Previous studies showed that many wood-rotting fungi were attractive to termites; however, little attention has been paid to the relationship between termites and soil fungus. In the present study, different designs of two-choice tests were conducted to investigate the behaviors of two subterranean termites, Coptotermes formosanus Shiraki (wood-feeding lower termites) and Odontotermes formosanus (Shiraki) (fungus-growing higher termites), in response to soil (or sand) treated with the commercial conidial formulations of Trichoderma harzianum Rifai (BioWorks) and Trichoderma viride Pers. ex Fries (Shuiguxin). The short-term (1 d) choice tests showed no significant difference in termite aggregation (C. formosanus and O. formosanus) between treated and untreated soil, regardless of Trichoderma species and concentrations. However, in the long-term choice tests, C. formosanus consumed significantly more wood in the chambers containing soil treated with the conidial formulation of T. viride (1 × 10⁸ conidia/g) than that containing untreated soil. The tunneling choice tests showed that sand treated with T. viride (1 × 10⁶ or 1 × 10⁸ conidia/g) or T. harzianum (1 × 10⁶ conidia/g) significantly increased the tunneling activities of C. formosanus. However, sand treated with T. viride (1 × 10⁶ or 1 × 10⁸ conidia/g) had a repellent effect on O. formosanus. Our study showed that the two subterranean termites behaved differently when responding to the conidial formulations of Trichoderma.

The food-burying behavior has been reported in many mammals and birds, but was rarely observed in invertebrates. The red imported fire ants, Solenopsis invicta Buren, is an invasive pest in many areas of the world that usually performing food-burying during the foraging processes. However, the impacted factors and measureable patterns of this behavior is largely unknown. In the present study, food-burying vs food-transport behaviors of Solenopsis invicta were observed under laboratory and field conditions. When starved (no food was provided for 37 days) in the laboratory, food (sausage) was consumed by large numbers of ants, and few burying behaviors were observed. However, when food was provided until satiation of the colonies, food-transport was suppressed and significantly more soil particles were relocated on the food and graph paper square (where the food was placed) when compared with these colonies exposed to starved conditions. Videotapes showed that soil particles (1.47 ± 0.09 mm²) were preferentially placed adjacent to (in contact with) the food items at the beginning; and after the edges were covered, ants transported significantly smaller soil particles (1.13 ± 0.06 mm²) to cover the food. Meanwhile, larger particles (1.96 ± 0.08 mm²) were pulled/dragged around (but not in contact with) the food. Interestingly, only a small number of ants, mainly the small workers, were involved in food-burying, and the ants tended to repeatedly transport soil particles. A total of 12 patterns of particle transport were identified, and soil particles were most frequently picked from the foraging arena and subsequently placed adjacent to the food. In the field, almost all released food was actively transported by Solenopsis invicta workers, and no burying behavior was observed. Our results show that the food-burying behavior of Solenopsis invicta may be associated with the suppressed foraging activity, and the burying task may be carried out by certain groups of workers.