Predicting oviposition by corn earworm (H. zea) in sweet corn with pheromone traps

Pest managers currently apply insecticides to sweet corn for control of Helicoverpa zea (Boddie) when fresh silks are present and 10 or more moths are caught in a pheromone trap. This study has three major objectives. First, determine the relationship between catches of male H.zea moths in pheromone traps with oviposition and subsequent larval damage to ears of sweet corn. Secondly, determine how environmental conditions such as temperature, wind speed, relative humidity, and rainfall affect pheromone trap catches and oviposition on sweet corn ears. Finally, determine how the stage of development of field corn grown in the immediate vicinity affects the level of oviposition in sweet corn. Linear regression, used to compare the relationship between trap catch and oviposition, yielded low correlation values at four locations over two years. Multiple regression and best model selection were used to attempt to explain the lack of correlation between trap catch and oviposition. These tests took into account several variables, but ultimately showed no significant relationship or successful predictive model. The most important variable identified is the maturity of surrounding field corn. When field corn was in an attractive stage (green silks present), the damage in sweet corn plots significantly decreased. When field corn had completely matured and was no longer in an attractive stage, oviposition and damage in the sweet corn increased.