Relative field susceptibility of rice varieties to infestation by the rice leaf roller Cnaphalocrocis medinalis Guenee

Abstract

Eighteen varieties of paddy were screened for their relative susceptibility to infestation by Cnaphalocrocismedinalis The cviposition response of the different varieties varied significantly. The varieties could be ranked in the following ascending order with reference to the extent of preference: Kochuvithu, TKM6, TKM1, Adt27, Ptb9, Pankaj, Triveni, 1' 1. Cavery, IR20, Aswathi, Karuna, Jagannath, Annapoorna, Rohini, Mashoori Jaya and iRH- Based on the extent of leaf damage caused by the larvae, Kochuvithu ranked as the least susceptible variety followed by TKM6, TKM1, Ptb9, Adt 27, Pankaj, Triveni, IR20, H4 Cavery, Aswathi, Karuna, Annapoorna and Jagannath there being no significant difference among themselves. IR8, Jaya, Rohini and Mashoori were most susceptible. Based on the extent of leaf damage caused by the larvae Kochuvithu ranked as the least susceptible variety followed by TKM6, TKM1, Ptb9, Adt 27, Pankaj, Triveni. IR20, H4, Cavery, Aswathi, Karuna, Annapoorna and Jagannath, there be ing no significant difference among themselves. Susceptibility of the riee varieties to damage by leaf roller in the field was positively correlated with the number of eggs laid on them.