Varietal screening and development of rice weevil, Sitophilus oryzae (L.) in advanced rice genotypes at different temperatures

The present study was conducted to screen out six rice genotypes including two course and four fine advanced varieties against Coleopterous insect rice weevil, Sitophilus oryzae (L.) under laboratory conditions. Weighing 100g sample of each genotype in plastic jars having capacity of 250g. Thirty adult insects of rice weevil, reared in laboratory were released in each jar. Quantitative losses as weight loss, percent damaged grains, progeny development and frass weight was recorded after 90 days of storage at 28oC, 32oC and 35oC. Percentage damage grains, adult emergence and frass weight was significantly high at 32, 28 and 35°C respectively. Maximum infestation in case of percentage damaged grains recorded in course genotype KSK-133(20.58%) and Basmati515(16.90%) followed by Basmati-2006(13.033%), and Super Basmati (12.433%) at 28°C. In a similar way but minimum weight loss (0.5%) was observed in KSK-282 at 35°C and (1%) in Basmati-2006 at 32oC. Overall, low resistance level with highest insect development was counted in KSK-133 (114), (101), (86) and Basmati-515(85), (90), (64.3) at 32, 35 and 28°C respectively. But under similar conditions Basmati-385(53), (43), (42) showed resistance in insect multiplication. Findings should be incorporate in breeding programme and can also be helpful in post-harvest storage.