Influence of weather factors on the population dynamics of chewing pests of lowland paddy in mizoram

Chaetocnema spp. was active from the last week of August to second week of October with a peak level of population during first week of September (8.17). Monolepta signata Oliver reached peak level of population during third week of September (5.17) followed by first week of September (5.00). The mean population of Chaetocnema spp. and M. signata over the season recorded was 4.53 and 2.88 beetles per 5 plants, respectively. Melanitis leda ismene Cramer reached peak level of population during first week of September (3.42). Cnaphalocrocis medinalis Guenee recorded its peak population during third week of September (0.33). The mean population of M. leda ismene and C. medinalis over the season recorded was 1.56 and 0.14 larvae per 5 plants. The coefficient of determination (R²) was found to be 91% (Chaetocnema spp.), 77% (M. signata), 45% (M. leda ismene) and 87% (C. medinalis). Correlation coefficient between chewing pests and abiotic factors revealed that Chaetocnema spp. had positive significant correlation with maximum relative humidity (r = 0.713), while C. medinalis established negative significant correlation with maximum temperature (r = -0.707). M. signata showed positive correlation with all the weather factors, whereas M. leda ismene had positive correlation with minimum temperature (r = 0.633) and minimum relative humidity (r = 0.114) but was negative correlation with maximum temperature (r = -0.301), maximum relative humidity (r = -0.262) and rainfall (r = -0.393).