Two resistance screening assays were developed for evaluating rice varieties' Oryza sativa (L.) resistance to the Striped Stem Borer (SSB), Chilo Suppressalis Wlk., in laboratory conditions during 1996-97. In the first assay, in a no - chioce screening test, using larval feeding severity and feeding ratio on stem pieces of host plant were tested for 48 and 120 hrs., respectively. There were no significant correlations observed between feeding severity and feeding ratio (r-0.182). In the second assay, in a choice test using orientation and settling responses of 3rd - 4th instars of SSB larvae on stem pieces of tested varieties were assayed after one and 24 hrs., respectively. The rice varieties were significantly different in their degree of resistance to the pest, and there exited positive correlations between feeding ratio and oriented as well as settling larvae (r-0.470* and 0.489* respectively). The relative resistance of given test varieties was determined using feeding index. In these tests the variety Nemat exhibited resistance similar to that determined by field screening. The two assays are complementary providing useful information on antixenosis and antibiosis.
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