The frigid temperatures that gripped Iowa dur­ing the past winter knocked out some yield-robbing insects but had little impact on others, university experts said as they look ahead to the 2014 growing season.

Predicted mortality rates of bean leaf beetle in Iowa are the highest in 25 years, ranging from 89 to 99 percent, said Iowa State University (ISU) entomologist Erin Hodgson. The bitter cold also likely contributed to an increase in mortality of corn rootworm eggs. However, experts predict soybean cyst nematode (SCN) will still threaten yields this year.

Most bean leaf beetle adults won’t survive when air temperatures fall below 14 degrees, although they have adapted to winter by seeking cover under plant debris and loose soil, Hodgson said. A university model predicts bean leaf beetle mortality at more than 99 percent north of Interstate 80, she said. The average mortality rate in central...