Studies on the Relationship between Occurrence Degree of Cotton Bollworm and Rainfall

[Objective] The aim of the study is to investigate the factors causing the outbreak of cotton bollworm and to provide effective measures for controlling cotton bollworm. [Method] Based on the analysis of the data about insect and weather situation in Luyi County in 32 years,the meteorological prediction model was established for monitoring the quarterly or monthly occurrence trend of cotton bollworm. [Result] The cotton bollworm occurred slightly in the years with rainfalls of 3 months over 500 nm and severely in the years with rainfalls of 3 months less than 400 nm. The results of correlation analysis show that annual occurrence degrees of cotton bollworm and occurrence degrees of 4th generation of cotton bollworm are extremely negatively correlated with rainfall during June-August; the occurrence degrees of 3rd and 4th generations of cotton bollworm are also extremely negatively correlated with rainfall in July. [Conclusion] The occurrence of cotton bollworm in field is heavily influenced by rainfall in at its occurrence stage,moreover,the rainfall during June-August is the decisive factors influencing the occurrence of cotton bollworm.