Cold hardiness of the corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae)

Corn earworm is an increasingly pervasive pest of sweet corn in the Midwestern U.S. While it is currently assumed to not overwinter north of the 40^th latitude, many questions remain regarding its response to low temperatures (cold hardiness) and potential to expand its overwintering range. Since the magnitude of insect infestations can be positively correlated with overwintering survival, understanding the cold hardiness of an insect could greatly enhance the ability to forecast the timing and magnitude of pest infestations. The objective of this study was to measure the cold hardiness of the overwintering stage of corn earworm (pupa) using the laboratory methods of supercooling point, lower lethal temperature, and lower lethal time. The effects of sex, preconditioning, and diapause on low temperature survival were also assessed. In addition to providing a more effective management strategy for growers, the data generated can also be applied to models within the context of climate change.