Relative Humidity Preference and Survival of Starved Formosan Subterranean Termites (Isoptera: Rhinotermitidae) at Various Temperature and Relative Humidity Conditions

• Published in: Environmental entomology Vol. 40; no. 5; pp. 1232 - 1238
• Main Authors: Gautam, Bal K, Henderson, Gregg
• Format: Journal Article
• Language: English
• Published: England Entomological Society of America 01.10.2011
• Subjects: Animals; containers; Coptotermes formosanus; foraging; Humidity; Isoptera - physiology; mortality; relative humidity; silica gel; Starvation; subterranean termites; Survival Analysis; Temperature
• ISSN: 0046-225X; 1938-2936
• DOI: 10.1603/en11062

Foraging groups of Formosan subterranean termites, Coptotermes formosanus Shiraki were tested for their relative humidity (RH) preference in a humidity gradient arena in the laboratory at a constant temperature of 26°G Five RH levels (9%, 33%, 53%, 75%, and 98%) were maintained in the test arena comprising of a series of closed containers by using dry silica gel, saturated salt solutions, or distilled water alone. Termites gradually aggregated to the highest RH chamber in the arena. After 1h, a significantly greater percentage of termites (approximately equal to 46%) aggregated to the highest RH chamber (98%) than to the lower RH chambers (≤75%). After 12 h, > 97% of the termites aggregated to the 98% RH chamber. In survival tests, where termites were exposed to 15 combinatorial treatments of five RH levels (9%, 33%, 53%, 75%, and 98%) and three temperatures (20°C, 28°C, and 36°C) for a week, the survival was significantly influenced by RH, temperature, and their interaction. A significantly higher mortality was observed on termites exposed to less than 75% RH chambers than to 98% RH chamber at the three temperatures and significantly lower survival was found at 36°C than at 28°C or 20°C. The combination of temperature and RH plays an important role in the survival of C. formosanus.