Relationship between western bean cutworm (Striacosta albicosta) infestation, damage and yield reduction of field corn in three ecozones in Nebraska State

Western Bean Cutworm (WBC) is a native pest of dry beans and corn in the west-central part of United States. In the beginning of 2000, outbreaks of WBC have been registering with more frequency in the entire north central of the United States and Canada. Studies of the relationship between larval density and dent stage corn detected a yield reduction of 3.7 bu/acre at an infestation of 1 larvae /ear. However, more information is necessary in order to refine the Economic Injury Levels (EILs) and Economic Thresholds (ETs) in field corn. This experimental was conducted at three locations representing different ecozones at University of Nebraska facilities (Concord; Clay Center; and Scottsbluff) in order to determine the relationships between WBC infestation, injury, and yield in corn field in the three ecozones. The experimental design was a random complete block with four replications. The artificial infestation was done with egg masses removing from commercial cornfields and the range of egg mass infestation was 0, 1, 3, 5 and 10% of the plants. The success of infestation was estimated by counting the number of unhatched eggs. At harvest,the amount of injury (square cm of grain surface with WBC injury/ear), number of ears/plot with injury, grain moisture, and grain yield was recorded. The results indicate significant differences in egg survival WBC injury, and grain yield as a function of different levels of infestation and different ecozones across Nebraska.