Wood Consumption by Formosan Subterranean Termites (Isoptera: Rhinotermitidae) as Affected by Wood Moisture Content and Temperature

Understanding foraging behaviors and food preferences of termite colonies is critical to optimizing control strategies. The relationship between the moisture content (MC) of wood blocks and the feeding preference of Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae) at three ambient temperatures (19, 28, and 35 degrees C) was investigated with multiple-choice as well as no-choice feeding bioassays. In multiple-choice tests, when four wood blocks with initial MC as dry (0-3%), low MC (22-24%), medium MC (70-90%), and high MC (125-150%) were exposed to workers and soldiers, the highest consumption was found in the high MC wood blocks at all three temperatures, although high MC wood consumption at 19 degrees C was significantly lower than that at 28 or 35 degrees C. The preference for high MC wood blocks was detectable within the first few hours and continued for the duration of the test. In no-choice tests, the highest wood consumption also was obtained on the high MC wood blocks at all three temperatures. However, in no-choice tests, significant mortality was observed with termites exposed to dry or low MC wood blocks. Termite mortality was found to be higher with higher ambient temperature. Sustained feeding was not observed on wood blocks with <= 24% MC. When wood moisture is low, no free water exists in the cell cavities, which perhaps influenced feeding choices. Temperature played a vital and complementary role for wood consumption at all moisture levels.