Comparative toxicity of Mospilan, Kaiqi and Regent on the workers of the Formosan subterranean termite, Coptotermes formosanus (Isoptera: Rhinotermitidae)

Toxicities of commercial products of acetamiprid, imidacloprid and fipronil on the workers of Coptotermes formosanus Shiraki were compared with the toxic loam contact method, the chemical-dipping wood block method and the toxic loam pillar method. The results indicated that acetamiprid had significantly faster action on the workers than that of imidacloprid and fipronil (P < 0.05) but the lethal effect of fipronil on the workers was significantly better than acetamiprid and imidacloprid (P < 0.05) while no significant difference existed between acetamiprid and imidacloprid on the lethal effect (P < 0.05). The wood blocks treated by acetamiprid or imidacloprid at all concentrations tested exhibited stronger repellency on the workers but no repellency was observed for fipronil at the same concentrations tested. Acetamiprid, imidacloprid and fipronil applied in loam had greater effects on the tunneling behavior of C. formosanus. Among them, the effect of acetamiprid on the tunneling behavior of the workers was the largest and the fipronil was the least. The workers tunneled only 0.00 +/- 0.00, 1.17 +/- 0.76 and 3.50 +/- 0.00 cm long tunnels in the loam with 8.0 mg/kg of acetamiprid, or imidacloprid and fipronil at 8 days after treatment, respectively. These results suggest acetamiprid might be a potential termiticide.