The why, where, and when of cereal leaf beetle (Oulema melanopus L.)

Because of the difficulty in predicting when and where cereal leaf beetle outbreaks will occur many growers in the Southeast apply insecticides on a calendar basis rather than using a threshold-based IPM approach. Our challenge is to develop new information and procedures that will encourage growers to reevaluate the way they are approaching spring-time insect control in wheat, and consider adoption of the IPM approach. Using small plot trials in 2010 and 2011, we found that a number of t insecticides were effective at controlling CLB when applied at the right time. We also found that an IPM approach was more effective at controlling CLB than an automatic application. In addition, large scale surveys indicated that CLB was not randomly distributed on a field and regional scale. Finally, degree day information was used to create a predictive model for when peak CLB egg laying will occur. This model was used to predict the average calendar date of peak eggs for each population as well as for the average of all populations. In 2010 and 2011, the model predicted the average egg peak within 2 days and 1 day, respectively. Larval peaks occurred approximately 16 days after egg peak in 2010 and 17 days after egg peak in 2011. Given the accuracy of 182 DD, historical weather information was used to create a predictive map of when areas will exceed 182DD. This map predicted the calendar date for each area in Virginia within 4 days.