Evaluation of rice tissue culture lines for resistance to the rice water weevil (Coleoptera: Curculionidae)

Preliminary field evaluation of 66 rice tissue culture lines in 1990 for resistance to the rice water weevil, Lissorhoptrus oryzophilus Kuschel, identified several lines with potential for tolerance, antixenosis, and antibiosis. These lines were divided in two groups for further evaluation. One group, consisting of five lines (67, 93, 112, 120, 4754), was evaluated in 1991 and 1992 specifically for tolerance. The other group, consisting of four lines (185, 244, 2051, 2232), was tested in the greenhouse in 1991 and in the field in 1992 for antibiosis and antixenosis. Significant differences were found among the lines tested for tolerance with respect to rice water weevil larval populations, root damage ratings, plant height, and grain yield. Comparison of untreated and treated plots indicated that lines 112 and 4754 showed tolerance to the rice water weevil. Tolerance was primarily expressed as the ability of the lines to recover from root damage and produce high yield while supporting a high rice water weevil larval population. Lines 244 and 2232 showed antixenosis to the rice water weevil. The antixenotic lines had significantly lower larval populations than the susceptible standard 'Mars'