Doctor of Philosophy (PhD)
The Formosan subterranean termite is an important structural pest in the southern United States, especially Louisiana. Baiting systems and spot treatment with non-repellent delayed action termiticides are among the most eco-friendly control approaches. However, to achieve a desired success from these approaches requires a sophisticated knowledge of foraging behavior and food transfer system of these social insects. Moisture and temperature play a vital role in influencing the foraging behavior of these desiccation prone insects. A series of laboratory experiments were conducted to understand the subtleties of foraging behavior of Coptotermes formosanus Shiraki in relation to moisture, relative humidity and temperature. Foraging behavior, food consumption and distribution pattern were studied in a suitably designed sand moisture gradient arena. Results showed that C. formosanus can adapt to a wide range of sand moisture levels but not in dry and saturated sand. Next, termites were studied to determine how combinations of various food moisture and temperature levels impact their foraging behavior. C. formosanus was unable to maintain sustained feeding when the wood moisture was lower than the fiber saturation point (~ 25% wt/wt). In the absence of moist soil, C. formosanus always preferred the highest moisture wood with the optimum feeding and survival obtained at 28°C. Relative humidity and temperature mainly determine the water loss from an organism. Soldiers and workers of C. formosanus, which are extremely prone to desiccation, were exposed to various temperature and relative humidity conditions to determine their survival. Even the near saturated relative humidity (~99%) level was not sufficient to keep them from desiccating, indicating that a continuous supply of moisture either from moist substrate or food is required for their normal survival. Likewise, impact of food source disturbance on termites’ escape behavior was studied with wet versus dry sand conditions in the periphery of the food source, and its implications for termite baiting is discussed. Finally, exploratory tunneling behavior was examined in different substrates in different moisture and temperature situations. With the same moisture level, sand was found to be the preferred substrate for aggregation and tunnel construction to sandy loam and loam.
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Gautam, Bal Krishna, "Role of substrate moisture, relative humidity and temperature on survival and foraging behavior of Formosan subterranean termites" (2011). LSU Doctoral Dissertations. 3213.