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Temperature-mediated development thresholds of Sparganothis sulfureana (Lepidoptera: Tortricidae) in cranberries
- Deutsch, Annie E., Rodriguez-Saona, Cesar R., Zalapa, Juan E., Steffan, Shawn A.
- Environmental entomology 2015 v.44 no.2 pp. 400-405
- Sparganothis sulfureana, cranberries, growing season, heat sums, insect development, insect growth, insect larvae, larval development, models, rearing, temperature
- Larvae of Sparganothis sulfureana Clemens, frequently attack cranberries, often resulting in economic damage to the crop. Because temperature dictates insect growth rate, development can be accurately estimated based on daily temperature measurements. To better predict S. sulfureana development across the growing season, we investigated the temperature range within which S. sulfureana larvae can feed and grow. Larvae were reared at 13 constant temperatures ranging from 6.5-38.6°C. Larval growth rate was determined by the rate of change of larval weight across time. The respective growth rates among these temperatures were modeled using a linear, cubic, and Lactin nonlinear development functions. These models isolated the lower temperature threshold at which growth became non-zero and the upper temperature at which growth was maximized. All three models were significantly predictive of S. sulfureana growth, but the cubic model best represented the observed growth rates, effectively isolating lower and upper thresholds of 9.97 and 29.89°C, respectively. We propose that these thresholds should be used to create a degree-day model of temperature-mediated S. sulfureana development.