Atmospheric Trajectory Analysis to Project Long-Range Migration of Black Cutworm (Lepidoptera: Noctuidae) Adults

The black cutworm, Agrotis ipsilon (Hufnagel), larva is a pest of seedling corn in the Midwest. Adults migrate from the south during the spring. Determination of their arrival date is critical to anticipate accurately the time of appearance of larvae in the field. A simplified and easily applied procedure called the moth influx potential (MIP) system was developed to project black cutworm moth movement. The procedure uses National Weather Service atmospheric trajectory forecasts in a backtracking trajectory strategy that projects moth movement from source regions estimated by soil temperature analysis. The MIP system was tested for its ability to determine nights of introduction of A. ipsilon moths into central Iowa; estimates were compared with numbers of adult males captured in traps baited with synthetic sex pheromone. Pooled data from 5 yr (1978-1981 and 1983) were used for these comparisons. Regression analysis revealed a significant (P < 0.01) but weak correlation (r = 0.210) between square-root transformations of daily MIPs and trap captures. The correlation of 4-d (r = 0.292), 5-d (r = 0.311), 6-d (r = 0.366), and 7-d averages (r = 0.369) of MIP and trap captures increased sequentially. Significant linear (r = 0.400) and quadratic trends (r = 0.366) were also detected between calendar week and trap captures. Stepwise regression of 7-d MIP and time variables provided a model for predicting trap captures.