Climatic limitations to the overwintering survival of Dectes texanus larvae in soybean

Soybean stem borers, Dectes texanus Le Conte, can cause serious damage to soybean, either through physiological yield losses or by lodging soybean plants late in the season, which often renders these plants unharvestable. For the past few decades, D. texanus has been found infesting soybean fields throughout western to central Kansas as well as other parts of the central, eastern and southern US. However, reasons for its expansion and successful colonization of soybean and factors contributing to seasonal variability in infestation rates are still under investigation. With significant increases in conservation tillage practices, potential impacts of freezing temperatures on overwintering life stages, and increased host availability, our goal was to identify key factors driving D. texanus overwintering survival in Kansas and other parts of the North Central US. The objective of this study was to assess the cold hardiness of D. texanus larvae collected from soybean and identify potential physiological mechanisms for freeze avoidance. Effect of freezing temperatures on D. texanus larval survival, results from acclimation experiments, and the interaction between subzero temperatures and host plant (e.g., soybean, sunflower, cocklebur) will be discussed.