HORTICULTURAL ENTOMOLOGY Degree-Day Benchmarks for Sparganothis sulfureana (Lepidoptera: Tortricidae) Development in Cranberries ANNIE E. DEUTSCH, 1 CESAR R. RODRIGUEZ-SAONA, 2 VERA KYRYCZENKO-ROTH, 2 JAYNE SOJKA, 3 JUAN E. ZALAPA, 4 AND SHAWN A. STEFFAN 1,4,5 J. Econ. Entomol. 107(6): 2130Ð2136 (2014); DOI: http://dx.doi.org/10.1603/EC14261 ABSTRACT 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 unre- liable 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 speciÞc to S. sulfureana, and then linked these DD accu- mulations to discrete biological events observed during S. sulfureana development in Wisconsin and New Jersey cranberries. Here, we provide the DDs associated with ßight initiation, peak ßight, ßight 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. KEY WORDS cranberry IPM, degree-day, developmental model, phenology, sparganothis fruit- worm In agricultural systems, timing of pesticide applica- tions is important for successful management of crop pests. In Wisconsin (WI) cranberries, Sparganothis sulfureana Clemens (Lepidoptera: Tortricidae) is a perennial pest that often requires insecticide applica- tions to keep its population in check. Currently, this insect is also a major pest for Massachusetts and New Jersey (NJ) cranberry growers, and has been found in economically damaging numbers in all North Ameri- can cranberry-growing regions except Washington and Oregon (Patten and Daniels 2014). S. sulfureana is native to North America and feeds on a variety of plant species, including those in the Vac- cinium genus, such as the American cranberry, V. macrocarpon Aiton (Chapman and Lienk 1971, Eck 1990). Overwintered Þrst-instar larvae emerge from the bog ßoor as temperatures warm in the spring, and the young larvae feed on foliage (Chapman and Lienk 1971). Adults emerge in early summer and deposit egg clusters on cranberry leaves (Beckwith 1938). These second-generation larvae soon emerge and feed on leaves, fruit, or both. Direct injuries to young fruit make the second-generation larvae particularly det- rimental to crop yield. Additionally, these larvae are protected from insecticides while feeding inside the fruit, so it is difÞcult to treat for them once they have hatched and begun to feed. It is important, there- fore, to either target the Þrst-generation larvae when they are emerging from diapause in spring, or to ac- curately time midsummer sprays to treat for second- generation larvae. Because insects are poikilothermic, their develop- ment is constrained by ambient temperatures; thus, temperature-based development models are an effec- tive way to predict their development. These models often identify the temperature at which insect devel- opment begins (the lower threshold) and the tem- perature which results in maximum growth (the upper threshold; e.g., Wagner et al. 1984). Many of these models also allow for the calculation of heat units, or degree-days (DDs), to track and predict insect de- velopment. Previous work has shown that S. sulfureana larvae have a lower developmental threshold of 10.0C (49.9F) and an upper developmental threshold of 29.9C (85.8F; Deutsch et al. 2015). By using these thresholds, we can determine DD accumulations spe- ciÞc to S. sulfureana activity and more accurately pre- dict its growth. The objective of our study was to determine the number of DDs needed for S. sulfureana ßight initia- tion, peak ßight, ßight termination, adult life span, preovipositional period, ovipositional period, and egg 1 Department of Entomology, University of Wisconsin, Madison, WI 53706. 2 Department of Entomology, Rutgers University, P.E. Marucci Center for Blueberry and Cranberry Research and Extension, 125A Lake Oswego Rd., Chatsworth, NJ 08019. 3 Lady Bug IPM, Pittsville, WI 54466. 4 USDAÐARS Vegetable Crops Research Unit, Madison, WI 53706. 5 Corresponding author, e-mail: steffan@entomology.wisc.edu.