Degree-Day Benchmarks for Sparganothis sulfureana (Lepidoptera: Tortricidae) Development in Cranberries.

Sparganothis sulfureana Clemens is a severe pest of cranberries in the Midwest and northeast United States. Timing for insecticide applications has relied primarily on calendar dates and pheromone trap-catch; however, abiotic conditions can vary greatly, rendering such methods unreliable as indicators of optimal treatment timing. Phenology models based on degree-day (DD) accrual represent a proven, superior approach to assessing the development of insect populations, particularly for larvae. Previous studies of S. sulfureana development showed that the lower and upper temperature thresholds for larval development were 10.0 and 29.9°C (49.9 and 85.8°F), respectively. We used these thresholds to generate DD accumulations specific to S. sulfureana, and then linked these DD accumulations to discrete biological events observed during S. sulfureana development in Wisconsin and New Jersey cranberries. Here, we provide the DDs associated with flight initiation, peak flight, flight termination, adult life span, preovipositional period, ovipositional period, and egg hatch. These DD accumulations represent key developmental benchmarks, allowing for the creation of a phenology model that facilitates wiser management of S. sulfureana in the cranberry system.