Title: Low temperature in the hemlock woolly adelgid system
Author: Costa, Scott D.; Trotter, R. Talbot; Montgomery, Michael; Fortney, Michael.
Source: In: Onken, Brad; Reardon, Richard, comps. Fourth Symposium on hemlock woolly adelgid in the eastern United States; 2008 February 12-14; Hartford, CT. FHTET 2008-01. Morgantown, WV: U.S. Forest Service, Forest Health Technology Enterprise Team: 47-52.
Description: Hemlock woolly adelgid (HWA) vary in their susceptibility to temperatures considerably below freezing. Many individuals may die by -20°C (-4°F), but more cold-tolerant individuals will allow populations to persist. Managers wanting to gauge temperature impacts on future adelgid pressure to hemlock forests may benefit from using available daily records of minimum low temperatures. More robust data on adelgid temperature response will enhance development of models/tools to assist in their forecasts. Exotic predators being released to suppress adelgid populations (Sasajiscymnus tsugae, Scymnus sinuanodulus, Scymnus ningshanensis, and Laricobius nigrinus) may be slightly less cold-tolerant than the adelgid, but the cold-tolerance does not appear to be affected by feeding. These predators are able to feed at near 0oC temperatures. In areas with relatively cold climates, the low winter temperature and the four predators tested could work together to regulate HWA populations.
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Costa, Scott D.; Trotter, R. Talbot; Montgomery, Michael; Fortney, Michael. 2008. Low temperature in the hemlock woolly adelgid system. In: Onken, Brad; Reardon, Richard, comps. Fourth Symposium on hemlock woolly adelgid in the eastern United States; 2008 February 12-14; Hartford, CT. FHTET 2008-01. Morgantown, WV: U.S. Forest Service, Forest Health Technology Enterprise Team: 47-52.
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