Impact of sand moisture level on food consumption and distribution of Formosan subterranean termites with different soldier percentage

ABSTRACT Formosan subterranean termites, Coptotermes formosanus Shiraki were tested under laboratory conditions to determine whether preferential differences exist among different sand moisture levels. Foraging behavior, rate of filter paper consumption and distribution patterns of the termites were studied among three different soldier ratios: low (4% soldier), normal (16% soldier) and high (32% soldier) and 8 sand moisture gradients (0, 4, 8, 12, 16, 20, 24 and 28% by weight) in a circular three dimensional arena. The results showed that sand moisture had a significant effect on distribution and filter paper consumption but not soldier proportions. There were no significant differences in distribution or consumption among moisture levels ranging from 4 to 24%. However, significant differences were obtained when these moisture levels were compared with either dry sand (0% moisture) or saturated sand (28% moisture). Generally, termites would not locate themselves in dry or saturated sand chambers. More than 60% of the total released termites were aggregated in one of the 6 moisture chambers. Importantly, amongst the replicates no particular moisture chamber was chosen for aggregation indicating that Formosan subterranean termites can adapt to a wide range of substrate moisture in nature. Filter paper consumption generally corresponded with aggregation sites. Aggregation patterns and behavioral adaptation of termites like transferring moisture to drier areas are discussed.