Formosan Subterranean Termite (Isoptera: Rhinotermitidae) Wood Consumption and Worker Survival as Affected by Temperature and Soldier Proportion

Abstract

The effect of temperature and soldier proportion on worker survival, soldier production, and wood consumption of the Formosan subterranean termite, Coptotermes formosanus Shiraki, was evaluated in the laboratory with termites from a single colony. Soldier production was influenced by temperature and the initial proportion of soldiers. On average, termites had a significantly higher survival rate when the initial soldier proportion was <20%. Soldier caste development was at its highest at 30°C, and when treatment started with no soldiers in the colony. Termite survival was significantly higher at 30°C than at 25 and 33°C after 12 d of testing. There was a significant interaction of temperature and soldier proportion on termite survival after 36 d. C. formosanus could support higher proportions of soldiers with an increase in temperature. There was no significant decrease in survival rates with increasing numbers of soldiers at 25 and 33°C. At 60 d, survival at 20 and 25°C declined significantly when soldier proportions exceeded 20%. At 30 and 33°C, termite survival did not decline significantly when soldier proportions increased from 20 to 30% (30°C) or 40% (33°C). Consumption rates increased significantly with rising temperature up to 30°C. Consumption rates tended to increase as soldier proportion increased. There was no significant interaction between temperature and soldier proportion on wood consumption rate.