Interactions between the striped stem borer Chilo suppressalis (Walk.) (Lep., Pyralidae) larvae and rice plants in response to nitrogen fertilization

Abstract

A screenhouse experiment was conducted to examine the damage and compensation in rice plants when injured by the striped stem borer, Chilo suppressalis (Walker), larvae at tillering stage, as well as larval survival and development of the insect at different nitrogen (N) fertilization levels. Potted plants were fertilized at late seedling stage at the rates 0, 200, 400, 600 and 800 mgN/pot, respectively. More deadheads were caused as fertilization increased. Plants compensated well for injury at the fertilization concentrations of 200 and 400 mgN/pot by producing new tillers, but such compensation did not take place at 600 and 800 mgN/pot. Two weeks after infestation, the highest number of remaining healthy tillers was found in plants fertilized at 400 mgN/pot. Larval survival varied little among the treatments 200 to 800 mgN/pot. Larval weight attainment and/or developmental rate increased with increasing fertilization level from 200 to 600 mgN/pot, but both declined rapidly as fertilization reached 800 mgN/pot, indicating the great dependence of plant suitability on N fertilization levels. Conclusively, both the compensation response of rice plants and their suitability for C. suppressalis larvae could be significantly affected by N fertilization levels.