Point of No Return From Water Loss in Coptotermes formosanus (Isoptera: Rhinotermitidae)

Describing desiccation stages based on the physical appearance of termites has not been evaluated previously. Formosan subterranean termites were studied to determine the rate of water loss, singly and in groups, in the laboratory. The stages of water loss are described based on changes in physical appearance and percent total body water loss evaluated at 2- to 8-h time intervals up to 32 h. Workers in groups lost water slower than individual worker trials. Weight loss was linear over time for worker groups and individuals, as was individual soldier only trials. Water loss in individual workers was significantly faster than in soldiers. Three physical stages of desiccation are described for living workers: (I) curling of antennae, (II) on back but with assistance able to right themselves and walk, and (III) unable to get off back; and two stages for living soldiers (II and III). Recovery was determined from termites in a second trial by transferring stage I, II, and III individuals from open, dry Petri dishes to those with moist filter paper at 4, 6, 10, 12, 14, 16, 24, 26 and 28 h. After 12 h on moist filter paper, stage I workers had a 83% recovery rate, stage II had a 33%, and stage III had a 7% recovery. Soldiers had a 56% recovery at stage II and was similar to the recovery of workers at stage III. Most termites that reached stage III were destined to die.