Oviposition behaviour of Scirpophaga incertulas (Walker) (Lepidoptera: Pyralidae) on Sarawak rice landraces

The yellow rice stem borer, Scirpophaga incertulas (Walker) is an important pest of rice in Sarawak, Malaysian Borneo. For a better management of this pest, it is crucial to understand the oviposition behaviour of S. incertulas which is unknown for Sarawak rice landraces. This study observed several aspects of S. incertulas oviposition behaviour on Sarawak rice landraces in a net house experiment. Adult female stem borers were collected using light trap from the nearby rice field at night A total of 180 females of S. incertulas were given access to six different rice landraces at three plant ages. The results indicated that rice plants at four-month old (heading to flowering) were strongly preferred for oviposition regardless of landraces. The vertical distribution of egg masses on plant were varied. Oviposition on leaf surfaces showed a clear preference on the abaxial leaf surface. To summarize, S. incertulas showed no oviposition preference to the six rice landraces tested in this study. The morphology of rice plants will affect the oviposition behaviour of S. incertulas.