Abstract: In August of 2007 and 2008, a field investigation was made to study the relationships among Cyrtotrachelus buqueti larval density and wormhole number and bamboo shoot damage degree in Sichuan Province. The three pairs of variables, i.e., C. buqueti larval density and wormhole number, C. buqueti larval density and bamboo shoot damage degree, and C. buqueti wormhole number and bamboo shoot damage degree, fitted cubic equations well, with the correlation coefficients at P=0001. Based on these mathematical models, the forecast tables for C. buqueti larval density and bamboo shoot damage degree were established, and the thresholds of C. buqueti larval density and wormhole number were 013 and 040 individual per bamboo, respectively.

Key words: Cyrtotrachelus buqueti, larval density, wormhole number, damage degree, mathematical model, intercropping system, maize, phosphorus,  , dry matter accumulation, yield, phosphorus use efficiency.