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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 simple linear, cubic, and Lactin nonlinear development functions. These models isolated the lower temperature threshold at which growth became nonzero 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 be used to create a degree-day model of temperature-mediated S. sulfureana development. [ABSTRACT FROM AUTHOR]

We evaluated mortality of Sparganothis sulfureana (Clemens) caused by exposing submerged insects to hypoxic (low oxygen) conditions. Taking advantage of the harvest flood in New Jersey, we measured changes in dissolved oxygen (DO) in a cranberry bog and the mortality of first-instar larvae submerged for 1 d. The DO in floodwater rose to 9.2 ppm during the day, dropped during the night to 7.1 ppm at sunrise, and increased again during the morning. Larval mortality was 3.5 ± 2,1%. In the laboratory, we evaluated the effect of submerging first-instar larvae in water at different DO for 1 d. Larval mortality was similar in all treatments but tended to increase with submergence in water with low DO. When first-through third-instar larvae were submerged in water at 15°C and 6.1 ppm DO for different periods of time, their mortality increased with longer submergence. Although long submergence (9 d) caused substantial mortality of S. sulfureana larvae, especially second and third instars, we conclude that a flood of similar duration will likely not be used because if applied to nondormant vines it could potentially impact the cranberry plant. Two important cautions for future studies were identified: (1) mortality can be substantially overestimated if hypoxia-induced lethargy is mistaken for death and (2) the impact of hypoxia may be underestimated if delayed mortality after removal from the water is not considered. [ABSTRACT FROM AUTHOR]