Wood consumption by Formosan subterranean termites (Isoptera: Rhinotermitidae) as affected by wood moisture and temperature

The relationship between the moisture content (MC) of wood blocks and the feeding preference of Coptotermes formosanus Shiraki at three ambient temperatures 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 of C. formosanus, the highest consumption was found in the high MC wood blocks at all three temperatures, although high MC wood block consumption at 19°C was significantly lower than at 28°C or 35°C. C. formosanus showed the preference for high MC wood blocks within the first few hours and continued to feed on the same wood blocks. In no-choice tests also the highest wood consumption was obtained in the high MC wood blocks at all the temperatures. However, in no-choice tests, significant mortality was observed with termites exposed to dry and low MC wood blocks; termite mortality was higher with higher ambient temperature. Wood block with MC at or below 24% was not found to have a sustained feeding in both choice and no-choice tests. Below 24% wood moisture, the free water in the cell cavities is absent which perhaps significantly influenced feeding. Temperature played a vital and complementary role for wood consumption at all moisture levels.