestation was seen to be highest in the variety Pnah sticky (25.5±9.5) followed by Jowain white (24.6±4.5), Lakangbaso (19.4±3.5) and lowest in black rice (11.4±7.5). It was found that in the variety Jowain white the adult longevity was highest in both male (54.0±2.0) days and female (74.7±5.9) days. It was seen that the sex ratio (male: female) was highest in Lakangbaso and Pnah sticky (1.7:1). The male population was seen to be higher in the varieties except Lakangbaleigh (0.9:1), Pnah sticky (0.9:1) and Mynriumiam (0.6:1). Considering the findings of the present study may be concluded that Prolonged storage of rice in lower temperature is beneficial and among the local varieties evaluated Lakangbaleigh was found to be relatively resistant to the pest S.oryzae.